/* * Copyright (C) 2005-2009 Andre Noll * * Licensed under the GPL v2. For licencing details see COPYING. */ /** \file alsa_write.c paraslash's alsa output plugin */ /* * Based in parts on aplay.c from the alsa-utils-1.0.8 package, * Copyright (c) by Jaroslav Kysela , which is * based on the vplay program by Michael Beck. */ #include #include #include #include "para.h" #include "fd.h" #include "string.h" #include "list.h" #include "sched.h" #include "ggo.h" #include "write.h" #include "alsa_write.cmdline.h" #include "error.h" /** always use 16 bit little endian */ #define FORMAT SND_PCM_FORMAT_S16_LE /** Data specific to the alsa writer. */ struct private_alsa_write_data { /** The alsa handle */ snd_pcm_t *handle; /** Determined and set by alsa_open(). */ int bytes_per_frame; /** The approximate maximum buffer duration in us. */ unsigned buffer_time; /* Number of frames that fit into the buffer. */ unsigned buffer_frames; /** * The samplerate given by command line option or the decoder * of the writer node group. */ unsigned samplerate; /** * The number of channels, given by command line option or the * decoder of the writer node group. */ unsigned channels; }; /* Install PCM software and hardware configuration. */ static int alsa_init(struct private_alsa_write_data *pad, struct alsa_write_args_info *conf) { snd_pcm_hw_params_t *hwparams; snd_pcm_sw_params_t *swparams; snd_pcm_uframes_t buffer_size, start_threshold, stop_threshold; snd_pcm_uframes_t period_size; int err; err = snd_pcm_open(&pad->handle, conf->device_arg, SND_PCM_STREAM_PLAYBACK, SND_PCM_NONBLOCK); if (err < 0) return -E_PCM_OPEN; snd_pcm_hw_params_alloca(&hwparams); snd_pcm_sw_params_alloca(&swparams); if (snd_pcm_hw_params_any(pad->handle, hwparams) < 0) return -E_BROKEN_CONF; if (snd_pcm_hw_params_set_access(pad->handle, hwparams, SND_PCM_ACCESS_RW_INTERLEAVED) < 0) return -E_ACCESS_TYPE; if (snd_pcm_hw_params_set_format(pad->handle, hwparams, FORMAT) < 0) return -E_SAMPLE_FORMAT; if (snd_pcm_hw_params_set_channels(pad->handle, hwparams, pad->channels) < 0) return -E_CHANNEL_COUNT; if (snd_pcm_hw_params_set_rate_near(pad->handle, hwparams, &pad->samplerate, NULL) < 0) return -E_SET_RATE; err = snd_pcm_hw_params_get_buffer_time_max(hwparams, &pad->buffer_time, NULL); if (err < 0 || !pad->buffer_time) return -E_GET_BUFFER_TIME; PARA_INFO_LOG("buffer time: %d\n", pad->buffer_time); if (snd_pcm_hw_params_set_buffer_time_near(pad->handle, hwparams, &pad->buffer_time, NULL) < 0) return -E_SET_BUFFER_TIME; if (snd_pcm_hw_params(pad->handle, hwparams) < 0) return -E_HW_PARAMS; snd_pcm_hw_params_get_period_size(hwparams, &period_size, NULL); snd_pcm_hw_params_get_buffer_size(hwparams, &buffer_size); PARA_INFO_LOG("buffer size: %lu, period_size: %lu\n", buffer_size, period_size); if (period_size == buffer_size) return -E_BAD_PERIOD; snd_pcm_sw_params_current(pad->handle, swparams); snd_pcm_sw_params_set_avail_min(pad->handle, swparams, period_size); if (buffer_size < 1) start_threshold = 1; else start_threshold = PARA_MIN(buffer_size, (snd_pcm_uframes_t)pad->samplerate); if (snd_pcm_sw_params_set_start_threshold(pad->handle, swparams, start_threshold) < 0) return -E_START_THRESHOLD; stop_threshold = buffer_size; if (snd_pcm_sw_params_set_stop_threshold(pad->handle, swparams, stop_threshold) < 0) return -E_STOP_THRESHOLD; if (snd_pcm_sw_params(pad->handle, swparams) < 0) PARA_WARNING_LOG("unable to install sw params\n"); pad->bytes_per_frame = snd_pcm_format_physical_width(FORMAT) * pad->channels / 8; if (pad->bytes_per_frame <= 0) return -E_PHYSICAL_WIDTH; PARA_INFO_LOG("bytes per frame: %d\n", pad->bytes_per_frame); if (snd_pcm_nonblock(pad->handle, 1)) PARA_ERROR_LOG("failed to set nonblock mode\n"); pad->buffer_frames = 1000 * pad->buffer_time / pad->samplerate; PARA_INFO_LOG("max buffered frames: %d\n", pad->buffer_frames); return 1; } /* Open an instance of the alsa writer. */ static int alsa_open(struct writer_node *wn) { struct alsa_write_args_info *conf = wn->conf; struct writer_node_group *wng = wn->wng; struct private_alsa_write_data *pad = para_calloc(sizeof(*pad)); wn->private_data = pad; if (!conf->samplerate_given && wng->samplerate) pad->samplerate = *wng->samplerate; else pad->samplerate = conf->samplerate_arg; if (!conf->channels_given && wng->channels) pad->channels = *wng->channels; else pad->channels = conf->channels_arg; PARA_INFO_LOG("%d channel(s), %dHz\n", pad->channels, pad->samplerate); return 1; } static int alsa_write_pre_select(struct sched *s, struct writer_node *wn) { struct private_alsa_write_data *pad = wn->private_data; struct writer_node_group *wng = wn->wng; struct timeval tv; snd_pcm_sframes_t avail, underrun; if (!pad->handle) return 1; if (*wng->loaded - wn->written < pad->bytes_per_frame) return 1; /* * Data is available to be written to the alsa handle. Compute number * of milliseconds until next buffer underrun would occur. * * snd_pcm_avail_update() updates the current available count of * samples for writing. It is a light method to obtain current stream * position, because it does not require the user <-> kernel context * switch, but the value is less accurate, because ring buffer pointers * are updated in kernel drivers only when an interrupt occurs. */ avail = snd_pcm_avail_update(pad->handle); if (avail < 0) avail = 0; underrun = (pad->buffer_frames - avail) * pad->buffer_time / pad->buffer_frames / 1000; if (underrun < 50) underrun = 50; underrun -= 50; ms2tv(underrun, &tv); if (tv_diff(&s->timeout, &tv, NULL) > 0) s->timeout = tv; return 1; } static int alsa_write_post_select(__a_unused struct sched *s, struct writer_node *wn) { struct private_alsa_write_data *pad = wn->private_data; struct writer_node_group *wng = wn->wng; size_t bytes = *wng->loaded - wn->written; unsigned char *data = (unsigned char*)*wng->bufp + wn->written; snd_pcm_sframes_t ret, frames, avail; if (*wng->input_error < 0 && (!pad->handle || bytes < pad->bytes_per_frame)) { wn->written = *wng->loaded; return *wng->input_error; } if (!bytes) /* no data available */ return 0; if (!pad->handle) { int err = alsa_init(pad, wn->conf); if (err < 0) return err; } frames = bytes / pad->bytes_per_frame; if (!frames) /* less than a single frame available */ return 0; avail = snd_pcm_avail_update(pad->handle); if (avail <= 0) return 0; frames = PARA_MIN(frames, avail); ret = snd_pcm_writei(pad->handle, data, frames); if (ret >= 0) { wn->written += ret * pad->bytes_per_frame; return 1; } PARA_WARNING_LOG("%s\n", snd_strerror(-ret)); if (ret == -EPIPE) { snd_pcm_prepare(pad->handle); return 0; } if (ret == -EAGAIN) return 0; return -E_ALSA_WRITE; } static void alsa_close(struct writer_node *wn) { struct private_alsa_write_data *pad = wn->private_data; PARA_INFO_LOG("closing writer node %p\n", wn); if (pad->handle) { snd_pcm_drain(pad->handle); snd_pcm_close(pad->handle); snd_config_update_free_global(); } free(pad); } __malloc static void *alsa_parse_config(const char *options) { int ret; struct alsa_write_args_info *conf = para_calloc(sizeof(struct alsa_write_args_info)); PARA_INFO_LOG("options: %s, %zd\n", options, strcspn(options, " \t")); ret = alsa_cmdline_parser_string(options, conf, "alsa_write"); if (ret) goto err_out; PARA_INFO_LOG("help given: %d\n", conf->help_given); return conf; err_out: free(conf); return NULL; } /** * the init function of the alsa writer * * \param w pointer to the writer to initialize * * \sa struct writer */ void alsa_write_init(struct writer *w) { struct alsa_write_args_info dummy; alsa_cmdline_parser_init(&dummy); w->open = alsa_open; w->close = alsa_close; w->pre_select = alsa_write_pre_select; w->post_select = alsa_write_post_select; w->parse_config = alsa_parse_config; w->shutdown = NULL; /* nothing to do */ w->help = (struct ggo_help) { .short_help = alsa_write_args_info_help, .detailed_help = alsa_write_args_info_detailed_help }; alsa_cmdline_parser_free(&dummy); }