dbus control of volume?

[Mark Greenwood]

On Wednesday 17 Mar 2010 17:06:55 D. R. Evans wrote:
> Nils Kassube said the following at 03/17/2010 10:17 AM :
> > D. R. Evans wrote:
> >> In KDE3, the following command mutes the audio volume:
> >>   dcop kmix Mixer0 setVolume 0 0
> >>
> >> What's the right command to do the same thing in KDE4 (i.e., with
> >>  dbus)?
> > 
> > Is it mandatory for you to use dbus? For scripts I always use amixer to 
> > control the mixer settings.
> 
> The man page says that amixer is for ALSA. I don't pretend to understand
> the morass that KDE4 sound is, but my understanding (which could be
> completely wrong) is that ALSA has been superceded by Phonon.

No, Phonon is just (yet) another layer. ALSA is still driving your sound card. Phonon is just a library that makes it easier to develop audio programs, and allows users to choose between multiple outputs for different 'classes' of application.

In the most complex case now, if you have Pulseaudio enabled, your sound routing now looks like this:

KDE Application->Phonon->Xine->Pulseaudio->ALSA

For non-KDE (i.e. non Phonon-aware) applications it now looks like this:

Application->Pulseaudio->ALSA

And Phonon is meant to simplify things...??? :-)

Anyway, it all means you can still use ALSA commands and KMix still controls the ALSA mixer settings. There is no mixer in Phonon.

Mark

> 
> Just in case my understanding is wrong, I tried one of the examples from
> the man page:
> 
> [H:N] amixer -c 1 -- sset Master playback -20dB
> amixer: Unable to find simple control 'Master',0
> 
>   Doc
> 
>