Crack sounds in playback

[Hynek Hanke <hanke@brailcom.org>]

Hello everyone,

after all the suggestions (thanks for them), I got the alsa playback working
with the non-blocking/polling approach. I'm checking for xrun and suspend
states in the poll loop and after I send all the samples, I set avail_min to
the whole buffer and poll() until the states gets to XRUN. I open the device
before playing each track and close it after that. Sometimes, I interrupt the
sound in the middle through snd_pcm_drop() and immediatelly close the device.

I'm setting the usual hw parameters. From software parameters, I set only
avail_min at the end, when I need to ,,drain''.

The playback seems good now, but my colleague is reporting he hears some crack
sounds on his SoundBlaster Platinum. They appear mostly at the beginning and at
the end, but in the middle sometimes too. They appear often.

I've examined the log and the device does never get to XRUN or SUSPEND, except
for the last stage, when I set avail_min to the size of the buffer and wait
until it's empty -- but that's expected behavior. None of snd_pcm_ calls
returns any error.

Any ideas of what am I doing wrong or how to debug this?

Thank you,
Hynek Hanke


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