[pulseaudio-discuss] pulseaudio overwrites correct channel mapping provided by alsa

[Tanu Kaskinen]

On Sat, 2016-03-26 at 15:16 +0100, Dennis Heuer wrote:
> Hello Tanu,
> 
> schouldn't we post to the list instead of private?

Yes, certainly. That's what's already happening. My mail was sent to
you directly and to the mailing list. I'll send this mail only to the
list to avoid further confusion.

> On Sat, 26 Mar 2016 13:44:10 +0200
> Tanu Kaskinen <tanuk at iki.fi> wrote:
> 
> > 
> > Where is this "front-left,front-left-of-center,front-center,front-
> > right,front-right-of-center,rear-center" coming from? PulseAudio
> > doesn't use such map by default, and if I understood correctly, you
> > are not trying to use such map either. Where do you see this map
> > occurring? Does "pactl list sinks" show that, or is that visible
> > somewhere else?
> "pactl stat" shows this. And this is also what I hear. The first email
> has the files attached. "pactl list sinks" shows correct mapping. I
> appended the file.

OK. "pactl stat" only shows the default channel map, but that has
little practical effect, because the device auto-detection will use a
channel map that fits the hardware rather than trying to use the same
channel map with all hardware.

"pactl list sinks" shows the actual state of the playback devices on
the system. The channel map shown there is what PulseAudio actually
uses.

If you want to modify the surround51 channel map, you can do that by
editing /usr/share/pulseaudio/alsa-mixer/profile-sets/default.conf.
Search for string "surround51", you'll find the channel map definition
nearby. However, that file is not meant to be modified by users - if
modification is needed for the channels to be assigned correctly,
that's an alsa bug, because the "surround51" device should always have
channel map "front-left,front-right,rear-left,rear-right,front-
center,lfe".

> > > I did put this line in default.pa, which worked but without effect:
> > > 
> > > load-module module-alsa-sink
> > > sink_name=alsa_output.pci-0000_00_14.2.analog-surround-51
> > > device_id=1 channels=6
> > > channel_map=front-left,front-right,rear-left,rear-right,front-center,lfe
> > I don't know what "device_id=1" is supposed to do when given to
> > module- alsa-sink. I tried to look it up in the code, but I gave up,
> > because the code in question was too complicated. Usually when you
> > load module- alsa-sink, you would use "device=surround51:1", if
> > you're trying to use 5.1 on card 1.
> > 
> > In any case, this is likely to conflict with the sinks that get
> > automatically loaded, unless you have removed module-udev-detect from
> > the configuration.
> The desktop stalls. Static module-loading also stalls the desktop. Tbh,
> PulseAudio is far too complicated to be mastered without knowing the
> code in detail. This is a very bad situation...

Does the desktop stall if you revert all configuration to what it was
by default?

-- 
Tanu