[alsa-devel] alsactl adds volume controls?

[Takashi Iwai]

At Sat, 28 Aug 2010 06:58:20 +0800,
Raymond Yau wrote:
> 
> 2010/8/28 David Henningsson <david.henningsson at canonical.com>
> 
> > 2010-08-27 17:43, Clemens Ladisch skrev:
> > > David Henningsson wrote:
> > >> So I've discovered that my sound card has a "PCM Playback Volume"
> > >> control, but changing that control does not alter the volume.
> > >>
> > >> Interestingly enough, this control does not come from the HDA parser, it
> > >> is added by alsactl at boot time...!
> > >
> > > This control was created by the software volume plugin.  When not using
> > > this plugin, the control does not have any effect.
> > >
> > > To get rid of it, delete its entry from /etc/asound.state.
> >
> > Hmm, I wonder if this is an Ubuntu-specific bug then? Because when I run
> > Maverick (the upcoming Ubuntu release) from a Live-CD, the "PCM Playback
> > Volume" control is still there (and there is no asound.state, neither in
> > /etc or in /var/lib/alsa).
> > When I use the plughw interface, the "PCM Playback Volume" does not
> > affect volume output. Should I use another device string to test the
> > softvol plugin, to see if it's there or not?
> >
> 
> The softvol plugin it is defined in "front" device in
> /usr/share/alsa/cards/HDA-Intel.conf
> 
> reason is some HDA codec does not has any hardware volume control (analog)
> 
> this user-defined control only effective when the application use "front"
> device

Hm, but if PA opens the device with SND_PCM_NO_SOFTVOL flag, the
softvol should be skipped.


Takashi