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hosted: Improve buffer underrun handling in the ALSA driver

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* Bump internal mix buffer size by 4x, to 1K frames (matching ALSA period)
 * Handle an underrun that occurs when filling the audio buffer
 * Log underruns and make them available in the debug info

Change-Id: I28d56dd35d88851fa167ad92368a5882937a758f
This commit is contained in:
Solomon Peachy 2020-11-18 14:08:17 -05:00
parent 473aa615de
commit 3027cead01
4 changed files with 66 additions and 19 deletions
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65
firmware/target/hosted/pcm-alsa.c
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@ -62,6 +62,12 @@
#define DEFAULT_PLAYBACK_DEVICE "plughw:0,0"
#define DEFAULT_CAPTURE_DEVICE "default"
#if MIX_FRAME_SAMPLES < 512
#error "MIX_FRAME_SAMPLES needs to be at least 512!"
#elif MIX_FRAME_SAMPLES < 1024
#warning "MIX_FRAME_SAMPLES <1024 may cause dropouts!"
#endif
static const snd_pcm_access_t access_ = SND_PCM_ACCESS_RW_INTERLEAVED; /* access mode */
#if defined(SONY_NWZ_LINUX) || defined(HAVE_FIIO_LINUX_CODEC)
/* Sony NWZ must use 32-bit per sample */
@ -83,6 +89,8 @@ static sample_t *frames = NULL;
static const void *pcm_data = 0;
static size_t pcm_size = 0;
static unsigned int xruns = 0;
static snd_async_handler_t *ahandler = NULL;
static pthread_mutex_t pcm_mtx;
static char signal_stack[SIGSTKSZ];
@ -117,17 +125,21 @@ static int set_hwparams(snd_pcm_t *handle)
snd_pcm_hw_params_malloc(&params);
/* Size playback buffers based on sample rate.
Note these are in FRAMES, and are sized to be about 10ms
for the buffer and 2.5ms for the period */
Buffer size must be at least 4x period size!
Note these are in FRAMES, and are sized to be about 8.5ms
for the buffer and 2.1ms for the period
*/
if (pcm_sampr > SAMPR_96) {
buffer_size = MIX_FRAME_SAMPLES * 16 * 4; /* 32k */
period_size = MIX_FRAME_SAMPLES * 4 * 4; /* 4k */
buffer_size = MIX_FRAME_SAMPLES * 4 * 4;
period_size = MIX_FRAME_SAMPLES * 4;
} else if (pcm_sampr > SAMPR_48) {
buffer_size = MIX_FRAME_SAMPLES * 16 * 2; /* 16k */
period_size = MIX_FRAME_SAMPLES * 4 * 2; /* 2k */
buffer_size = MIX_FRAME_SAMPLES * 2 * 4;
period_size = MIX_FRAME_SAMPLES * 2;
} else {
buffer_size = MIX_FRAME_SAMPLES * 16; /* 4k */
period_size = MIX_FRAME_SAMPLES * 4; /* 1k */
buffer_size = MIX_FRAME_SAMPLES * 4;
period_size = MIX_FRAME_SAMPLES;
}
/* choose all parameters */
@ -407,7 +419,8 @@ static void async_callback(snd_async_handler_t *ahandler)
if (state == SND_PCM_STATE_XRUN)
{
logf("underrun!");
xruns++;
logf("initial underrun!");
err = snd_pcm_recover(handle, -EPIPE, 0);
if (err < 0) {
logf("XRUN Recovery error: %s", snd_strerror(err));
@ -432,8 +445,20 @@ static void async_callback(snd_async_handler_t *ahandler)
{
if (copy_frames(false))
{
retry:
err = snd_pcm_writei(handle, frames, period_size);
if (err < 0 && err != period_size && err != -EAGAIN)
if (err == -EPIPE)
{
logf("mid underrun!");
xruns++;
err = snd_pcm_recover(handle, -EPIPE, 0);
if (err < 0) {
logf("XRUN Recovery error: %s", snd_strerror(err));
goto abort;
}
goto retry;
}
else if (err != period_size)
{
logf("Write error: written %i expected %li", err, period_size);
break;
@ -452,7 +477,18 @@ static void async_callback(snd_async_handler_t *ahandler)
while (snd_pcm_avail_update(handle) >= period_size)
{
int err = snd_pcm_readi(handle, frames, period_size);
if (err < 0 && err != period_size && err != -EAGAIN)
if (err == -EPIPE)
{
logf("rec mid underrun!");
xruns++;
err = snd_pcm_recover(handle, -EPIPE, 0);
if (err < 0) {
logf("XRUN Recovery error: %s", snd_strerror(err));
goto abort;
}
continue; /* buffer contents trashed, no sense in trying to copy */
}
else if (err != period_size)
{
logf("Read error: read %i expected %li", err, period_size);
break;
@ -751,11 +787,16 @@ void pcm_play_dma_postinit(void)
#endif
}
int pcm_alsa_get_rate(void)
unsigned int pcm_alsa_get_rate(void)
{
return real_sample_rate;
}
unsigned int pcm_alsa_get_xruns(void)
{
return xruns;
}
#ifdef HAVE_RECORDING
void pcm_rec_lock(void)
{