[alsa-devel] alsactl adds volume controls?

[Raymond Yau]

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

it is a bug in PA server to open "front" device for playback and capture

it is not easy to remove the control unless you know the trick

shutdown without alsactl store