[alsa-devel] wrong decibel data?

[Raymond Yau]

2010/5/27 Clemens Ladisch <clemens at ladisch.de>

> Colin Guthrie wrote:
> > state.Intel {
> >       control.1 {
> >               comment.access 'read write'
> >               comment.type INTEGER
> >               comment.count 2
> >               comment.range '0 - 31'
> >               comment.dbmin -4650
> >               comment.dbmax 0
> >               iface MIXER
> >               name 'Master Playback Volume'
> >               value.0 30
> >               value.1 30
> >       }
>
> This is the hardware volume control.
>
> >       control.11 {
> >               comment.access 'read write user'
> >               comment.type INTEGER
> >               comment.count 2
> >               comment.range '0 - 255'
> >               comment.tlv '0000000100000008ffffec1400000014'
> >               comment.dbmin -5100
> >               comment.dbmax 0
> >               iface MIXER
> >               name 'PCM Playback Volume'
> >               value.0 253
> >               value.1 253
> >       }
>
> This is the emulated software volume control that is created by the
> softvol plugin.  This control gets recreated by "alsactl restore" even
> when the plugin is not running.
>
> Might it be possible that PA is trying to use this, but that it doesn't
> have any effect because PA is using PCM device hw:0?  (Try unloading
> snd-hda-intel and then deleting that entry from /etc/asound.state.)
>
>
> Regards,
> Clemens
>

if I make a customised device "test" with softvol plugin with name "P
Playback Volume" in .asounrd

aplay -D test.wav

alsamixer -c0 show the "P" control and volume change as expected

Then change the name from "P Playback Volume" to "Q Playack Volume" and play
audio through device "test" again

alsamixer -c0 show both "P" and "Q" controls

"P" control can go up/down with no effect of course

but "Q" stayed at 100%

Is this a bug ?