[Bug 147643] Multichannel audio is broken

[Rudd-O]

Public bug reported:

This bug is really odd.  I have a SBLive! on another machine which uses
PulseAudio to turn the machine into an audio server.

This machine of course is capable of 4-channel multichannel audio.  But,
being the cheap bastard that I am, the machine only has one stereo
system connected, to which my stereo headset is attached.  Therefore, I
took the liberty of creating the following ALSA sound card definitions
in /etc/asound.conf:

pcm.simulatedsurround {
    type            softvol
    slave {
        pcm         "downmix51"
    }
    control {
        name        "Virtual surround volume"
        card        0
    }
}


pcm.downmix51 {
    type        route
    slave.pcm   "default"
    slave.channels    2
    ttable {
        0.0    0.25
        1.1    0.25
        2.0    0.25
        3.1    0.25
        4.0    0.25
        4.1    0.25
        5.0    0.25
        5.1    0.25
    }
}

So far, so good. Speaker-test with channels set to six reports both
center and LFE are mapped stereo, and the rear channels are mapped to
the front.  Basically, all sound from all "channels" reaches my ears.
So far so good.

The problem arises because I don't watch DVDs on that machine.  I watch
my DVDs on my PowerEdge (another machine yet holds the CD-ROM drive,
long story, 1U servers can't hold full-size DVDs, so I'm using GNBD to
export the drive through the network).

Now, here's the relevant snippet of my /etc/pulse/default.pa:

load-module module-alsa-sink device=hw:0 sink_name=stereo
load-module module-alsa-sink device=simulatedsurround channels=6 sink_name=simulatedsurround
set-default-sink stereo

I have verified using paplay that the stereo sink works fine with stereo
files.  Moreover, I have also verified using paplay's device and
--channel-map arguments, that mono,, stereo and multichannel sound files
play correctly on my "simulatedsurround" output.  This *works*.

But Xine doesn't.  Thus, Kaffeine doesn't.  Both refuse to use the
pulseaudio ALSA output plugin on my PowerEdge (strangely, because all
other alsa apps work OK).  Both autochoose the pulseaudio output plugin.
And the pulseaudio output plugin in Xine/Kaffeine actually *outputs
sound* when playing 5.1 DVDs -- just not the dialogs.  When watching the
PulseAudio volume meter on the monitor output, I can see that the front
channels are being fed what appears to sound like ambient music, and the
LFE/center channels are also being fed similar signal.

What's it gonna take for me to have surround sound working properly with
my DVDs?

Kaffeine does work correctly with stereo sound DVDs.

The a/52 downmix toggle does not have any effect in Xine.

Please help.  GMPlayer is also refusing to play the DVDs (for altogether
different reasons, might I add).

** Affects: kaffeine (Ubuntu)
     Importance: Undecided
         Status: New

-- 
Multichannel audio is broken
https://bugs.launchpad.net/bugs/147643
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