[alsa-devel] Keyboard volume buttons

[Takashi Iwai]

At Fri, 27 Feb 2009 08:06:43 +0100,
Vedran Miletić wrote:
> 
> On Fri, Feb 27, 2009 at 3:20 AM, Harsha, Priya <priya.harsha at intel.com> wrote:
> > Hi,
> >
> > Can anyone tell me how keyboard's volume buttons are converted into real volume change? Will there be an application that monitors the keyboard volume button events and call ALSA API to set the volume?
> >
> > Thanks
> > Harsha
> >
> > _______________________________________________
> > Alsa-devel mailing list
> > Alsa-devel at alsa-project.org
> > http://mailman.alsa-project.org/mailman/listinfo/alsa-devel
> >
> 
> Yes, X catches keypress and lets the window manager know about it. In
> case of metacity, which is what GNOME uses, if that key is bound to a
> volume control action, it calls gnome-volume-control to do the
> apropriate change. I _believe_ it is so, never checked source code.

For most ACPI-events, yes, it works like that.  The window manager is
responsible for the volume control.

In some cases, the volume is changed in the driver side.  For example,
some devices issue an IRQ per volume-control action.  Some HD-audio
codecs have the volume-knob widget that is required to be handled by
the codec driver via unsolicited events.

Also, some (old) thinkpads have their own hardware layer and the h/w
volume is handled differently.


Takashi