From: Andre Noll Date: Sun, 13 Dec 2015 14:16:27 +0000 (+0100) Subject: Convert manual and NEWS from grutatxt to markdown. X-Git-Tag: v0.5.6~36^2 X-Git-Url: http://git.tue.mpg.de/?a=commitdiff_plain;h=a2c5e36;p=paraslash.git Convert manual and NEWS from grutatxt to markdown. Grutatext still works but the project seems to be dead, so we have to switch to something else eventually. This patch converts the two grutatext documents in the tree to the markdown language, getting rid of the dependency on grutatext at the expense of a new dependency on the markdown executable. Only the discount markdown converter has been tested and is known to work. The commit also changes the "Tools" section of the manual to list discount instead of grutatext. --- diff --git a/NEWS b/NEWS deleted file mode 100644 index a5bef9f6..00000000 --- a/NEWS +++ /dev/null @@ -1,1273 +0,0 @@ -NEWS -==== - ------------------------------------------- -current master branch "cascading gradient" ------------------------------------------- - - - para_afh learned to modify meta tags of mp3 wma ogg spx - opus flac aac files. - - afs commands propagate error codes to the client. - - The check command now also checks the attribute table for - inconsistencies. - - New -v flag for the version command (print verbose version string) - - New option --priority for para_server and para_audiod. - - --------------------------------------- -0.5.5 (2015-09-20) "magnetic momentum" --------------------------------------- - -Many new features and a lot of other improvements. - - - On Linux systems, local sockets are now created in the - abstract name space by default. This allows to get rid of - the socket specials in /var/paraslash. - - The --user-allow option of para_audiod now accepts also - usernames rather than only user IDs. - - New autoconf macros to avoid duplication in configure.ac. - - Status items (as shown by para_gui) are updated correctly - when the meta information of the current audio changes. - - para_server and para_audiod no longer refuse to start in - the background if no log file is given. Instead, all log - messages go to /dev/null in this case. - - Web page cleanup. - - New syntax for the -l and -s options of the ls command. - These options should now be specified as -l=v rather than - -lv, for example. The old syntax still works, but support - will be dropped in v0.6.0. - -Download: ./releases/paraslash-0.5.5.tar.bz2 (tarball) -./releases/paraslash-0.5.5.tar.bz2.asc (signature) - ------------------------------------------- -0.5.4 (2015-01-23) "exponential alignment" ------------------------------------------- - -Another cleanup and bugfix release. - - - New server command: tasks. - - Minor cleanups to daemon.c. - - New URLs for home page and git services. - - Improved error diagnostics for the mvblob commands. - - New sender subcommand: status. - - Improved help text for server and afs commands. - - audiod memory leak fixes. - - Miscellaneous improvements to the build system. - - oss_writer improvements. - - Improved handling of mp3 files with both id3v1 and id3v2 tags. - -Downloads: ./releases/paraslash-0.5.4.tar.bz2 (tarball) -./releases/paraslash-0.5.4.tar.bz2.asc (signature) - ---------------------------------------------- -0.5.3 (2014-08-01) "symbolic synchronization" ---------------------------------------------- - -Not many new features, but lots of fixes and usability improvements. - - - para_gui has been converted to use the paraslash scheduler. - - Various alsa-related fixes, mostly for the raspberry pi. - - Many scheduler improvements and cleanups. - - The test suite has been extended to include sanity checks - for the generated man pages. - - ao_writer fixes. This writer was in a quite bad shape. Many - serious bugs have been fixed. - - new audiod command: version. - - Minor improvements to the bitstream API. - - The cpsi command now prints a meaningful error message if - none of the given patterns matched any audio file. - -Downloads: ./releases/paraslash-0.5.3.tar.bz2 (tarball), -./releases/paraslash-0.5.3.tar.bz2.asc (signature) - ----------------------------------------- -0.5.2 (2014-04-11) "orthogonal interior" ----------------------------------------- - -The new sync filter, the AES_CTR128 stream cipher and the overhauled -network code are the highlights of this release. It also includes a -fair number of smaller fixes and improvements not mentioned here. - - - The new sync filter synchronizes playback between multiple - clients. - - Connections between para_server and para_client are now - encrypted by means of AES rather than RC4 if both sides - support it. RC4 is still available as a fallback. This - feature is fully transparent, i.e. no command line options - are necessary, and a client linked against openssl can - speak with a server linked against libgcrypt and vice versa. - - Major cleanup of the networking subsystem. - - Improvements to para_fade: the new set mode, multi-channel - initial volumes, better error logging. - - The man pages of para_audiod, para_filter, para_recv, and - para_write contain the relevant options for receivers, filters, - writers. This broke in 0.5.0. - - ogg/vorbis latency improvements. - - Improved user manual. - - Minor fixes to avoid clang warnings. - -Downloads: ./releases/paraslash-0.5.2.tar.bz2 (tarball), -./releases/paraslash-0.5.2.tar.bz2.asc (signature) - ------------------------------------------- -0.5.1 (2013-12-20) "temporary implication" ------------------------------------------- - -Lots of fixes and improvements all over the place, and a major overhaul -of the build system. - - - Audiod improvements and fixes. - - Buffer tree robustness improvements. - - Cleanup of the mood subsystem. - - Fixes and cleanups for the flac decoder. - - Latency improvements for the ogg/opus decoder. - - Crypto support is now optional. On systems without - openssl/gcrypt, the build succeeds but para_server, - para_audiod, para_client won't be built. - - The build system now works for cross-compile setups. - - The dependency tree has been flattened, which speeds up - builds and avoids to recreate the man pages on every change. - - The error code helper has been rewritten from perl to C, - which further improves build time. - - Many small bugs in the build system have been identified - and fixed. - -Downloads: ./releases/paraslash-0.5.1.tar.bz2 (tarball), -./releases/paraslash-0.5.1.tar.bz2.asc (signature) - ----------------------------------------- -0.5.0 (2013-08-23) "invertible validity" ----------------------------------------- - -Some API-breaking changes, one serious bug fix, and a lot of bike-shedding. - - - The sideband compatibility code has been removed, hence - sideband connections (introduced in 0.4.11) are now mandatory. - - Addblob commands can produce output. - - The stat command no longer sends garbage when para_server was - compiled against libgcrypt. - - Dependencies for gengetopt files are computed automatically. - This eliminates a constant source of build bugs. - - The setatt command now accepts file name patterns rather than only - path names. - - overview.pdf is now based on dia, a simple diagram creation program. - The new version is much more detailed and contains descriptions of - the various programs of the paraslash package. - - The separator of all multi-word options has been changed from - underscore to dash. For example --log_color becomes --log-color. - - Overhauled web pages and the new logo. - -Downloads: ./releases/paraslash-0.5.0.tar.bz2 (tarball), -./releases/paraslash-0.5.0.tar.bz2.asc (signature) - --------------------------------------- -0.4.13 (2013-07-29) "spectral gravity" --------------------------------------- - -One more 0.4.x release before the API-breaking changes for 0.5.0 go -in. The main features of this release are the ogg/opus audio format, -and UTF-8 support, but it includes also tons of other improvements -and fixes all over the place. - - - New audio format: ogg/opus. - - UTF8 support for para_gui and the mp3 audio format handler. - - Scheduler improvements and fixes. - - The obsolete gettimeofday() function has been replaced - by clock_gettime() on systems which support it. - - Speed and usability improvements for para_gui. - - para_client now restores the fd flags of stdin and stdout - on shutdown. - - Improved manual pages. - - Consistent version strings for all executables. - - Reduced dependencies on generated files result in fewer - recompilations on changes. - - Performance improvements for the compress filter. - - Improved downloads web page. - ------------------------------------------ -0.4.12 (2012-12-20) "volatile relativity" ------------------------------------------ -The new command line player, the resample filter, ALSA support for -para_fade, and the improved build system are the highlights of this -release which probably marks the end of the 0.4.x series. - - - The afh receiver and the para_play executable. - - The resample filter: A sample rate converter based on - libsamplerate. - - The "versions" directory has been removed from the master - branch. The tarballs of the old releases are now available - in the new "releases" branch. - - Overhaul of the build system: All generated files are now - written to the "build" directory. - - The modular mixer API and the alsa mixer. - - Minor fixes for the osx writer. - --------------------------------------- -0.4.11 (2012-07-20) "mutual diversity" --------------------------------------- - -The major feature in this release is the new sideband API for -client-server communication. This API will be used exclusively starting -with 0.5.0, which breaks backward compatibility but allows to get rid -of quite some compatibility code. Other noteworthy changes include -decoder latency improvements and a long-standing bug fix for the -ALSA writer. - - - Sideband connections: If both para_server and para_client - support this feature, data is sent as a multiplexed stream. - - The --no_default_filters option of para_filter has been - removed. - - Several fixes and latency improvements to various decoders. - - The ALSA writer now limits the prebuffer time to 500ms. - - Documentation improvements. - - Overhaul of the command_util.sh script. - - Fixes for some minor problems found by the clang analyzer. - - Compiles (almost) without warnings on gcc-3. - - Robustness improvements of the buffer tree code. - ------------------------------------------- -0.4.10 (2012-03-30) "heterogeneous vacuum" ------------------------------------------- - -Nothing earth-shaking in this release, but quite a few usability -improvements and the usual mix of cleanups and fixes. - - - The --no_default_filters option of para_filter has been - deprecated. It still works but has no effect and will be - removed in the next version. - - para_gui now prints also the stderr output of the executing - command in the bottom window. - - Cleanup and consolidation of the various wrappers for - write(), writev(), send() and friends. - - The obscure error messages on mmap() failures have been - replaced by meaningful messages. This affects mainly - para_afh. - - para_audioc: Cleanups and memory leak fixes. - - Test 0004-server no longer fails if para_server is not - being built. - - New configure options: --with-id3tag-{headers,libs}. - -------------------------------------- -0.4.9 (2011-12-06) "hybrid causality" -------------------------------------- - -Support for another audio format, interactive mode for para_client -and para_audiod and many small improvements/fixes all over the place. - - - Support for flac, the free lossless audio codec. - - Fix for an endless loop in the mp3 decoder for certain - (corrupt) mp3 files. - - When executed without specifying a command, para_client - and para_audioc start an interactive shell (requires - libreadline being installed). The interactive mode offers - full tab completion and command line history. - - autogen.sh now detects a distcc setup and adjusts the - parameter for the -j option of make accordingly. - - Shared memory areas are no longer restricted to 64K. We now - detect the maximal size of a shared memory area at runtime. - - cleanup of the internal uptime API. - - para_server prefaults the mmapped audio file to avoid - delays on slow media. - - A new test for the test-suite that exercises the - communication between para_server and para_audiod. - - The alsa writer eats up less CPU cycles when configured to - use the DMIX plugin. - - Simplified and unified receiver code. - - Makefile cleanups. - - Commands which print a list of matching audio files now - emit a meaningful error message if no audio file matched the - given pattern(s). - --------------------------------------- -0.4.8 (2011-08-19) "nested assignment" --------------------------------------- - -Gcrypt support, the overhauled osx writer and regex format specifiers -are the highlights of this release. - - - support for libgcrypt as a drop-in replacement for openssl. - Run configure --enable-cryptolib=gcrypt to link against - libgcrypt. The two crypto implementations are compatible to - each other, i.e. a para_client executable linked against - gcrypt can connect to para_server linked against libssl - and vice versa. - - Rewrite of the osx writer (output plugin for Mac OS). - - audiod: The format specifier for receivers, filters and - writers is now treated as a regular expression. This allows - to replace 5 lines in the config file (one for each audio - format) by one single line. See the manual for details. - - The *.cmdline.[ch] files are no longer contained in the released - tarballs. This reduces the size of the tarballs but requires - gengetopt to build the tarball. - - Compiles cleanly also with llvm/clang. - - Corrupt mp3 files are handled more gracefully. - - The alsa writer uses poll fds instead of computing timeouts. - - Cleanup of the generic writer API. - - sched: Optimized zero timeouts. - - vss timeout cleanups. - - oggdec fixes and improvements. - --------------------------------------- -0.4.7 (2011-06-01) "infinite rollback" --------------------------------------- - -The new ao writer, support for ssh RSA keys and a couple of other -enhancements. - - - Support for ESD, Pulseaudio, AIX, Solaris, IRIX and other - platforms through the libao audio library. - - Support for RSA keys generated with ssh-keygen. - - configure: improved options for ogg/vorbis/speex. - - The git version reported by --version always matches HEAD. - - The autogen script detects the number of processors and - runs a parallel make if possible. - - Major cleanup of the crypto API. - - Documentation updates. - ------------------------------------------- -0.4.6 (2011-03-31) "deterministic entropy" ------------------------------------------- - -Lots of ogg/vorbis improvements, the new test suite, enhancements -for para_gui and a fair amount of other bug fixes. - - - For DCCP/OGG streams the audio file header is only sent once - at the beginning of the stream rather than periodically - every five seconds. This reduces network traffic and the - FEC group size. - - The vorbis comment header is replaced by an empty dummy header - before the header is sent over the network. This also results in - less network traffic and smaller FEC groups. - - The new "test" make target allows to perform some sanity checks prior - to installing the package. - - ogg timing fixes and performance improvements - - Scheduler improvements - - Proper exit codes for para_write - - para_gui: New option --theme to select a startup theme. Several - other improvements and fixes. - - aacdec error message cleanups - - simplified color error handling - --------------------------------------------- -0.4.5 (2010-12-17) "symmetric randomization" --------------------------------------------- - -Bug fixes, internal cleanups and variable-sized FEC slices. - - - Contains a fix for an invalid-free-bug in the ogg audio format - handler code. - - Switching off the DCCP sender works again. - - para_audiod handles crashes of para_server more robustly. - - Internal scheduler and writer cleanups. - - Reduced latency due to variable-sized FEC slices. - - Improved documentation and error diagnostics. - - The build of para_server is now optional, allowing the build - to succeed in case libosl is not installed. - ------------------------------------------- -0.4.4 (2010-08-06) "persistent regularity" ------------------------------------------- - -Support for yet another audio format, para_write improvements and -bug fixes. - - - Support for the speex codec. - - Support for sample formats other than 16 bit little endian. - - error2.h is now created by a perl script which speeds up configure - considerably. - - Fix a bug in the aac decoder which could lead to segfaults in - para_filter/para_audiod. - - Fixes for autoconf-2.66. - ----------------------------------------- -0.4.3 (2010-07-05) "imaginary radiation" ----------------------------------------- - -Many improvements for the DCCP and the UDP transport, the new user -manual and the usual mix of bug fixes and internal improvements. - - - FEC support for the DCCP sender (Gerrit Renker). The new - --dccp_max_slice_size, --dccp_data_slices_per_group and - --dccp_slices_per_group options can be used to set the FEC - parameters for the DCCP transport. - - DNS lookups for UDP targets (Gerrit Renker). - - The new user manual replaces the README, README.afs, REQUIREMENTS - and INSTALL documents. - - Fix an end-of-file detection bug in the oggdec filter. - - The new nonblock API. - - Both options of the oggdec filter have been removed. - - New debug mode for the internal scheduler. - ------------------------------------------- -0.4.2 (2010-04-23) "associative expansion" ------------------------------------------- - -It's been some time since the last release, but finally here is -paraslash-0.4.2. The bulk of the changes comes from the new buffer -tree API, but there are changes all over the tree. Mainly performance -and usability improvements, but also quite some bug fixes. - - - The new buffer tree API. - - DCCP: Support for CCID negotiation (Gerrit Renker). - - UDP robustness fixes. - - The --bufsize option for mp3dec is gone as it no longer makes sense - for the new buffer tree API. - - Fix audible buffer underruns for wma streams. - - The alsa writer no longer prints meaningless underrun durations. - - audiod: Defaults work also for udp streams. If no filter is - given for an audio format that is received via upd, fecdec is - automatically added as the first filter (along with the decoder). - ---------------------------------------- -0.4.1 (2009-12-22) "concurrent horizon" ---------------------------------------- - -Support for another audio format, minor feature enhancements and lots of bug -fixes. All fixes that have been accumulated in the maint branch (in particular -those mentionened in the 0.3.6 release notes) appear in this release as well. - - - wma support. - - new afh option: --human to activate human-readable output. - - new server/audiod option: --log-timing to print timing information. - - build system improvements. - - source code documentation updates. - -------------------------------------- -0.3.6 (2009-12-07) "cubic continuity" -------------------------------------- - -Quite a few bugs have been found and fixed since 0.3.5, so here's -another 0.3.x release. No new features. - - - Always check return value of malloc(). - - ogg vorbis/FEC: Do not write garbage after the audio file header. - - exit if root privileges could not be dropped. - - FEC: Fix computation of extra slices. - - oss: Fix check for empty input buffer. - - Avoid buffer underruns due to filter chain output buffer constraints. - - server: Fix assignment of afs_pid. - - Don't panic if the afs database contains unknown audio formats. - - http/dccp: Do not send the audio file header twice. - - FEC: Timing improvements. - ----------------------------------------------- -0.4.0 (2009-11-10) "simultaneous independence" ----------------------------------------------- - -Two significant changes which require the new version number: The -improved authentication dialog and the fact that the database code -has been moved to a library, libosl. To use the new version, you have -to generate new RSA keys, see INSTALL for details. A shell script is -provided for conversion of the 0.3 database to the new 0.4 format. - - - stronger crypto for client authentication - - the database code has been moved to a library - - improved status item handling - - cleanup of the build system - - The "-V" option now also prints the git version - - the new parser-friendly listing mode for the ls and stat commands - - mandatory rc4 encryption - - major audio format handler cleanups - - (id3,...) tags are no longer stored as a combined string in the database - - new mood methods: artist_matches, title_matches, comment_matches, - album_matches, year_maches, year. - --------------------------------------------- -0.3.5 (2009-09-21) "symplectic separability" --------------------------------------------- - -Full client support for *BSD Unixes, complete re-write of the ogg -vorbis audio format handler, various improvements all over the place -and the usual mix of bugfixes. This release marks the end of the 0.3 -series if no serious problems show up. - - - the new oss writer (supported on *BSD and Linux) - - rewrite of the ogg vorbis audio format handler. It's - recommended to replace the chunk tables of existing ogg - vorbis files in the afs database by re-adding these files - with "add -f". - - support for netmask subsets (Gerrit Renker) - - the new prebuffer filter - - improved signal handling - - variable fec output buffer size - - improved FEC timing fixes audible buffer underruns in UDP mode - - --log_color actually works - - new ls option: -d (print dates as seconds after the epoch) - - update to gengetopt 2.22.2 - - support for RSA keys of size > 512 bits - - new option "mixer_channel" for para_fade - ------------------------------------------ -0.3.4 (2009-05-07) "elliptic inheritance" ------------------------------------------ - -The new udp sender, forward error correction, colored logs and various -other improvements. As the udp sender does not depend on any special -libraries, it is built unconditionally. - - - The udp sender replaces the ortp sender. The new code uses forward - error correction to protect against packet losses. Many thanks to - Gerrit Renker for providing ipv6 support. - - The default port for udp streaming now defaults to 8000, like - for the http and the dccp senders/receivers. - - Loglevels are now specified as symbolic names, e.g. - "--loglevel info". - - improved ipv4 and ipv6 URI parser (Gerrit Renker). - - para_server/para_audiod: Color support for log messages. - - new options for mp3dec: --ignore-crc, --bufsize - - new audiod option: --config-file. - - gengetopt cleanups. - - Improved help/man pages: The documentation of para_audiod, - para_recv, para_filter and para_write now also contains - all options of the available receivers/filters/writers. The - man page of para_fade contains a description of the different - modes of operation. - - More source code documentation. - - vss timing fixes. - --------------------------------------------- -0.3.3 (2008-12-01) "axiomatic perspectivity" --------------------------------------------- - -Internal code cleanups, bug fixes, improved tag handling and the new -amplification filter. - - - para_server uses the generic scheduling code. - - overhaul of the virtual streaming system. - - mp3: id3 version 2 support via libid3tag (optional) - - ogg: vorbis comment support. - - aac meta info support. - - mp3 audio format handler cleanups. - - new filter: "amp" to amplify the amplitude of the audio stream - - new status item/database entry: amplification. It is - used by the amp filter to pre-amplify the audio stream. - - fix a close-without-open bug in para_write. - - fix a bug in com_init() which was introduced in 0.3.2. - - better error diagnostics for para_client. - ------------------------------------------ -0.3.2 (2008-04-11) "probabilistic parity" ------------------------------------------ - -The new para_afh executable, scheduling and documentation improvements. - - - new ls option: -lc (list chunk table) - - new executable: para_afh, the stand-alone audio file handler tool - - afs commands can send output more than SHMMAX (32MB on Linux). This - also reduces the memory usage of commands that produce large amounts - of output. - - major scheduler and audiod cleanups. - - more detailed and much nicer man pages. - ---------------------------------------- -0.3.1 (2008-02-23) "liquid interaction" ---------------------------------------- - -A mix of cleanups, bug fixes, improvements, and some new features. No -significant changes to the new database (osl) code, which is generally -a good sign. - - - Share some similar/duplicate code between the http and the - dccp sender. - - Generic access control lists for paraslash senders. - - dccp sender: Access control lists, connection limiting and support - for the allow,deny,on,off,help sender commands. - - The default dccp port changed from 5001 to 8000 (suggested by - Gerrit Renker). - - para_server starts even if not all public keys could be loaded. - - Audiod performance improvements. - - fix a bug in the "off" command of the http sender. - - fix some fd and memory leaks. - - Update to gengetopt-2.22. - -------------------------------------- -0.3.0 (2008-01-12) "solar saturation" -------------------------------------- - -paraslash.0.3.0 -- 'WWDBND --what would databases never do?'. - - -Usually one might expect lots of new features AND a big increase in size -for a major release like this. - -However, paraslash-0.3.0.tar.bz2 is the smallest paraslash tarball -ever. The decrease in size is mostly due to the removal of some -graphical tools (which were only quick hacks anyway). But also the -fact that the mysql code is gone cuts down the size a bit. - -Being independent of mysql comes at a cost: The fact that paraslash -now contains its own database (the object storage layer, osl) increases -the (stripped) binary size of para_server by ~50K on i386. - - - no more restrictions on unique basenames. - - independent of mysql: The new self-contained object - storage layer (osl) replaces the mysql database. - - New executable para_fsck: Check integrity of osl tables. - - Lyrics support. - - Reliable audio file move/rename detection. - - More portable than ever: Tested on Linux (x86_32, x86_64, sparc64), - MacOS (ppc32, x86_32), FreeBSD (x86_32), NetBSD (x86_32) and - Solaris (sparc64). - - the new osl-based audio file selector (afs) replaces the random, - the playlist and the mysql selector of paraslash-0.2.x. - - IPv6 support (thanks to Gerrit Renker). - - paraslash-0.2.x streams are now called "moods". Writing - 0.3.x-mood definitions should be both easier and more - powerful than writing 0.2.x-stream definitions. - - para_krell, para_slider, para_para_sdl_gui, para_dbadm have - been removed. The world is a better place without them. However, - para_gui is still there. - - afs tracks audio file selection also in playlist mode. - - few easy-to-use afs commands replace the many not-so-easy-to-use - mysql commands (and are available also in playlist mode). - - Improved error subsystem. - - The earth-shaking new logo. - ------------------------------------------ -0.2.17 (2007-11-20) "isotropic threshold" ------------------------------------------ - -Mainly bugfixes and cleanups in this version which marks the end of -the 0.2.x series if no serious bugs show up after the release. - - - mysql_selector: fix a locking bug. - - universal chunk queueing. - - dccp sender uses chunk queueing if write() returns EAGAIN (thanks - to Gerrit Renker). - - be more carful wrt. signed vs. unsigned argument passing. - - cleanup error.h and fix some references to invalid error - codes. - - update to gengetopt-2.21. - - update to ortp-0.13.1. - - autoconf: extend checks for headers, library functions and - compiler characteristics. - - Fix streaming of large mp3 files. - - Fix an off-by-one bug in playlist handling. - --------------------------------------- -0.2.16 (2007-04-05) "neural discharge" --------------------------------------- - -The main change in this release is the major audio format handler -cleanup which removes some similar/duplicate code and makes it easier -to implement plugins for other audio formats. Of course, the usual mix -of other improvements/changes/bugfixes also made it into the release. - - - simplified audio format handlers (most of the handling functions - were moved one layer up to the virtual streaming system). - - para_server uses mmap to read audio files - - repositioning of mp3 streams is much faster, in particular for - jumping near the end of large mp3 files. - - permission flags DB_READ,DB_WRITE have been renamed to AFS_READ - and AFS_WRITE. - - fix a bug in para_filter that caused decoding of aac files - to start only after a few seconds. - - fix osx_writer hangs - - simplified dccp code (thanks to Gerrit Renker) - - the compress filter works also on big endian systems (ppc) - ------------------------------------------ -0.2.15 (2007-02-16) "inductive resonance" ------------------------------------------ - -Minor improvements, more documentation and a bunch of bug fixes. - - - para_server: The server.users file is only read once on server - startup rather than for each connection - - mp3dec: Fix decoding of corrupt mp3 files - - afs (audio file sender) is now called vss (virtual streaming - system). Consequently, the permission flags specified in - ~/.paraslash/server.users have also changed: AFS_READ and AFS_WRITE - become VSS_READ and VSS_WRITE respectively. - - para_audiod/para_filter: Fix a bug that caused the last chunk - of audio data not being written under certain circumstances - - audiod: compute the difference of server time and local time - correctly - - para_server/para_audiod: Fix some memory leaks - - documentation improvements - - configure.ac: fix checks for para_krell - - new man pages - -------------------------------------------- -0.2.14 (2006-10-15) "transient singularity" -------------------------------------------- - -The only major enhancement of this version is the osx writer which completes -the Mac OS Port and was originally planned already for 0.2.13 but had to wait -until now for reasons beyond the scope of this changelog entry. - - - new output plugin for Mac Os: the osx writer - - rename configure command line options from --enable-xxx-headers to - --with-xxx-headers and --enable-xxx-libs to --with-xxx-libs - - configure: new command line options: --with-mad-headers, - --with-mad-libs, --with-oggvorbis-headers, and --with-oggvorbis-libs - - some robustness fixes - - dymamic audio format recognition for audiod - - para_server: new command line option: --autoplay_delay - - para_audiod: new command line option: --clock_diff_count - ---------------------------------------- -0.2.13 (2006-07-14) "sonic convolution" ---------------------------------------- - -A bunch of new features and core changes. - - - the new paraslash scheduler, short and sweet. - - Support for m4a/mp4 files via the new aac audio format - handler/filter (requires libfaad). - - each writer has its own command line parser, just like - para_recv and para_filter. - - para_client and para_audioc use the error subsystem - - writers are integrated in para_audiod (currently linux-only) - - para_client is integrated in para_audiod - - random/playlist selector: improved info strings - - new audiod commands: tasks, kill - - update to libortp-0.10.1 - - para_fade: wake time defaults to 8 hours from now - - update to autoconf-2.60 - ------------------------------------------- -0.2.12 (2006-05-12) "oriented abstraction" ------------------------------------------- - -Many user-visible changes in this release and lots of new -features: - - - - the new optional dccp sender/receiver. It uses the datagram - congestion control protocol. You'll need a fairly new kernel - for this. - - paraslash works on Mac OS X (thanks to Gerd Becker) - - para_play renamed to para_write - - modular output plugin design (writers) for para_write - - new file_writer output plugin for para_write - - compress filter speed improvements - - update to libortp-0.9.1 - - update to gengetopt-2.17rc - - para_client no longer depends on libreadline (as the - code for the interactive mode was removed). - - gcc-2-95 is no longer a supported compiler. It may still - work, but it gets no more testing. - - the tarball no longer contains the screenshot images which - reduces its size quite a bit. - - configure: new command line options: --enable-mysql-headers - and --enable-mysql-libs - ------------------------------------- -0.2.11 (2006-03-11) "atomic duality" ------------------------------------- - -Here it is, the first paraslash release developed with git. There -are fairly many user-visible changes in this release. As two out of -the three "database tools" of paraslash don't use a database at all, -they are now called "audio file selectors" instead. - - - - the cdt command (change database tool) becomes chs (change - selector) - - no more colon separators: The syntax of some options of - para_audiod and para_filter have changed. Use --help for - more info (and some examples). - - update to gengetopt-2.16 (thanks to Lorenzo Bettini) - - switch from cvs to git (should've done that earlier) - - the new ipc subsystem - - new audio file selector: playlist - - para_server: the dopey selector is now called "random", - and is the default selector. Use the --selector option to - choose another selector at startup, or the chs command to - change the selector at runtime. - - X86_64 fixes (thanks to Steffen Klassert) - - para_play fixes - --------------------------------------- -0.2.10 (2006-02-17) "cyclic attractor" --------------------------------------- - -Huge documentation update, a scrollable window for para_gui, ortp -improvements, and of course many small fixes not mentioned here. -The diffstat below is rather misleading as most insertions are due -to the new source documentation. - - - autoconf cleanup - - para_server also uses the new error subsystem - - lots of new documentation (UTSL) - - gui improvements: - - keysyms for cursor keys and for next/previous page keys - - scrollable output window - - new internal commands: scroll up/down, page up/down - - fix color of command output. - - ortp: the --chunk_time and --header flags are no longer needed - for para_recv/para_audiod as this information is now encoded in - each rtp packet sent by para_server. - -------------------------------------------- -0.2.9 (2006-01-24) "progressive turbulence" -------------------------------------------- - -Internal audiod receivers/filters, the new error subsystem and -a lot of small improvements. - - - para_recv and para_filter are integrated into the para_audiod - binary, i.e. audiod no longer spawns a new process for - each receiver/filter. As