[pulseaudio-tickets] [PulseAudio] #782: loud "woof" when closing a player

PulseAudio trac-noreply at tango.0pointer.de
Tue Jan 19 09:48:15 PST 2010

#782: loud "woof" when closing a player
 Reporter:  patrakov at gmail.com  |       Owner:  lennart
     Type:  defect              |      Status:  new    
Milestone:                      |   Component:  daemon 
 Keywords:                      |  
 To reproduce:

 0) disable event sounds

 1) install decibel-audio-player

 2) start it with the --playbin2 argument, play some music from a CD

 3) notice that it is too loud, use the built-in volume control slider to
 change volume

 4) use mouse wheel on gnome-volume-control to change volume again

 This stupid sequence of actions creates a situation when the device volume
 is not the same as the stream volume. Yes, I know that decibel-audio-
 player should not use the internal volume control.

 5) Close decibel-audio-player while it is playing.

 Actual result: loud "woof"
 Expected result: playback stops without any audible transition effects

 I suppose that this happens because with flat volumes, pulseaudio adjusts
 ALSA mixer elements each time a stream begins or ends, and this races with
 PCM playback. I.e., if the hardware volume is adjusted by pulseaudio
 before the stream actually ends, the above-mentioned "woof" is emitted.

 I think that this defect is not fixable if the device volume is affected
 only by currently-playing stream volumes. Any of the following actions
 will fix the problem:

  * disable flat volumes (BTW - is this configuration supported and
 supposed to work in the future?)
  * take volumes of the past streams into account in the flat-volume logic
 (so that end of stream doesn't lead to hardware volume change - but this
 also needs some means to display and/or forget past stream volumes)

 A gradual volume change will somewhat mask this "woof".

Ticket URL: <http://pulseaudio.org/ticket/782>
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