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alsa: more tweaks

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Set the lowest possible period time, this lowers the latency.
Adjust slaved stream when we are drifting too much.
Use faster snd_pcm_avail and only use get_status when in error.
This commit is contained in:
Wim Taymans 2018-11-20 16:08:57 +01:00
parent afd9a6c95f
commit d70b4b2b10
1 changed files with 62 additions and 48 deletions
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110
spa/plugins/alsa/alsa-utils.c
View file

@ -428,13 +428,11 @@ int spa_alsa_set_format(struct state *state, struct spa_audio_info *fmt, uint32_
state->rate = info->rate;
state->frame_size = info->channels * (snd_pcm_format_physical_width(format) / 8);
CHECK(snd_pcm_hw_params_get_buffer_size_max(params, &state->buffer_frames), "get_buffer_size_max");
CHECK(snd_pcm_hw_params_set_buffer_size_near(hndl, params, &state->buffer_frames), "set_buffer_size_near");
dir = 0;
period_size = state->buffer_frames;
period_size = 8;
CHECK(snd_pcm_hw_params_set_period_size_near(hndl, params, &period_size, &dir), "set_period_size_near");
CHECK(snd_pcm_hw_params_get_buffer_size_max(params, &state->buffer_frames), "get_buffer_size_max");
CHECK(snd_pcm_hw_params_set_buffer_size_near(hndl, params, &state->buffer_frames), "set_buffer_size_near");
state->period_frames = period_size;
periods = state->buffer_frames / state->period_frames;
@ -493,20 +491,21 @@ static int set_timeout(struct state *state, uint64_t time)
return 0;
}
static int get_status(struct state *state, snd_pcm_sframes_t *delay)
static int alsa_recover(struct state *state, int err)
{
snd_pcm_status_t *status;
snd_pcm_sframes_t av;
int res, st;
snd_pcm_status_t *status;
snd_pcm_status_alloca(&status);
again:
if ((res = snd_pcm_status(state->hndl, status)) < 0) {
spa_log_error(state->log, "snd_pcm_status error: %s", snd_strerror(res));
return res;
}
st = snd_pcm_status_get_state(status);
if (st == SND_PCM_STATE_XRUN) {
switch (st) {
case SND_PCM_STATE_XRUN:
{
struct timeval now, trigger, diff;
uint64_t xrun, missing;
@ -517,37 +516,40 @@ again:
xrun = SPA_TIMEVAL_TO_USEC(&diff);
missing = xrun * state->rate / SPA_USEC_PER_SEC;
state->sample_time = state->sample_count;
state->sample_count += missing;
state->dll.t0 -= xrun * 1e-6;
#if 0
state->safety = SPA_MIN(state->safety + 0.000333, 0.0013333);
dll_bandwidth(&state->dll, DLL_BW_MAX);
#endif
spa_log_error(state->log, "xrun of %"PRIu64" usec %"PRIu64" %f",
xrun, missing, state->safety);
if ((res = snd_pcm_prepare(state->hndl)) < 0) {
spa_log_error(state->log, "snd_pcm_prepare error: %s", snd_strerror(res));
}
if (state->stream == SND_PCM_STREAM_CAPTURE) {
if ((res = snd_pcm_start(state->hndl)) < 0) {
spa_log_error(state->log, "snd_pcm_start: %s", snd_strerror(res));
return res;
}
state->alsa_started = true;
} else {
state->alsa_started = false;
}
spa_alsa_write(state, state->threshold * 2, true);
goto again;
break;
}
default:
spa_log_error(state->log, "recover from error state %d", st);
break;
}
av = snd_pcm_status_get_avail(status);
if (av > state->buffer_frames)
av = state->buffer_frames;
if ((res = snd_pcm_recover(state->hndl, err, true)) < 0) {
spa_log_error(state->log, "snd_pcm_recover error: %s", snd_strerror(res));
return res;
}
dll_init(&state->dll, DLL_BW_MAX);
if (state->stream == SND_PCM_STREAM_CAPTURE) {
if ((res = snd_pcm_start(state->hndl)) < 0) {
spa_log_error(state->log, "snd_pcm_start: %s", snd_strerror(res));
return res;
}
state->alsa_started = true;
} else {
state->alsa_started = false;
spa_alsa_write(state, state->threshold * 2, true);
}
return 0;
}
static int get_status(struct state *state, snd_pcm_sframes_t *delay)
{
snd_pcm_sframes_t av;
if ((av = snd_pcm_avail(state->hndl)) < 0)
return alsa_recover(state, av);
if (delay) {
if (state->stream == SND_PCM_STREAM_PLAYBACK)
@ -651,6 +653,11 @@ int spa_alsa_write(struct state *state, snd_pcm_uframes_t silence, bool start)
spa_log_trace(state->log, "slave %f %"PRIi64" %"PRIu64" %d",
state->dll.dt, nsec, delay, state->rate);
if (delay > state->threshold * 2) {
snd_pcm_rewind(state->hndl, state->threshold);
delay -= state->threshold;
}
}
total_written = 0;
@ -803,23 +810,19 @@ push_frames(struct state *state,
return total_frames;
}
static void alsa_on_playback_timeout_event(struct spa_source *source)
static int handle_play(struct state *state)
{
int res;
struct state *state = source->data;
snd_pcm_sframes_t delay;
uint64_t nsec, expire;
uint64_t nsec;
int64_t jitter;
if (state->started && read(state->timerfd, &expire, sizeof(uint64_t)) != sizeof(uint64_t))
spa_log_warn(state->log, "error reading timerfd: %s", strerror(errno));
if (state->position && state->threshold != state->position->size)
state->threshold = state->position->size;
clock_gettime(CLOCK_MONOTONIC, &state->now);
if ((res = get_status(state, &delay)) < 0)
return;
return 0;
nsec = SPA_TIMESPEC_TO_NSEC(&state->now);
jitter = nsec - state->next_time;
@ -829,11 +832,11 @@ static void alsa_on_playback_timeout_event(struct spa_source *source)
if (delay >= state->threshold * 2) {
spa_log_trace(state->log, "early wakeup %ld %d", delay, state->threshold);
state->next_time = nsec + (state->threshold / 2) * SPA_NSEC_PER_SEC / state->rate;
goto next;
return 0;
}
if ((res = update_time(state, nsec, delay, false)) < 0)
return;
return 0;
if (spa_list_is_empty(&state->ready)) {
struct spa_io_buffers *io = state->io;
@ -851,10 +854,21 @@ static void alsa_on_playback_timeout_event(struct spa_source *source)
else {
spa_alsa_write(state, 0, true);
}
next:
set_timeout(state, state->next_time);
return 0;
}
static void alsa_on_playback_timeout_event(struct spa_source *source)
{
struct state *state = source->data;
uint64_t expire;
if (state->started && read(state->timerfd, &expire, sizeof(uint64_t)) != sizeof(uint64_t))
spa_log_warn(state->log, "error reading timerfd: %s", strerror(errno));
handle_play(state);
set_timeout(state, state->next_time);
}
static void alsa_on_capture_timeout_event(struct spa_source *source)
{