para_recv and para_filter might be - useful as standalone programs, they still get built (linked - against the same object files that are also used for audiod). - - further ortp timing improvements should reduce the CPU usage - of the ortp receiver. - - improved audio grabbing. The 'grab' command of para_audiod - has its own set of command line options. Read the output of - "para_audioc help grab" for more info. - - oggdec: configurable input prebuffer size. - - the new error subsystem gives better error diagnostics - and reduces code size. - ------------------------------------------ -0.2.8 (2006-01-02) "dynamic accumulation" ------------------------------------------ - -The new modular filter design and the para_play-hangs bugfix. - - - new executable: para_filter. It combines para_mp3dec, - para_oggdec and para_compress. It also adds a further filter - type, wav, that just inserts a wave header at the desired point - of the filter chain. All 'piping' is done in-memory (i.e. no - read/write operations are used). - - para_play: fix a stupid bug that caused it to hang under - certain circumstances. - -------------------------------------------- -0.2.7 (2006-12-27) "transparent invariance" -------------------------------------------- - -Not many user-visible changes but a fair amount of internal improvements. - - - - The http sender buffers data if it can not be sent - out immediately (because the socket is not writable). This - should prevent para_server from shutting down the connection - too early on a loaded network. - - para_play also prebuffers data if it is told to start at a - future time by the --start_time option. - - The return of para_recv: It combines para_ortp_recv and - para_http_recv. Use the --receiver option to switch between - the two. para_recv builds without libortp, but contains - only the http receiver in this case. - - update to ortp 0.8.1. As this ortp release contains incompatible - changes, para_recv-0.2.7 won't link against older ortp libs. - - improved ortp timings. - - use of gcc-extensions that #define away for non-gcc and - gcc < 3.0. - -------------------------------------------- -0.2.6 (2005-10-29) "recursive compensation" -------------------------------------------- - -Transparent session encryption (uses openssl's Alleged RC4 cipher), -the internal find command and several other improvements and cleanups. - - - Encrypt the session if encryption is requested by the client - (default for para_client 0.2.6). This is backwards - compatible, so older clients can still connect to para_server - 0.2.6. Use the new client option --plain to request an - uncrypted session (off by default, must be set to on in - order to connect to para_server 0.2.x with 0 <= x <= 5). - - para_server uses an internal function to locate audio files - rather than calling find(1). The server option - --mysql_audio_file_dir replaces --mysql_find_cmd. - - documentation update - - man pages - - header file cleanup - - para_client code cleanup - - para_gui: faster display of output of display commands - ------------------------------------------- -0.2.5 (2005-10-13) "aggressive resolution" ------------------------------------------- - -This release adds internal senders, i.e. no more external programs are -spawned for sending out the audio data. There are two different senders -available: The http sender and the ortp sender (former para_send which -is no longer needed). - -The new sender code has a plugin-like design so it can be easily -extended should there be be any future need for supporting another -network streaming protocol. All senders are completely independent of -each other. In particular, the http and the ortp sender can operate -in parallel. - - - new server command: sender to control senders at runtime. - Read the output of "para_server -h" and "para_client help - sender" for more information. - - para_recv renamed to para_ortp_recv - - new executable: para_http_recv, a simple command line - http receiver. - - major afs/mp3/ogg code simplifications due to internal - senders. - - ogg timing improvements - - fix several minor memory leaks (found by valgrind) - - empty stream definitions work again - - com_ne(): ignore errors on remove - - audiod: fix segfault on server restart - ---------------------------------------- -0.2.4 (2005-09-21) "toxic anticipation" ---------------------------------------- - -Several small improvements, fixes and the new grab command. - - - audiod: - - new command: "grab" to grab the output of the stream reader - or any filters. Read the output of "para_audioc help grab" - for more information. - - fix memory leak - - code cleanup - - audioc: new command line option: --bufsize to specify a - buffer size different from the default size 8192. - - improved error diagnostics for para_play. - - new configure option: --enable-ssldir so search for openssl in - non-standard places - - sdl_gui: Make it look nice again for 1024x768 - - server: report total size of memory allocated with sbrk by malloc, - new command line option: --announce_time - ------------------------------------------ -0.2.3 (2005-09-01) "hydrophilic movement" ------------------------------------------ - -Two new executables and major feature enhancements. - - - audiod filters: It is now possible to specify arbitrary many - (including none) filters for each supported audio - format. This can be used e.g. for normalizing volume, - transforming or grabbing the audio stream, or for using - visualizers. Read the output of "para_audiod -h" for the - syntax of the new --filter_cmd option. - - new executable: para_play, a tiny alsa player. It - can play wave files or raw pcm (16 bit little endian) - from stdin. - - new executable: para_compress, a dynamic range compressor - intended to keep audio output at a consistent volume. Derived - from AudioCompress, http://trikuare.cx/code/AudioCompress.html. - - audiod: New option: --stream_delay. This can be used in - a local network to syncronize the audio output of all - clients that play the same stream. - ------------------------------------------- -0.2.2 (2005-08-19) "tangential excitation" ------------------------------------------- - -Mostly internal changes in this release, but also some new commands -for the mysql database tool. - - - cleanup exec.c, fix para_exec bug - - compile time loglevel (log messages below the given level - won't be compiled in, which reduces the size of the - resulting binaries) - - new log macros that shorten the size of the source code. - - workaround a gcc-4.1 bug (?) that caused send_cred_buffer() - to send only zeros. With this workaround, para_audioc works - again. - - avoid gcc-4 warning: conflicting types for built-in function 'clog' - - new mysql commands: "rm" (remove entry), "mv" (rename entry) "ne" - (new entry), "snp" (set numplayed). Read the manual for more - information. - ---------------------------------------- -0.2.1 (2005-08-15) "surreal experience" ---------------------------------------- - -Here comes paraslash-0.2.1. It contains a couple of new features and, -surprise, only minor bug fixes. - - - kill noisy mp3 debug message - - cleanup of the build system - - para_server and para_client directly use the crypto routines - of the openssl library rather than invoking the openssl command - line utitlity - - server/audiod: new option --user to switch to the given user - when invoked as root. Read the output of "para_server -h" for - more information. - - gui/sdl_gui: new option --stat_cmd to be used to retrieve the - status. Default: "para_audioc stat" - - sdl_gui: new option --pic_cmd to be used to download the picture. - Default: "para_client pic" - - audiod: 5 slots ought to be enough for everybody - - audiod: new status item: Uptime, kill hup command - ------------------------------------------- -0.2.0 (2005-08-06) "distributed diffusion" ------------------------------------------- - -After several month of increased development activity, paraslash-0.2.0 -has arrived. It contains many new features and is much more -self-contained than the old 0.1.x series. Enjoy! - - - - para_server: fix hang on song change and crash on sighup. - Speed up mysql queries. The DIR_LIKE macro is gone. - - new executables: para_audiod, the local audio daemon that - starts playback (uses SCM_CREDENTIALS socket magic) and - para_audioc, the corresponding client. - - new executables: para_mp3dec/para_oggdec, two really teensy - decoders. para_mp3dec is based on libmad, para_oggdec requires - libvorbisfile. - - ovsend/ovrecv are capable of streaming ogg as well as mp3, so - they are now called para_send and para_recv respectively. - - documentation updates - - para_gui is themable. For now there is the default theme that - looks as before and the simple theme: blue and easy. - - gui: audio streaming is now handled by audiod. Time display shows - playback time rather than streaming time - - slider: update to libzmw-0.2.0 - - para_krell: fix crash on server shutdown - - switch from gzip to bzip2 - ----------------------------------------- -0.1.7 (2005-04-18) "melting penetration" ----------------------------------------- - -The main change in this release is clearly the oggvorbis rewrite, -but there are also lots of smaller changes. If you intend to use both -the mp3 and the ogg plugin, it is recommended to use software mixing, -e.g. the dmix plugin which is provided by ALSA. - - - new executables: para_ovsend and para_ovrecv for sending/receiving - oggvorbis files via rtp. Requires the open rtp library. Get it at - http://www.linphone.org/ortp/ - - rewrite of the ogg_vorbis core code - - configure detects libzmw and, if detected, includes - para_slider to the list of binaries to be built by make - - server stream writers read from their associated fifo rather - than from stdin - - slider: two new sliders, lastplayed and numplayed - - fix nasty double free bug which caused random segfaults in case of - mp3 files with invalid header information - - gui: new command line option: --stream_timeout=seconds to - deactivate a slot if it is idle for that many seconds (default=`5') - - diffstats - ---------------------------------------- -0.1.6 (2005-03-05) "asymptotic balance" ---------------------------------------- - -Only little user-visible changes in this release. Mainly bugfixes and -core code cleanup. This is probably the most stable version ever if you -stick to mp3... - - - fix several memory leaks - - rename default name of mysql database from "music" to "paraslash". - Use para_server's --mysql_database option if you do not want to - rename your old database. - - rework ogg vorbis code - - make update command work on mysql servers with LOCAL_INFILE - disabled - - gui: improved stream I/O (slots) - - simplified audio format API - - para_pob_ogg is gone - ------------------------------------- -0.1.5 (2004-12-31) "opaque eternity" ------------------------------------- - -Let's slide gently into the new year. - - - new: para_slider (not built automatically, type "make - para_slider" to build). A toy for those who always felt that - creating stream definitions is difficult. See screenshots, - README and FEATURES for more info. - - improved signal handling. Fixes server segfault on SIGHUP - for linux kernels newer than Aug 24 2004 and makes para_gui - race-free. - - reload database tool on SIGHUP - - improved help message for sl - - do not log "broken pipe" messages as errors. They are - perfectly ok. - - fix wrong error message on permission errors - ------------------------------------------ -0.1.4 (2004-12-19) "tunneling transition" ------------------------------------------ - -Bugfix release. As expected, 0.1.3 introduced a bunch of new bugs. -Hopefully, most of them got wiped out with this release. Some -enhancements went also in. - - - improved error diagnostics for all commands - - stradd/picadd: overwrite previous contents if entry already - exists, rather than returning errors - - stradd: use current stream if invoked without args - - faster (and hopefully more stable) ogg-vorbis handling - - para_krell: reap children to avoid zombie-flooding in case - no server is running - - si: report also server pid - - server: don't busy-loop if dbtool reports only invalid files. - - gui: CTRL+C works again, fix stream_read command line option - - fix pic_add, hist - - fix mysql dbtool startup in case no database exists - - many small fixes and cleanups - ---------------------------------------- -0.1.3: (2004-12-10) "vanishing inertia" ---------------------------------------- - -Starting from this release, the database tools are integrated in the -server binary. This decreases server startup time, reduces code size -and speeds up database commands. However, the layout of the underlying -mysql database changed only slightly and 0.1.3 should be backwards -compatible in that respect. - -Visible changes: - - - If mysql is not detected at compile time, or fails to init - at runtime, fall back to the dopey database tool which should - always work. - - para_dbtool and dbtool.conf are gone. All mysql specific - options are read from server.conf and are prefixed by 'mysql_'. - - new command: cdt (change database tool) - - new command line option: dbtool (choose startup database tool) - - The name of current stream is now stored in the database, - so paraslash remembers its current stream when restarted. - - new command: csp (change stream and play) - - para_gui also reports current database tool and server uptime - -------------------------------------------- -0.1.2: (2004-11-28) "spherical fluctuation" -------------------------------------------- - -Point release before the big dbtool changes go in. - - - dbtool: rename ca to cam (copy all meta data). It now also - copies numplayed and lastplayed time as well as the picture - id. - - fix endless-loop-bug caused by mp3 files with invalid header - ------------------------------------------ -0.1.1: (2004-11-05) "floating atmosphere" ------------------------------------------ - - - gkrellm plugin - - new dbtool command: mbox. Browse your sound-file collection - with your favorite mail reader. - - several small fixes - -------------------------------------- -0.1.0: (2004-10-22) "rotating cortex" -------------------------------------- - - - fix logging bug for loglevel > VERBOSE - - fix skip command - - correct timings for vbr mp3s - - modular audio format support - - ogg-vorbis support (experimental) - - new server option: autoplay - ------------------------------------------ -0.0.99: (2004-07-25) "harmonic deviation" ------------------------------------------ - - - rename projectname from icc to paraslash (play, archive, rate - and stream large audio sets happily) - - paraslash is no longer restricted to one particular audio - streaming software - - new dbtool commands (stradd, strq, strdel) for easy stream - managment w/o configuration file. That obsoletes stream_defs - file/config option for dbtool. - - picadd accepts jpeg data from stdin - - new server commands: ps (select previous stream), sc (song change) - - new default pictures for sdl_gui - - gui: new key_map option for binding commands and internal - functions to arbitrary keys, nice help screen, rip out - soundcard/linux specific stuff, avoid noise artefacts while jumping, - show silly logo on startup - - new executables: para_fade for fading volume, para_dbadm for - manipulating attributes - - cdb adds _all_ tables to mysql database - - revised and beautified documentation - - sample dbtool rewritten in C - - autoconf - ---------------------------------------------- -0.0.98: (2003-12-26) "incremental smoothness" ---------------------------------------------- - - - kick icecast in favour of poc. That removes some races and reduces - core code considerably. - - cbr/vbr is displayed by stat and gui/sdl_gui. New status flags - give finer info on afs' status. - - gui can start decoder (see config options). Further new gui - commands: refresh (^L), jmp (F1-F10) - - gui rereads conf on SIGUSR1 instead of SIGHUP. SIGHUP - terminates gui. This fixes dead instances consuming memory - continuously. - - new dbtool command: verb for sending verbatim sql queries. - - fix pid_list races (by removing pid_list) - - codename funnies - --------------------- -0.0.97: (2003-10-26) --------------------- - - - installation prefix now defaults to /usr/local - - new commands for gui: snozze, sleep and reread config - - config file for gui and sdl_gui - - fix problems with filenames containing funny characters - (reported by Thomas Forell) - - improved signal handling for gui, now it rereads conf on SIGHUP - - new dbtool command: cdb (create database) - - switch from argtable to gengetopt - - major code cleanup and speed improvements - - fix several potential buffer overflows - - many small fixes and cleanups - -------------------- -0.0.96 (2003-08-30) -------------------- - - - easy stream_defs syntax - - sdl_gui can display images associated to the file being played - - Major feature enhancements for icc_gui including dynamic text - placement and the top/bottom window design - - vrfy/clean now also checks for NULL values in attributes as - well as for invalid picture pointers - - fix long outstanding case sensitivity bug - - many small fixes and cleanups - -------------------- -0.0.95 (2003-06-29) -------------------- - - - sdl gui runs much faster - - new dbtool command: ca (copy attributes) - - count and display number of times the song has been played - - new feature: scoring - - command line options for sdl_gui - - simpler syntax of streams file - - decrease network traffic of stat - - fix zombie bug - - many small fixes and cleanups - -------------------- -0.0.94 (2003-05-04) -------------------- - - - new server command: ns (next stream) - - new icc_gui command: c (change stream) - - internal mp3info - - stat shows also id3 tag info - - new sdl based gui - - log flodding bug fixed - - many small fixes and cleanups - -------------------- -0.0.93 (2003-03-28) -------------------- - - - colors for icc_gui - - icc_gui sets volume directly (linux only) - - proper locking that fixes some races - - fix security bug that caused commands to be executed even - with unsufficient permissions - - new command: hup to make all servers reread their configuration file - - icecast meta data streaming - - many small fixes and cleanups diff --git a/NEWS.md b/NEWS.md new file mode 100644 index 00000000..7f61b920 --- /dev/null +++ b/NEWS.md @@ -0,0 +1,1275 @@ +NEWS +==== + +------------------------------------------ +current master branch "cascading gradient" +------------------------------------------ + +- para_afh learned to modify meta tags of mp3 wma ogg spx + opus flac aac files. +- afs commands propagate error codes to the client. +- The check command now also checks the attribute table for + inconsistencies. +- New -v flag for the version command (print verbose version string) +- New option --priority for para_server and para_audiod. + + +-------------------------------------- +0.5.5 (2015-09-20) "magnetic momentum" +-------------------------------------- + +Many new features and a lot of other improvements. + +- On Linux systems, local sockets are now created in the + abstract name space by default. This allows to get rid of + the socket specials in /var/paraslash. +- The --user-allow option of para_audiod now accepts also + usernames rather than only user IDs. +- New autoconf macros to avoid duplication in configure.ac. +- Status items (as shown by para_gui) are updated correctly + when the meta information of the current audio changes. +- para_server and para_audiod no longer refuse to start in + the background if no log file is given. Instead, all log + messages go to /dev/null in this case. +- Web page cleanup. +- New syntax for the -l and -s options of the ls command. + These options should now be specified as -l=v rather than + -lv, for example. The old syntax still works, but support + will be dropped in v0.6.0. + +Downloads: +[tarball](./releases/paraslash-0.5.5.tar.bz2), +[signature](./releases/paraslash-0.5.5.tar.bz2.asc) + +------------------------------------------ +0.5.4 (2015-01-23) "exponential alignment" +------------------------------------------ + +Another cleanup and bugfix release. + +- New server command: tasks. +- Minor cleanups to daemon.c. +- New URLs for home page and git services. +- Improved error diagnostics for the mvblob commands. +- New sender subcommand: status. +- Improved help text for server and afs commands. +- audiod memory leak fixes. +- Miscellaneous improvements to the build system. +- oss_writer improvements. +- Improved handling of mp3 files with both id3v1 and id3v2 tags. + +Downloads: +[tarball](./releases/paraslash-0.5.4.tar.bz2), +[signature](./releases/paraslash-0.5.4.tar.bz2.asc) + +--------------------------------------------- +0.5.3 (2014-08-01) "symbolic synchronization" +--------------------------------------------- + +Not many new features, but lots of fixes and usability improvements. + +- para_gui has been converted to use the paraslash scheduler. +- Various alsa-related fixes, mostly for the raspberry pi. +- Many scheduler improvements and cleanups. +- The test suite has been extended to include sanity checks + for the generated man pages. +- ao_writer fixes. This writer was in a quite bad shape. Many + serious bugs have been fixed. +- new audiod command: version. +- Minor improvements to the bitstream API. +- The cpsi command now prints a meaningful error message if + none of the given patterns matched any audio file. + +Downloads: +[tarball](./releases/paraslash-0.5.3.tar.bz2), +[signature](./releases/paraslash-0.5.3.tar.bz2.asc) + +---------------------------------------- +0.5.2 (2014-04-11) "orthogonal interior" +---------------------------------------- + +The new sync filter, the AES_CTR128 stream cipher and the overhauled +network code are the highlights of this release. It also includes a +fair number of smaller fixes and improvements not mentioned here. + +- The new sync filter synchronizes playback between multiple + clients. +- Connections between para_server and para_client are now + encrypted by means of AES rather than RC4 if both sides + support it. RC4 is still available as a fallback. This + feature is fully transparent, i.e. no command line options + are necessary, and a client linked against openssl can + speak with a server linked against libgcrypt and vice versa. +- Major cleanup of the networking subsystem. +- Improvements to para_fade: the new set mode, multi-channel + initial volumes, better error logging. +- The man pages of para_audiod, para_filter, para_recv, and + para_write contain the relevant options for receivers, filters, + writers. This broke in 0.5.0. +- ogg/vorbis latency improvements. +- Improved user manual. +- Minor fixes to avoid clang warnings. + +Downloads: +[tarball](./releases/paraslash-0.5.2.tar.bz2), +[signature](./releases/paraslash-0.5.2.tar.bz2.asc) + +------------------------------------------ +0.5.1 (2013-12-20) "temporary implication" +------------------------------------------ + +Lots of fixes and improvements all over the place, and a major overhaul +of the build system. + +- Audiod improvements and fixes. +- Buffer tree robustness improvements. +- Cleanup of the mood subsystem. +- Fixes and cleanups for the flac decoder. +- Latency improvements for the ogg/opus decoder. +- Crypto support is now optional. On systems without + openssl/gcrypt, the build succeeds but para_server, + para_audiod, para_client won't be built. +- The build system now works for cross-compile setups. +- The dependency tree has been flattened, which speeds up + builds and avoids to recreate the man pages on every change. +- The error code helper has been rewritten from perl to C, + which further improves build time. +- Many small bugs in the build system have been identified + and fixed. + +Downloads: +[tarball](./releases/paraslash-0.5.1.tar.bz2), +[signature](./releases/paraslash-0.5.1.tar.bz2.asc) + +---------------------------------------- +0.5.0 (2013-08-23) "invertible validity" +---------------------------------------- + +Some API-breaking changes, one serious bug fix, and a lot of bike-shedding. + +- The sideband compatibility code has been removed, hence + sideband connections (introduced in 0.4.11) are now mandatory. +- Addblob commands can produce output. +- The stat command no longer sends garbage when para_server was + compiled against libgcrypt. +- Dependencies for gengetopt files are computed automatically. + This eliminates a constant source of build bugs. +- The setatt command now accepts file name patterns rather than only + path names. +- overview.pdf is now based on dia, a simple diagram creation program. + The new version is much more detailed and contains descriptions of + the various programs of the paraslash package. +- The separator of all multi-word options has been changed from + underscore to dash. For example --log_color becomes --log-color. +- Overhauled web pages and the new logo. + +Downloads: +[tarball](./releases/paraslash-0.5.0.tar.bz2), +[signature](./releases/paraslash-0.5.0.tar.bz2.asc) + +-------------------------------------- +0.4.13 (2013-07-29) "spectral gravity" +-------------------------------------- + +One more 0.4.x release before the API-breaking changes for 0.5.0 go +in. The main features of this release are the ogg/opus audio format, +and UTF-8 support, but it includes also tons of other improvements +and fixes all over the place. + +- New audio format: ogg/opus. +- UTF8 support for para_gui and the mp3 audio format handler. +- Scheduler improvements and fixes. +- The obsolete gettimeofday() function has been replaced + by clock_gettime() on systems which support it. +- Speed and usability improvements for para_gui. +- para_client now restores the fd flags of stdin and stdout + on shutdown. +- Improved manual pages. +- Consistent version strings for all executables. +- Reduced dependencies on generated files result in fewer + recompilations on changes. +- Performance improvements for the compress filter. +- Improved downloads web page. + +----------------------------------------- +0.4.12 (2012-12-20) "volatile relativity" +----------------------------------------- +The new command line player, the resample filter, ALSA support for +para_fade, and the improved build system are the highlights of this +release which probably marks the end of the 0.4.x series. + +- The afh receiver and the para_play executable. +- The resample filter: A sample rate converter based on + libsamplerate. +- The "versions" directory has been removed from the master + branch. The tarballs of the old releases are now available + in the new "releases" branch. +- Overhaul of the build system: All generated files are now + written to the "build" directory. +- The modular mixer API and the alsa mixer. +- Minor fixes for the osx writer. + +-------------------------------------- +0.4.11 (2012-07-20) "mutual diversity" +-------------------------------------- + +The major feature in this release is the new sideband API for +client-server communication. This API will be used exclusively starting +with 0.5.0, which breaks backward compatibility but allows to get rid +of quite some compatibility code. Other noteworthy changes include +decoder latency improvements and a long-standing bug fix for the +ALSA writer. + +- Sideband connections: If both para_server and para_client + support this feature, data is sent as a multiplexed stream. +- The --no_default_filters option of para_filter has been + removed. +- Several fixes and latency improvements to various decoders. +- The ALSA writer now limits the prebuffer time to 500ms. +- Documentation improvements. +- Overhaul of the command_util.sh script. +- Fixes for some minor problems found by the clang analyzer. +- Compiles (almost) without warnings on gcc-3. +- Robustness improvements of the buffer tree code. + +------------------------------------------ +0.4.10 (2012-03-30) "heterogeneous vacuum" +------------------------------------------ + +Nothing earth-shaking in this release, but quite a few usability +improvements and the usual mix of cleanups and fixes. + +- The --no_default_filters option of para_filter has been + deprecated. It still works but has no effect and will be + removed in the next version. +- para_gui now prints also the stderr output of the executing + command in the bottom window. +- Cleanup and consolidation of the various wrappers for + write(), writev(), send() and friends. +- The obscure error messages on mmap() failures have been + replaced by meaningful messages. This affects mainly + para_afh. +- para_audioc: Cleanups and memory leak fixes. +- Test 0004-server no longer fails if para_server is not + being built. +- New configure options: --with-id3tag-{headers,libs}. + +------------------------------------- +0.4.9 (2011-12-06) "hybrid causality" +------------------------------------- + +Support for another audio format, interactive mode for para_client +and para_audiod and many small improvements/fixes all over the place. + +- Support for flac, the free lossless audio codec. +- Fix for an endless loop in the mp3 decoder for certain + (corrupt) mp3 files. +- When executed without specifying a command, para_client + and para_audioc start an interactive shell (requires + libreadline being installed). The interactive mode offers + full tab completion and command line history. +- autogen.sh now detects a distcc setup and adjusts the + parameter for the -j option of make accordingly. +- Shared memory areas are no longer restricted to 64K. We now + detect the maximal size of a shared memory area at runtime. +- cleanup of the internal uptime API. +- para_server prefaults the mmapped audio file to avoid + delays on slow media. +- A new test for the test-suite that exercises the + communication between para_server and para_audiod. +- The alsa writer eats up less CPU cycles when configured to + use the DMIX plugin. +- Simplified and unified receiver code. +- Makefile cleanups. +- Commands which print a list of matching audio files now + emit a meaningful error message if no audio file matched the + given pattern(s). + +-------------------------------------- +0.4.8 (2011-08-19) "nested assignment" +-------------------------------------- + +Gcrypt support, the overhauled osx writer and regex format specifiers +are the highlights of this release. + +- support for libgcrypt as a drop-in replacement for openssl. + Run configure --enable-cryptolib=gcrypt to link against + libgcrypt. The two crypto implementations are compatible to + each other, i.e. a para_client executable linked against + gcrypt can connect to para_server linked against libssl + and vice versa. +- Rewrite of the osx writer (output plugin for Mac OS). +- audiod: The format specifier for receivers, filters and + writers is now treated as a regular expression. This allows + to replace 5 lines in the config file (one for each audio + format) by one single line. See the manual for details. +- The \*.cmdline.