Alsa improvement and fixes.

Wait until pending frames are played.

The old code was buggy because snd_pcm_drain() always fails on a
non-blocking fd. We therefore called snd_pcm_close() while frames
for playback are still availabe, causing the last few frames being
skipped.

diff --git a/alsa_write.c b/alsa_write.c
index e2ca45b626dd6f04ca84c14ac25e98c0d47cc741..8b56f31a4e9c71443205f7c681a5ba0c2799f031 100644 (file)
--- a/alsa_write.c
+++ b/alsa_write.c
@@ -27,6 +27,7 @@
 #include "ggo.h"
 #include "buffer_tree.h"
 #include "write.h"
+#include "write_common.h"
 #include "alsa_write.cmdline.h"
 #include "error.h"
 
@@ -38,11 +39,11 @@ struct private_alsa_write_data {
        /** The alsa handle */
        snd_pcm_t *handle;
        /** Determined and set by alsa_open(). */
-       int bytes_per_frame;
+       int bytes_per_frame; /* TODO: Kill this after btr switch */
        /** The approximate maximum buffer duration in us. */
        unsigned buffer_time;
        /* Number of frames that fit into the buffer. */
-       unsigned buffer_frames;
+       snd_pcm_uframes_t buffer_frames;
        /**
         * The samplerate given by command line option or the decoder
         * of the writer node group.
@@ -61,7 +62,7 @@ static int alsa_init(struct private_alsa_write_data *pad,
 {
        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 start_threshold, stop_threshold;
        snd_pcm_uframes_t period_size;
        int err;
 
@@ -96,22 +97,22 @@ static int alsa_init(struct private_alsa_write_data *pad,
        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,
+       snd_pcm_hw_params_get_buffer_size(hwparams, &pad->buffer_frames);
+       PARA_INFO_LOG("buffer size: %lu, period_size: %lu\n", pad->buffer_frames,
                period_size);
-       if (period_size == buffer_size)
+       if (period_size == pad->buffer_frames)
                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)
+       if (pad->buffer_frames < 1)
                start_threshold = 1;
        else
-               start_threshold = PARA_MIN(buffer_size,
+               start_threshold = PARA_MIN(pad->buffer_frames,
                        (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;
+       stop_threshold = pad->buffer_frames;
        if (snd_pcm_sw_params_set_stop_threshold(pad->handle, swparams,
                        stop_threshold) < 0)
                return -E_STOP_THRESHOLD;
@@ -124,8 +125,6 @@ static int alsa_init(struct private_alsa_write_data *pad,
        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;
 }
 
@@ -175,8 +174,12 @@ static int alsa_write_pre_select(struct sched *s, struct writer_node *wn)
                return 1;
        if (wn->btrn) {
                size_t sz = btr_get_input_queue_size(wn->btrn);
-               if (sz < pad->bytes_per_frame)
-                       return 1;
+               if (sz < pad->bytes_per_frame) {
+                       if (!btr_no_parent(wn->btrn))
+                               return 1;
+                       underrun = 10;
+                       goto timeout;
+               }
        } else {
                if (*wng->loaded - wn->written < pad->bytes_per_frame)
                        return 1;
@@ -199,6 +202,7 @@ static int alsa_write_pre_select(struct sched *s, struct writer_node *wn)
        if (underrun < 50)
                underrun = 50;
        underrun -= 50;
+timeout:
        ms2tv(underrun, &tv);
        if (tv_diff(&s->timeout, &tv, NULL) > 0)
                s->timeout = tv;
@@ -278,6 +282,11 @@ static void alsa_close(struct writer_node *wn)
        PARA_INFO_LOG("closing writer node %p\n", wn);
 
        if (pad->handle) {
+               /*
+                * It's OK to have a blocking operation here because we already
+                * made sure that the PCM output buffer is (nearly) empty.
+                */
+               snd_pcm_nonblock(pad->handle, 0);
                snd_pcm_drain(pad->handle);
                snd_pcm_close(pad->handle);
                snd_config_update_free_global();
@@ -290,18 +299,29 @@ static void alsa_write_post_select_btr(__a_unused struct sched *s,
 {
        struct writer_node *wn = container_of(t, struct writer_node, task);
        struct private_alsa_write_data *pad = wn->private_data;
+       struct btr_node *btrn = wn->btrn;
        char *data;
        size_t bytes;
        snd_pcm_sframes_t frames, avail;
        int ret;
 
