From: Timo Wischer twischer@de.adit-jv.com

Block on drain till available samples played

Without this commit the JACK thread will be stopped before the ALSA buffer was completely forwarded to the JACK daemon.

Signed-off-by: Timo Wischer twischer@de.adit-jv.com ---

This patch is depending on http://mailman.alsa-project.org/pipermail/alsa-devel/2018-January/130991.htm...

diff --git a/jack/pcm_jack.c b/jack/pcm_jack.c index e75aadc..ec94583 100644 --- a/jack/pcm_jack.c +++ b/jack/pcm_jack.c @@ -28,6 +28,17 @@ #include <alsa/asoundlib.h> #include <alsa/pcm_external.h>

+/* ALSA supports up to 64 periods per buffer. + * Therefore at least 64 retries are valid and + * should not be handled as an error case + */ +#define MAX_DRAIN_RETRIES 100 +/* ALSA supports a a period with 8192 frames. + * This would result in ~170ms at 48kHz. + * Therefore a time out of 1 second is sufficient + */ +#define DRAIN_TIMEOUT 1000 + typedef enum _jack_format { SND_PCM_JACK_FORMAT_RAW } snd_pcm_jack_format_t; @@ -146,7 +157,13 @@ static int pcm_poll_unblock_check(snd_pcm_ioplug_t *io) snd_pcm_jack_t *jack = io->private_data;

avail = snd_pcm_avail_update(io->pcm); - if (avail < 0 || avail >= jack->min_avail) { + /* In draining state poll_fd is used to wait + * till all pending frames are played. + * Therefore it has to be guarantee that a poll event is also generated + * if the buffer contains less than min_avail frames + */ + if (avail < 0 || avail >= jack->min_avail || + jack->state == SND_PCM_STATE_DRAINING) { write(jack->fd, &buf, 1); return 1; } @@ -242,7 +259,8 @@ snd_pcm_jack_process_cb(jack_nframes_t nframes, snd_pcm_ioplug_t *io) }

hw_ptr = jack->hw_ptr; - if (jack->state == SND_PCM_STATE_RUNNING) { + if (jack->state == SND_PCM_STATE_RUNNING || + jack->state == SND_PCM_STATE_DRAINING) { const snd_pcm_channel_area_t *areas = snd_pcm_ioplug_mmap_areas(io);

while (xfer < nframes) { @@ -402,6 +420,61 @@ static int snd_pcm_jack_start(snd_pcm_ioplug_t *io) return err; }

+static int snd_pcm_jack_drain(snd_pcm_ioplug_t *io) +{ + snd_pcm_jack_t *jack = io->private_data; + const snd_pcm_state_t state = jack->state; + unsigned int retries = MAX_DRAIN_RETRIES; + char buf[32]; + + /* Immediately stop on capture device. + * snd_pcm_jack_stop() will be automatically called + * by snd_pcm_ioplug_drain() + */ + if (io->stream == SND_PCM_STREAM_CAPTURE) { + return 0; + } + + if (snd_pcm_jack_hw_avail(io, jack->hw_ptr, io->appl_ptr) <= 0) { + /* No data pending. Nothing to drain. */ + return 0; + } + + /* start device if not yet done */ + if (state == SND_PCM_STATE_PREPARED) { + snd_pcm_jack_start(io); + } + + /* FIXME: io->state will not be set to SND_PCM_STATE_DRAINING by the + * ALSA library before calling this function. + * Therefore this state has to be stored internally. + */ + jack->state = SND_PCM_STATE_DRAINING; + + struct pollfd pfd; + pfd.fd = io->poll_fd; + pfd.events = io->poll_events | POLLERR | POLLNVAL; + + while (snd_pcm_jack_hw_avail(io, jack->hw_ptr, io->appl_ptr) > 0) { + if (retries <= 0) { + SNDERR("Pending frames not yet processed."); + return -ETIMEDOUT; + } + + if (poll(&pfd, 1, DRAIN_TIMEOUT) < 0) { + SNDERR("Waiting for next JACK process callback failed (err %d)", + -errno); + return -errno; + } + + /* clean pending events. */ + while (read(io->poll_fd, &buf, sizeof(buf)) == sizeof(buf)) + ; + } + + return 0; +} + static int snd_pcm_jack_stop(snd_pcm_ioplug_t *io) { snd_pcm_jack_t *jack = io->private_data; @@ -433,6 +506,7 @@ static snd_pcm_ioplug_callback_t jack_pcm_callback = { .stop = snd_pcm_jack_stop, .pointer = snd_pcm_jack_pointer, .prepare = snd_pcm_jack_prepare, + .drain = snd_pcm_jack_drain, .poll_revents = snd_pcm_jack_poll_revents, };