[ch] files are no longer contained in the released + tarballs. This reduces the size of the tarballs but requires + gengetopt to build the tarball. +- Compiles cleanly also with llvm/clang. +- Corrupt mp3 files are handled more gracefully. +- The alsa writer uses poll fds instead of computing timeouts. +- Cleanup of the generic writer API. +- sched: Optimized zero timeouts. +- vss timeout cleanups. +- oggdec fixes and improvements. + +-------------------------------------- +0.4.7 (2011-06-01) "infinite rollback" +-------------------------------------- + +The new ao writer, support for ssh RSA keys and a couple of other +enhancements. + +- Support for ESD, Pulseaudio, AIX, Solaris, IRIX and other + platforms through the libao audio library. +- Support for RSA keys generated with ssh-keygen. +- configure: improved options for ogg/vorbis/speex. +- The git version reported by --version always matches HEAD. +- The autogen script detects the number of processors and + runs a parallel make if possible. +- Major cleanup of the crypto API. +- Documentation updates. + +------------------------------------------ +0.4.6 (2011-03-31) "deterministic entropy" +------------------------------------------ + +Lots of ogg/vorbis improvements, the new test suite, enhancements +for para_gui and a fair amount of other bug fixes. + +- For DCCP/OGG streams the audio file header is only sent once + at the beginning of the stream rather than periodically + every five seconds. This reduces network traffic and the + FEC group size. +- The vorbis comment header is replaced by an empty dummy header + before the header is sent over the network. This also results in + less network traffic and smaller FEC groups. +- The new "test" make target allows to perform some sanity checks prior + to installing the package. +- ogg timing fixes and performance improvements +- Scheduler improvements +- Proper exit codes for para_write +- para_gui: New option --theme to select a startup theme. Several + other improvements and fixes. +- aacdec error message cleanups +- simplified color error handling + +-------------------------------------------- +0.4.5 (2010-12-17) "symmetric randomization" +-------------------------------------------- + +Bug fixes, internal cleanups and variable-sized FEC slices. + +- Contains a fix for an invalid-free-bug in the ogg audio format + handler code. +- Switching off the DCCP sender works again. +- para_audiod handles crashes of para_server more robustly. +- Internal scheduler and writer cleanups. +- Reduced latency due to variable-sized FEC slices. +- Improved documentation and error diagnostics. +- The build of para_server is now optional, allowing the build + to succeed in case libosl is not installed. + +------------------------------------------ +0.4.4 (2010-08-06) "persistent regularity" +------------------------------------------ + +Support for yet another audio format, para_write improvements and +bug fixes. + +- Support for the speex codec. +- Support for sample formats other than 16 bit little endian. +- error2.h is now created by a perl script which speeds up configure + considerably. +- Fix a bug in the aac decoder which could lead to segfaults in + para_filter/para_audiod. +- Fixes for autoconf-2.66. + +---------------------------------------- +0.4.3 (2010-07-05) "imaginary radiation" +---------------------------------------- + +Many improvements for the DCCP and the UDP transport, the new user +manual and the usual mix of bug fixes and internal improvements. + +- FEC support for the DCCP sender (Gerrit Renker). The new + --dccp_max_slice_size, --dccp_data_slices_per_group and + --dccp_slices_per_group options can be used to set the FEC + parameters for the DCCP transport. +- DNS lookups for UDP targets (Gerrit Renker). +- The new user manual replaces the README, README.afs, REQUIREMENTS + and INSTALL documents. +- Fix an end-of-file detection bug in the oggdec filter. +- The new nonblock API. +- Both options of the oggdec filter have been removed. +- New debug mode for the internal scheduler. + +------------------------------------------ +0.4.2 (2010-04-23) "associative expansion" +------------------------------------------ + +It's been some time since the last release, but finally here is +paraslash-0.4.2. The bulk of the changes comes from the new buffer +tree API, but there are changes all over the tree. Mainly performance +and usability improvements, but also quite some bug fixes. + +- The new buffer tree API. +- DCCP: Support for CCID negotiation (Gerrit Renker). +- UDP robustness fixes. +- The --bufsize option for mp3dec is gone as it no longer makes sense + for the new buffer tree API. +- Fix audible buffer underruns for wma streams. +- The alsa writer no longer prints meaningless underrun durations. +- audiod: Defaults work also for udp streams. If no filter is + given for an audio format that is received via upd, fecdec is + automatically added as the first filter (along with the decoder). + +--------------------------------------- +0.4.1 (2009-12-22) "concurrent horizon" +--------------------------------------- + +Support for another audio format, minor feature enhancements and lots of bug +fixes. All fixes that have been accumulated in the maint branch (in particular +those mentionened in the 0.3.6 release notes) appear in this release as well. + +- wma support. +- new afh option: --human to activate human-readable output. +- new server/audiod option: --log-timing to print timing information. +- build system improvements. +- source code documentation updates. + +------------------------------------- +0.3.6 (2009-12-07) "cubic continuity" +------------------------------------- + +Quite a few bugs have been found and fixed since 0.3.5, so here's +another 0.3.x release. No new features. + +- Always check return value of malloc(). +- ogg vorbis/FEC: Do not write garbage after the audio file header. +- exit if root privileges could not be dropped. +- FEC: Fix computation of extra slices. +- oss: Fix check for empty input buffer. +- Avoid buffer underruns due to filter chain output buffer constraints. +- server: Fix assignment of afs_pid. +- Don't panic if the afs database contains unknown audio formats. +- http/dccp: Do not send the audio file header twice. +- FEC: Timing improvements. + +---------------------------------------------- +0.4.0 (2009-11-10) "simultaneous independence" +---------------------------------------------- + +Two significant changes which require the new version number: The +improved authentication dialog and the fact that the database code +has been moved to a library, libosl. To use the new version, you have +to generate new RSA keys, see INSTALL for details. A shell script is +provided for conversion of the 0.3 database to the new 0.4 format. + +- stronger crypto for client authentication +- the database code has been moved to a library +- improved status item handling +- cleanup of the build system +- The "-V" option now also prints the git version +- the new parser-friendly listing mode for the ls and stat commands +- mandatory rc4 encryption +- major audio format handler cleanups +- (id3,...) tags are no longer stored as a combined string in the database +- new mood methods: artist_matches, title_matches, comment_matches, + album_matches, year_maches, year. + +-------------------------------------------- +0.3.5 (2009-09-21) "symplectic separability" +-------------------------------------------- + +Full client support for \*BSD Unixes, complete re-write of the ogg +vorbis audio format handler, various improvements all over the place +and the usual mix of bugfixes. This release marks the end of the 0.3 +series if no serious problems show up. + +- the new oss writer (supported on \*BSD and Linux) +- rewrite of the ogg vorbis audio format handler. It's + recommended to replace the chunk tables of existing ogg + vorbis files in the afs database by re-adding these files + with "add -f". +- support for netmask subsets (Gerrit Renker) +- the new prebuffer filter +- improved signal handling +- variable fec output buffer size +- improved FEC timing fixes audible buffer underruns in UDP mode +- --log_color actually works +- new ls option: -d (print dates as seconds after the epoch) +- update to gengetopt 2.22.2 +- support for RSA keys of size > 512 bits +- new option "mixer_channel" for para_fade + +----------------------------------------- +0.3.4 (2009-05-07) "elliptic inheritance" +----------------------------------------- + +The new udp sender, forward error correction, colored logs and various +other improvements. As the udp sender does not depend on any special +libraries, it is built unconditionally. + +- The udp sender replaces the ortp sender. The new code uses forward + error correction to protect against packet losses. Many thanks to + Gerrit Renker for providing ipv6 support. +- The default port for udp streaming now defaults to 8000, like + for the http and the dccp senders/receivers. +- Loglevels are now specified as symbolic names, e.g. + "--loglevel info". +- improved ipv4 and ipv6 URI parser (Gerrit Renker). +- para_server/para_audiod: Color support for log messages. +- new options for mp3dec: --ignore-crc, --bufsize +- new audiod option: --config-file. +- gengetopt cleanups. +- Improved help/man pages: The documentation of para_audiod, + para_recv, para_filter and para_write now also contains + all options of the available receivers/filters/writers. The + man page of para_fade contains a description of the different + modes of operation. +- More source code documentation. +- vss timing fixes. + +-------------------------------------------- +0.3.3 (2008-12-01) "axiomatic perspectivity" +-------------------------------------------- + +Internal code cleanups, bug fixes, improved tag handling and the new +amplification filter. + +- para_server uses the generic scheduling code. +- overhaul of the virtual streaming system. +- mp3: id3 version 2 support via libid3tag (optional) +- ogg: vorbis comment support. +- aac meta info support. +- mp3 audio format handler cleanups. +- new filter: "amp" to amplify the amplitude of the audio stream +- new status item/database entry: amplification. It is + used by the amp filter to pre-amplify the audio stream. +- fix a close-without-open bug in para_write. +- fix a bug in com_init() which was introduced in 0.3.2. +- better error diagnostics for para_client. + +----------------------------------------- +0.3.2 (2008-04-11) "probabilistic parity" +----------------------------------------- + +The new para_afh executable, scheduling and documentation improvements. + +- new ls option: -lc (list chunk table) +- new executable: para_afh, the stand-alone audio file handler tool +- afs commands can send output more than SHMMAX (32MB on Linux). This + also reduces the memory usage of commands that produce large amounts + of output. +- major scheduler and audiod cleanups. +- more detailed and much nicer man pages. + +--------------------------------------- +0.3.1 (2008-02-23) "liquid interaction" +--------------------------------------- + +A mix of cleanups, bug fixes, improvements, and some new features. No +significant changes to the new database (osl) code, which is generally +a good sign. + +- Share some similar/duplicate code between the http and the + dccp sender. +- Generic access control lists for paraslash senders. +- dccp sender: Access control lists, connection limiting and support + for the allow,deny,on,off,help sender commands. +- The default dccp port changed from 5001 to 8000 (suggested by + Gerrit Renker). +- para_server starts even if not all public keys could be loaded. +- Audiod performance improvements. +- fix a bug in the "off" command of the http sender. +- fix some fd and memory leaks. +- Update to gengetopt-2.22. + +------------------------------------- +0.3.0 (2008-01-12) "solar saturation" +------------------------------------- + +paraslash.0.3.0 -- 'WWDBND --what would databases never do?'. + + +Usually one might expect lots of new features AND a big increase in size +for a major release like this. + +However, paraslash-0.3.0.tar.bz2 is the smallest paraslash tarball +ever. The decrease in size is mostly due to the removal of some +graphical tools (which were only quick hacks anyway). But also the +fact that the mysql code is gone cuts down the size a bit. + +Being independent of mysql comes at a cost: The fact that paraslash +now contains its own database (the object storage layer, osl) increases +the (stripped) binary size of para_server by ~50K on i386. + +- no more restrictions on unique basenames. +- independent of mysql: The new self-contained object + storage layer (osl) replaces the mysql database. +- New executable para_fsck: Check integrity of osl tables. +- Lyrics support. +- Reliable audio file move/rename detection. +- More portable than ever: Tested on Linux (x86_32, x86_64, sparc64), + MacOS (ppc32, x86_32), FreeBSD (x86_32), NetBSD (x86_32) and + Solaris (sparc64). +- the new osl-based audio file selector (afs) replaces the random, + the playlist and the mysql selector of paraslash-0.2.x. +- IPv6 support (thanks to Gerrit Renker). +- paraslash-0.2.x streams are now called "moods". Writing + 0.3.x-mood definitions should be both easier and more + powerful than writing 0.2.x-stream definitions. +- para_krell, para_slider, para_para_sdl_gui, para_dbadm have + been removed. The world is a better place without them. However, + para_gui is still there. +- afs tracks audio file selection also in playlist mode. +- few easy-to-use afs commands replace the many not-so-easy-to-use + mysql commands (and are available also in playlist mode). +- Improved error subsystem. +- The earth-shaking new logo. + +----------------------------------------- +0.2.17 (2007-11-20) "isotropic threshold" +----------------------------------------- + +Mainly bugfixes and cleanups in this version which marks the end of +the 0.2.x series if no serious bugs show up after the release. + +- mysql_selector: fix a locking bug. +- universal chunk queueing. +- dccp sender uses chunk queueing if write() returns EAGAIN (thanks + to Gerrit Renker). +- be more carful wrt. signed vs. unsigned argument passing. +- cleanup error.h and fix some references to invalid error + codes. +- update to gengetopt-2.21. +- update to ortp-0.13.1. +- autoconf: extend checks for headers, library functions and + compiler characteristics. +- Fix streaming of large mp3 files. +- Fix an off-by-one bug in playlist handling. + +-------------------------------------- +0.2.16 (2007-04-05) "neural discharge" +-------------------------------------- + +The main change in this release is the major audio format handler +cleanup which removes some similar/duplicate code and makes it easier +to implement plugins for other audio formats. Of course, the usual mix +of other improvements/changes/bugfixes also made it into the release. + +- simplified audio format handlers (most of the handling functions + were moved one layer up to the virtual streaming system). +- para_server uses mmap to read audio files +- repositioning of mp3 streams is much faster, in particular for + jumping near the end of large mp3 files. +- permission flags DB_READ,DB_WRITE have been renamed to AFS_READ + and AFS_WRITE. +- fix a bug in para_filter that caused decoding of aac files + to start only after a few seconds. +- fix osx_writer hangs +- simplified dccp code (thanks to Gerrit Renker) +- the compress filter works also on big endian systems (ppc) + +----------------------------------------- +0.2.15 (2007-02-16) "inductive resonance" +----------------------------------------- + +Minor improvements, more documentation and a bunch of bug fixes. + +- para_server: The server.users file is only read once on server + startup rather than for each connection +- mp3dec: Fix decoding of corrupt mp3 files +- afs (audio file sender) is now called vss (virtual streaming + system). Consequently, the permission flags specified in + ~/.paraslash/server.users have also changed: AFS_READ and AFS_WRITE + become VSS_READ and VSS_WRITE respectively. +- para_audiod/para_filter: Fix a bug that caused the last chunk + of audio data not being written under certain circumstances +- audiod: compute the difference of server time and local time + correctly +- para_server/para_audiod: Fix some memory leaks +- documentation improvements +- configure.ac: fix checks for para_krell +- new man pages + +------------------------------------------- +0.2.14 (2006-10-15) "transient singularity" +------------------------------------------- + +The only major enhancement of this version is the osx writer which completes +the Mac OS Port and was originally planned already for 0.2.13 but had to wait +until now for reasons beyond the scope of this changelog entry. + +- new output plugin for Mac Os: the osx writer +- rename configure command line options from --enable-xxx-headers to + --with-xxx-headers and --enable-xxx-libs to --with-xxx-libs +- configure: new command line options: --with-mad-headers, + --with-mad-libs, --with-oggvorbis-headers, and --with-oggvorbis-libs +- some robustness fixes +- dymamic audio format recognition for audiod +- para_server: new command line option: --autoplay_delay +- para_audiod: new command line option: --clock_diff_count + +--------------------------------------- +0.2.13 (2006-07-14) "sonic convolution" +--------------------------------------- + +A bunch of new features and core changes. + +- the new paraslash scheduler, short and sweet. +- Support for m4a/mp4 files via the new aac audio format + handler/filter (requires libfaad). +- each writer has its own command line parser, just like + para_recv and para_filter. +- para_client and para_audioc use the error subsystem +- writers are integrated in para_audiod (currently linux-only) +- para_client is integrated in para_audiod +- random/playlist selector: improved info strings +- new audiod commands: tasks, kill +- update to libortp-0.10.1 +- para_fade: wake time defaults to 8 hours from now +- update to autoconf-2.60 + +------------------------------------------ +0.2.12 (2006-05-12) "oriented abstraction" +------------------------------------------ + +Many user-visible changes in this release and lots of new +features: + +- the new optional dccp sender/receiver. It uses the datagram + congestion control protocol. You'll need a fairly new kernel + for this. +- paraslash works on Mac OS X (thanks to Gerd Becker) +- para_play renamed to para_write +- modular output plugin design (writers) for para_write +- new file_writer output plugin for para_write +- compress filter speed improvements +- update to libortp-0.9.1 +- update to gengetopt-2.17rc +- para_client no longer depends on libreadline (as the + code for the interactive mode was removed). +- gcc-2-95 is no longer a supported compiler. It may still + work, but it gets no more testing. +- the tarball no longer contains the screenshot images which + reduces its size quite a bit. +- configure: new command line options: --enable-mysql-headers + and --enable-mysql-libs + +------------------------------------ +0.2.11 (2006-03-11) "atomic duality" +------------------------------------ + +Here it is, the first paraslash release developed with git. There +are fairly many user-visible changes in this release. As two out of +the three "database tools" of paraslash don't use a database at all, +they are now called "audio file selectors" instead. + +- the cdt command (change database tool) becomes chs (change + selector) +- no more colon separators: The syntax of some options of + para_audiod and para_filter have changed. Use --help for + more info (and some examples). +- update to gengetopt-2.16 (thanks to Lorenzo Bettini) +- switch from cvs to git (should've done that earlier) +- the new ipc subsystem +- new audio file selector: playlist +- para_server: the dopey selector is now called "random", + and is the default selector. Use the --selector option to + choose another selector at startup, or the chs command to + change the selector at runtime. +- X86_64 fixes (thanks to Steffen Klassert) +- para_play fixes + +-------------------------------------- +0.2.10 (2006-02-17) "cyclic attractor" +-------------------------------------- + +Huge documentation update, a scrollable window for para_gui, ortp +improvements, and of course many small fixes not mentioned here. +The diffstat below is rather misleading as most insertions are due +to the new source documentation. + +- autoconf cleanup +- para_server also uses the new error subsystem +- lots of new documentation (UTSL) +- gui improvements: + - keysyms for cursor keys and for next/previous page keys + - scrollable output window + - new internal commands: scroll up/down, page up/down + - fix color of command output. +- ortp: the --chunk_time and --header flags are no longer needed +for para_recv/para_audiod as this information is now encoded in +each rtp packet sent by para_server. + +------------------------------------------- +0.2.9 (2006-01-24) "progressive turbulence" +------------------------------------------- + +Internal audiod receivers/filters, the new error subsystem and +a lot of small improvements. + +- para_recv and para_filter are integrated into the para_audiod + binary, i.e. audiod no longer spawns a new process for + each receiver/filter. As para_recv and para_filter might be + useful as standalone programs, they still get built (linked + against the same object files that are also used for audiod). +- further ortp timing improvements should reduce the CPU usage + of the ortp receiver. +- improved audio grabbing. The 'grab' command of para_audiod + has its own set of command line options. Read the output of + "para_audioc help grab" for more info. +- oggdec: configurable input prebuffer size. +- the new error subsystem gives better error diagnostics + and reduces code size. + +----------------------------------------- +0.2.8 (2006-01-02) "dynamic accumulation" +----------------------------------------- + +The new modular filter design and the para_play-hangs bugfix. + +- new executable: para_filter. It combines para_mp3dec, + para_oggdec and para_compress. It also adds a further filter + type, wav, that just inserts a wave header at the desired point + of the filter chain. All 'piping' is done in-memory (i.e. no + read/write operations are used). +- para_play: fix a stupid bug that caused it to hang under + certain circumstances. + +------------------------------------------- +0.2.7 (2006-12-27) "transparent invariance" +------------------------------------------- + +Not many user-visible changes but a fair amount of internal improvements. + +- The http sender buffers data if it can not be sent + out immediately (because the socket is not writable). This + should prevent para_server from shutting down the connection + too early on a loaded network. +- para_play also prebuffers data if it is told to start at a + future time by the --start_time option. +- The return of para_recv: It combines para_ortp_recv and + para_http_recv. Use the --receiver option to switch between + the two. para_recv builds without libortp, but contains + only the http receiver in this case. +- update to ortp 0.8.1. As this ortp release contains incompatible + changes, para_recv-0.2.7 won't link against older ortp libs. +- improved ortp timings. +- use of gcc-extensions that #define away for non-gcc and + gcc < 3.0. + +------------------------------------------- +0.2.6 (2005-10-29) "recursive compensation" +------------------------------------------- + +Transparent session encryption (uses openssl's Alleged RC4 cipher), +the internal find command and several other improvements and cleanups. + +- Encrypt the session if encryption is requested by the client + (default for para_client 0.2.6). This is backwards + compatible, so older clients can still connect to para_server + 0.2.6. Use the new client option --plain to request an + uncrypted session (off by default, must be set to on in + order to connect to para_server 0.2.x with 0 <= x <= 5). +- para_server uses an internal function to locate audio files + rather than calling find(1). The server option + --mysql_audio_file_dir replaces --mysql_find_cmd. +- documentation update +- man pages +- header file cleanup +- para_client code cleanup +- para_gui: faster display of output of display commands + +------------------------------------------ +0.2.5 (2005-10-13) "aggressive resolution" +------------------------------------------ + +This release adds internal senders, i.e. no more external programs are +spawned for sending out the audio data. There are two different senders +available: The http sender and the ortp sender (former para_send which +is no longer needed). + +The new sender code has a plugin-like design so it can be easily +extended should there be be any future need for supporting another +network streaming protocol. All senders are completely independent of +each other. In particular, the http and the ortp sender can operate +in parallel. + +- new server command: sender to control senders at runtime. + Read the output of "para_server -h" and "para_client help + sender" for more information. +- para_recv renamed to para_ortp_recv +- new executable: para_http_recv, a simple command line + http receiver. +- major afs/mp3/ogg code simplifications due to internal + senders. +- ogg timing improvements +- fix several minor memory leaks (found by valgrind) +- empty stream definitions work again +- com_ne(): ignore errors on remove +- audiod: fix segfault on server restart + +--------------------------------------- +0.2.4 (2005-09-21) "toxic anticipation" +--------------------------------------- + +Several small improvements, fixes and the new grab command. + +- audiod: + - new command: "grab" to grab the output of the stream reader + or any filters. Read the output of "para_audioc help grab" + for more information. + - fix memory leak + - code cleanup +- audioc: new command line option: --bufsize to specify a + buffer size different from the default size 8192. +- improved error diagnostics for para_play. +- new configure option: --enable-ssldir so search for openssl in + non-standard places +- sdl_gui: Make it look nice again for 1024x768 +- server: report total size of memory allocated with sbrk by malloc, + new command line option: --announce_time + +----------------------------------------- +0.2.3 (2005-09-01) "hydrophilic movement" +----------------------------------------- + +Two new executables and major feature enhancements. + +- audiod filters: It is now possible to specify arbitrary many + (including none) filters for each supported audio + format. This can be used e.g. for normalizing volume, + transforming or grabbing the audio stream, or for using + visualizers. Read the output of "para_audiod -h" for the + syntax of the new --filter_cmd option. +- new executable: para_play, a tiny alsa player. It + can play wave files or raw pcm (16 bit little endian) + from stdin. +- new executable: para_compress, a dynamic range compressor + intended to keep audio output at a consistent volume. Derived + from [AudioCompress](http://trikuare.cx/code/AudioCompress.html). +- audiod: New option: --stream_delay. This can be used in + a local network to syncronize the audio output of all + clients that play the same stream. + +------------------------------------------ +0.2.2 (2005-08-19) "tangential excitation" +------------------------------------------ + +Mostly internal changes in this release, but also some new commands +for the mysql database tool. + +- cleanup exec.c, fix para_exec bug +- compile time loglevel (log messages below the given level + won't be compiled in, which reduces the size of the + resulting binaries) +- new log macros that shorten the size of the source code. +- workaround a gcc-4.1 bug (?) that caused send_cred_buffer() + to send only zeros. With this workaround, para_audioc works + again. +- avoid gcc-4 warning: conflicting types for built-in function 'clog' +- new mysql commands: "rm" (remove entry), "mv" (rename entry) "ne" + (new entry), "snp" (set numplayed). Read the manual for more + information. + +--------------------------------------- +0.2.1 (2005-08-15) "surreal experience" +--------------------------------------- + +Here comes paraslash-0.2.1. It contains a couple of new features and, +surprise, only minor bug fixes. + +- kill noisy mp3 debug message +- cleanup of the build system +- para_server and para_client directly use the crypto routines + of the openssl library rather than invoking the openssl command + line utitlity +- server/audiod: new option --user to switch to the given user + when invoked as root. Read the output of "para_server -h" for + more information. +- gui/sdl_gui: new option --stat_cmd to be used to retrieve the + status. Default: "para_audioc stat" +- sdl_gui: new option --pic_cmd to be used to download the picture. + Default: "para_client pic" +- audiod: 5 slots ought to be enough for everybody +- audiod: new status item: Uptime, kill hup command + +------------------------------------------ +0.2.0 (2005-08-06) "distributed diffusion" +------------------------------------------ + +After several month of increased development activity, paraslash-0.2.0 +has arrived. It contains many new features and is much more +self-contained than the old 0.1.x series. Enjoy! + +- para_server: fix hang on song change and crash on sighup. + Speed up mysql queries. The DIR_LIKE macro is gone. +- new executables: para_audiod, the local audio daemon that + starts playback (uses SCM_CREDENTIALS socket magic) and + para_audioc, the corresponding client. +- new executables: para_mp3dec/para_oggdec, two really teensy + decoders. para_mp3dec is based on libmad, para_oggdec requires + libvorbisfile. +- ovsend/ovrecv are capable of streaming ogg as well as mp3, so + they are now called para_send and para_recv respectively. +- documentation updates +- para_gui is themable. For now there is the default theme that + looks as before and the simple theme: blue and easy. +- gui: audio streaming is now handled by audiod. Time display shows + playback time rather than streaming time +- slider: update to libzmw-0.2.0 +- para_krell: fix crash on server shutdown +- switch from gzip to bzip2 + +---------------------------------------- +0.1.7 (2005-04-18) "melting penetration" +---------------------------------------- + +The main change in this release is clearly the oggvorbis rewrite, +but there are also lots of smaller changes. If you intend to use both +the mp3 and the ogg plugin, it is recommended to use software mixing, +e.g. the dmix plugin which is provided by ALSA. + +- new executables: para_ovsend and para_ovrecv for sending/receiving + oggvorbis files via rtp. Requires the open rtp library. Get it at + http://www.linphone.org/ortp/ +- rewrite of the ogg_vorbis core code +- configure detects libzmw and, if detected, includes + para_slider to the list of binaries to be built by make +- server stream writers read from their associated fifo rather + than from stdin +- slider: two new sliders, lastplayed and numplayed +- fix nasty double free bug which caused random segfaults in case of + mp3 files with invalid header information +- gui: new command line option: --stream_timeout=seconds to + deactivate a slot if it is idle for that many seconds (default=`5') +- diffstats + +--------------------------------------- +0.1.6 (2005-03-05) "asymptotic balance" +--------------------------------------- + +Only little user-visible changes in this release. Mainly bugfixes and +core code cleanup. This is probably the most stable version ever if you +stick to mp3... + +- fix several memory leaks +- rename default name of mysql database from "music" to "paraslash". + Use para_server's --mysql_database option if you do not want to + rename your old database. +- rework ogg vorbis code +- make update command work on mysql servers with LOCAL_INFILE + disabled +- gui: improved stream I/O (slots) +- simplified audio format API +- para_pob_ogg is gone + +------------------------------------ +0.1.5 (2004-12-31) "opaque eternity" +------------------------------------ + +Let's slide gently into the new year. + +- new: para_slider (not built automatically, type "make + para_slider" to build). A toy for those who always felt that + creating stream definitions is difficult. See screenshots, + README and FEATURES for more info. +- improved signal handling. Fixes server segfault on SIGHUP + for linux kernels newer than Aug 24 2004 and makes para_gui + race-free. +- reload database tool on SIGHUP +- improved help message for sl +- do not log "broken pipe" messages as errors. They are + perfectly ok. +- fix wrong error message on permission errors + +----------------------------------------- +0.1.4 (2004-12-19) "tunneling transition" +----------------------------------------- + +Bugfix release. As expected, 0.1.3 introduced a bunch of new bugs. +Hopefully, most of them got wiped out with this release. Some +enhancements went also in. + +- improved error diagnostics for all commands +- stradd/picadd: overwrite previous contents if entry already + exists, rather than returning errors +- stradd: use current stream if invoked without args +- faster (and hopefully more stable) ogg-vorbis handling +- para_krell: reap children to avoid zombie-flooding in case + no server is running +- si: report also server pid +- server: don't busy-loop if dbtool reports only invalid files. +- gui: CTRL+C works again, fix stream_read command line option +- fix pic_add, hist +- fix mysql dbtool startup in case no database exists +- many small fixes and cleanups + +--------------------------------------- +0.1.3: (2004-12-10) "vanishing inertia" +--------------------------------------- + +Starting from this release, the database tools are integrated in the +server binary. This decreases server startup time, reduces code size +and speeds up database commands. However, the layout of the underlying +mysql database changed only slightly and 0.1.3 should be backwards +compatible in that respect. + +Visible changes: + +- If mysql is not detected at compile time, or fails to init + at runtime, fall back to the dopey database tool which should + always work. +- para_dbtool and dbtool.conf are gone. All mysql specific + options are read from server.conf and are prefixed by 'mysql_'. +- new command: cdt (change database tool) +- new command line option: dbtool (choose startup database tool) +- The name of current stream is now stored in the database, + so paraslash remembers its current stream when restarted. +- new command: csp (change stream and play) +- para_gui also reports current database tool and server uptime + +------------------------------------------- +0.1.2: (2004-11-28) "spherical fluctuation" +------------------------------------------- + +Point release before the big dbtool changes go in. + +- dbtool: rename ca to cam (copy all meta data). It now also + copies numplayed and lastplayed time as well as the picture + id. +- fix endless-loop-bug caused by mp3 files with invalid header + +----------------------------------------- +0.1.1: (2004-11-05) "floating atmosphere" +----------------------------------------- + +- gkrellm plugin +- new dbtool command: mbox. Browse your sound-file collection + with your favorite mail reader. +- several small fixes + +------------------------------------- +0.1.0: (2004-10-22) "rotating cortex" +------------------------------------- + +- fix logging bug for loglevel > VERBOSE +- fix skip command +- correct timings for vbr mp3s +- modular audio format support +- ogg-vorbis support (experimental) +- new server option: autoplay + +----------------------------------------- +0.0.99: (2004-07-25) "harmonic deviation" +----------------------------------------- + +- rename projectname from icc to paraslash (play, archive, rate + and stream large audio sets happily) +- paraslash is no longer restricted to one particular audio + streaming software +- new dbtool commands (stradd, strq, strdel) for easy stream + managment w/o configuration file. That obsoletes stream_defs + file/config option for dbtool. +- picadd accepts jpeg data from stdin +- new server commands: ps (select previous stream), sc (song change) +- new default pictures for sdl_gui +- gui: new key_map option for binding commands and internal + functions to arbitrary keys, nice help screen, rip out + soundcard/linux specific stuff, avoid noise artefacts while jumping, + show silly logo on startup +- new executables: para_fade for fading volume, para_dbadm for + manipulating attributes +- cdb adds _all_ tables to mysql database +- revised and beautified documentation +- sample dbtool rewritten in C +- autoconf + +--------------------------------------------- +0.0.98: (2003-12-26) "incremental smoothness" +--------------------------------------------- + +- kick icecast in favour of poc. That removes some races and reduces + core code considerably. +- cbr/vbr is displayed by stat and gui/sdl_gui. New status flags + give finer info on afs' status. +- gui can start decoder (see config options). Further new gui + commands: refresh (^L), jmp (F1-F10) +- gui rereads conf on SIGUSR1 instead of SIGHUP. SIGHUP + terminates gui. This fixes dead instances consuming memory + continuously. +- new dbtool command: verb for sending verbatim sql queries. +- fix pid_list races (by removing pid_list) +- codename funnies + +-------------------- +0.0.97: (2003-10-26) +-------------------- + +- installation prefix now defaults to /usr/local +- new commands for gui: snozze, sleep and reread config +- config file for gui and sdl_gui +- fix problems with filenames containing funny characters + (reported by Thomas Forell) +- improved signal handling for gui, now it rereads conf on SIGHUP +- new dbtool command: cdb (create database) +- switch from argtable to gengetopt +- major code cleanup and speed improvements +- fix several potential buffer overflows +- many small fixes and cleanups + +------------------- +0.0.96 (2003-08-30) +------------------- + +- easy stream_defs syntax +- sdl_gui can display images associated to the file being played +- Major feature enhancements for icc_gui including dynamic text + placement and the top/bottom window design +- vrfy/clean now also checks for NULL values in attributes as + well as for invalid picture pointers +- fix long outstanding case sensitivity bug +- many small fixes and cleanups + +------------------- +0.0.95 (2003-06-29) +------------------- + +- sdl gui runs much faster +- new dbtool command: ca (copy attributes) +- count and display number of times the song has been played +- new feature: scoring +- command line options for sdl_gui +- simpler syntax of streams file +- decrease network traffic of stat +- fix zombie bug +- many small fixes and cleanups + +------------------- +0.0.94 (2003-05-04) +------------------- + +- new server command: ns (next stream) +- new icc_gui command: c (change stream) +- internal mp3info +- stat shows also id3 tag info +- new sdl based gui +- log flodding bug fixed +- many small fixes and cleanups + +------------------- +0.0.93 (2003-03-28) +------------------- + +- colors for icc_gui +- icc_gui sets volume directly (linux only) +- proper locking that fixes some races +- fix security bug that caused commands to be executed even + with unsufficient permissions +- new command: hup to make all servers reread their configuration file +- icecast meta data streaming +- many small fixes and cleanups diff --git a/web/manual.m4 b/web/manual.m4 deleted file mode 100644 index d63b07e8..00000000 --- a/web/manual.m4 +++ /dev/null @@ -1,2236 +0,0 @@ -dnl To generate the html version, execute -dnl m4 web/manual.m4 | grutatxt --toc - -define(`LOCAL_LINK_NAME', `translit(`$1', `A-Z -', `a-z__')') -define(`REMOVE_NEWLINE', `translit(`$1',` -', ` ')') - -define(`REFERENCE', ./``#''`LOCAL_LINK_NAME($1)' (`REMOVE_NEWLINE($2)')) -define(`XREFERENCE', `$1' (`REMOVE_NEWLINE($2)')) -define(`EMPH', ``_''`REMOVE_NEWLINE($1)'``_'') - -Paraslash user manual -===================== - -This document describes how to install, configure and use the paraslash -network audio streaming system. Most chapters start with a chapter -overview and conclude with an example section. We try to focus on -general concepts and on the interaction of the various pieces of the -paraslash package. Hence this user manual is not meant as a replacement -for the manual pages that describe all command line options of each -paraslash executable. - ------------- -Introduction ------------- - -In this chapter we give an REFERENCE(Overview, overview) of the -interactions of the two main programs contained in the paraslash -package, followed by REFERENCE(The paraslash executables, brief -descriptions) of all executables. - -Overview -~~~~~~~~ - -The core functionality of the para suite is provided by two main -executables, para_server and para_audiod. The former maintains a -database of audio files and streams these files to para_audiod which -receives and plays the stream. - -In a typical setting, both para_server and para_audiod act as -background daemons whose functionality is controlled by client -programs: the para_audioc client controls para_audiod over a local -socket while the para_client program connects to para_server over a -local or remote networking connection. - -Typically, these two daemons run on different hosts but a local setup -is also possible. - -A simplified picture of a typical setup is as follows -<< -
