Support multichannel audio output (e.g. AC3)

[Philippe Normand]

Check the new playbin engine correctly supports AC3 sound output.

[Michael Kötter (cmdrcord)]

What do you mean by "AC3 sound output"? If its "AC3 passthrough", it does not work with current trunk. It decodes AC3, but downsamples to stereo in my case.
Looking at the playbin description, I cannot find any property that would activate AC3 passthrough.

Maybe it can be achieved by using the "alsaspdifsink" audio sink? But then, this should only be used when the actual sound stream is AC3, so the player has to check that.

[Michael Kötter (cmdrcord)]

sorry, accidentally set severity.. although important, this is definitely no blocker ;)

[Benjamin Kampmann (benjamin-fluendo)]

[http://seamless.sourceforge.net/ seamless] has interesting [http://pastebin.com/f41f5b01b concept for support of ac3 and normal sound playback] even if it is for DVD mainly...

[Michael Kötter (cmdrcord)]

The way seamless does it (ac3iec958 raw=true ! audioconvert ! alsasink) did work for me with an ICE1712 based card, but not with my audigy2. According to msmith, to whom I spoke on #gstreamer, this might have a number of reasons, among them as far as I remember:

- audioconvert must be in the pipeline to get correct endianess. But it might also do other things to the data that can potentially corrupt it.

- If frame drops occur, alsasink just drops the PCM frames. An IEC958 (aka s/pdif) frame consists of multiple PCM frames (something about 15xx), so there would be incomplete IEC frames on the wire which might upset some receivers.

The preferred way to output IEC958 would be using "alsaspdifsink", which unfortunately will not work at all in its current state.
I tried to fix it (see http://bugzilla.gnome.org/show_bug.cgi?id=485462, the latest patch), so if someone wants to test it go ahead :)

[Danny Haak (d-j-t-haak)]

Is there a way to test this? - Because I have the same problem and would like it to work :)

[Philippe Normand (philn)]

Some recent informations at http://www.moovida.com/wiki/TipsAndTricks/AC3PassThrough

[dino99 (9d9)]

The latest free moovida 1.09 does not get any maintenance since a while. Now moovidadb.com is supporting Linux and support can be found at : http://www.fluendo.com/faq/