 again:
-       bytes = btr_next_buffer(wn->btrn, &data);
-       //PARA_CRIT_LOG("have: %zu\n", bytes);
        t->error = 0;
-       ret = -E_ALSA_ORPHAN;
-       if (btr_no_parent(wn->btrn) && (!pad->handle || bytes < pad->bytes_per_frame))
-               goto err;
+       ret = prepare_writer_node(wn);
+       if (ret == 0)
+               return;
+       bytes = btr_next_buffer(btrn, &data);
+       if (bytes < pad->bytes_per_frame) { /* eof */
+               assert(btr_no_parent(btrn));
+               ret = -E_ALSA_EOF;
+               if (!pad->handle)
+                       goto err;
+               /* wait until pending frames are played */
+               avail = snd_pcm_avail_update(pad->handle);
+               if (avail + 1000 > pad->buffer_frames)
+                       goto err;
+               return;
+       }
        if (!pad->handle) {
                char *buf;
                struct alsa_write_args_info *conf = wn->conf;
@@ -314,7 +334,7 @@ again:
                if (!conf->samplerate_given) { /* config option trumps btr_exec */
                        /* ask parent btr nodes */
                        buf = NULL;
-                       ret = btr_exec_up(wn->btrn, "samplerate", &buf);
+                       ret = btr_exec_up(btrn, "samplerate", &buf);
                        PARA_CRIT_LOG("ret: %d\n", ret);
                        if (ret >= 0) {
                                int32_t rate;
@@ -328,7 +348,7 @@ again:
                }
                if (!conf->channels_given) {
                        buf = NULL;
-                       ret = btr_exec_up(wn->btrn, "channels", &buf);
+                       ret = btr_exec_up(btrn, "channels", &buf);
                        if (ret >= 0) {
                                int32_t ch;
 
@@ -344,16 +364,7 @@ again:
                ret = alsa_init(pad, wn->conf);
                if (ret < 0)
                        goto err;
-       }
-       for (;;) {
-               if (bytes == 0)
-                       return;
-               if (bytes >= pad->bytes_per_frame)
-                       break;
-               /* should not be possible to reach this */
-               PARA_CRIT_LOG("dropping %zu byte buffer\n", bytes);
-               btr_consume(wn->btrn, bytes);
-               bytes = btr_next_buffer(wn->btrn, &data);
+               wn->min_iqs = pad->bytes_per_frame;
        }
        frames = bytes / pad->bytes_per_frame;
        avail = snd_pcm_avail_update(pad->handle);
@@ -363,7 +374,7 @@ again:
        //PARA_CRIT_LOG("writing %ld frames\n", frames);
        frames = snd_pcm_writei(pad->handle, data, frames);
        if (frames >= 0) {
-               btr_consume(wn->btrn, frames * pad->bytes_per_frame);
+               btr_consume(btrn, frames * pad->bytes_per_frame);
                goto again;
        }
        if (frames == -EPIPE) {
@@ -377,9 +388,8 @@ again:
        ret = -E_ALSA_WRITE;
 err:
        assert(ret < 0);
+       btr_del_node(btrn);
        alsa_close(wn);
-       btr_del_node(wn->btrn);
-       wn->btrn = NULL;
        t->error = ret;
 }
 

diff --git a/error.h b/error.h
index 08d6bd6e13da2ba04c9b2caa1f99f413887837ef..bf633f543cc68a8bba90e6af8e357ac1011e7af4 100644 (file)
--- a/error.h
+++ b/error.h
@@ -412,7 +412,7 @@ extern const char **para_errlist[];
        PARA_ERROR(SET_RATE, "snd_pcm_hw_params_set_rate_near failed"), \
        PARA_ERROR(START_THRESHOLD, "snd_pcm_sw_params_set_start_threshold() failed"), \
        PARA_ERROR(STOP_THRESHOLD, "snd_pcm_sw_params_set_stop_threshold() failed"), \
-       PARA_ERROR(ALSA_ORPHAN, "alsa btr node has no parent"), \
+       PARA_ERROR(ALSA_EOF, "alsa: end of file"), \
 
 
 #define FILE_WRITE_ERRORS \