- server_host                                  client_host
- ~~~~~~~~~~~                                  ~~~~~~~~~~~
- 
- +-----------+         audio stream           +-----------+
- |para_server| -----------------------------> |para_audiod|
- +-----------+                                +-----------+
-      ^                                            ^
-      |                                            |
-      |                                            | connect
-      |                                            |
-      |                                            |
-      |                                       +-----------+
-      |                                       |para_audioc|
-      |                                       +-----------+
-      |
-      |
-      |                  connect              +-----------+
-      +-------------------------------------- |para_client|
-                                              +-----------+
-
->> - -The paraslash executables -~~~~~~~~~~~~~~~~~~~~~~~~~ - -*para_server* - -para_server streams binary audio data (MP3, ...) over local and/or -remote networks. It listens on a TCP port and accepts commands such -as play, stop, pause, next from authenticated clients. There are -many more commands though, see the man page of para_server for a -description of all commands. - -It supports three built-in network streaming protocols -(senders/receivers): HTTP, DCCP, or UDP. This is explained in more -detail in the section on REFERENCE(Networking, networking). - -The built-in audio file selector of paraslash is used to manage your -audio files. It maintains statistics on the usage of all available -audio files such as last-played time, and the number of times each -file was selected. - -Additional information may be added to the database to allow -fine-grained selection based on various properties of the audio file, -including information found in (ID3) tags. However, old-fashioned -playlists are also supported. - -It is also possible to store images (album covers) and lyrics in the -database and associate these to the corresponding audio files. - -The section on the REFERENCE(The audio file selector, audio file -selector) discusses this topic. - - -*para_client* - -The client program to connect to para_server. paraslash commands -are sent to para_server and the response is dumped to STDOUT. This -can be used by any scripting language to produce user interfaces with -little programming effort. - -All connections between para_server and para_client are encrypted -with a symmetric session key. For each user of paraslash you must -create a public/secret RSA key pair for authentication. - -If para_client is started without non-option arguments, an interactive -session (shell) is started. Command history and command completion are -supported through libreadline. - -*para_audiod* - -The local daemon that collects information from para_server. - -It runs on the client side and connects to para_server. As soon as -para_server announces the availability of an audio stream, para_audiod -starts an appropriate receiver, any number of filters and a paraslash -writer to play the stream. - -Moreover, para_audiod listens on a local socket and sends status -information about para_server and para_audiod to local clients on -request. Access via this local socket may be restricted by using Unix -socket credentials, if available. - - -*para_audioc* - -The client program which talks to para_audiod. Used to control -para_audiod, to receive status info, or to grab the stream at any -point of the decoding process. Like para_client, para_audioc supports -interactive sessions on systems with libreadline. - -*para_recv* - -A command line HTTP/DCCP/UDP stream grabber. The http mode is -compatible with arbitrary HTTP streaming sources (e.g. icecast). -In addition to the three network streaming modes, para_recv can also -operate in local (afh) mode. In this mode it writes the content of -an audio file on the local file system in complete chunks to stdout, -optionally 'just in time'. This allows to cut an audio file without -first decoding it, and it enables third-party software which is unaware -of the particular audio format to send complete frames in real time. - -*para_filter* - -A filter program that reads from STDIN and writes to STDOUT. -Like para_recv, this is an atomic building block which can be used to -assemble higher-level audio receiving facilities. It combines several -different functionalities in one tool: decoders for multiple audio -formats and a number of processing filters, among these a normalizer -for audio volume. - -*para_afh* - -A small stand-alone program that prints tech info about the given -audio file to STDOUT. It can be instructed to print a "chunk table", -an array of offsets within the audio file. - -*para_write* - -A modular audio stream writer. It supports a simple file writer -output plug-in and optional WAV/raw players for ALSA (Linux) and for -coreaudio (Mac OS). para_write can also be used as a stand-alone WAV -or raw audio player. - -*para_play* - -A command line audio player. - -*para_gui* - -Curses-based gui that presents status information obtained in a curses -window. Appearance can be customized via themes. para_gui provides -key-bindings for the most common server commands and new key-bindings -can be added easily. - - -*para_fade* - -An alarm clock and volume-fader for OSS and ALSA. - ------------ -Quick start ------------ - -This chapter lists the REFERENCE(Requirements, necessary software) -that must be installed to compile the paraslash package, describes -how to REFERENCE(Installation, compile and install) the paraslash -source code and the steps that have to be performed in order to -REFERENCE(Quick start, set up) a typical server and client. - -Requirements -~~~~~~~~~~~~ -For the impatient: - - git clone git://git.tuebingen.mpg.de/osl - cd osl && make && sudo make install && sudo ldconfig - sudo apt-get install autoconf libssl-dev help2man gengetopt \ - libmad0-dev libid3tag0-dev libasound2-dev libvorbis-dev \ - libfaad-dev libspeex-dev libFLAC-dev libsamplerate-dev \ - libasound2-dev libao-dev libreadline-dev libncurses-dev \ - libopus-dev - -Detailed description: In any case you'll need - - - XREFERENCE(http://people.tuebingen.mpg.de/maan/osl/, libosl). - The _object storage layer_ library is used by para_server. To - clone the source code repository, execute - - git clone git://git.tuebingen.mpg.de/osl - - - XREFERENCE(ftp://ftp.gnu.org/pub/gnu/gcc, gcc) or - XREFERENCE(http://clang.llvm.org, clang). All gcc versions - >= 3.3 are currently supported. Clang version 1.1 or newer - should work as well. - - - XREFERENCE(ftp://ftp.gnu.org/pub/gnu/make, gnu make) is - also shipped with the disto. On BSD systems the gnu make - executable is often called gmake. - - - XREFERENCE(ftp://ftp.gnu.org/pub/gnu/bash, bash). Some - scripts which run during compilation require the EMPH(Bourne - again shell). It is most likely already installed. - - - XREFERENCE(ftp://ftp.gnu.org/pub/gnu/gengetopt/, gengetopt) - is needed to generate the C code for the command line parsers - of all paraslash executables. - - - XREFERENCE(ftp://ftp.gnu.org/pub/gnu/help2man, help2man) - is used to create the man pages. - -Optional: - - - XREFERENCE(http://www.openssl.org/, openssl) or - XREFERENCE(ftp://ftp.gnupg.org/gcrypt/libgcrypt/, libgcrypt). - At least one of these two libraries is needed as the backend - for cryptographic routines on both the server and the client - side. Both openssl and libgcrypt are usually shipped with the - distro, but you might have to install the development package - (libssl-dev or libgcrypt-dev on debian systems) as well. - - - XREFERENCE(http://www.underbit.com/products/mad/, libmad). - To compile in MP3 support for paraslash, the development - package must be installed. It is called libmad0-dev on - debian-based systems. Note that libmad is not necessary on - the server side, i.e. for sending MP3 files. - - - XREFERENCE(http://www.underbit.com/products/mad/, - libid3tag). For version-2 ID3 tag support, you'll need - the libid3tag development package libid3tag0-dev. Without - libid3tag, only version-1 tags are recognized. The mp3 tagger - also needs this library for modifying (id3v1 and id3v2) tags. - - - XREFERENCE(http://www.xiph.org/downloads/, ogg vorbis). - For ogg vorbis streams you'll need libogg, libvorbis, - libvorbisfile. The corresponding Debian packages are called - libogg-dev and libvorbis-dev. - - - XREFERENCE(http://www.audiocoding.com/, libfaad). For aac - files (m4a) you'll need libfaad (libfaad-dev). - - - XREFERENCE(http://www.speex.org/, speex). In order to stream - or decode speex files, libspeex (libspeex-dev) is required. - - - XREFERENCE(http://flac.sourceforge.net/, flac). To stream - or decode files encoded with the _Free Lossless Audio Codec_, - libFLAC (libFLAC-dev) must be installed. - - - XREFERENCE(http://www.mega-nerd.com/SRC/index.html, - libsamplerate). The resample filter will only be compiled if - this library is installed. Debian package: libsamplerate-dev. - - - XREFERENCE(ftp://ftp.alsa-project.org/pub/lib/, alsa-lib). On - Linux, you'll need to have ALSA's development package - libasound2-dev installed. - - - XREFERENCE(http://downloads.xiph.org/releases/ao/, - libao). Needed to build the ao writer (ESD, PulseAudio,...). - Debian package: libao-dev. - - - XREFERENCE(ftp://ftp.gnu.org/pub/gnu/ncurses, curses). Needed - for para_gui. Debian package: libncurses-dev. - - - XREFERENCE(http://cnswww.cns.cwru.edu/php/chet/readline/rltop.html, - GNU Readline). If this library (libreadline-dev) is installed, - para_client, para_audioc and para_play support interactive - sessions. - -Installation -~~~~~~~~~~~~ -To build the sources from a tarball, execute - - ./configure && make - -To build from git or a gitweb snapshot, run this command instead: - - ./autogen.sh - -There should be no errors but probably some warnings about missing -packages which usually implies that not all audio formats will be -supported. If headers or libs are installed at unusual locations you -might need to tell the configure script where to find them. Try - - ./configure --help - -to see a list of options. If the paraslash package was compiled -successfully, execute (optionally) - - make test - -to run the paraslash test suite. If all tests pass, execute as root - - make install - -to install executables under /usr/local/bin and the man pages under -/usr/local/man. - -Configuration -~~~~~~~~~~~~~ - -*Step 1*: Create a paraslash user - -In order to control para_server at runtime you must create a paraslash -user. As authentication is based on the RSA crypto system you'll have -to create an RSA key pair. If you already have a user and an RSA key -pair, you may skip this step. - -In this section we'll assume a typical setup: You would like to run -para_server on some host called server_host as user foo, and you want -to connect to para_server from another machine called client_host as -user bar. - -As foo@server_host, create ~/.paraslash/server.users by typing the -following commands: - - user=bar - target=~/.paraslash/server.users - key=~/.paraslash/id_rsa.pub.$user - perms=AFS_READ,AFS_WRITE,VSS_READ,VSS_WRITE - mkdir -p ~/.paraslash - echo "user $user $key $perms" >> $target - -Next, change to the "bar" account on client_host and generate the -key pair with the commands - - ssh-keygen -q -t rsa -b 2048 -N '' -f $key - -This generates the two files id_rsa and id_rsa.pub in ~/.ssh. Note -that para_server won't accept keys shorter than 2048 bits. Moreover, -para_client rejects private keys which are world-readable. - -para_server only needs to know the public key of the key pair just -created. Copy this public key to server_host: - - src=~/.ssh/id_rsa.pub - dest=.paraslash/id_rsa.pub.$LOGNAME - scp $src foo@server_host:$dest - -Finally, tell para_client to connect to server_host: - - conf=~/.paraslash/client.conf - echo 'hostname server_host' > $conf - - -*Step 2*: Start para_server - -For this first try, we'll use the info loglevel to make the output -of para_server more verbose. - - para_server -l info - -Now you can use para_client to connect to the server and issue -commands. Open a new shell as bar@client_host and try - - para_client help - para_client si - -to retrieve the list of available commands and some server info. -Don't proceed if this doesn't work. - -*Step 3*: Create and populate the database - -An empty database is created with - - para_client init - -This initializes a couple of empty tables under -~/.paraslash/afs_database-0.4. You normally don't need to look at these -tables, but it's good to know that you can start from scratch with - - rm -rf ~/.paraslash/afs_database-0.4 - -in case something went wrong. - -Next, you need to add some audio files to that database so that -para_server knows about them. Choose an absolute path to a directory -containing some audio files and add them to the audio file table: - - para_client add /my/mp3/dir - -This might take a while, so it is a good idea to start with a directory -containing not too many files. Note that the table only contains data -about the audio files found, not the files themselves. - -You may print the list of all known audio files with - - para_client ls - -*Step 4*: Configure para_audiod - -We will have to tell para_audiod that it should receive the audio -stream from server_host via http: - - para_audiod -l info -r '.:http -i server_host' - -You should now be able to listen to the audio stream once para_server -starts streaming. To activate streaming, execute - - para_client play - -Since no playlist has been specified yet, the "dummy" mode which -selects all known audio files is activated automatically. See the -section on the REFERENCE(The audio file selector, audio file selector) -for how to use playlists and moods to specify which files should be -streamed in which order. - -*Troubleshooting* - -If you receive a socket related error on server or audiod startup, -make sure you have write permissions to the /var/paraslash directory: - - sudo chown $LOGNAME /var/paraslash - -Alternatively, use the --afs-socket (para_server) or --socket -(para_audiod) option to specify a different socket pathname. - -To identify streaming problems try to receive, decode and play the -stream manually using para_recv, para_filter and para_write as follows. -For simplicity we assume that you're running Linux/ALSA and that only -MP3 files have been added to the database. - - para_recv -r 'http -i server_host' > file.mp3 - # (interrupt with CTRL+C after a few seconds) - ls -l file.mp3 # should not be empty - para_filter -f mp3dec -f wav < file.mp3 > file.wav - ls -l file.wav # should be much bigger than file.mp3 - para_write -w alsa < file.wav - -Double check what is logged by para_server and use the --loglevel -option of para_recv, para_filter and para_write to increase verbosity. - ---------------- -User management ---------------- - -para_server uses a challenge-response mechanism to authenticate -requests from incoming connections, similar to ssh's public key -authentication method. Authenticated connections are encrypted using -a stream cipher, either RC4 or AES in integer counter mode. - -In this chapter we briefly describe RSA, RC4 and AES, and sketch the -REFERENCE(Client-server authentication, authentication handshake) -between para_client and para_server. User management is discussed -in the section on REFERENCE(The user_list file, the user_list file). -These sections are all about communication between the client and the -server. Connecting para_audiod is a different matter and is described -in a REFERENCE(Connecting para_audiod, separate section). - - - -RSA, RC4, AES -~~~~~~~~~~~~~ - -RSA is an asymmetric block cipher which is used in many applications, -including ssh and gpg. An RSA key consists in fact of two keys, -called the public key and the private key. A message can be encrypted -with either key and only the counterpart of that key can decrypt -the message. While RSA can be used for both signing and encrypting -a message, paraslash uses RSA only for the latter purpose. The -RSA public key encryption and signatures algorithms are defined in -detail in RFC 2437. - -RC4 is a stream cipher, i.e. the input is XORed with a pseudo-random -key stream to produce the output. Decryption uses the same function -calls as encryption. While RC4 supports variable key lengths, -paraslash uses a fixed length of 256 bits, which is considered a -strong encryption by today's standards. Since the same key must never -be used twice, a different, randomly-generated key is used for every -new connection. - -AES, the advanced encryption standard, is a well-known symmetric block -cipher, i.e. a transformation operating on fixed-length blocks which -is determined by a single key for both encryption and decryption. Any -block cipher can be turned into a stream cipher by generating -a pseudo-random key stream by encrypting successive values of a -counter. The AES_CTR128 stream cipher used in paraslash is obtained -in this way from the AES block cipher with a 128 bit block size. - - -Client-server authentication -~~~~~~~~~~~~~~~~~~~~~~~~~~~~ - -The authentication handshake between para_client and para_server goes -as follows: - - - para_client connects to para_server and sends an - authentication request for a user. It does so by connecting - to TCP port 2990 of the server host. This port is called the - para_server _control port_. - - - para_server accepts the connection and forks a child process - which handles the incoming request. The parent process keeps - listening on the control port while the child process (also - called para_server below) continues as follows. - - - para_server loads the RSA public key of that user, fills a - fixed-length buffer with random bytes, encrypts that buffer - using the public key and sends the encrypted buffer to the - client. The first part of the buffer is the challenge which - is used for authentication while the second part is the - session key. - - - para_client receives the encrypted buffer and decrypts it - with the user's private key, thereby obtaining the challenge - buffer and the session key. It sends the SHA1 hash value of - the challenge back to para_server and stores the session key - for further use. - - - para_server also computes the SHA1 hash of the challenge - and compares it against what was sent back by the client. - - - If the two hashes do not match, the authentication has - failed and para_server closes the connection. - - - Otherwise the user is considered authenticated and the client - is allowed to proceed by sending a command to be executed. From - this point on the communication is encrypted using the stream - cipher with the session key known to both peers. - -paraslash relies on the quality of the pseudo-random bytes provided -by the crypto library (openssl or libgcrypt), on the security of -the implementation of the RSA, RC4 and AES crypto routines and on the -infeasibility to invert the SHA1 function. - -Neither para_server or para_client create RSA keys on their own. This -has to be done once for each user as sketched in REFERENCE(Quick start, -Quick start) and discussed in more detail REFERENCE(The user_list -file, below). - -The user_list file -~~~~~~~~~~~~~~~~~~ - -At startup para_server reads the user list file which contains one -line per user. The default location of the user list file may be -changed with the --user-list option. - -There should be at least one user in this file. Each user must have -an RSA key pair. The public part of the key is needed by para_server -while the private key is needed by para_client. Each line of the -user list file must be of the form - - user - -where _username_ is an arbitrary string (usually the user's login -name), _key_ is the full path to that user's public RSA key, and -_perms_ is a comma-separated list of zero or more of the following -permission bits: - - +---------------------------------------------------------+ - | AFS_READ | read the contents of the databases | - +-----------+---------------------------------------------+ - | AFS_WRITE | change database contents | - +-----------+---------------------------------------------+ - | VSS_READ | obtain information about the current stream | - +-----------+---------------------------------------------+ - | VSS_WRITE | change the current stream | - +---------------------------------------------------------+ - -The permission bits specify which commands the user is allowed to -execute. The output of - - para_client help - -contains in the third column the permissions needed to execute the -command. - -It is possible to make para_server reread the user_list file by -executing the paraslash "hup" command or by sending SIGHUP to the -PID of para_server. - - -Connecting para_audiod -~~~~~~~~~~~~~~~~~~~~~~ - -para_audiod listens on a Unix domain socket. Those sockets are -for local communication only, so only local users can connect to -para_audiod. The default is to let any user connect but this can be -restricted on platforms that support UNIX socket credentials which -allow para_audiod to obtain the Unix credentials of the connecting -process. - -Use para_audiod's --user-allow option to allow connections only for -a limited set of users. - ------------------------ -The audio file selector ------------------------ - -paraslash comes with a sophisticated audio file selector (AFS), -whose main task is to determine which file to stream next, based on -information on the audio files stored in a database. It communicates -also with para_client whenever an AFS command is executed, for example -to answer a database query. - -Besides the traditional playlists, AFS supports audio file selection -based on _moods_ which act as a filter that limits the set of all -known audio files to those which satisfy certain criteria. It also -maintains tables containing images (e.g. album cover art) and lyrics -that can be associated with one or more audio files. - -AFS uses XREFERENCE(http://people.tuebingen.mpg.de/maan/osl/, libosl), the -object storage layer library, as the backend library for storing -information on audio files, playlists, etc. This library offers -functionality similar to a relational database, but is much more -lightweight than a full database backend. - -In this chapter we sketch the setup of the REFERENCE(The AFS process, -AFS process) during server startup and proceed with the description -of the REFERENCE(Database layout, layout) of the various database -tables. The section on REFERENCE(Playlists and moods, playlists -and moods) explains these two audio file selection mechanisms -in detail and contains pratical examples. The way REFERENCE(File -renames and content changes, file renames and content changes) are -detected is discussed briefly before the REFERENCE(Troubleshooting, -Troubleshooting) section concludes the chapter. - -The AFS process -~~~~~~~~~~~~~~~ - -On startup, para_server forks to create the AFS process which opens -the OSL database tables. The server process communicates with the -AFS process via pipes and shared memory. Usually, the AFS process -awakes only briefly whenever the current audio file changes. The AFS -process determines the next audio file, opens it, verifies it has -not been changed since it was added to the database and passes the -open file descriptor to the server process, along with audio file -meta-data such as file name, duration, audio format and so on. The -server process then starts to stream the audio file. - -The AFS process also accepts connections from local clients via -a well-known socket. However, only child processes of para_server -may connect through this socket. All server commands that have the -AFS_READ or AFS_WRITE permission bits use this mechanism to query or -change the database. - -Database layout -~~~~~~~~~~~~~~~ - -*The audio file table* - -This is the most important and usually also the largest table of the -AFS database. It contains the information needed to stream each audio -file. In particular the following data is stored for each audio file. - - - SHA1 hash value of the audio file contents. This is computed - once when the file is added to the database. Whenever AFS - selects this audio file for streaming the hash value is - recomputed and checked against the value stored in the - database to detect content changes. - - - The time when this audio file was last played. - - - The number of times the file has been played so far. - - - The attribute bitmask. - - - The image id which describes the image associated with this - audio file. - - - The lyrics id which describes the lyrics associated with - this audio file. - - - The audio format id (MP3, OGG, ...). - - - An amplification value that can be used by the amplification - filter to pre-amplify the decoded audio stream. - - - The chunk table. It describes the location and the timing - of the building blocks of the audio file. This is used by - para_server to send chunks of the file at appropriate times. - - - The duration of the audio file. - - - Tag information contained in the audio file (ID3 tags, - Vorbis comments, ...). - - - The number of channels - - - The encoding bitrate. - - - The sampling frequency. - -To add or refresh the data contained in the audio file table, the _add_ -command is used. It takes the full path of either an audio file or a -directory. In the latter case, the directory is traversed recursively -and all files which are recognized as valid audio files are added to -the database. - -*The attribute table* - -The attribute table contains two columns, _name_ and _bitnum_. An -attribute is simply a name for a certain bit number in the attribute -bitmask of the audio file table. - -Each of the 64 bits of the attribute bitmask can be set for each -audio file individually. Hence up to 64 different attributes may be -defined. For example, "pop", "rock", "blues", "jazz", "instrumental", -"german_lyrics", "speech", whatever. You are free to choose as -many attributes as you like and there are no naming restrictions -for attributes. - -A new attribute "test" is created by - - para_client addatt test -and - para_client lsatt - -lists all available attributes. You can set the "test" attribute for -an audio file by executing - - para_client setatt test+ /path/to/the/audio/file - -Similarly, the "test" bit can be removed from an audio file with - - para_client setatt test- /path/to/the/audio/file - -Instead of a path you may use a shell wildcard pattern. The attribute -is applied to all audio files matching this pattern: - - para_client setatt test+ '/test/directory/*' - -The command - - para_client -- ls -l=v - -gives you a verbose listing of your audio files also showing which -attributes are set. - -In case you wonder why the double-dash in the above command is needed: -It tells para_client to not interpret the options after the dashes. If -you find this annoying, just say - - alias para='para_client --' - -and be happy. In what follows we shall use this alias. - -The "test" attribute can be dropped from the database with - - para rmatt test - -Read the output of - - para help ls - para help setatt - -for more information and a complete list of command line options to -these commands. - -*Blob tables* - -The image, lyrics, moods and playlists tables are all blob tables. -Blob tables consist of three columns each: The identifier which is -a positive non-negative number that is auto-incremented, the name -(an arbitrary string) and the content (the blob). - -All blob tables support the same set of actions: cat, ls, mv, rm -and add. Of course, _add_ is used for adding new blobs to the table -while the other actions have the same meaning as the corresponding -Unix commands. The paraslash commands to perform these actions are -constructed as the concatenation of the table name and the action. For -example addimg, catimg, lsimg, mvimg, rmimg are the commands that -manipulate or query the image table. - -The add variant of these commands is special as these commands read -the blob contents from stdin. To add an image to the image table the -command - - para addimg image_name < file.jpg - -can be used. - -Note that the images and lyrics are not interpreted at all, and also -the playlist and the mood blobs are only investigated when the mood -or playlist is activated with the select command. - -*The score table* - -Unlike all other tables the contents of the score table remain in -memory and are never stored on disk. The score table contains two -columns: The SHA1 hash value (of an audio file) and its current -score. - -However, only those files which are admissible for the current mood -or playlist are contained in the score table. The audio file selector -always chooses the row with the highest score as the file to stream -next. While doing so, it computes the new score and updates the -last_played and the num_played fields in the audio file table. - -The score table is recomputed by the select command which loads a -mood or playlist. Audio files are chosen for streaming from the rows -of the score table on a highest-score-first basis. - - -Playlists and moods -~~~~~~~~~~~~~~~~~~~ - -Playlists and moods offer two different ways of specifying the set of -admissible files. A playlist in itself describes a set of admissible -files. A mood, in contrast, describes the set of admissible files in -terms of attributes and other type of information available in the -audio file table. As an example, a mood can define a filename pattern, -which is then matched against the names of audio files in the table. - -*Playlists* - -Playlists are accommodated in the playlist table of the afs database, -using the aforementioned blob format for tables. A new playlist is -created with the addpl command by specifying the full (absolute) -paths of all desired audio files, separated by newlines. Example: - - find /my/mp3/dir -name "*.mp3" | para addpl my_playlist - -If _my_playlist_ already exists it is overwritten. To activate the -new playlist, execute - - para select p/my_playlist - -The audio file selector will assign scores to each entry of the list, -in descending order so that files will be selected in order. If a -file could not be opened for streaming, its entry is removed from -the score table (but not from the playlist). - -*Moods* - -A mood consists of a unique name and its *mood definition*, which is -a set of *mood lines* containing expressions in terms of attributes -and other data contained in the database. - -At any time at most one mood can be *active* which means that -para_server is going to select only files from that subset of -admissible files. - -So in order to create a mood definition one has to write a set of -mood lines. Mood lines come in three flavours: Accept lines, deny -lines and score lines. - -The general syntax of the three types of mood lines is - - - accept [with score ] [if] [not] [options] - deny [with score ] [if] [not] [options] - score [if] [not] [options] - - -Here is either an integer or the string "random" which assigns -a random score to all matching files. The score value changes the -order in which admissible files are going to be selected, but is of -minor importance for this introduction. - -So we concentrate on the first two forms, i.e. accept and deny -lines. As usual, everything in square brackets is optional, i.e. -accept/deny lines take the following form when ignoring scores: - - accept [if] [not] [options] - -and analogously for the deny case. The "if" keyword is only syntactic -sugar and has no function. The "not" keyword just inverts the result, -so the essence of a mood line is the mood method part and the options -following thereafter. - -A *mood method* is realized as a function which takes an audio file -and computes a number from the data contained in the database. -If this number is non-negative, we say the file *matches* the mood -method. The file matches the full mood line if it either - - - matches the mood method and the "not" keyword is not given, -or - - does not match the mood method, but the "not" keyword is given. - -The set of admissible files for the whole mood is now defined as those -files which match at least one accept mood line, but no deny mood line. -More formally, an audio file F is admissible if and only if - - (F ~ AL1 or F ~ AL2...) and not (F ~ DL1 or F ~ DN2 ...) - -where AL1, AL2... are the accept lines, DL1, DL2... are the deny -lines and "~" means "matches". - -The cases where no mood lines of accept/deny type are defined need -special treatment: - - - Neither accept nor deny lines: This treats all files as - admissible (in fact, that is the definition of the dummy mood - which is activated automatically if no moods are available). - - - Only accept lines: A file is admissible iff it matches at - least one accept line: - - F ~ AL1 or F ~ AL2 or ... - - - Only deny lines: A file is admissible iff it matches no - deny line: - - not (F ~ DL1 or F ~ DN2 ...) - - - -*List of mood_methods* - - no_attributes_set - -Takes no arguments and matches an audio file if and only if no -attributes are set. - - is_set - -Takes the name of an attribute and matches iff that attribute is set. - - path_matches - -Takes a filename pattern and matches iff the path of the audio file -matches the pattern. - - artist_matches - album_matches - title_matches - comment_matches - -Takes an extended regular expression and matches iff the text of the -corresponding tag of the audio file matches the pattern. If the tag -is not set, the empty string is matched against the pattern. - - year ~ - bitrate ~ - frequency ~ - channels ~ - num_played ~ - -Takes a comparator ~ of the set {<, =, <=, >, >=, !