[alsa-devel] Adjust volume may cause audio playback corruption

Clemens Ladisch clemens at ladisch.de
Thu May 17 21:05:26 CEST 2012

cee1 wrote:
> We've found a way the can reproduce the problem more quickly on our product:
> 1. do audio playback
> 2. alsamixer, select 'Master', press 'm' and hold for a while.
> Then release 'm', playback corrupts(sounds similar to
> http://dev.lemote.com/files/upload/software/PA-apc/corrupted_sound.ogg).

Is the output supposed to be playing or muted at this time?

This appears to be a problem with PA's volume handling.
It might be caused by incorrect dB volume information of the HDA codec,
or by a bug in PA.

> What does rewind do? Why we need rewind here?

It allows to rewrite already written parts of the audio buffer; it's used
to apply the new volume to samples that have not yet been actually played.


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