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ao_alsa: reduce spurious wakeups

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Apparently this can happen. So actually only return from waiting if ALSA
excplicitly signals that new output is available, or if we are woken up
externally.
This commit is contained in:
wm4 2014-05-30 23:54:11 +02:00
parent 3053a68d2d
commit 9c9f23eee9
2 changed files with 16 additions and 8 deletions
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18
audio/out/ao_alsa.c
View File

@ -712,14 +712,20 @@ static int audio_wait(struct ao *ao, pthread_mutex_t *lock)
err = snd_pcm_poll_descriptors(p->alsa, fds, num_fds);
CHECK_ALSA_ERROR("cannot get pollfds");
int r = ao_wait_poll(ao, fds, num_fds, lock);
if (r < 0)
return r;
while (1) {
int r = ao_wait_poll(ao, fds, num_fds, lock);
if (r)
return r;
unsigned short revents;
snd_pcm_poll_descriptors_revents(p->alsa, fds, num_fds, &revents);
CHECK_ALSA_ERROR("cannot read poll events");
unsigned short revents;
snd_pcm_poll_descriptors_revents(p->alsa, fds, num_fds, &revents);
CHECK_ALSA_ERROR("cannot read poll events");
if (revents & POLLERR)
return -1;
if (revents & POLLOUT)
return 0;
}
return 0;
alsa_error:

6
audio/out/push.c
View File

@ -410,7 +410,7 @@ int ao_play_silence(struct ao *ao, int samples)
// Call poll() for the given fds. This will extend the given fds with the
// wakeup pipe, so ao_wakeup_poll() will basically interrupt this function.
// Unlocks the lock temporarily.
// Returns <0 on error, 0 on success.
// Returns <0 on error, 0 on success, 1 if the caller should return immediately.
int ao_wait_poll(struct ao *ao, struct pollfd *fds, int num_fds,
pthread_mutex_t *lock)
{
@ -434,13 +434,15 @@ int ao_wait_poll(struct ao *ao, struct pollfd *fds, int num_fds,
pthread_mutex_lock(&p->lock);
memcpy(fds, p_fds, num_fds * sizeof(fds[0]));
bool wakeup = false;
if (p_fds[num_fds].revents & POLLIN) {
wakeup = true;
// flush the wakeup pipe contents - might "drown" some wakeups, but
// that's ok for our use-case
char buf[100];
read(p->wakeup_pipe[0], buf, sizeof(buf));
}
return (r >= 0 || r == -EINTR) ? 0 : -1;
return (r >= 0 || r == -EINTR) ? wakeup : -1;
}
void ao_wakeup_poll(struct ao *ao)