=} and a number -. Matches an audio file iff the condition ~ is -satisfied where val is the corresponding value of the audio file -(value of the year tag, bitrate in kbit/s, frequency in Hz, channel -count, play count). - -The year tag is special as its value is undefined if the audio file -has no year tag or the content of the year tag is not a number. Such -audio files never match. Another difference is the special treatment -if the year tag is a two-digit number. In this case either 1900 or -2000 is added to the tag value, depending on whether the number is -greater than 2000 plus the current year. - - -*Mood usage* - -To create a new mood called "my_mood", write its definition into -some temporary file, say "tmpfile", and add it to the mood table -by executing - - para addmood my_mood < tmpfile - -If the mood definition is really short, you may just pipe it to the -client instead of using temporary files. Like this: - - echo "$MOOD_DEFINITION" | para addmood my_mood - -There is no need to keep the temporary file since you can always use -the catmood command to get it back: - - para catmood my_mood - -A mood can be activated by executing - - para select m/my_mood - -Once active, the list of admissible files is shown by the ls command -if the "-a" switch is given: - - para ls -a - - -*Example mood definition* - -Suppose you have defined attributes "punk" and "rock" and want to define -a mood containing only Punk-Rock songs. That is, an audio file should be -admissible if and only if both attributes are set. Since - - punk and rock - -is obviously the same as - - not (not punk or not rock) - -(de Morgan's rule), a mood definition that selects only Punk-Rock -songs is - - deny if not is_set punk - deny if not is_set rock - - - -File renames and content changes -~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ - -Since the audio file selector knows the SHA1 of each audio file that -has been added to the afs database, it recognizes if the content of -a file has changed, e.g. because an ID3 tag was added or modified. -Also, if a file has been renamed or moved to a different location, -afs will detect that an entry with the same hash value already exists -in the audio file table. - -In both cases it is enough to just re-add the new file. In the -first case (file content changed), the audio table is updated, while -metadata such as the num_played and last_played fields, as well as -the attributes, remain unchanged. In the other case, when the file -is moved or renamed, only the path information is updated, all other -data remains as before. - -It is possible to change the behaviour of the add command by using the -"-l" (lazy add) or the "-f" (force add) option. - -Troubleshooting -~~~~~~~~~~~~~~~ - -Use the debug loglevel (-l debug) to show debugging info. All paraslash -executables have a brief online help which is displayed when -h is -given. The --detailed-help option prints the full help text. - -If para_server crashed or was killed by SIGKILL (signal 9), it -may refuse to start again because of "dirty osl tables". In this -case you'll have to run the oslfsck program of libosl to fix your -database: - - oslfsck -fd ~/.paraslash/afs_database-0.4 - -However, make sure para_server isn't running before executing oslfsck. - -If you don't mind to recreate your database you can start -from scratch by removing the entire database directory, i.e. - - rm -rf ~/.paraslash/afs_database-0.4 - -Be aware that this removes all attribute definitions, all playlists -and all mood definitions and requires to re-initialize the tables. - -Although oslfsck fixes inconsistencies in database tables it doesn't -care about the table contents. To check for invalid table contents, use - - para_client check - -This prints out references to missing audio files as well as invalid -playlists and mood definitions. - -Similarly, para_audiod refuses to start if its socket file exists, since -this indicates that another instance of para_audiod is running. After -a crash a stale socket file might remain and you must run - - para_audiod --force - -once to fix it up. - ---------------------------------------- -Audio formats and audio format handlers ---------------------------------------- - -Audio formats -~~~~~~~~~~~~~ - -The following audio formats are supported by paraslash: - -*MP3* - -Mp3, MPEG-1 Audio Layer 3, is a common audio format for audio storage, -designed as part of its MPEG-1 standard. An MP3 file is made up of -multiple MP3 frames, which consist of a header and a data block. The -size of an MP3 frame depends on the bit rate and on the number -of channels. For a typical CD-audio file (sample rate of 44.1 kHz -stereo), encoded with a bit rate of 128 kbit, an MP3 frame is about -400 bytes large. - -*OGG/Vorbis* - -OGG is a standardized audio container format, while Vorbis is an -open source codec for lossy audio compression. Since Vorbis is most -commonly made available via the OGG container format, it is often -referred to as OGG/Vorbis. The OGG container format divides data into -chunks called OGG pages. A typical OGG page is about 4KB large. The -Vorbis codec creates variable-bitrate (VBR) data, where the bitrate -may vary considerably. - -*OGG/Speex* - -Speex is an open-source speech codec that is based on CELP (Code -Excited Linear Prediction) coding. It is designed for voice -over IP applications, has modest complexity and a small memory -footprint. Wideband and narrowband (telephone quality) speech are -supported. As for Vorbis audio, Speex bit-streams are often stored -in OGG files. As of 2012 this codec is considered obsolete since the -Oppus codec, described below, surpasses its performance in all areas. - -*OGG/Opus* - -Opus is a lossy audio compression format standardized through RFC -6716 in 2012. It combines the speech-oriented SILK codec and the -low-latency CELT (Constrained Energy Lapped Transform) codec. Like -OGG/Vorbis and OGG/Speex, Opus data is usually encapsulated in OGG -containers. All known software patents which cover Opus are licensed -under royalty-free terms. - -*AAC* - -Advanced Audio Coding (AAC) is a standardized, lossy compression -and encoding scheme for digital audio which is the default audio -format for Apple's iPhone, iPod, iTunes. Usually MPEG-4 is used as -the container format and audio files encoded with AAC have the .m4a -extension. A typical AAC frame is about 700 bytes large. - -*WMA* - -Windows Media Audio (WMA) is an audio data compression technology -developed by Microsoft. A WMA file is usually encapsulated in the -Advanced Systems Format (ASF) container format, which also specifies -how meta data about the file is to be encoded. The bit stream of WMA -is composed of superframes, each containing one or more frames of -2048 samples. For 16 bit stereo a WMA superframe is about 8K large. - -*FLAC* - -The Free Lossless Audio Codec (FLAC) compresses audio without quality -loss. It gives better compression ratios than a general purpose -compressor like zip or bzip2 because FLAC is designed specifically -for audio. A FLAC-encoded file consists of frames of varying size, up -to 16K. Each frame starts with a header that contains all information -necessary to decode the frame. - -Meta data -~~~~~~~~~ - -Unfortunately, each audio format has its own conventions how meta -data is added as tags to the audio file. - -For MP3 files, ID3, version 1 and 2 are widely used. ID3 version 1 -is rather simple but also very limited as it supports only artist, -title, album, year and comment tags. Each of these can only be at most -32 characters long. ID3, version 2 is much more flexible but requires -a separate library being installed for paraslash to support it. - -Ogg vorbis, ogg speex and flac files contain meta data as Vorbis -comments, which are typically implemented as strings of the form -"[TAG]=[VALUE]". Unlike ID3 version 1 tags, one may use whichever -tags are appropriate for the content. - -AAC files usually use the MPEG-4 container format for storing meta -data while WMA files wrap meta data as special objects within the -ASF container format. - -paraslash only tracks the most common tags that are supported by -all tag variants: artist, title, year, album, comment. When a file -is added to the AFS database, the meta data of the file is extracted -and stored in the audio file table. - -Chunks and chunk tables -~~~~~~~~~~~~~~~~~~~~~~~ - -paraslash uses the word "chunk" as common term for the building blocks -of an audio file. For MP3 files, a chunk is the same as an MP3 frame, -while for OGG files a chunk is an OGG page, etc. Therefore the chunk -size varies considerably between audio formats, from a few hundred -bytes (MP3) up to 16K (FLAC). - -The chunk table contains the offsets within the audio file that -correspond to the chunk boundaries of the file. Like the meta data, -the chunk table is computed and stored in the database whenever an -audio file is added. - -The paraslash senders (see below) always send complete chunks. The -granularity for seeking is therefore determined by the chunk size. - -Audio format handlers -~~~~~~~~~~~~~~~~~~~~~ - -For each audio format paraslash contains an audio format handler whose -first task is to tell whether a given file is a valid audio file of -this type. If so, the audio file handler extracts some technical data -(duration, sampling rate, number of channels etc.), computes the -chunk table and reads the meta data. - -The audio format handler code is linked into para_server and executed -via the _add_ command. The same code is also available as a stand-alone -tool, para_afh, which prints the technical data, the chunk table -and the meta data of a file. Moreover, all audio format handlers are -combined in the afh receiver which is part of para_recv and para_play. - ----------- -Networking ----------- - -Paraslash uses different network connections for control and data. -para_client communicates with para_server over a dedicated TCP control -connection. To transport audio data, separate data connections are -used. For these data connections, a variety of transports (UDP, DCCP, -HTTP) can be chosen. - -The chapter starts with the REFERENCE(The paraslash control -service, control service), followed by a section on the various -REFERENCE(Streaming protocols, streaming protocols) in which the data -connections are described. The way audio file headers are embedded into -the stream is discussed REFERENCE(Streams with headers and headerless -streams, briefly) before the REFERENCE(Networking examples, example -section) which illustrates typical commands for real-life scenarios. - -Both IPv4 and IPv6 are supported. - -The paraslash control service -~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ - -para_server is controlled at runtime via the paraslash control -connection. This connection is used for server commands (play, stop, -...) as well as for afs commands (ls, select, ...). - -The server listens on a TCP port and accepts connections from clients -that connect the open port. Each connection causes the server to fork -off a client process which inherits the connection and deals with that -client only. In this classical accept/fork approach the server process -is unaffected if the child dies or goes crazy for whatever reason. In -fact, the child process can not change address space of server process. - -The section on REFERENCE(Client-server authentication, client-server -authentication) above described the early connection establishment -from the crypto point of view. Here it is described what happens -after the connection (including crypto setup) has been established. -There are four processes involved during command dispatch as sketched -in the following diagram. - -<< -
- server_host                                   client_host
- ~~~~~~~~~~~                                   ~~~~~~~~~~~
-
- +-----------+             connect            +-----------+
- |para_server|<------------------------------ |para_client|
- +-----------+                                +-----------+
-      |                                             ^
-      |     fork   +---+                            |
-      +----------> |AFS|                            |
-      |            +---+                            |
-      |              ^                              |
-      |              |                              |
-      |              | connect (cookie)             |
-      |              |                              |
-      |              |                              |
-      |    fork   +-----+    inherited connection   |
-      +---------->|child|<--------------------------+
-                  +-----+
-
->> - -Note that the child process is not a child of the afs process, -so communication of these two processes has to happen via local -sockets. In order to avoid abuse of the local socket by unrelated -processes, a magic cookie is created once at server startup time just -before the server process forks off the AFS process. This cookie is -known to the server, AFS and the child, but not to unrelated processes. - -There are two different kinds of commands: First there are commands -that cause the server to respond with some answer such as the list -of all audio files. All but the addblob commands (addimg, addlyr, -addpl, addmood) are of this kind. The addblob commands add contents -to the database, so they need to transfer data the other way round, -from the client to the server. - -There is no knowledge about the server commands built into para_client, -so it does not know about addblob commands. Instead, the server sends -a special "awaiting data" packet for these commands. If the client -receives this packet, it sends STDIN to the server, otherwise it -dumps data from the server to STDOUT. - -Streaming protocols -~~~~~~~~~~~~~~~~~~~ - -A network (audio) stream usually consists of one streaming source, -the _sender_, and one or more _receivers_ which read data over the -network from the streaming source. - -Senders are thus part of para_server while receivers are part of -para_audiod. Moreover, there is the stand-alone tool para_recv which -can be used to manually download a stream, either from para_server -or from a web-based audio streaming service. - -The following three streaming protocols are supported by paraslash: - - - HTTP. Recommended for public streams that can be played by - any player like mpg123, xmms, itunes, winamp, etc. The HTTP - sender is supported on all operating systems and all platforms. - - - DCCP. Recommended for LAN streaming. DCCP is currently - available only for Linux. - - - UDP. Recommended for multicast LAN streaming. - -See the Appendix on REFERENCE(Network protocols, network protocols) -for brief descriptions of the various protocols relevant for network -audio streaming with paraslash. - -It is possible to activate more than one sender simultaneously. -Senders can be controlled at run time and via config file and command -line options. - -Note that audio connections are _not_ encrypted. Transport or Internet -layer encryption should be used if encrypted data connections are -needed. - -Since DCCP and TCP are both connection-oriented protocols, connection -establishment/teardown and access control are very similar between -these two streaming protocols. UDP is the most lightweight option, -since in contrast to TCP/DCCP it is connectionless. It is also the -only protocol supporting IP multicast. - -The HTTP and the DCCP sender listen on a (TCP/DCCP) port waiting for -clients to connect and establish a connection via some protocol-defined -handshake mechanism. Both senders maintain two linked lists each: -The list of all clients which are currently connected, and the list -of access control entries which determines who is allowed to connect. -IP-based access control may be configured through config file and -command line options and via the "allow" and "deny" sender subcommands. - -Upon receiving a GET request from the client, the HTTP sender sends -back a status line and a message. The body of this message is the -audio stream. This is common practice and is supported by many popular -clients which can thus be used to play a stream offered by para_server. -For DCCP things are a bit simpler: No messages are exchanged between -the receiver and sender. The client simply connects and the sender -starts to stream. - -DCCP is an experimental protocol which offers a number of new features -not available for TCP. Both ends can negotiate these features using -a built-in negotiation mechanism. In contrast to TCP/HTTP, DCCP is -datagram-based (no retransmissions) and thus should not be used over -lossy media (e.g. WiFi networks). One useful feature offered by DCCP -is access to a variety of different congestion-control mechanisms -called CCIDs. Two different CCIDs are available per default on Linux: - - - - _CCID 2_. A Congestion Control mechanism similar to that - of TCP. The sender maintains a congestion window and halves - this window in response to congestion. - - - - _CCID-3_. Designed to be fair when competing for bandwidth. - It has lower variation of throughput over time compared with - TCP, which makes it suitable for streaming media. - -Unlike the HTTP and DCCP senders, the UDP sender maintains only a -single list, the _target list_. This list describes the set of clients -to which the stream is sent. There is no list for access control and -no "allow" and "deny" commands for the UDP sender. Instead, the "add" -and "delete" commands can be used to modify the target list. - -Since both UDP and DCCP offer an unreliable datagram-based transport, -additional measures are necessary to guard against disruptions over -networks that are lossy or which may be subject to interference (as -is for instance the case with WiFi). Paraslash uses FEC (Forward -Error Correction) to guard against packet losses and reordering. The -stream is FEC-encoded before it is sent through the UDP socket and -must be decoded accordingly on the receiver side. - -The packet size and the amount of redundancy introduced by FEC can -be configured via the FEC parameters which are dictated by server -and may also be configured through the "sender" command. The FEC -parameters are encoded in the header of each network packet, so no -configuration is necessary on the receiver side. See the section on -REFERENCE(Forward error correction, FEC) below. - -Streams with headers and headerless streams -~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ - -For OGG/Vorbis, OGG/Speex and wma streams, some of the information -needed to decode the stream is only contained in the audio file -header of the container format but not in each data chunk. Clients -must be able to obtain this information in case streaming starts in -the middle of the file or if para_audiod is started while para_server -is already sending a stream. - -This is accomplished in different ways, depending on the streaming -protocol. For connection-oriented streams (HTTP, DCCP) the audio file -header is sent prior to audio file data. This technique however does -not work for the connectionless UDP transport. Hence the audio file -header is periodically being embedded into the UDP audio data stream. -By default, the header is resent after five seconds. The receiver has -to wait until the next header arrives before it can start decoding -the stream. - -Examples -~~~~~~~~ - -The "si" (server info) command lists some information about the -currently running server process. - --> Show PIDs, number of connected clients, uptime, and more: - - para_client si - -The sender command of para_server prints information about senders, -like the various access control lists, and it allows to (de-)activate -senders and to change the access permissions at runtime. - --> List all senders - - para_client sender - --> Obtain general help for the sender command: - - para_client help sender - --> Get help for a specific sender (contains further examples): - - s=http # or dccp or udp - para_client sender $s help - --> Show status of the http sender - - para_client sender http status - -By default para_server activates both the HTTP and th DCCP sender on -startup. This can be changed via command line options or para_server's -config file. - --> List config file options for senders: - - para_server -h - -All senders share the "on" and "off" commands, so senders may be -activated and deactivated independently of each other. - --> Switch off the http sender: - - para_client sender http off - --> Receive a DCCP stream using CCID2 and write the output into a file: - - host=foo.org; ccid=2; filename=bar - para_recv --receiver "dccp --host $host --ccid $ccid" > $filename - -Note the quotes around the arguments for the dccp receiver. Each -receiver has its own set of command line options and its own command -line parser, so arguments for the dccp receiver must be protected -from being interpreted by para_recv. - --> Start UDP multicast, using the default multicast address: - - para_client sender udp add 224.0.1.38 - --> Receive FEC-encoded multicast stream and write the output into a file: - - filename=foo - para_recv -r udp > $filename - --> Add an UDP unicast for a client to the target list of the UDP sender: - - t=client.foo.org - para_client sender udp add $t - --> Receive this (FEC-encoded) unicast stream: - - filename=foo - para_recv -r 'udp -i 0.0.0.0' > $filename - --> Create a minimal config for para_audiod for HTTP streams: - - c=$HOME/.paraslash/audiod.conf.min; s=server.foo.com - echo receiver \".:http -i $s\" > $c - para_audiod --config $c - -------- -Filters -------- - -A paraslash filter is a module which transforms an input stream into -an output stream. Filters are included in the para_audiod executable -and in the stand-alone tool para_filter which usually contains the -same modules. - -While para_filter reads its input stream from STDIN and writes -the output to STDOUT, the filter modules of para_audiod are always -connected to a receiver which produces the input stream and a writer -which absorbs the output stream. - -Some filters depend on a specific library and are not compiled in -if this library was not found at compile time. To see the list of -supported filters, run para_filter and para_audiod with the --help -option. The output looks similar to the following: - - Available filters: - compress wav amp fecdec wmadec prebuffer oggdec aacdec mp3dec - -Out of these filter modules, a chain of filters can be constructed, -much in the way Unix pipes can be chained, and analogous to the use -of modules in gstreamer: The output of the first filter becomes the -input of the second filter. There is no limitation on the number of -filters and the same filter may occur more than once. - -Like receivers, each filter has its own command line options which -must be quoted to protect them from the command line options of -the driving application (para_audiod or para_filter). Example: - - para_filter -f 'mp3dec --ignore-crc' -f 'compress --damp 1' - -For para_audiod, each audio format has its own set of filters. The -name of the audio format for which the filter should be applied can -be used as the prefix for the filter option. Example: - - para_audiod -f 'mp3:prebuffer --duration 300' - -The "mp3" prefix above is actually interpreted as a POSIX extended -regular expression. Therefore - - para_audiod -f '.:prebuffer --duration 300' - -activates the prebuffer filter for all supported audio formats (because -"." matches all audio formats) while - - para_audiod -f 'wma|ogg:prebuffer --duration 300' - -activates it only for wma and ogg streams. - -Decoders -~~~~~~~~ - -For each supported audio format there is a corresponding filter -which decodes audio data in this format to 16 bit PCM data which -can be directly sent to the sound device or any other software that -operates on undecoded PCM data (visualizers, equalizers etc.). Such -filters are called _decoders_ in general, and xxxdec is the name of -the paraslash decoder for the audio format xxx. For example, the mp3 -decoder is called mp3dec. - -Note that the output of the decoder is about 10 times larger than -its input. This means that filters that operate on the decoded audio -stream have to deal with much more data than filters that transform -the audio stream before it is fed to the decoder. - -Paraslash relies on external libraries for most decoders, so these -libraries must be installed for the decoder to be included in the -executables. For example, the mp3dec filter depends on the mad library. - -Forward error correction -~~~~~~~~~~~~~~~~~~~~~~~~ - -As already mentioned REFERENCE(Streaming protocols, earlier), -paraslash uses forward error correction (FEC) for the unreliable UDP -and DCCP transports. FEC is a technique which was invented already -in 1960 by Reed and Solomon and which is widely used for the parity -calculations of storage devices (RAID arrays). It is based on the -algebraic concept of finite fields, today called Galois fields, in -honour of the mathematician Galois (1811-1832). The FEC implementation -of paraslash is based on code by Luigi Rizzo. - -Although the details require a sound knowledge of the underlying -mathematics, the basic idea is not hard to understand: For positive -integers k and n with k < n it is possible to compute for any k given -data bytes d_1, ..., d_k the corresponding r := n -k parity bytes p_1, -..., p_r such that all data bytes can be reconstructed from *any* -k bytes of the set - - {d_1, ..., d_k, p_1, ..., p_r}. - -FEC-encoding for unreliable network transports boils down to slicing -the audio stream into groups of k suitably sized pieces called _slices_ -and computing the r corresponding parity slices. This step is performed -in para_server which then sends both the data and the parity slices -over the unreliable network connection. If the client was able -to receive at least k of the n = k + r slices, it can reconstruct -(FEC-decode) the original audio stream. - -From these observations it is clear that there are three different -FEC parameters: The slice size, the number of data slices k, and the -total number of slices n. It is crucial to choose the slice size -such that no fragmentation of network packets takes place because -FEC only guards against losses and reordering but fails if slices are -received partially. - -FEC decoding in paralash is performed through the fecdec filter which -usually is the first filter (there can be other filters before fecdec -if these do not alter the audio stream). - - -Volume adjustment (amp and compress) -~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ - -The amp and the compress filter both adjust the volume of the audio -stream. These filters operate on uncompressed audio samples. Hence -they are usually placed directly after the decoding filter. Each -sample is multiplied with a scaling factor (>= 1) which makes amp -and compress quite expensive in terms of computing power. - -*amp* - -The amp filter amplifies the audio stream by a fixed scaling factor -that must be known in advance. For para_audiod this factor is derived -from the amplification field of the audio file's entry in the audio -file table while para_filter uses the value given at the command line. - -The optimal scaling factor F for an audio file is the largest real -number F >= 1 such that after multiplication with F all samples still -fit into the sample interval [-32768, 32767]. One can use para_filter -in combination with the sox utility to compute F: - - para_filter -f mp3dec -f wav < file.mp3 | sox -t wav - -e stat -v - -The amplification value V which is stored in the audio file table, -however, is an integer between 0 and 255 which is connected to F -through the formula - - V = (F - 1) * 64. - -To store V in the audio file table, the command - - para_client -- touch -a=V file.mp3 - -is used. The reader is encouraged to write a script that performs -these computations :) - -*compress* - -Unlike the amplification filter, the compress filter adjusts the volume -of the audio stream dynamically without prior knowledge about the peak -value. It maintains the maximal volume of the last n samples of the -audio stream and computes a suitable amplification factor based on that -value and the various configuration options. It tries to chose this -factor such that the adjusted volume meets the desired target level. - -Note that it makes sense to combine amp and compress. - -Misc filters (wav and prebuffer) -~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ - -These filters are rather simple and do not modify the audio stream at -all. The wav filter is only useful with para_filter and in connection -with a decoder. It asks the decoder for the number of channels and the -sample rate of the stream and adds a Microsoft wave header containing -this information at the beginning. This allows to write wav files -rather than raw PCM files (which do not contain any information about -the number of channels and the sample rate). - -The prebuffer filter simply delays the output until the given time has -passed (starting from the time the first byte was available in its -input queue) or until the given amount of data has accumulated. It -is mainly useful for para_audiod if the standard parameters result -in buffer underruns. - -Both filters require almost no additional computing time, even when -operating on uncompressed audio streams, since data buffers are simply -"pushed down" rather than copied. - -Examples -~~~~~~~~ - --> Decode an mp3 file to wav format: - - para_filter -f mp3dec -f wav < file.mp3 > file.wav - --> Amplify a raw audio file by a factor of 1.5: - - para_filter -f amp --amp 32 < foo.raw > bar.raw - ------- -Output ------- - -Once an audio stream has been received and decoded to PCM format, -it can be sent to a sound device for playback. This part is performed -by paraslash _writers_ which are described in this chapter. - -Writers -~~~~~~~ - -A paraslash writer acts as a data sink that consumes but does not -produce audio data. Paraslash writers operate on the client side and -are contained in para_audiod and in the stand-alone tool para_write. - -The para_write program reads uncompressed audio data from STDIN. If -this data starts with a wav header, sample rate, sample format and -channel count are read from the header. Otherwise CD audio (44.1KHz -16 bit little endian, stereo) is assumed but this can be overridden -by command line options. para_audiod, on the other hand, obtains -the sample rate and the number of channels from the decoder. - -Like receivers and filters, each writer has an individual set of -command line options, and for para_audiod writers can be configured -per audio format separately. It is possible to activate more than -one writer for the same stream simultaneously. - -OS-dependent APIs -~~~~~~~~~~~~~~~~~ - -Unfortunately, the various flavours of Unix on which paraslash -runs on have different APIs for opening a sound device and starting -playback. Hence for each such API there is a paraslash writer that -can play the audio stream via this API. - -*ALSA*. The _Advanced Linux Sound Architecture_ is only available on -Linux systems. Although there are several mid-layer APIs in use by -the various Linux distributions (ESD, Jack, PulseAudio), paraslash -currently supports only the low-level ALSA API which is not supposed -to be change. ALSA is very feature-rich, in particular it supports -software mixing via its DMIX plugin. ALSA is the default writer on -Linux systems. - -*OSS*. The _Open Sound System_ is the only API on *BSD Unixes and -is also available on Linux systems, usually provided by ALSA as an -emulation for backwards compatibility. This API is rather simple but -also limited. For example only one application can open the device -at any time. The OSS writer is activated by default on BSD Systems. - -*OSX*. Mac OS X has yet another API called CoreAudio. The OSX writer -for this API is only compiled in on such systems and is of course -the default there. - -*FILE*. The file writer allows to capture the audio stream and -write the PCM data to a file on the file system rather than playing -it through a sound device. It is supported on all platforms and is -always compiled in. - -*AO*. _Libao_ is a cross-platform audio library which supports a wide -variety of platforms including PulseAudio (gnome), ESD (Enlightened -Sound Daemon), AIX, Solaris and IRIX. The ao writer plays audio -through an output plugin of libao. - -Examples -~~~~~~~~ - --> Use the OSS writer to play a wav file: - - para_write --writer oss < file.wav - --> Enable ALSA software mixing for mp3 streams - - para_audiod --writer 'mp3:alsa -d plug:swmix' - - ---- -Gui ---- - -para_gui executes an arbitrary command which is supposed to print -status information to STDOUT. It then displays this information in -a curses window. By default the command - - para_audioc -- stat -p - -is executed, but this can be customized via the --stat-cmd option. In -particular it possible to use - - para_client -- stat -p - -to make para_gui work on systems on which para_audiod is not running. - -Key bindings -~~~~~~~~~~~~ - -It is possible to bind keys to arbitrary commands via custom -key-bindings. Besides the internal keys which can not be changed (help, -quit, loglevel, version...), the following flavours of key-bindings -are supported: - - - external: Shutdown curses before launching the given command. - Useful for starting other ncurses programs from within - para_gui, e.g. aumix or dialog scripts. Or, use the mbox - output format to write a mailbox containing one mail for each - (admissible) file the audio file selector knows about. Then - start mutt from within para_gui to browse your collection! - - - display: Launch the command and display its stdout in - para_gui's bottom window. - - - para: Like display, but start "para_client " instead of "". - -The