I'm getting buffer underruns when running on an old program I recently
brought back from the ashes.
The program loads up a raw sound file fully into memory (2100 bytes
long, 525 frames) and prepares ALSA for output (44.1khz, 2 channels,
signed 16 bit):
if ((err = snd_pcm_set_params(audio_handle,
SND_PCM_FORMAT_S16_LE,
SND_PCM_ACCESS_RW_INTERLEAVED,
2,
44100,
1,
sound.playback_us)) < 0) {
printf("E: Failed to prepare PCM: %s\n", snd_strerror(err));
return -1;
}
PCM state is PREPARED prior to first playing the sound. Sound plays
correctly the first time around, however, the second time it is played,
state is RUNNING and a -EPIPE ("Broken pipe") is thrown by
snd_pcm_writei. Playback logic:
frames = snd_pcm_writei(audio_handle,
sound.data,
write_size);
if(frames < 0) {
printf("E: %s: attempting to recover\n", snd_strerror(frames));
frames = snd_pcm_recover(audio_handle, frames, 0);
}
if(frames < 0) {
printf("E: snd_pcm_writei failed\n");
break;
} else if(frames > 0 && frames < write_size)
printf("E: Short write (expected %li, wrote %li)\n", write_size,
frames);
else
printf("wrote %li frames\n", frames);
Strangely, it plays correctly at the third time, failing once again the
following time. In other words, it fails with a -EPIPE error every other
time.
For the sake of simplicity, I'm playing the sounds at 1 second intervals.
What's wrong with the logic above?
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