On 11/12/2009 08:12 AM, Takashi Iwai wrote:
Yes, snd_pcm_recover() is *recommended*. You can write the recovery routine by yourself. The function isn't referred here just because it's relatively new. Better to be documented, indeed.
Thanks a lot for you answer, Takashi. That was very helpful.
But when I hack pcm_min.c to log the state at the beginning of the loop and then enforces an underrun by pausing the program then it sometimes locks up:
$ ./pcm_min state 2 SND_PCM_STATE_PREPARED state 2 SND_PCM_STATE_PREPARED Short write (expected 16384, wrote 7616) state 3 SND_PCM_STATE_RUNNING state 3 SND_PCM_STATE_RUNNING state 3 SND_PCM_STATE_RUNNING state 3 SND_PCM_STATE_RUNNING [ctrl-s ... waiting for silence ... ctrl q] ALSA lib pcm.c:7234:(snd_pcm_recover) underrun occured state 2 SND_PCM_STATE_PREPARED state 2 SND_PCM_STATE_PREPARED state 3 SND_PCM_STATE_RUNNING [hanging in snd_pcm_writei]
It seems like pcm_min.cs use of snd_pcm_recover isn't enough to recover fully? The playback never gets started again, so the async writes in PREPARED succeeds, but the first blocking write hangs waiting forever? What is missing?
It also surprises me that the last PREPARED write isn't a short write. Why is that?
Regards, Mads