Re: [Alsa-user] SPDIF Out and multiple channels

[Dennis v. d. M. <dv...@wa...>]

>>>I have a Terratec Aureon Space 7.1 and I'm able to play music through
>>>my digital out without any problems. There is just one thing that I can't
>>>seem to be able to do somehow. I would like to be able to duplicate
>>>channels. Currently I can only send 2 channels (left + right). I have a
>>>5.1 DTS receiver and the necessary speakers so I would like to be
>>>able to copy the front left to the rear left and the front right to the rear
>>>right. Is this at all possible with the digital out?
>>
>>No, your receiver must do this or software must encode the stream to AC3 
>>or DTS formats. The consumer S/PDIF can do only stereo PCM.
>>                                                 Jaroslav
>
>Perhaps this helps? http://essej.net/ac3jack/
>Haven't tried it adverts to do just this.

Unfortunately it doesn't work as I would have hoped.

I have installed the following apps:
         ffmpeg v0.4.8 (needed for ac3jack)
         ac3jack v0.1.1
         xmms-jack v0.6
         qjackctl v0.2.1

jackd is started with the following commandline (through qjackctl):
         jackd -R -t500 -dalsa -dhw:0 -r44100 -p1024 -n2

ac3jack is started with the following commandline and
the output is piped through ac3dec.
/usr/local/bin/ac3jack -o stdout | /usr/local/bin/ac3dec -C

After a few seconds of ac3 going on and off on my receiver
it remains on and all channels are active.

Now I start playing an mp3 through xmms (with the xmms-jack plugin).
There is no sound yet but I first have to make some connections.
I use qjackctl for this:
         Readable Clients:       bio2jack_0
         Writable Clients:       ac3jack
                                         Center
                                         Left
                                         LeftSurround
                                         LFE
                                         Right
                                         RightSurround
I drag the bio2jack_0 to all input ports and I have sound.
Unfortunately still only left, Right, Center and LFE.
LeftSurround and RightSurround go to Left and Right and
not the back speakers for some reason.

And then there's the problem of the output that can only
be 48000 Khz. Since xmms won't accept 48000 when playing
the mp3's (why would it, it would distort the sound) I have
to run jackd with 44100 Khz so a lot of the time there are
distortions in the sound because of the conversion.

In other words: It was a nice suggestion but unfortunately
no luck :(