[pulseaudio-discuss] Gnome volume applet

Ritesh Kumar ritesh at cs.unc.edu
Sat Dec 22 13:43:21 PST 2007

On Dec 22, 2007 10:38 AM, Bill Moseley <moseley at hank.org> wrote:

> On Fri, Dec 21, 2007 at 04:11:02PM -0500, Ritesh Kumar wrote:
> > The big picture ain't that pretty, isn't it? :)
> Eh, no it's not.
> And I'm still not even clear in the LTSP environment who is the pulse
> client and who is the server. ;)

He he... I am sorry though... I have little idea of the LTSP setup. But the
pulse server will always likely to be where the sound card is ... similar to
the X server which is always where the display is.

> Let me as a simple question, which maybe you answered in your reply
> and I didn't recognize.   On my normal workstations that uses ALSA
> both the GNOME volume applet and alsamixer work.
> On the LTSP setup, the GNOME applet looks the same but doesn't work,
> yet alsamixer seems to know that it should be using pulse.  How does
> alsamixer know this yet the applet doesn't?

That is odd... can you check if GNOME applet is using anything other than
ALSA for controlling its audio. If Gnome is using the ALSA interface, then
things should work properly.

> Also, is this problem not related to Pulse?  The volume control on the
> LTSP server isn't suppose to use Pulse to run the hardware volume on
> the LTSP thin client, correct?  Rather, it controls  a soft volume
> control on the audio stream before it's passed via pulse to the
> hardware on the remote client, right?

The pulse server should run on the machine where the soundcard is. However,
alsa could be running anywhere if all its doing is redirecting to the pulse

> So the trick is getting the GNOME applet to use a soft volume control
> -- which I believe is what you are showing below.

What I was trying to show below was how the default alsa configuration on
the machine having the sound card on it could cause the pulse server not be
able to control its volume. The client machines will work without problems
if they all redirect any alsa calls to the pulse server and the pulse server
is able to correctly control the volume.

> > If you want a quick solution try adding a device=default in you
> > module-alsa-sink configuration. This is not optimal as it layer dmix
> below
> > pulseaudio instead of eliminating it from the pipeline.
> And that would be on the LTSP thin client?  I don't have a default.pa
> on the LTSP server, only on the client:
>    /opt/ltsp/i386/etc/pulse/default.pa

That seems reasonable given that the sound needs to be produced on the

> Currently, that module is commented out -- is that expected?
>    $ fgrep module-alsa-sink /opt/ltsp/i386/etc/pulse/default.pa
>    #load-module module-alsa-sink
>    #add-autoload-sink output module-alsa-sink sink_name=output
> > What I recommend you do is ditch the default alsa configuration and make
> > your own. The first thing to do is to make your own virtual device and
> add a
> > "Master" softvol to it if necessary. Use the following as a guide
> line...
> > use your local ~/.asoundrc if you don't feel like modifying
> /etc/asound.conf
> > pcm.!default { type pulse }
> > ctl.!default { type pulse }
> > # Create softvol devices for intelHDA.
> > # For intelHDA, its "PCM" control controls its default (not used)
> softvol.
> > pcm.intelHDA {
> >         type softvol
> >         slave.pcm "hw:0,0"
> >         control.name "Master"
> >         control.card 0
> > }
> >
> > # It seems we require these dummies as pulseaudio tries to look up mixer
> > devices.
> > ctl.intelHDA {
> >         type hw
> >         card 0
> > }
> >
> > Then use intelHDA or whatever name you use above in your
> module-alsa-sink
> > configuration. Something like module-alsa-sink device=intelHDA
> Is "intelHDA" just a name?  That is, I could call it anything?

Yes, only some pcm names are reserved (like default).
You might want to isolate the problem first. Why don't you first run a
little alsa app on the thin clients directly and see if 1) the sound plays
through pulseaudio (use pacmd to list the sink-inputs) 2) Check if alsamixer
is able to control pulseaudio's volume (alsamixer should show pulseaudio as
the soundcard's name) 2) Check if the gnome volume applet works.
Then configure alsa on the remote machine to redirect to pulseaudio and
repeat the steps above.

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