PA by default

[Lennart Poettering]

On Thu, 16.08.07 22:53, Bastien Nocera (bnocera at redhat.com) wrote:

> Heya,
> 
> Before Fedora 8, is there a plan to fix a few regressions or integration
> issue with PA?
> 
> From:
> https://www.redhat.com/archives/fedora-devel-list/2007-August/msg01196.html
> 
> > You also have to make sure that some GConf keys are set up properly:
> > 
> >   /system/gstreamer/0.10/default/audiosrc -> pulsesrc
> >   /system/gstreamer/0.10/default/audiosink -> pulsesink (or autoaudiosink)
> >   /system/gstreamer/0.10/default/chataudiosink -> pulsesink (or autoaudiosink)
> >   /system/gstreamer/0.10/default/musicaudiosink -> pulsesink (or autoaudiosink)
> 
> This means that the "Devices" part of the Sound Preferences in GNOME is
> pretty useless. I guess there's a PA specific way of changing the
> default input and output, but you lose integration with the desktop.

Hmm, this capplet somhow vanished completely on my Fedora
system. Anyone knows where I can find it?

GStreamer supports all kinds of interfaces to enumerate sound
devices. gst-pulse supports those. Hence the dialog should work, but I
cannot really say since I haven't testes this. (see above) qThe
gnome-volume-control device selection does work the last time I
looked. 

> This will also probably break the device selection that the volume
> applet uses (it uses the same as the default sound events device,
> iirc).

Presumable the applet uses the same interfaces as gnome-volume-control
and thus should work. A quick check seems to prove that.

> I'm also thinking of applications' volume setup. At least Totem and
> Rhythmbox have the concept of "system volume" (which is per device, and
> they don't touch), and the "application volume" (which they do). Here,
> we're adding the "PA volume".

The "application volume" and the "PA volume" should be "merged". (see
below)

> How do we plan on handling that?

Volume control is a very difficult topic. It had a couple of
discussions with a couple of people how we should expose this
best. (Takashi, Kay, thanks!) One has to consider that usually people
don't expect that there is a whole series of volume controls one after
the other: software volume control in rhythmbox, then a software
volume control in PA, the hardware volume control of the WAVE control
in ALSA, then the MASTER control in ALSA and finally (if you have a
thinkpad at least like I do) another hw amplifier. That's five
controls in a row. (let alone the external controls of your active
loudspeakers or your hifi system, which we will ignore here for
now). FIVE! That's about three and a half too many, I would say. And
these are five that you might accidentaly have set to -Inf dB, and
which might be the reason why your sound doesn't work.

If you look how Apple does volume control in MacOSX (Apple usually
does these things right, so it's where we should belook), they have
exactly two. One per-app in sw and a one global in hw. Some people
might still find this confusing, i.e. one too many, but on the other
hand per-app volume control is deadly sexy.

So, what I would like to see implemented is this: ALSA hides away
unncessary volume controls and initializes them to sane defaults
(i.e. "0 dB"), and makes sure there is always a "Master" volume
control which is the actual control for the amplification in HW. This
is what Takashi has started to work on. PA already exposes this single
per-device volume control, and ignores all the rest the hw might
expose. That's volume control #1, the per-device hw-based one. 

For volume #2, the per-stream sw-based one: the PA per-stream volume
and the volume adjustment done in GST should be "merged". PA has all
the necessary APIs but Gstreamer needs some non-trivial changes for
this. Right now GST's mixer control is awful and designed with
per-device controls in mind and hardware backends. Hence I am unable
to expose the PA per-stream volume properly in gst-pulse.

I brought this up to some GST people a while back, but I guess
everyone was just too busy and PA was not yet installed by default on
Fedora and hence not important enough. 

Ideally, Rhythmbox should only show the per-stream volume control. If
you right click on it a popup menu should open to replace the widget
by the hw per-device volume control. Another option of that popup
should be to start the volume control tool.

Right now we are in the very unfortunate situation to have two volume
control tools. One being "pavucontrol" which uses PA and exposes a lot
of fun functionality but looks ... shitty -- because I wrote it. And
the other one being gnome-volume-control which looks much better but
exposes all those unnecessary mixer tracks and doesn't know anything
about per-stream volumes. This situation needs some real fixing. I am
hoping that eventually someone eventually will pick up this mess and
try to find a good solution. (i.e. maybe beef up the gst volume
control stuff to new levels, or give my PA UI tools some serious love)
Anyone?

Lennart

-- 
Lennart Poettering                        Red Hat, Inc.
lennart [at] poettering [dot] net         ICQ# 11060553
http://0pointer.net/lennart/           GnuPG 0x1A015CC4