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alsa: re-enable-nonblocking, but sleep if busy

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Instead of letting ALSA block for us (and potentially allowing
something stupid on certain hardware or drivers), we do the
sleeping ourselves.  We calculate the sleep to be a fraction of
period_time to avoid oversleeping (and thus audible skipping).
This commit is contained in:
Eric Wong 2008-09-23 23:59:54 +02:00 committed by Max Kellermann
parent 9899ab5ac2
commit e4f5d6bdf4
1 changed files with 10 additions and 7 deletions
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17
src/audioOutputs/audioOutput_alsa.c
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@ -37,9 +37,6 @@ static const char default_device[] = "default";
#include <alsa/asoundlib.h>
/* #define MPD_SND_PCM_NONBLOCK SND_PCM_NONBLOCK */
#define MPD_SND_PCM_NONBLOCK 0
typedef snd_pcm_sframes_t alsa_writei_t(snd_pcm_t * pcm, const void *buffer,
snd_pcm_uframes_t size);
@ -49,6 +46,7 @@ typedef struct _AlsaData {
alsa_writei_t *writei;
unsigned int buffer_time;
unsigned int period_time;
unsigned int period_sleep;
int sampleSize;
int useMmap;
} AlsaData;
@ -160,18 +158,16 @@ static int alsa_openDevice(struct audio_output *audioOutput)
ad->device, audioFormat->bits);
err = snd_pcm_open(&ad->pcmHandle, ad->device,
SND_PCM_STREAM_PLAYBACK, MPD_SND_PCM_NONBLOCK);
SND_PCM_STREAM_PLAYBACK, SND_PCM_NONBLOCK);
if (err < 0) {
ad->pcmHandle = NULL;
goto error;
}
#if MPD_SND_PCM_NONBLOCK == SND_PCM_NONBLOCK
cmd = "snd_pcm_nonblock";
err = snd_pcm_nonblock(ad->pcmHandle, 0);
if (err < 0)
goto error;
#endif /* MPD_SND_PCM_NONBLOCK == SND_PCM_NONBLOCK */
period_time_ro = period_time = ad->period_time;
configure_hw:
@ -254,6 +250,8 @@ configure_hw:
if (retry != MPD_ALSA_RETRY_NR)
DEBUG("ALSA period_time set to %d\n", period_time);
ad->period_sleep = period_time >> 1;
cmd = "snd_pcm_hw_params_get_buffer_size";
err = snd_pcm_hw_params_get_buffer_size(hwparams, &alsa_buffer_size);
if (err < 0)
@ -388,7 +386,12 @@ static int alsa_playAudio(struct audio_output *audioOutput,
while (size > 0) {
ret = ad->writei(ad->pcmHandle, playChunk, size);
if (ret == -EAGAIN || ret == -EINTR)
if (ret == -EAGAIN) {
DEBUG("ALSA busy, sleeping %d\n", ad->period_sleep);
my_usleep(ad->period_sleep);
continue;
}
if (ret == -EINTR)
continue;
if (ret < 0) {