general form of a key binding is - - key_map k:m:c - -which maps key k to command c using mode m. Mode may be x, d or p -for external, display and paraslash commands, respectively. - -Themes -~~~~~~ - -Currently there are only two themes for para_gui. It is easy, however, -to add more themes. To create a new theme one has to define the -position, color and geometry for for each status item that should be -shown by this theme. See gui_theme.c for examples. - -The "." and "," keys are used to switch between themes. - -Examples -~~~~~~~~ - --> Show server info: - - key_map "i:p:si" - --> Jump to the middle of the current audio file by pressing F5: - - key_map ":p:jmp 50" - --> vi-like bindings for jumping around: - - key_map "l:p:ff 10" - key_map "h:p:ff 10-" - key_map "w:p:ff 60" - key_map "b:p:ff 60-" - --> Print the current date and time: - - key_map "D:d:date" - --> Call other curses programs: - - key_map "U:x:aumix" - key_map "!:x:/bin/bash" - key_map "^E:x:/bin/sh -c 'vi ~/.paraslash/gui.conf'" - ------------ -Development ------------ - -Tools -~~~~~ - -In order to compile the sources from the git repository (rather than -from tar balls) and for contributing non-trivial changes to the -paraslash project, some additional tools should be installed on a -developer machine. - -http://git.or.cz/ (git). As described in more detail REFERENCE(Git -branches, below), the git source code management tool is used for -paraslash development. It is necessary for cloning the git repository -and for getting updates. - -ftp://ftp.gnu.org/pub/gnu/m4/ (m4). Some input files for gengetopt -are generated from templates by the m4 macro processor. - -ftp://ftp.gnu.org/pub/gnu/autoconf/ (autoconf) GNU autoconf creates -the configure file which is shipped in the tarballs but has to be -generated when compiling from git. - -http://www.triptico.com/software/grutatxt.html (grutatxt). The -HTML version of this manual and some of the paraslash web pages are -generated by the grutatxt plain text to HTML converter. If changes -are made to these text files the grutatxt package must be installed -to regenerate the HTML files. - -http://www.stack.nl/~dimitri/doxygen/ (doxygen). The documentation -of paraslash's C sources uses the doxygen documentation system. The -conventions for documenting the source code is described in the -REFERENCE(Doxygen, Doxygen section). - -ftp://ftp.gnu.org/pub/gnu/global (global). This is used to generate -browsable HTML from the C sources. It is needed by doxygen. - -Git branches -~~~~~~~~~~~~ - -Paraslash has been developed using the git source code management -tool since 2006. Development is organized roughly in the same spirit -as the git development itself, as described below. - -The following text passage is based on "A note from the maintainer", -written by Junio C Hamano, the maintainer of git. - -There are four branches in the paraslash repository that track the -source tree: "master", "maint", "next", and "pu". - -The "master" branch is meant to contain what is well tested and -ready to be used in a production setting. There could occasionally be -minor breakages or brown paper bag bugs but they are not expected to -be anything major, and more importantly quickly and easily fixable. -Every now and then, a "feature release" is cut from the tip of this -branch, named with three dotted decimal digits, like 0.4.2. - -Whenever changes are about to be included that will eventually lead to -a new major release (e.g. 0.5.0), a "maint" branch is forked off from -"master" at that point. Obvious, safe and urgent fixes after the major -release are applied to this branch and maintenance releases are cut -from it. New features never go to this branch. This branch is also -merged into "master" to propagate the fixes forward. - -A trivial and safe enhancement goes directly on top of "master". -New development does not usually happen on "master", however. -Instead, a separate topic branch is forked from the tip of "master", -and it first is tested in isolation; Usually there are a handful such -topic branches that are running ahead of "master". The tip of these -branches is not published in the public repository to keep the number -of branches that downstream developers need to worry about low. - -The quality of topic branches varies widely. Some of them start out as -"good idea but obviously is broken in some areas" and then with some -more work become "more or less done and can now be tested by wider -audience". Luckily, most of them start out in the latter, better shape. - -The "next" branch is to merge and test topic branches in the latter -category. In general, this branch always contains the tip of "master". -It might not be quite rock-solid production ready, but is expected to -work more or less without major breakage. The maintainer usually uses -the "next" version of paraslash for his own pleasure, so it cannot -be _that_ broken. The "next" branch is where new and exciting things -take place. - -The two branches "master" and "maint" are never rewound, and "next" -usually will not be either (this automatically means the topics that -have been merged into "next" are usually not rebased, and you can find -the tip of topic branches you are interested in from the output of -"git log next"). You should be able to safely build on top of them. - -However, at times "next" will be rebuilt from the tip of "master" to -get rid of merge commits that will never be in "master". The commit -that replaces "next" will usually have the identical tree, but it -will have different ancestry from the tip of "master". - -The "pu" (proposed updates) branch bundles the remainder of the -topic branches. The "pu" branch, and topic branches that are only in -"pu", are subject to rebasing in general. By the above definition -of how "next" works, you can tell that this branch will contain quite -experimental and obviously broken stuff. - -When a topic that was in "pu" proves to be in testable shape, it -graduates to "next". This is done with - - git checkout next - git merge that-topic-branch - -Sometimes, an idea that looked promising turns out to be not so good -and the topic can be dropped from "pu" in such a case. - -A topic that is in "next" is expected to be polished to perfection -before it is merged to "master". Similar to the above, this is -done with - - git checkout master - git merge that-topic-branch - git branch -d that-topic-branch - -Note that being in "next" is not a guarantee to appear in the next -release (being in "master" is such a guarantee, unless it is later -found seriously broken and reverted), nor even in any future release. - -Coding Style -~~~~~~~~~~~~ - -The preferred coding style for paraslash coincides more or less -with the style of the Linux kernel. So rather than repeating what is -written XREFERENCE(http://www.kernel.org/doc/Documentation/CodingStyle, -there), here are the most important points. - - - Burn the GNU coding standards. - - Never use spaces for indentation. - - Tabs are 8 characters, and thus indentations are also 8 characters. - - Don't put multiple assignments on a single line. - - Avoid tricky expressions. - - Don't leave whitespace at the end of lines. - - The limit on the length of lines is 80 columns. - - Use K&R style for placing braces and spaces: - - if (x is true) { - we do y - } - - - Use a space after (most) keywords. - - Do not add spaces around (inside) parenthesized expressions. - - Use one space around (on each side of) most binary and ternary operators. - - Do not use cute names like ThisVariableIsATemporaryCounter, call it tmp. - - Mixed-case names are frowned upon. - - Descriptive names for global variables are a must. - - Avoid typedefs. - - Functions should be short and sweet, and do just one thing. - - The number of local variables shouldn't exceed 10. - - Gotos are fine if they improve readability and reduce nesting. - - Don't use C99-style "// ..." comments. - - Names of macros defining constants and labels in enums are capitalized. - - Enums are preferred when defining several related constants. - - Always use the paraslash wrappers for allocating memory. - - If the name of a function is an action or an imperative. - command, the function should return an error-code integer - (<0 means error, >=0 means success). If the name is a - predicate, the function should return a "succeeded" boolean. - - -Doxygen -~~~~~~~ - -Doxygen is a documentation system for various programming -languages. The API reference on the paraslash web page is generated -by doxygen. - -It is more illustrative to look at the source code for examples than -to describe the conventions in this manual, so we only describe which -parts of the code need doxygen comments, but leave out details on -documentation conventions. - -As a rule, only the public part of the C source is documented with -Doxygen. This includes structures, defines and enumerations in header -files as well as public (non-static) C functions. These should be -documented completely. For example, each parameter and the return -value of a public function should get a descriptive doxygen comment. - -No doxygen comments are necessary for static functions and for -structures and enumerations in C files (which are used only within -this file). This does not mean, however, that those entities need -no documentation at all. Instead, common sense should be applied to -document what is not obvious from reading the code. - --------- -Appendix --------- - -Network protocols -~~~~~~~~~~~~~~~~~ - -*IP*. The _Internet Protocol_ is the primary networking protocol -used for the Internet. All protocols described below use IP as the -underlying layer. Both the prevalent IPv4 and the next-generation -IPv6 variant are being deployed actively worldwide. - -*Connection-oriented and connectionless protocols*. Connectionless -protocols differ from connection-oriented ones in that state -associated with the sending/receiving endpoints is treated -implicitly. Connectionless protocols maintain no internal knowledge -about the state of the connection. Hence they are not capable of -reacting to state changes, such as sudden loss or congestion on the -connection medium. Connection-oriented protocols, in contrast, make -this knowledge explicit. The connection is established only after -a bidirectional handshake which requires both endpoints to agree -on the state of the connection, and may also involve negotiating -specific parameters for the particular connection. Maintaining an -up-to-date internal state of the connection also in general means -that the sending endpoints perform congestion control, adapting to -qualitative changes of the connection medium. - -*Reliability*. In IP networking, packets can be lost, duplicated, -or delivered out of order, and different network protocols handle -these problems in different ways. We call a transport-layer protocol -_reliable_, if it turns the unreliable IP delivery into an ordered, -duplicate- and loss-free delivery of packets. Sequence numbers -are used to discard duplicates and re-arrange packets delivered -out-of-order. Retransmission is used to guarantee loss-free -delivery. Unreliable protocols, in contrast, do not guarantee ordering -or data integrity. - -*Classification*. With these definitions the protocols which are used -by paraslash for steaming audio data may be classified as follows. - - - HTTP/TCP: connection-oriented, reliable, - - UDP: connectionless, unreliable, - - DCCP: connection-oriented, unreliable. - -Below we give a short descriptions of these protocols. - -*TCP*. The _Transmission Control Protocol_ provides reliable, -ordered delivery of a stream and a classic window-based congestion -control. In contrast to UDP and DCCP (see below), TCP does not have -record-oriented or datagram-based syntax, i.e. it provides a stream -which is unaware and independent of any record (packet) boundaries. -TCP is used extensively by many application layers. Besides HTTP (the -Hypertext Transfer Protocol), also FTP (the File Transfer protocol), -SMTP (Simple Mail Transfer Protocol), SSH (Secure Shell) all sit on -top of TCP. - -*UDP*. The _User Datagram Protocol_ is the simplest transport-layer -protocol, built as a thin layer directly on top of IP. For this reason, -it offers the same best-effort service as IP itself, i.e. there is no -detection of duplicate or reordered packets. Being a connectionless -protocol, only minimal internal state about the connection is -maintained, which means that there is no protection against packet -loss or network congestion. Error checking and correction (if at all) -are performed in the application. - -*DCCP*. The _Datagram Congestion Control Protocol_ combines the -connection-oriented state maintenance known from TCP with the -unreliable, datagram-based transport of UDP. This means that it -is capable of reacting to changes in the connection by performing -congestion control, offering multiple alternative approaches. But it -is bound to datagram boundaries (the maximum packet size supported -by a medium), and like UDP it lacks retransmission to protect -against loss. Due to the use of sequence numbers, it is however -able to react to loss (interpreted as a congestion indication) and -to ignore out-of-order and duplicate packets. Unlike TCP it allows -to negotiate specific, binding features for a connection, such as -the choice of congestion control: classic, window-based congestion -control known from TCP is available as CCID-2, rate-based, "smooth" -congestion control is offered as CCID-3. - -*HTTP*. _The Hypertext Transfer Protocol_ is an application layer -protocol on top of TCP. It is spoken by web servers and is most often -used for web services. However, as can be seen by the many Internet -radio stations and YouTube/Flash videos, http is by far not limited to -the delivery of web pages only. Being a simple request/response based -protocol, the semantics of the protocol also allow the delivery of -multimedia content, such as audio over http. - -*Multicast*. IP multicast is not really a protocol but a technique -for one-to-many communication over an IP network. The challenge is to -deliver information to a group of destinations simultaneously using -the most efficient strategy to send the messages over each link of -the network only once. This has benefits for streaming multimedia: -the standard one-to-one unicast offered by TCP/DCCP means that -n clients listening to the same stream also consume n-times the -resources, whereas multicast requires to send the stream just once, -irrespective of the number of receivers. Since it would be costly to -maintain state for each listening receiver, multicast often implies -connectionless transport, which is the reason that it is currently -only available via UDP. - -Abstract socket namespace -~~~~~~~~~~~~~~~~~~~~~~~~~ -UNIX domain sockets are a traditional way to communicate between -processes on the same machine. They are always reliable (see above) -and don't reorder datagrams. Unlike TCP and UDP, UNIX domain sockets -support passing open file descriptors or process credentials to -other processes. - -The usual way to set up a UNIX domain socket (as obtained from -socket(2)) for listening is to first bind the socket to a file system -pathname and then call listen(2), then accept(2). Such sockets are -called _pathname sockets_ because bind(2) creates a special socket -file at the specified path. Pathname sockets allow unrelated processes -to communicate with the listening process by binding to the same path -and calling connect(2). - -There are two problems with pathname sockets: - - * The listing process must be able to (safely) create the - socket special in a directory which is also accessible to - the connecting process. - - * After an unclean shutdown of the listening process, a stale - socket special may reside on the file system. - -The abstract socket namespace is a non-portable Linux feature which -avoids these problems. Abstract sockets are still bound to a name, -but the name has no connection with file system pathnames. - -License -~~~~~~~ - -Paraslash is licensed under the GPL, version 2. Most of the code -base has been written from scratch, and those parts are GPL V2 -throughout. Notable exceptions are FEC and the WMA decoder. See the -corresponding source files for licencing details for these parts. Some -code sniplets of several other third party software packages have -been incorporated into the paraslash sources, for example log message -coloring was taken from the git sources. These third party software -packages are all published under the GPL or some other license -compatible to the GPL. - -Acknowledgements -~~~~~~~~~~~~~~~~ - -Many thanks to Gerrit Renker who read an early draft of this manual -and contributed significant improvements. - ----------- -References ----------- - -Articles -~~~~~~~~ - - Reed, Irving S.; Solomon, Gustave (1960), - XREFERENCE(http://kom.aau.dk/~heb/kurser/NOTER/KOFA01.PDF, - Polynomial Codes over Certain Finite Fields), Journal of the - Society for Industrial and Applied Mathematics (SIAM) 8 (2): - 300-304, doi:10.1137/0108018) - -RFCs -~~~~ - - - XREFERENCE(http://www.ietf.org/rfc/rfc768.txt, RFC 768) (1980): - User Datagram Protocol - - XREFERENCE(http://www.ietf.org/rfc/rfc791.txt, RFC 791) (1981): - Internet Protocol - - XREFERENCE(http://www.ietf.org/rfc/rfc2437.txt, RFC 2437) (1998): - RSA Cryptography Specifications - - XREFERENCE(http://www.ietf.org/rfc/rfc4340.txt, RFC 4340) - (2006): Datagram Congestion Control Protocol (DCCP) - - XREFERENCE(http://www.ietf.org/rfc/rfc4341.txt, RFC 4341) (2006): - Congestion Control ID 2: TCP-like Congestion Control - - XREFERENCE(http://www.ietf.org/rfc/rfc4342.txt, RFC 4342) (2006): - Congestion Control ID 3: TCP-Friendly Rate Control (TFRC) - - XREFERENCE(http://www.ietf.org/rfc/rfc6716.txt, RFC 6716) (2012): - Definition of the Opus Audio Codec - -Application web pages -~~~~~~~~~~~~~~~~~~~~~ - - - XREFERENCE(http://people.tuebingen.mpg.de/maan/paraslash/, paraslash) - - XREFERENCE(http://paraslash.systemlinux.org/, paraslash (alternative page)) - - XREFERENCE(http://xmms2.org/wiki/Main_Page, xmms) - - XREFERENCE(http://www.mpg123.de/, mpg123) - - XREFERENCE(http://gstreamer.freedesktop.org/, gstreamer) - - XREFERENCE(http://www.icecast.org/, icecast) - - XREFERENCE(http://beesbuzz.biz/code/audiocompress.php, Audio Compress) - -External documentation -~~~~~~~~~~~~~~~~~~~~~~ - - - XREFERENCE(http://kernel.org/pub/linux/kernel/people/hpa/raid6.pdf, - H. Peter Anvin: The mathematics of Raid6) - - XREFERENCE(http://info.iet.unipi.it/~luigi/fec_ccr.ps.gz, - Luigi Rizzo: Effective Erasure Codes for reliable Computer - Communication Protocols) - -Code -~~~~ - - XREFERENCE(http://info.iet.unipi.it/~luigi/vdm.tar.gz, - Original FEC implementation by Luigi Rizzo) - diff --git a/web/manual.md b/web/manual.md new file mode 100644 index 00000000..7d2c4cf3 --- /dev/null +++ b/web/manual.md @@ -0,0 +1,2223 @@ +**Paraslash user manual** + +This document describes how to install, configure and use the paraslash +network audio streaming system. Most chapters start with a chapter +overview and conclude with an example section. We try to focus on +general concepts and on the interaction of the various pieces of the +paraslash package. Hence this user manual is not meant as a replacement +for the manual pages that describe all command line options of each +paraslash executable. + +============ +Introduction +============ + +In this chapter we give an [overview](#Overview) of the interactions of +the two main programs contained in the paraslash package, followed by +[brief descriptions](#The.paraslash.executables) of all executables. + +Overview +-------- + +The core functionality of the para suite is provided by two main +executables, para_server and para_audiod. The former maintains a +database of audio files and streams these files to para_audiod which +receives and plays the stream. + +In a typical setting, both para_server and para_audiod act as +background daemons whose functionality is controlled by client +programs: the para_audioc client controls para_audiod over a local +socket while the para_client program connects to para_server over a +local or remote networking connection. + +Typically, these two daemons run on different hosts but a local setup +is also possible. + +A simplified picture of a typical setup is as follows + + server_host client_host + ~~~~~~~~~~~ ~~~~~~~~~~~ + + +-----------+ audio stream +-----------+ + |para_server| -----------------------------> |para_audiod| + +-----------+ +-----------+ + ^ ^ + | | + | | connect + | | + | | + | +-----------+ + | |para_audioc| + | +-----------+ + | + | + | connect +-----------+ + +-------------------------------------- |para_client| + +-----------+ +The paraslash executables +------------------------- + +### para_server ### + +para_server streams binary audio data (MP3, ...) over local and/or +remote networks. It listens on a TCP port and accepts commands such +as play, stop, pause, next from authenticated clients. There are +many more commands though, see the man page of para_server for a +description of all commands. + +It supports three built-in network streaming protocols +(senders/receivers): HTTP, DCCP, or UDP. This is explained in more +detail in the section on [networking](#Networking). + +The built-in audio file selector of paraslash is used to manage your +audio files. It maintains statistics on the usage of all available +audio files such as last-played time, and the number of times each +file was selected. + +Additional information may be added to the database to allow +fine-grained selection based on various properties of the audio file, +including information found in (ID3) tags. However, old-fashioned +playlists are also supported. + +It is also possible to store images (album covers) and lyrics in the +database and associate these to the corresponding audio files. + +The section on the [audio file selector](#The.audio.file.selector) +discusses this topic. + + +### para_client ### + +The client program to connect to para_server. paraslash commands +are sent to para_server and the response is dumped to STDOUT. This +can be used by any scripting language to produce user interfaces with +little programming effort. + +All connections between para_server and para_client are encrypted +with a symmetric session key. For each user of paraslash you must +create a public/secret RSA key pair for authentication. + +If para_client is started without non-option arguments, an interactive +session (shell) is started. Command history and command completion are +supported through libreadline. + +### para_audiod ### + +The local daemon that collects information from para_server. + +It runs on the client side and connects to para_server. As soon as +para_server announces the availability of an audio stream, para_audiod +starts an appropriate receiver, any number of filters and a paraslash +writer to play the stream. + +Moreover, para_audiod listens on a local socket and sends status +information about para_server and para_audiod to local clients on +request. Access via this local socket may be restricted by using Unix +socket credentials, if available. + + +### para_audioc ### + +The client program which talks to para_audiod. Used to control +para_audiod, to receive status info, or to grab the stream at any +point of the decoding process. Like para_client, para_audioc supports +interactive sessions on systems with libreadline. + +### para_recv ### + +A command line HTTP/DCCP/UDP stream grabber. The http mode is +compatible with arbitrary HTTP streaming sources (e.g. icecast). +In addition to the three network streaming modes, para_recv can also +operate in local (afh) mode. In this mode it writes the content of +an audio file on the local file system in complete chunks to stdout, +optionally 'just in time'. This allows to cut an audio file without +first decoding it, and it enables third-party software which is unaware +of the particular audio format to send complete frames in real time. + +### para_filter ### + +A filter program that reads from STDIN and writes to STDOUT. +Like para_recv, this is an atomic building block which can be used to +assemble higher-level audio receiving facilities. It combines several +different functionalities in one tool: decoders for multiple audio +formats and a number of processing filters, among these a normalizer +for audio volume. + +### para_afh ### + +A small stand-alone program that prints tech info about the given +audio file to STDOUT. It can be instructed to print a "chunk table", +an array of offsets within the audio file. + +### para_write ### + +A modular audio stream writer. It supports a simple file writer +output plug-in and optional WAV/raw players for ALSA (Linux) and for +coreaudio (Mac OS). para_write can also be used as a stand-alone WAV +or raw audio player. + +### para_play ### + +A command line audio player. + +### para_gui ### + +Curses-based gui that presents status information obtained in a curses +window. Appearance can be customized via themes. para_gui provides +key-bindings for the most common server commands and new key-bindings +can be added easily. + +### para_fade ### + +An alarm clock and volume-fader for OSS and ALSA. + +=========== +Quick start +=========== + +This chapter lists the [necessary software](#Requirements) +that must be installed to compile the paraslash package, describes +how to [compile and install](#Installation) the paraslash +source code and the steps that have to be performed in order to +[set up](#Configuration) a typical server and client. + +Requirements +------------ +### For the impatient ### + + git clone git://git.tuebingen.mpg.de/osl + cd osl && make && sudo make install && sudo ldconfig + sudo apt-get install autoconf libssl-dev help2man gengetopt \ + libmad0-dev libid3tag0-dev libasound2-dev libvorbis-dev \ + libfaad-dev libspeex-dev libFLAC-dev libsamplerate-dev \ + libasound2-dev libao-dev libreadline-dev libncurses-dev \ + libopus-dev + +### Detailed description ### + +In any case you will need + +- [libosl](http://people.tuebingen.mpg.de/maan/osl/). The _object +storage layer_ library is used by para_server. To clone the source +code repository, execute + + git clone git://git.tuebingen.mpg.de/osl + +- [gcc](ftp://ftp.gnu.org/pub/gnu/gcc) or +[clang](http://clang.llvm.org). All gcc versions >= 3.3 are currently +supported. Clang version 1.1 or newer should work as well. + +- [gnu make](ftp://ftp.gnu.org/pub/gnu/make) is also shipped with the +disto. On BSD systems the gnu make executable is often called gmake. + +- [bash](ftp://ftp.gnu.org/pub/gnu/bash). Some scripts which run +during compilation require the _Bourne again shell_. It is most +likely already installed. + +- [gengetopt](ftp://ftp.gnu.org/pub/gnu/gengetopt/) is needed to +generate the C code for the command line parsers of all paraslash +executables. + +- [help2man](ftp://ftp.gnu.org/pub/gnu/help2man) is used to create +the man pages. + +Optional: + +- [openssl](http://www.openssl.org/) or +[libgcrypt](ftp://ftp.gnupg.org/gcrypt/libgcrypt/). At least one +of these two libraries is needed as the backend for cryptographic +routines on both the server and the client side. Both openssl and +libgcrypt are usually shipped with the distro, but you might have +to install the development package (`libssl-dev` or `libgcrypt-dev` +on debian systems) as well. + +- [libmad](http://www.underbit.com/products/mad/). To compile in MP3 +support for paraslash, the development package must be installed. It +is called `libmad0-dev` on debian-based systems. Note that libmad is +not necessary on the server side, i.e., for sending MP3 files. + +- [libid3tag](http://www.underbit.com/products/mad/). For version-2 +ID3 tag support, you willl need the libid3tag development package +`libid3tag0-dev`. Without libid3tag, only version-1 tags are +recognized. The mp3 tagger also needs this library for modifying +(id3v1 and id3v2) tags. + +- [ogg vorbis](http://www.xiph.org/downloads/). For ogg vorbis streams +you need libogg, libvorbis, libvorbisfile. The corresponding Debian +packages are called `libogg-dev` and `libvorbis-dev`. + +- [libfaad](http://www.audiocoding.com/). For aac files (m4a) you +need libfaad (`libfaad-dev`). + +- [speex](http://www.speex.org/). In order to stream or decode speex +files, libspeex (`libspeex-dev`) is required. + +- [flac](http://flac.sourceforge.net/). To stream or decode files +encoded with the _Free Lossless Audio Codec_, libFLAC (`libFLAC-dev`) +must be installed. + +- [libsamplerate](http://www.mega-nerd.com/SRC/index.html). The +resample filter will only be compiled if this library is +installed. Debian package: `libsamplerate-dev`. + +- [alsa-lib](ftp://ftp.alsa-project.org/pub/lib/). On Linux, you will +need to have the ALSA development package `libasound2-dev` installed. + +- [libao](http://downloads.xiph.org/releases/ao/). Needed to build +the ao writer (ESD, PulseAudio,...). Debian package: `libao-dev`. + +- [curses](ftp://ftp.gnu.org/pub/gnu/ncurses). Needed for +para_gui. Debian package: `libncurses-dev`. + +- [GNU +Readline](http://cnswww.cns.cwru.edu/php/chet/readline/rltop.html). If +this library (`libreadline-dev`) is installed, para_client, para_audioc +and para_play support interactive sessions. + +Installation +------------ +To build the sources from a tarball, execute + + ./configure && make + +To build from git or a gitweb snapshot, run this command instead: + + ./autogen.sh + +There should be no errors but probably some warnings about missing +packages which usually implies that not all audio formats will be +supported. If headers or libs are installed at unusual locations you +might need to tell the configure script where to find them. Try + + ./configure --help + +to see a list of options. If the paraslash package was compiled +successfully, execute (optionally) + + make test + +to run the paraslash test suite. If all tests pass, execute as root + + make install + +to install executables under /usr/local/bin and the man pages under +/usr/local/man. + +Configuration +------------- + +### Create a paraslash user ### + +In order to control para_server at runtime you must create a paraslash +user. As authentication is based on the RSA crypto system you'll have +to create an RSA key pair. If you already have a user and an RSA key +pair, you may skip this step. + +In this section we'll assume a typical setup: You would like to run +para_server on some host called server_host as user foo, and you want +to connect to para_server from another machine called client_host as +user bar. + +As foo@server_host, create ~/.paraslash/server.users by typing the +following commands: + + user=bar + target=~/.paraslash/server.users + key=~/.paraslash/id_rsa.pub.$user + perms=AFS_READ,AFS_WRITE,VSS_READ,VSS_WRITE + mkdir -p ~/.paraslash + echo "user $user $key $perms" >> $target + +Next, change to the "bar" account on client_host and generate the +key pair with the commands + + ssh-keygen -q -t rsa -b 2048 -N '' -f $key + +This generates the two files id_rsa and id_rsa.pub in ~/.ssh. Note +that para_server won't accept keys shorter than 2048 bits. Moreover, +para_client rejects private keys which are world-readable. + +para_server only needs to know the public key of the key pair just +created. Copy this public key to server_host: + + src=~/.ssh/id_rsa.pub + dest=.paraslash/id_rsa.pub.$LOGNAME + scp $src foo@server_host:$dest + +Finally, tell para_client to connect to server_host: + + conf=~/.paraslash/client.conf + echo 'hostname server_host' > $conf + + +### Start para_server ### + +For this first try, we'll use the info loglevel to make the output +of para_server more verbose. + + para_server -l info + +Now you can use para_client to connect to the server and issue +commands. Open a new shell as bar@client_host and try + + para_client help + para_client si + +to retrieve the list of available commands and some server info. +Don't proceed if this doesn't work. + +### Create and populate the database ### + +An empty database is created with + + para_client init + +This initializes a couple of empty tables under +~/.paraslash/afs_database-0.4. You normally don't need to look at these +tables, but it's good to know that you can start from scratch with + + rm -rf ~/.paraslash/afs_database-0.4 + +in case something went wrong. + +Next, you need to add some audio files to that database so that +para_server knows about them. Choose an absolute path to a directory +containing some audio files and add them to the audio file table: + + para_client add /my/mp3/dir + +This might take a while, so it is a good idea to start with a directory +containing not too many files. Note that the table only contains data +about the audio files found, not the files themselves. + +You may print the list of all known audio files with + + para_client ls + +### Configure para_audiod ### + +We will have to tell para_audiod that it should receive the audio +stream from server_host via http: + + para_audiod -l info -r '.:http -i server_host' + +You should now be able to listen to the audio stream once para_server +starts streaming. To activate streaming, execute + + para_client play + +Since no playlist has been specified yet, the "dummy" mode which +selects all known audio files is activated automatically. See the +section on the [audio file selector](#The.audio.file.selector) for how +to use playlists and moods to specify which files should be streamed +in which order. + +Troubleshooting +--------------- + +If you receive a socket related error on server or audiod startup, +make sure you have write permissions to the /var/paraslash directory: + + sudo chown $LOGNAME /var/paraslash + +Alternatively, use the --afs-socket (para_server) or --socket +(para_audiod) option to specify a different socket pathname. + +To identify streaming problems try to receive, decode and play the +stream manually using para_recv, para_filter and para_write as follows. +For simplicity we assume that you're running Linux/ALSA and that only +MP3 files have been added to the database. + + para_recv -r 'http -i server_host' > file.mp3 + # (interrupt with CTRL+C after a few seconds) + ls -l file.mp3 # should not be empty + para_filter -f mp3dec -f wav < file.mp3 > file.wav + ls -l file.wav # should be much bigger than file.mp3 + para_write -w alsa < file.wav + +Double check what is logged by para_server and use the --loglevel +option of para_recv, para_filter and para_write to increase verbosity. + +=============== +User management +=============== + +para_server uses a challenge-response mechanism to authenticate +requests from incoming connections, similar to ssh's public key +authentication method. Authenticated connections are encrypted using +a stream cipher, either RC4 or AES in integer counter mode. + +In this chapter we briefly describe RSA, RC4 and AES, and sketch the +[authentication handshake](#Client-server.authentication) +between para_client and para_server. User management is discussed +in the section on [the user_list file](#The.user_list.file). +These sections are all about communication between the client and the +server. Connecting para_audiod is a different matter and is described +in a [separate section](#Connecting.para_audiod). + +RSA, RC4, AES +------------- + +RSA is an asymmetric block cipher which is used in many applications, +including ssh and gpg. An RSA key consists in fact of two keys, +called the public key and the private key. A message can be encrypted +with either key and only the counterpart of that key can decrypt +the message. While RSA can be used for both signing and encrypting +a message, paraslash uses RSA only for the latter purpose. The +RSA public key encryption and signatures algorithms are defined in +detail in RFC 2437. + +RC4 is a stream cipher, i.e. the input is XORed with a pseudo-random +key stream to produce the output. Decryption uses the same function +calls as encryption. While RC4 supports variable key lengths, +paraslash uses a fixed length of 256 bits, which is considered a +strong encryption by today's standards. Since the same key must never +be used twice, a different, randomly-generated key is used for every +new connection. + +AES, the advanced encryption standard, is a well-known symmetric block +cipher, i.e. a transformation operating on fixed-length blocks which +is determined by a single key for both encryption and decryption. Any +block cipher can be turned into a stream cipher by generating +a pseudo-random key stream by encrypting successive values of a +counter. The AES_CTR128 stream cipher used in paraslash is obtained +in this way from the AES block cipher with a 128 bit block size. + +Client-server authentication +---------------------------- + +The authentication handshake between para_client and para_server goes +as follows: + +- para_client connects to para_server and sends an authentication +request for a user. It does so by connecting to TCP port 2990 of the +server host. This port is called the para_server _control port_. + +- para_server accepts the connection and forks a child process which +handles the incoming request. The parent process keeps listening on the +control port while the child process (also called para_server below) +continues as follows. + +- para_server loads the RSA public key of that user, fills a +fixed-length buffer with random bytes, encrypts that buffer using the +public key and sends the encrypted buffer to the client. The first +part of the buffer is the challenge which is used for authentication +while the second part is the session key. + +- para_client receives the encrypted buffer and decrypts it with the +user's private key, thereby obtaining the challenge buffer and the +session key. It sends the SHA1 hash value of the challenge back to +para_server and stores the session key for further use. + +- para_server also computes the SHA1 hash of the challenge and compares +it against what was sent back by the client. + +- If the two hashes do not match, the authentication has failed and +para_server closes the connection. + +- Otherwise the user is considered authenticated and the client is +allowed to proceed by sending a command to be executed. From this +point on the communication is encrypted using the stream cipher with +the session key known to both peers. + +paraslash relies on the quality of the pseudo-random bytes provided +by the crypto library (openssl or libgcrypt), on the security of the +implementation of the RSA, RC4 and AES crypto routines and on the +infeasibility to invert the SHA1 function. + +Neither para_server or para_client create RSA keys on their +own. This has to be done once for each user as sketched in +[Quick start](#Quick.start) and discussed in more detail +[below](#The.user_list.file). + +The user_list file +------------------ + +At startup para_server reads the user list file which contains one +line per user. The default location of the user list file may be +changed with the --user-list option. + +There should be at least one user in this file. Each user must have +an RSA key pair. The public part of the key is needed by para_server +while the private key is needed by para_client. Each line of the +user list file must be of the form + + user + +where _username_ is an arbitrary string (usually the user's login +name), _key_ is the full path to that user's public RSA key, and +_perms_ is a comma-separated list of zero or more of the following +permission bits: + + +---------------------------------------------------------+ + | AFS_READ | read the contents of the databases | + +-----------+---------------------------------------------+ + | AFS_WRITE | change database contents | + +-----------+---------------------------------------------+ + | VSS_READ | obtain information about the current stream | + +-----------+---------------------------------------------+ + | VSS_WRITE | change the current stream | + +---------------------------------------------------------+ + +The permission bits specify which commands the user is allowed to +execute. The output of + + para_client help + +contains in the third column the permissions needed to execute the +command. + +It is possible to make para_server reread the user_list file by +executing the paraslash "hup" command or by sending SIGHUP to the +PID of para_server. + +Connecting para_audiod +---------------------- + +para_audiod listens on a Unix domain socket. Those sockets are +for local communication only, so only local users can connect to +para_audiod. The default is to let any user connect but this can be +restricted on platforms that support UNIX socket credentials which +allow para_audiod to obtain the Unix credentials of the connecting +process. + +Use para_audiod's --user-allow option to allow connections only for +a limited set of users. + +======================= +The audio file selector +======================= + +paraslash comes with a sophisticated audio file selector (AFS), +whose main task is to determine which file to stream next, based on +information on the audio files stored in a database. It communicates +also with para_client whenever an AFS command is executed, for example +to answer a database query. + +Besides the traditional playlists, AFS supports audio file selection +based on _moods_ which act as a filter that limits the set of all +known audio files to those which satisfy certain criteria. It also +maintains tables containing images (e.g. album cover art) and lyrics +that can be associated with one or more audio files. + +AFS employs [libosl](http://people.tuebingen.mpg.de/maan/osl/), the +object storage layer library, as the backend library for storing +information on audio files, playlists, etc. This library offers +functionality similar to a relational database, but is much more +lightweight than a full database backend. + +In this chapter we sketch the setup of the [AFS +process](#The.AFS.process) during server startup and proceed with the +description of the [layout](#Database.layout) of the various database +tables. The section on [playlists and moods](#Playlists.and.moods) +explains these two audio file selection mechanisms in detail +and contains pratical examples. The way [file renames and content +changes](#File.renames.and.content.changes) are detected is discussed +briefly before the [Troubleshooting](#Troubleshooting) section +concludes the chapter. + +The AFS process +--------------- + +On startup, para_server forks to create the AFS process which opens +the OSL database tables. The server process communicates with the +AFS process via pipes and shared memory. Usually, the AFS process +awakes only briefly whenever the current audio file changes. The AFS +process determines the next audio file, opens it, verifies it has +not been changed since it was added to the database and passes the +open file descriptor to the server process, along with audio file +meta-data such as file name, duration, audio format and so on. The +server process then starts to stream the audio file. + +The AFS process also accepts connections from local clients via +a well-known socket. However, only child processes of para_server +may connect through this socket. All server commands that have the +AFS_READ or AFS_WRITE permission bits use this mechanism to query or +change the database. + +Database layout +--------------- + +### The audio file table ### + +This is the most important and usually also the largest table of the +AFS database. It contains the information needed to stream each audio +file. In particular the following data is stored for each audio file. + +- SHA1 hash value of the audio file contents. This is computed once +when the file is added to the database. Whenever AFS selects this +audio file for streaming the hash value is recomputed and checked +against the value stored in the database to detect content changes. + +- The time when this audio file was last played. + +- The number of times the file has been played so far. + +- The attribute bitmask. + +- The image id which describes the image associated with this audio +file. + +- The lyrics id which describes the lyrics associated with this +audio file. + +- The audio format id (MP3, OGG, ...). + +- An amplification value that can be used by the amplification filter +to pre-amplify the decoded audio stream. + +- The chunk table. It describes the location and the timing of the +building blocks of the audio file. This is used by para_server to +send chunks of the file at appropriate times. + +- The duration of the audio file. + +- Tag information contained in the audio file (ID3 tags, Vorbis +comments, ...). + +- The number of channels + +- The encoding bitrate. + +- The sampling frequency. + +To add or refresh the data contained in the audio file table, the _add_ +command is used. It takes the full path of either an audio file or a +directory. In the latter case, the directory is traversed recursively +and all files which are recognized as valid audio files are added to +the database. + +### The attribute table ### + +The attribute table contains two columns, _name_ and _bitnum_. An +attribute is simply a name for a certain bit number in the attribute +bitmask of the audio file table. + +Each of the 64 bits of the attribute bitmask can be set for each +audio file individually. Hence up to 64 different attributes may be +defined. For example, "pop", "rock", "blues", "jazz", "instrumental", +"german_lyrics", "speech", whatever. You are free to choose as +many attributes as you like and there are no naming restrictions +for attributes. + +A new attribute "test" is created by + + para_client addatt test +and + para_client lsatt + +lists all available attributes. You can set the "test" attribute for +an audio file by executing + + para_client setatt test+ /path/to/the/audio/file + +Similarly, the "test" bit can be removed from an audio file with + + para_client setatt test- /path/to/the/audio/file + +Instead of a path you may use a shell wildcard pattern. The attribute +is applied to all audio files matching this pattern: + + para_client setatt test+ '/test/directory/*' + +The command + + para_client -- ls -l=v + +gives you a verbose listing of your audio files also showing which +attributes are set. + +In case you wonder why the double-dash in the above command is needed: +It tells para_client to not interpret the options after the dashes. If +you find this annoying, just say + + alias para='para_client --' + +and be happy. In what follows we shall use this alias. + +The "test" attribute can be dropped from the database with + + para rmatt test + +Read the output of + + para help ls + para help setatt + +for more information and a complete list of command line options to +these commands. + +### Blob tables ### + +The image, lyrics, moods and playlists tables are all blob tables. +Blob tables consist of three columns each: The identifier which is +a positive non-negative number that is auto-incremented, the name +(an arbitrary string) and the content (the blob). + +All blob tables support the same set of actions: cat, ls, mv, rm +and add. Of course, _add_ is used for adding new blobs to the table +while the other actions have the same meaning as the corresponding +Unix commands. The paraslash commands to perform these actions are +constructed as the concatenation of the table name and the action. For +example addimg, catimg, lsimg, mvimg, rmimg are the commands that +manipulate or query the image table. + +The add variant of these commands is special as these commands read +the blob contents from stdin. To add an image to the image table the +command + + para addimg image_name < file.jpg + +can be used. + +Note that the images and lyrics are not interpreted at all, and also +the playlist and the mood blobs are only investigated when the mood +or playlist is activated with the select command. + +### The score table ### + +Unlike all other tables the contents of the score table remain in +memory and are never stored on disk. The score table contains two +columns: The SHA1 hash value (of an audio file) and its current +score. + +However, only those files which are admissible for the current mood +or playlist are contained in the score table. The audio file selector +always chooses the row with the highest score as the file to stream +next. While doing so, it computes the new score and updates the +last_played and the num_played fields in the audio file table. + +The score table is recomputed by the select command which loads a +mood or playlist. Audio files are chosen for streaming from the rows +of the score table on a highest-score-first basis. + + +Playlists and moods +------------------- + +Playlists and moods offer two different ways of specifying the set of +admissible files. A playlist in itself describes a set of admissible +files. A mood, in contrast, describes the set of admissible files in +terms of attributes and other type of information available in the +audio file table. As an example, a mood can define a filename pattern, +which is then matched against the names of audio files in the table. + +### Playlists ### + +Playlists are accommodated in the playlist table of the afs database, +using the aforementioned blob format for tables. A new playlist is +created with the addpl command by specifying the full (absolute) +paths of all desired audio files, separated by newlines. Example: + + find /my/mp3/dir -name "*.mp3" | para addpl my_playlist + +If _my_playlist_ already exists it is overwritten. To activate the +new playlist, execute + + para select p/my_playlist + +The audio file selector will assign scores to each entry of the list, +in descending order so that files will be selected in order. If a +file could not be opened for streaming, its entry is removed from +the score table (but not from the playlist). + +### Moods ### + +A mood consists of a unique name and its *mood definition*, which is +a set of *mood lines* containing expressions in terms of attributes +and other data contained in the database. + +At any time at most one mood can be *active* which means that +para_server is going to select only files from that subset of +admissible files. + +So in order to create a mood definition one has to write a set of +mood lines. Mood lines come in three flavours: Accept lines, deny +lines and score lines. + +The general syntax of the three types of mood lines is + + + accept [with score ] [if] [not] [options] + deny [with score ] [if] [not] [options] + score [if] [not] [options] + + +Here is either an integer or the string "random" which assigns +a random score to all matching files. The score value changes the +order in which admissible files are going to be selected, but is of +minor importance for this introduction. + +So we concentrate on the first two forms, i.e. accept and deny +lines. As usual, everything in square brackets is optional, i.e. +accept/deny lines take the following form when ignoring scores: + + accept [if] [not] [options] + +and analogously for the deny case. The "if" keyword is only syntactic +sugar and has no function. The "not" keyword just inverts the result, +so the essence of a mood line is the mood method part and the options +following thereafter. + +A *mood method* is realized as a function which takes an audio file +and computes a number from the data contained in the database. +If this number is non-negative, we say the file *matches* the mood +method. The file matches the full mood line if it either + + - matches the mood method and the "not" keyword is not given, +or + - does not match the mood method, but the "not" keyword is given. + +The set of admissible files for the whole mood is now defined as those +files which match at least one accept mood line, but no deny mood line. +More formally, an audio file F is admissible if and only if + + (F ~ AL1 or F ~ AL2...) and not (F ~ DL1 or F ~ DN2 ...) + +where AL1, AL2... are the accept lines, DL1, DL2... are the deny +lines and "~" means "matches". + +The cases where no mood lines of accept/deny type are defined need +special treatment: + + - Neither accept nor deny lines: This treats all files as + admissible (in fact, that is the definition of the dummy mood + which is activated automatically if no moods are available). + + - Only accept lines: A file is admissible iff it matches at + least one accept line: + + F ~ AL1 or F ~ AL2 or ... + + - Only deny lines: A file is admissible iff it matches no + deny line: + + not (F ~ DL1 or F ~ DN2 ...) + + + +### List of mood_methods ### + + no_attributes_set + +Takes no arguments and matches an audio file if and only if no +attributes are set. + + is_set + +Takes the name of an attribute and matches iff that attribute is set. + + path_matches + +Takes a filename pattern and matches iff the path of the audio file +matches the pattern. + + artist_matches + album_matches + title_matches + comment_matches + +Takes an extended regular expression and matches iff the text of the +corresponding tag of the audio file matches the pattern. If the tag +is not set, the empty string is matched against the pattern. + + year ~ + bitrate ~ + frequency ~ + channels ~ + num_played ~ + +Takes a comparator ~ of the set {<, =, <=, >, >=, !=} and a number +. Matches an audio file iff the condition ~ is +satisfied where val is the corresponding value of the audio file +(value of the year tag, bitrate in kbit/s, frequency in Hz, channel +count, play count). + +The year tag is special as its value is undefined if the audio file +has no year tag or the content of the year tag is not a number. Such +audio files never match. Another difference is the special treatment +if the year tag is a two-digit number. In this case either 1900 or +2000 is added to the tag value, depending on whether the number is +greater than 2000 plus the current year. + + +### Mood usage ### + +To create a new mood called "my_mood", write its definition into +some temporary file, say "tmpfile", and add it to the mood table +by executing + + para addmood my_mood < tmpfile + +If the mood definition is really short, you may just pipe it to the +client instead of using temporary files. Like this: + + echo "$MOOD_DEFINITION" | para addmood my_mood + +There is no need to keep the temporary file since you can always use +the catmood command to get it back: + + para catmood my_mood + +A mood can be activated by executing + + para select m/my_mood + +Once active, the list of admissible files is shown by the ls command +if the "-a" switch is given: + + para ls -a + + +### Example mood definition ### + +Suppose you have defined attributes "punk" and "rock" and want to define +a mood containing only Punk-Rock songs. That is, an audio file should be +admissible if and only if both attributes are set. Since + + punk and rock + +is obviously the same as + + not (not punk or not rock) + +(de Morgan's rule), a mood definition that selects only Punk-Rock +songs is + + deny if not is_set punk + deny if not is_set rock + + + +File renames and content changes +-------------------------------- + +Since the audio file selector knows the SHA1 of each audio file that +has been added to the afs database, it recognizes if the content of +a file has changed, e.g. because an ID3 tag was added or modified. +Also, if a file has been renamed or moved to a different location, +afs will detect that an entry with the same hash value already exists +in the audio file table. + +In both cases it is enough to just re-add the new file. In the +first case (file content changed), the audio table is updated, while +metadata such as the num_played and last_played fields, as well as +the attributes, remain unchanged. In the other case, when the file +is moved or renamed, only the path information is updated, all other +data remains as before. + +It is possible to change the behaviour of the add command by using the +"-l" (lazy add) or the "-f" (force add) option. + +Troubleshooting +--------------- + +Use the debug loglevel (-l debug) to show debugging info. All paraslash +executables have a brief online help which is displayed when -h is +given. The --detailed-help option prints the full help text. + +If para_server crashed or was killed by SIGKILL (signal 9), it +may refuse to start again because of "dirty osl tables". In this +case you'll have to run the oslfsck program of libosl to fix your +database: + + oslfsck -fd ~/.paraslash/afs_database-0.4 + +However, make sure para_server isn't running before executing oslfsck. + +If you don't mind to recreate your database you can start +from scratch by removing the entire database directory, i.e. + + rm -rf ~/.paraslash/afs_database-0.4 + +Be aware that this removes all attribute definitions, all playlists +and all mood definitions and requires to re-initialize the tables. + +Although oslfsck fixes inconsistencies in database tables it doesn't +care about the table contents. To check for invalid table contents, use + + para_client check + +This prints out references to missing audio files as well as invalid +playlists and mood definitions. + +Similarly, para_audiod refuses to start if its socket file exists, since +this indicates that another instance of para_audiod is running. After +a crash a stale socket file might remain and you must run + + para_audiod --force + +once to fix it up. + +======================================= +Audio formats and audio format handlers +======================================= + +Audio formats +------------- + +The following audio formats are supported by paraslash: + +### MP3 ### + +Mp3, MPEG-1 Audio Layer 3, is a common audio format for audio storage, +designed as part of its MPEG-1 standard. An MP3 file is made up of +multiple MP3 frames, which consist of a header and a data block. The +size of an MP3 frame depends on the bit rate and on the number +of channels. For a typical CD-audio file (sample rate of 44.1 kHz +stereo), encoded with a bit rate of 128 kbit, an MP3 frame is about +400 bytes large. + +### OGG/Vorbis ### + +OGG is a standardized audio container format, while Vorbis is an +open source codec for lossy audio compression. Since Vorbis is most +commonly made available via the OGG container format, it is often +referred to as OGG/Vorbis. The OGG container format divides data into +chunks called OGG pages. A typical OGG page is about 4KB large. The +Vorbis codec creates variable-bitrate (VBR) data, where the bitrate +may vary considerably. + +### OGG/Speex ### + +Speex is an open-source speech codec that is based on CELP (Code +Excited Linear Prediction) coding. It is designed for voice +over IP applications, has modest complexity and a small memory +footprint. Wideband and narrowband (telephone quality) speech are +supported. As for Vorbis audio, Speex bit-streams are often stored +in OGG files. As of 2012 this codec is considered obsolete since the +Oppus codec, described below, surpasses its performance in all areas. + +### OGG/Opus ### + +Opus is a lossy audio compression format standardized through RFC +6716 in 2012. It combines the speech-oriented SILK codec and the +low-latency CELT (Constrained Energy Lapped Transform) codec. Like +OGG/Vorbis and OGG/Speex, Opus data is usually encapsulated in OGG +containers. All known software patents which cover Opus are licensed +under royalty-free terms. + +### AAC ### + +Advanced Audio Coding (AAC) is a standardized, lossy compression +and encoding scheme for digital audio which is the default audio +format for Apple's iPhone, iPod, iTunes. Usually MPEG-4 is used as +the container format and audio files encoded with AAC have the .m4a +extension. A typical AAC frame is about 700 bytes large. + +### WMA ### + +Windows Media Audio (WMA) is an audio data compression technology +developed by Microsoft. A WMA file is usually encapsulated in the +Advanced Systems Format (ASF) container format, which also specifies +how meta data about the file is to be encoded. The bit stream of WMA +is composed of superframes, each containing one or more frames of +2048 samples. For 16 bit stereo a WMA superframe is about 8K large. + +### FLAC ### + +The Free Lossless Audio Codec (FLAC) compresses audio without quality +loss. It gives better compression ratios than a general purpose +compressor like zip or bzip2 because FLAC is designed specifically +for audio. A FLAC-encoded file consists of frames of varying size, up +to 16K. Each frame starts with a header that contains all information +necessary to decode the frame. + +Meta data +--------- + +Unfortunately, each audio format has its own conventions how meta +data is added as tags to the audio file. + +For MP3 files, ID3, version 1 and 2 are widely used. ID3 version 1 +is rather simple but also very limited as it supports only artist, +title, album, year and comment tags. Each of these can only be at most +32 characters long. ID3, version 2 is much more flexible but requires +a separate library being installed for paraslash to support it. + +Ogg vorbis, ogg speex and flac files contain meta data as Vorbis +comments, which are typically implemented as strings of the form +"[TAG]=[VALUE]". Unlike ID3 version 1 tags, one may use whichever +tags are appropriate for the content. + +AAC files usually use the MPEG-4 container format for storing meta +data while WMA files wrap meta data as special objects within the +ASF container format. + +paraslash only tracks the most common tags that are supported by +all tag variants: artist, title, year, album, comment. When a file +is added to the AFS database, the meta data of the file is extracted +and stored in the audio file table. + +Chunks and chunk tables +----------------------- + +paraslash uses the word "chunk" as common term for the building blocks +of an audio file. For MP3 files, a chunk is the same as an MP3 frame, +while for OGG files a chunk is an OGG page, etc. Therefore the chunk +size varies considerably between audio formats, from a few hundred +bytes (MP3) up to 16K (FLAC). + +The chunk table contains the offsets within the audio file that +correspond to the chunk boundaries of the file. Like the meta data, +the chunk table is computed and stored in the database whenever an +audio file is added. + +The paraslash senders (see below) always send complete chunks. The +granularity for seeking is therefore determined by the chunk size. + +Audio format handlers +--------------------- + +For each audio format paraslash contains an audio format handler whose +first task is to tell whether a given file is a valid audio file of +this type. If so, the audio file handler extracts some technical data +(duration, sampling rate, number of channels etc.), computes the +chunk table and reads the meta data. + +The audio format handler code is linked into para_server and executed +via the _add_ command. The same code is also available as a stand-alone +tool, para_afh, which prints the technical data, the chunk table +and the meta data of a file. Moreover, all audio format handlers are +combined in the afh receiver which is part of para_recv and para_play. + +========== +Networking +========== + +Paraslash uses different network connections for control and data. +para_client communicates with para_server over a dedicated TCP control +connection. To transport audio data, separate data connections are +used. For these data connections, a variety of transports (UDP, DCCP, +HTTP) can be chosen. + +The chapter starts with the [control +service](#The.paraslash.control.service), followed by a section +on the various [streaming protocols](#Streaming.protocols) +in which the data connections are described. The way +audio file headers are embedded into the stream is discussed +[briefly](#Streams.with.headers.and.headerless.streams) before the +[example section](#Networking.examples) which illustrates typical +commands for real-life scenarios. + +Both IPv4 and IPv6 are supported. + +The paraslash control service +----------------------------- + +para_server is controlled at runtime via the paraslash control +connection. This connection is used for server commands (play, stop, +...) as well as for afs commands (ls, select, ...). + +The server listens on a TCP port and accepts connections from clients +that connect the open port. Each connection causes the server to fork +off a client process which inherits the connection and deals with that +client only. In this classical accept/fork approach the server process +is unaffected if the child dies or goes crazy for whatever reason. In +fact, the child process can not change address space of server process. + +The section on [client-server +authentication](#Client-server.authentication) above described the +early connection establishment from the crypto point of view. Here +it is described what happens after the connection (including crypto +setup) has been established. There are four processes involved during +command dispatch as sketched in the following diagram. + + server_host client_host + ~~~~~~~~~~~ ~~~~~~~~~~~ + + +-----------+ connect +-----------+ + |para_server|<------------------------------ |para_client| + +-----------+ +-----------+ + | ^ + | fork +---+ | + +----------> |AFS| | + | +---+ | + | ^ | + | | | + | | connect (cookie) | + | | | + | | | + | fork +-----+ inherited connection | + +---------->|child|<--------------------------+ + +-----+ + +Note that the child process is not a child of the afs process, +so communication of these two processes has to happen via local +sockets. In order to avoid abuse of the local socket by unrelated +processes, a magic cookie is created once at server startup time just +before the server process forks off the AFS process. This cookie is +known to the server, AFS and the child, but not to unrelated processes. + +There are two different kinds of commands: First there are commands +that cause the server to respond with some answer such as the list +of all audio files. All but the addblob commands (addimg, addlyr, +addpl, addmood) are of this kind. The addblob commands add contents +to the database, so they need to transfer data the other way round, +from the client to the server. + +There is no knowledge about the server commands built into para_client, +so it does not know about addblob commands. Instead, the server sends +a special "awaiting data" packet for these commands. If the client +receives this packet, it sends STDIN to the server, otherwise it +dumps data from the server to STDOUT. + +Streaming protocols +------------------- + +A network (audio) stream usually consists of one streaming source, +the _sender_, and one or more _receivers_ which read data over the +network from the streaming source. + +Senders are thus part of para_server while receivers are part of +para_audiod. Moreover, there is the stand-alone tool para_recv which +can be used to manually download a stream, either from para_server +or from a web-based audio streaming service. + +The following three streaming protocols are supported by paraslash: + +- HTTP. Recommended for public streams that can be played by any +player like mpg123, xmms, itunes, winamp, etc. The HTTP sender is +supported on all operating systems and all platforms. + +- DCCP. Recommended for LAN streaming. DCCP is currently available +only for Linux. + +- UDP. Recommended for multicast LAN streaming. + +See the Appendix on [network protocols](/#Network.protocols) +for brief descriptions of the various protocols relevant for network +audio streaming with paraslash. + +It is possible to activate more than one sender simultaneously. +Senders can be controlled at run time and via config file and command +line options. + +Note that audio connections are _not_ encrypted. Transport or Internet +layer encryption should be used if encrypted data connections are +needed. + +Since DCCP and TCP are both connection-oriented protocols, connection +establishment/teardown and access control are very similar between +these two streaming protocols. UDP is the most lightweight option, +since in contrast to TCP/DCCP it is connectionless. It is also the +only protocol supporting IP multicast. + +The HTTP and the DCCP sender listen on a (TCP/DCCP) port waiting for +clients to connect and establish a connection via some protocol-defined +handshake mechanism. Both senders maintain two linked lists each: +The list of all clients which are currently connected, and the list +of access control entries which determines who is allowed to connect. +IP-based access control may be configured through config file and +command line options and via the "allow" and "deny" sender subcommands. + +Upon receiving a GET request from the client, the HTTP sender sends +back a status line and a message. The body of this message is the +audio stream. This is common practice and is supported by many popular +clients which can thus be used to play a stream offered by para_server. +For DCCP things are a bit simpler: No messages are exchanged between +the receiver and sender. The client simply connects and the sender +starts to stream. + +DCCP is an experimental protocol which offers a number of new features +not available for TCP. Both ends can negotiate these features using +a built-in negotiation mechanism. In contrast to TCP/HTTP, DCCP is +datagram-based (no retransmissions) and thus should not be used over +lossy media (e.g. WiFi networks). One useful feature offered by DCCP +is access to a variety of different congestion-control mechanisms +called CCIDs. Two different CCIDs are available per default on Linux: + + +- _CCID 2_. A Congestion Control mechanism similar to that of TCP. The +sender maintains a congestion window and halves this window in response +to congestion. + + +- _CCID-3_. Designed to be fair when competing for bandwidth. +It has lower variation of throughput over time compared with TCP, +which makes it suitable for streaming media. + +Unlike the HTTP and DCCP senders, the UDP sender maintains only a +single list, the _target list_. This list describes the set of clients +to which the stream is sent. There is no list for access control and +no "allow" and "deny" commands for the UDP sender. Instead, the "add" +and "delete" commands can be used to modify the target list. + +Since both UDP and DCCP offer an unreliable datagram-based transport, +additional measures are necessary to guard against disruptions over +networks that are lossy or which may be subject to interference (as +is for instance the case with WiFi). Paraslash uses FEC (Forward +Error Correction) to guard against packet losses and reordering. The +stream is FEC-encoded before it is sent through the UDP socket and +must be decoded accordingly on the receiver side. + +The packet size and the amount of redundancy introduced by FEC can +be configured via the FEC parameters which are dictated by server +and may also be configured through the "sender" command. The FEC +parameters are encoded in the header of each network packet, so no +configuration is necessary on the receiver side. See the section on +[FEC](#Forward.error.correction) below. + +Streams with headers and headerless streams +------------------------------------------- + +For OGG/Vorbis, OGG/Speex and wma streams, some of the information +needed to decode the stream is only contained in the audio file +header of the container format but not in each data chunk. Clients +must be able to obtain this information in case streaming starts in +the middle of the file or if para_audiod is started while para_server +is already sending a stream. + +This is accomplished in different ways, depending on the streaming +protocol. For connection-oriented streams (HTTP, DCCP) the audio file +header is sent prior to audio file data. This technique however does +not work for the connectionless UDP transport. Hence the audio file +header is periodically being embedded into the UDP audio data stream. +By default, the header is resent after five seconds. The receiver has +to wait until the next header arrives before it can start decoding +the stream. + +Networking examples +------------------- + +The "si" (server info) command lists some information about the +currently running server process. + +-> Show PIDs, number of connected clients, uptime, and more: + + para_client si + +The sender command of para_server prints information about senders, +like the various access control lists, and it allows to (de-)activate +senders and to change the access permissions at runtime. + +-> List all senders + + para_client sender + +-> Obtain general help for the sender command: + + para_client help sender + +-> Get help for a specific sender (contains further examples): + + s=http # or dccp or udp + para_client sender $s help + +-> Show status of the http sender + + para_client sender http status + +By default para_server activates both the HTTP and th DCCP sender on +startup. This can be changed via command line options or para_server's +config file. + +-> List config file options for senders: + + para_server -h + +All senders share the "on" and "off" commands, so senders may be +activated and deactivated independently of each other. + +-> Switch off the http sender: + + para_client sender http off + +-> Receive a DCCP stream using CCID2 and write the output into a file: + + host=foo.org; ccid=2; filename=bar + para_recv --receiver "dccp --host $host --ccid $ccid" > $filename + +Note the quotes around the arguments for the dccp receiver. Each +receiver has its own set of command line options and its own command +line parser, so arguments for the dccp receiver must be protected +from being interpreted by para_recv. + +-> Start UDP multicast, using the default multicast address: + + para_client sender udp add 224.0.1.38 + +-> Receive FEC-encoded multicast stream and write the output into a file: + + filename=foo + para_recv -r udp > $filename + +-> Add an UDP unicast for a client to the target list of the UDP sender: + + t=client.foo.org + para_client sender udp add $t + +-> Receive this (FEC-encoded) unicast stream: + + filename=foo + para_recv -r 'udp -i 0.0.0.0' > $filename + +-> Create a minimal config for para_audiod for HTTP streams: + + c=$HOME/.paraslash/audiod.conf.min; s=server.foo.com + echo receiver \".:http -i $s\" > $c + para_audiod --config $c + +======= +Filters +======= + +A paraslash filter is a module which transforms an input stream into +an output stream. Filters are included in the para_audiod executable +and in the stand-alone tool para_filter which usually contains the +same modules. + +While para_filter reads its input stream from STDIN and writes +the output to STDOUT, the filter modules of para_audiod are always +connected to a receiver which produces the input stream and a writer +which absorbs the output stream. + +Some filters depend on a specific library and are not compiled in +if this library was not found at compile time. To see the list of +supported filters, run para_filter and para_audiod with the --help +option. The output looks similar to the following: + + Available filters: + compress wav amp fecdec wmadec prebuffer oggdec aacdec mp3dec + +Out of these filter modules, a chain of filters can be constructed, +much in the way Unix pipes can be chained, and analogous to the use +of modules in gstreamer: The output of the first filter becomes the +input of the second filter. There is no limitation on the number of +filters and the same filter may occur more than once. + +Like receivers, each filter has its own command line options which +must be quoted to protect them from the command line options of +the driving application (para_audiod or para_filter). Example: + + para_filter -f 'mp3dec --ignore-crc' -f 'compress --damp 1' + +For para_audiod, each audio format has its own set of filters. The +name of the audio format for which the filter should be applied can +be used as the prefix for the filter option. Example: + + para_audiod -f 'mp3:prebuffer --duration 300' + +The "mp3" prefix above is actually interpreted as a POSIX extended +regular expression. Therefore + + para_audiod -f '.:prebuffer --duration 300' + +activates the prebuffer filter for all supported audio formats (because +"." matches all audio formats) while + + para_audiod -f 'wma|ogg:prebuffer --duration 300' + +activates it only for wma and ogg streams. + +Decoders +-------- + +For each supported audio format there is a corresponding filter +which decodes audio data in this format to 16 bit PCM data which +can be directly sent to the sound device or any other software that +operates on undecoded PCM data (visualizers, equalizers etc.). Such +filters are called _decoders_ in general, and xxxdec is the name of +the paraslash decoder for the audio format xxx. For example, the mp3 +decoder is called mp3dec. + +Note that the output of the decoder is about 10 times larger than +its input. This means that filters that operate on the decoded audio +stream have to deal with much more data than filters that transform +the audio stream before it is fed to the decoder. + +Paraslash relies on external libraries for most decoders, so these +libraries must be installed for the decoder to be included in the +executables. For example, the mp3dec filter depends on the mad library. + +Forward error correction +------------------------ + +As already mentioned [earlier](#Streaming.protocols), paraslash +uses forward error correction (FEC) for the unreliable UDP and +DCCP transports. FEC is a technique which was invented already in +1960 by Reed and Solomon and which is widely used for the parity +calculations of storage devices (RAID arrays). It is based on the +algebraic concept of finite fields, today called Galois fields, in +honour of the mathematician Galois (1811-1832). The FEC implementation +of paraslash is based on code by Luigi Rizzo. + +Although the details require a sound knowledge of the underlying +mathematics, the basic idea is not hard to understand: For positive +integers k and n with k < n it is possible to compute for any k given +data bytes d_1, ..., d_k the corresponding r := n -k parity bytes p_1, +..., p_r such that all data bytes can be reconstructed from *any* +k bytes of the set + + {d_1, ..., d_k, p_1, ..., p_r}. + +FEC-encoding for unreliable network transports boils down to slicing +the audio stream into groups of k suitably sized pieces called _slices_ +and computing the r corresponding parity slices. This step is performed +in para_server which then sends both the data and the parity slices +over the unreliable network connection. If the client was able +to receive at least k of the n = k + r slices, it can reconstruct +(FEC-decode) the original audio stream. + +From these observations it is clear that there are three different +FEC parameters: The slice size, the number of data slices k, and the +total number of slices n. It is crucial to choose the slice size +such that no fragmentation of network packets takes place because +FEC only guards against losses and reordering but fails if slices are +received partially. + +FEC decoding in paralash is performed through the fecdec filter which +usually is the first filter (there can be other filters before fecdec +if these do not alter the audio stream). + +Volume adjustment (amp and compress) +------------------------------------ + +The amp and the compress filter both adjust the volume of the audio +stream. These filters operate on uncompressed audio samples. Hence +they are usually placed directly after the decoding filter. Each +sample is multiplied with a scaling factor (>= 1) which makes amp +and compress quite expensive in terms of computing power. + +### amp ### + +The amp filter amplifies the audio stream by a fixed scaling factor +that must be known in advance. For para_audiod this factor is derived +from the amplification field of the audio file's entry in the audio +file table while para_filter uses the value given at the command line. + +The optimal scaling factor F for an audio file is the largest real +number F >= 1 such that after multiplication with F all samples still +fit into the sample interval [-32768, 32767]. One can use para_filter +in combination with the sox utility to compute F: + + para_filter -f mp3dec -f wav < file.mp3 | sox -t wav - -e stat -v + +The amplification value V which is stored in the audio file table, +however, is an integer between 0 and 255 which is connected to F +through the formula + + V = (F - 1) * 64. + +To store V in the audio file table, the command + + para_client -- touch -a=V file.mp3 + +is used. The reader is encouraged to write a script that performs +these computations :) + +### compress ### + +Unlike the amplification filter, the compress filter adjusts the volume +of the audio stream dynamically without prior knowledge about the peak +value. It maintains the maximal volume of the last n samples of the +audio stream and computes a suitable amplification factor based on that +value and the various configuration options. It tries to chose this +factor such that the adjusted volume meets the desired target level. + +Note that it makes sense to combine amp and compress. + +Misc filters (wav and prebuffer) +-------------------------------- + +These filters are rather simple and do not modify the audio stream at +all. The wav filter is only useful with para_filter and in connection +with a decoder. It asks the decoder for the number of channels and the +sample rate of the stream and adds a Microsoft wave header containing +this information at the beginning. This allows to write wav files +rather than raw PCM files (which do not contain any information about +the number of channels and the sample rate). + +The prebuffer filter simply delays the output until the given time has +passed (starting from the time the first byte was available in its +input queue) or until the given amount of data has accumulated. It +is mainly useful for para_audiod if the standard parameters result +in buffer underruns. + +Both filters require almost no additional computing time, even when +operating on uncompressed audio streams, since data buffers are simply +"pushed down" rather than copied. + +Examples +-------- + +-> Decode an mp3 file to wav format: + + para_filter -f mp3dec -f wav < file.mp3 > file.wav + +-> Amplify a raw audio file by a factor of 1.5: + + para_filter -f amp --amp 32 < foo.raw > bar.raw + +====== +Output +====== + +Once an audio stream has been received and decoded to PCM format, +it can be sent to a sound device for playback. This part is performed +by paraslash _writers_ which are described in this chapter. + +Writers +------- + +A paraslash writer acts as a data sink that consumes but does not +produce audio data. Paraslash writers operate on the client side and +are contained in para_audiod and in the stand-alone tool para_write. + +The para_write program reads uncompressed audio data from STDIN. If +this data starts with a wav header, sample rate, sample format and +channel count are read from the header. Otherwise CD audio (44.1KHz +16 bit little endian, stereo) is assumed but this can be overridden +by command line options. para_audiod, on the other hand, obtains +the sample rate and the number of channels from the decoder. + +Like receivers and filters, each writer has an individual set of +command line options, and for para_audiod writers can be configured +per audio format separately. It is possible to activate more than +one writer for the same stream simultaneously. + +OS-dependent APIs +----------------- + +Unfortunately, the various flavours of Unix on which paraslash +runs on have different APIs for opening a sound device and starting +playback. Hence for each such API there is a paraslash writer that +can play the audio stream via this API. + +- *ALSA*. The _Advanced Linux Sound Architecture_ is only available on +Linux systems. Although there are several mid-layer APIs in use by +the various Linux distributions (ESD, Jack, PulseAudio), paraslash +currently supports only the low-level ALSA API which is not supposed +to be change. ALSA is very feature-rich, in particular it supports +software mixing via its DMIX plugin. ALSA is the default writer on +Linux systems. + +- *OSS*. The _Open Sound System_ is the only API on \*BSD Unixes and +is also available on Linux systems, usually provided by ALSA as an +emulation for backwards compatibility. This API is rather simple but +also limited. For example only one application can open the device +at any time. The OSS writer is activated by default on BSD Systems. + +- *OSX*. Mac OS X has yet another API called CoreAudio. The OSX writer +for this API is only compiled in on such systems and is of course +the default there. + +- *FILE*. The file writer allows to capture the audio stream and +write the PCM data to a file on the file system rather than playing +it through a sound device. It is supported on all platforms and is +always compiled in. + +- *AO*. _Libao_ is a cross-platform audio library which supports a wide +variety of platforms including PulseAudio (gnome), ESD (Enlightened +Sound Daemon), AIX, Solaris and IRIX. The ao writer plays audio +through an output plugin of libao. + +Examples +-------- + +-> Use the OSS writer to play a wav file: + + para_write --writer oss < file.wav + +-> Enable ALSA software mixing for mp3 streams: + + para_audiod --writer 'mp3:alsa -d plug:swmix' + + +=== +Gui +=== + +para_gui executes an arbitrary command which is supposed to print +status information to STDOUT. It then displays this information in +a curses window. By default the command + + para_audioc -- stat -p + +is executed, but this can be customized via the --stat-cmd option. In +particular it possible to use + + para_client -- stat -p + +to make para_gui work on systems on which para_audiod is not running. + +Key bindings +------------ + +It is possible to bind keys to arbitrary commands via custom +key-bindings. Besides the internal keys which can not be changed (help, +quit, loglevel, version...), the following flavours of key-bindings +are supported: + +- external: Shutdown curses before launching the given command. +Useful for starting other ncurses programs from within para_gui, +e.g. aumix or dialog scripts. Or, use the mbox output format to write +a mailbox containing one mail for each (admissible) file the audio +file selector knows about. Then start mutt from within para_gui to +browse your collection! + +- display: Launch the command and display its stdout in para_gui's +bottom window. + +- para: Like display, but start "para_client " +instead of "". + +The general form of a key binding is + + key_map k:m:c + +which maps key k to command c using mode m. Mode may be x, d or p +for external, display and paraslash commands, respectively. + +Themes +------ + +Currently there are only two themes for para_gui. It is easy, however, +to add more themes. To create a new theme one has to define the +position, color and geometry for for each status item that should be +shown by this theme. See gui_theme.c for examples. + +The "." and "," keys are used to switch between themes. + +Examples +-------- + +-> Show server info: + + key_map "i:p:si" + +-> Jump to the middle of the current audio file by pressing F5: + + key_map ":p:jmp 50" + +-> vi-like bindings for jumping around: + + key_map "l:p:ff 10" + key_map "h:p:ff 10-" + key_map "w:p:ff 60" + key_map "b:p:ff 60-" + +-> Print the current date and time: + + key_map "D:d:date" + +-> Call other curses programs: + + key_map "U:x:aumix" + key_map "!:x:/bin/bash" + key_map "^E:x:/bin/sh -c 'vi ~/.paraslash/gui.conf'" + +=========== +Development +=========== + +Tools +----- + +In order to compile the sources from the git repository (rather than +from tar balls) and for contributing non-trivial changes to the +paraslash project, some additional tools should be installed on a +developer machine. + +- [git](http://git.or.cz/). As described in more detail +[below](#Git.branches), the git source code management tool is used for +paraslash development. It is necessary for cloning the git repository +and for getting updates. + +- [m4](ftp://ftp.gnu.org/pub/gnu/m4/). Some input files for gengetopt +are generated from templates by the m4 macro processor. + +- [autoconf](ftp://ftp.gnu.org/pub/gnu/autoconf/) GNU autoconf creates +the configure file which is shipped in the tarballs but has to be +generated when compiling from git. + +- [discount](http://www.pell.portland.or.us/~orc/Code/discount). The +HTML version of this manual and some of the paraslash web pages are +written in the Markdown markup language and are translated into html +with the converter of the *Discount* package. + +- [doxygen](http://www.stack.nl/~dimitri/doxygen/). The documentation +of paraslash's C sources uses the doxygen documentation system. The +conventions for documenting the source code is described in the +[Doxygen section](#Doxygen). + +- [global](ftp://ftp.gnu.org/pub/gnu/global). This is used to generate +browsable HTML from the C sources. It is needed by doxygen. + +Git branches +------------ + +Paraslash has been developed using the git source code management +tool since 2006. Development is organized roughly in the same spirit +as the git development itself, as described below. + +The following text passage is based on "A note from the maintainer", +written by Junio C Hamano, the maintainer of git. + +There are four branches in the paraslash repository that track the +source tree: "master", "maint", "next", and "pu". + +The "master" branch is meant to contain what is well tested and +ready to be used in a production setting. There could occasionally be +minor breakages or brown paper bag bugs but they are not expected to +be anything major, and more importantly quickly and easily fixable. +Every now and then, a "feature release" is cut from the tip of this +branch, named with three dotted decimal digits, like 0.4.2. + +Whenever changes are about to be included that will eventually lead to +a new major release (e.g. 0.5.0), a "maint" branch is forked off from +"master" at that point. Obvious, safe and urgent fixes after the major +release are applied to this branch and maintenance releases are cut +from it. New features never go to this branch. This branch is also +merged into "master" to propagate the fixes forward. + +A trivial and safe enhancement goes directly on top of "master". +New development does not usually happen on "master", however. +Instead, a separate topic branch is forked from the tip of "master", +and it first is tested in isolation; Usually there are a handful such +topic branches that are running ahead of "master". The tip of these +branches is not published in the public repository to keep the number +of branches that downstream developers need to worry about low. + +The quality of topic branches varies widely. Some of them start out as +"good idea but obviously is broken in some areas" and then with some +more work become "more or less done and can now be tested by wider +audience". Luckily, most of them start out in the latter, better shape. + +The "next" branch is to merge and test topic branches in the latter +category. In general, this branch always contains the tip of "master". +It might not be quite rock-solid production ready, but is expected to +work more or less without major breakage. The maintainer usually uses +the "next" version of paraslash for his own pleasure, so it cannot +be _that_ broken. The "next" branch is where new and exciting things +take place. + +The two branches "master" and "maint" are never rewound, and "next" +usually will not be either (this automatically means the topics that +have been merged into "next" are usually not rebased, and you can find +the tip of topic branches you are interested in from the output of +"git log next"). You should be able to safely build on top of them. + +However, at times "next" will be rebuilt from the tip of "master" to +get rid of merge commits that will never be in "master". The commit +that replaces "next" will usually have the identical tree, but it +will have different ancestry from the tip of "master". + +The "pu" (proposed updates) branch bundles the remainder of the +topic branches. The "pu" branch, and topic branches that are only in +"pu", are subject to rebasing in general. By the above definition +of how "next" works, you can tell that this branch will contain quite +experimental and obviously broken stuff. + +When a topic that was in "pu" proves to be in testable shape, it +graduates to "next". This is done with + + git checkout next + git merge that-topic-branch + +Sometimes, an idea that looked promising turns out to be not so good +and the topic can be dropped from "pu" in such a case. + +A topic that is in "next" is expected to be polished to perfection +before it is merged to "master". Similar to the above, this is +done with + + git checkout master + git merge that-topic-branch + git branch -d that-topic-branch + +Note that being in "next" is not a guarantee to appear in the next +release (being in "master" is such a guarantee, unless it is later +found seriously broken and reverted), nor even in any future release. + +Coding Style +------------ + +The preferred coding style for paraslash coincides more or less +with the style of the Linux kernel. So rather than repeating what is +written [there](http://www.kernel.org/doc/Documentation/CodingStyle), +here are the most important points. + +- Burn the GNU coding standards. +- Never use spaces for indentation. +- Tabs are 8 characters, and thus indentations are also 8 characters. +- Don't put multiple assignments on a single line. +- Avoid tricky expressions. +- Don't leave whitespace at the end of lines. +- The limit on the length of lines is 80 columns. +- Use K&R style for placing braces and spaces: + + if (x is true) { + we do y + } + +- Use a space after (most) keywords. +- Do not add spaces around (inside) parenthesized expressions. +- Use one space around (on each side of) most binary and ternary operators. +- Do not use cute names like ThisVariableIsATemporaryCounter, call it tmp. +- Mixed-case names are frowned upon. +- Descriptive names for global variables are a must. +- Avoid typedefs. +- Functions should be short and sweet, and do just one thing. +- The number of local variables shouldn't exceed 10. +- Gotos are fine if they improve readability and reduce nesting. +- Don't use C99-style "// ..." comments. +- Names of macros defining constants and labels in enums are capitalized. +- Enums are preferred when defining several related constants. +- Always use the paraslash wrappers for allocating memory. +- If the name of a function is an action or an imperative. + command, the function should return an error-code integer + (<0 means error, >=0 means success). If the name is a + predicate, the function should return a "succeeded" boolean. + +Doxygen +------- + +Doxygen is a documentation system for various programming +languages. The API reference on the paraslash web page is generated +by doxygen. + +It is more illustrative to look at the source code for examples than +to describe the conventions in this manual, so we only describe which +parts of the code need doxygen comments, but leave out details on +documentation conventions. + +As a rule, only the public part of the C source is documented with +Doxygen. This includes structures, defines and enumerations in header +files as well as public (non-static) C functions. These should be +documented completely. For example, each parameter and the return +value of a public function should get a descriptive doxygen comment. + +No doxygen comments are necessary for static functions and for +structures and enumerations in C files (which are used only within +this file). This does not mean, however, that those entities need +no documentation at all. Instead, common sense should be applied to +document what is not obvious from reading the code. + +======== +Appendix +======== + +Network protocols +----------------- + +### IP ### + +The _Internet Protocol_ is the primary networking protocol used for +the Internet. All protocols described below use IP as the underlying +layer. Both the prevalent IPv4 and the next-generation IPv6 variant +are being deployed actively worldwide. + +### Connection-oriented and connectionless protocols ### + +Connectionless protocols differ from connection-oriented ones in +that state associated with the sending/receiving endpoints is treated +implicitly. Connectionless protocols maintain no internal knowledge +about the state of the connection. Hence they are not capable of +reacting to state changes, such as sudden loss or congestion on the +connection medium. Connection-oriented protocols, in contrast, make +this knowledge explicit. The connection is established only after +a bidirectional handshake which requires both endpoints to agree +on the state of the connection, and may also involve negotiating +specific parameters for the particular connection. Maintaining an +up-to-date internal state of the connection also in general means +that the sending endpoints perform congestion control, adapting to +qualitative changes of the connection medium. + +### Reliability ### + +In IP networking, packets can be lost, duplicated, or delivered +out of order, and different network protocols handle these +problems in different ways. We call a transport-layer protocol +_reliable_, if it turns the unreliable IP delivery into an ordered, +duplicate- and loss-free delivery of packets. Sequence numbers +are used to discard duplicates and re-arrange packets delivered +out-of-order. Retransmission is used to guarantee loss-free +delivery. Unreliable protocols, in contrast, do not guarantee ordering +or data integrity. + +### Classification ### + +With these definitions the protocols which are used by paraslash for +steaming audio data may be classified as follows. + + - HTTP/TCP: connection-oriented, reliable, + - UDP: connectionless, unreliable, + - DCCP: connection-oriented, unreliable. + +Below we give a short descriptions of these protocols. + +### TCP ### + +The _Transmission Control Protocol_ provides reliable, ordered delivery +of a stream and a classic window-based congestion control. In contrast +to UDP and DCCP (see below), TCP does not have record-oriented or +datagram-based syntax, i.e. it provides a stream which is unaware +and independent of any record (packet) boundaries. TCP is used +extensively by many application layers. Besides HTTP (the Hypertext +Transfer Protocol), also FTP (the File Transfer protocol), SMTP (Simple +Mail Transfer Protocol), SSH (Secure Shell) all sit on top of TCP. + +### UDP ### + +The _User Datagram Protocol_ is the simplest transport-layer protocol, +built as a thin layer directly on top of IP. For this reason, it offers +the same best-effort service as IP itself, i.e. there is no detection +of duplicate or reordered packets. Being a connectionless protocol, +only minimal internal state about the connection is maintained, which +means that there is no protection against packet loss or network +congestion. Error checking and correction (if at all) are performed +in the application. + +### DCCP ### + +The _Datagram Congestion Control Protocol_ combines the +connection-oriented state maintenance known from TCP with the +unreliable, datagram-based transport of UDP. This means that it +is capable of reacting to changes in the connection by performing +congestion control, offering multiple alternative approaches. But it +is bound to datagram boundaries (the maximum packet size supported +by a medium), and like UDP it lacks retransmission to protect +against loss. Due to the use of sequence numbers, it is however +able to react to loss (interpreted as a congestion indication) and +to ignore out-of-order and duplicate packets. Unlike TCP it allows +to negotiate specific, binding features for a connection, such as +the choice of congestion control: classic, window-based congestion +control known from TCP is available as CCID-2, rate-based, "smooth" +congestion control is offered as CCID-3. + +### HTTP ### + +The _Hypertext Transfer Protocol_ is an application layer protocol +on top of TCP. It is spoken by web servers and is most often used +for web services. However, as can be seen by the many Internet radio +stations and YouTube/Flash videos, http is by far not limited to the +delivery of web pages only. Being a simple request/response based +protocol, the semantics of the protocol also allow the delivery of +multimedia content, such as audio over http. + +### Multicast ### + +IP multicast is not really a protocol but a technique for one-to-many +communication over an IP network. The challenge is to deliver +information to a group of destinations simultaneously using the +most efficient strategy to send the messages over each link of the +network only once. This has benefits for streaming multimedia: the +standard one-to-one unicast offered by TCP/DCCP means that n clients +listening to the same stream also consume n-times the resources, +whereas multicast requires to send the stream just once, irrespective +of the number of receivers. Since it would be costly to maintain state +for each listening receiver, multicast often implies connectionless +transport, which is the reason that it is currently only available +via UDP. + +Abstract socket namespace +------------------------- +UNIX domain sockets are a traditional way to communicate between +processes on the same machine. They are always reliable (see above) +and don't reorder datagrams. Unlike TCP and UDP, UNIX domain sockets +support passing open file descriptors or process credentials to +other processes. + +The usual way to set up a UNIX domain socket (as obtained from +socket(2)) for listening is to first bind the socket to a file system +pathname and then call listen(2), then accept(2). Such sockets are +called _pathname sockets_ because bind(2) creates a special socket +file at the specified path. Pathname sockets allow unrelated processes +to communicate with the listening process by binding to the same path +and calling connect(2). + +There are two problems with pathname sockets: + + * The listing process must be able to (safely) create the + socket special in a directory which is also accessible to + the connecting process. + + * After an unclean shutdown of the listening process, a stale + socket special may reside on the file system. + +The abstract socket namespace is a non-portable Linux feature which +avoids these problems. Abstract sockets are still bound to a name, +but the name has no connection with file system pathnames. + +License +------- + +Paraslash is licensed under the GPL, version 2. Most of the code +base has been written from scratch, and those parts are GPL V2 +throughout. Notable exceptions are FEC and the WMA decoder. See the +corresponding source files for licencing details for these parts. Some +code sniplets of several other third party software packages have +been incorporated into the paraslash sources, for example log message +coloring was taken from the git sources. These third party software +packages are all published under the GPL or some other license +compatible to the GPL. + +Acknowledgements +---------------- + +Many thanks to Gerrit Renker who read an early draft of this manual +and contributed significant improvements. + +========== +References +========== + +Articles +-------- +- [Polynomial Codes over Certain Finite +Fields](http://kom.aau.dk/~heb/kurser/NOTER/KOFA01.PDF) by Reed, Irving +S.; Solomon, Gustave (1960), Journal of the Society for Industrial +and Applied Mathematics (SIAM) 8 (2): 300-304, doi:10.1137/0108018) + +RFCs +---- + +- [RFC 768](http://www.ietf.org/rfc/rfc768.txt) (1980): User Datagram +Protocol + +- [RFC 791](http://www.ietf.org/rfc/rfc791.txt) (1981): Internet +Protocol + +- [RFC 2437](http://www.ietf.org/rfc/rfc2437.txt) (1998): RSA +Cryptography Specifications + +- [RFC 4340](http://www.ietf.org/rfc/rfc4340.txt) (2006): Datagram +Congestion Control Protocol (DCCP) + +- [RFC 4341](http://www.ietf.org/rfc/rfc4341.txt) (2006): Congestion +Control ID 2: TCP-like Congestion Control + +- [RFC 4342](http://www.ietf.org/rfc/rfc4342.txt) (2006): Congestion +Control ID 3: TCP-Friendly Rate Control (TFRC) + +- [RFC 6716](http://www.ietf.org/rfc/rfc6716.txt) (2012): Definition +of the Opus Audio Codec + +Application web pages +--------------------- + +- [paraslash](http://people.tuebingen.mpg.de/maan/paraslash/) +- [alternative page](http://paraslash.systemlinux.org/) +- [xmms](http://xmms2.org/wiki/Main_Page) +- [mpg123](http://www.mpg123.de/) +- [gstreamer](http://gstreamer.freedesktop.org/) +- [icecast](http://www.icecast.org/) +- [Audio Compress](http://beesbuzz.biz/code/audiocompress.php) + +External documentation +---------------------- + +- [The mathematics of +Raid6](http://kernel.org/pub/linux/kernel/people/hpa/raid6.pdf) +by H. Peter Anvin + +- [Effective Erasure Codes for reliable Computer Communication +Protocols](http://info.iet.unipi.it/~luigi/fec_ccr.ps.gz) by Luigi +Rizzo + +Code +---- +- [Original FEC +implementation](http://info.iet.unipi.it/~luigi/vdm.tar.gz) by +Luigi Rizzo)