spdif only output stereo - AC97

hvengel · Guru Joined: 19 Sep 2004 Posts: 515

I am using the onboard AC97 controller on my nForce 4 motherboard and trying to get the spdif output working in Kaffeine/xine with ALSA. I am running a Logitech Z-5500 audio system which has support for spdif coax and also has DTS and Dolby hardware decoders. Also this is working as expected when I boot this machine over to Windows. So I know that hardware is correctly hooked up and working.

After installing Kaffeine 0.8.1 I now have output on both the spdif and analog output of the sound controller (at the same time) but the output on the spdif is stereo only no matter what the audio format of the content is. When playing stereo content such as an audio CD this works like I would expect. But when playing 5.1 content like a movie DVD the spdif output is missing the center and surround output channels.

I have looked at dozens of posts on this forum about setting up spdif as well as the Gentoo alsa installation guide and the Gentoo Wiki's about alsa and spdif. In addition I have tried to find something useful on the xine forums. So far I have found nothing that is useful and I am stuck. It appears from the number of posts about this here and other places that setting up a working spdif setup is a problem for many users.

When I set the output speaker_arrangement to Pass Through then I don't get any spdif output and Kaffeine will crash after is plays only a few seconds of the DVD content.

When I had Kaffeine 0.7.1-r2 (stable version) installed it would play DVDs with 5.1 audio in stereo only and would play the stereo content (the trailers) on the spdif outputs and when the DVD became 5.1 it would stop output on the spdif connection and the output would be directed to the analog connections. 0.7.1 would also crash when pass through was enabled. So 0.8.1 is doing better than the "stable" version of Kaffeine in that I at least get 5.1 output on the analog connection.

It appears that with Kaffeine 0.8.1 installed that I am much closer to having this working and that it might be just a matter of tweaks to the configuration of something. My problem is I don't knowq where to tweak and I have not found any documentation that is very helpful.

I would like to be able to setup a media player of some sort that works correctly and i don't really care which one. I emerged vlc but it's GUI is not working and it appears that it has been this way for months based on posts here. Should I try something other than Kaffeine? Would another front end work better? Is there some special setting in alsa that I need to change? Is there a tool available that would help me to configure this?

Do I need a different/addition module load or the sound controller? Currently these are the saound releated modules I have loaded.

hvengel · Guru Joined: 19 Sep 2004 Posts: 515

I wasn't try to play stup the band but it looks like I have.

beandog · Posted: Sat Aug 05, 2006 1:21 am Post subject:

Whats your setup? computer to 5.1 speakers or to a receiver?

Have you played around with mplayer at all? Any success?
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Jykke · Apprentice Joined: 31 Mar 2006 Posts: 246

Did you try mplayer with appropriate ALSA options. I am dying to remember it
mplayer -ao alsa:device=surroud51 dvd://

or something like that so that you have a DVD with surround bits on it and
play it. I had lots of stress figuring that one out since every program wants
to have definition of alsa device differently...

hvengel · Guru Joined: 19 Sep 2004 Posts: 515

I have a set of Logitech Z-5500's which has DTS and Dolby decoders. It also shows what type of digital signal it is getting from the sound card. With the latest version of Kaffeine it will play 5.1 but only through the analog connection from the sound card. It never does anything other than stereo through the digital connection. In Kaffeine (xine really) I am using ALSA surround51. I have not tried mplayer but I have never even been able to get it to run on this machine which is amd64 and I have not installed it since rebuilding my system drive after it failed a few weeks ago. The speaker are new so I did not have them when mplayer was installed.

The strange thing is how can the sound card to putting out 5.1 on the analog connection and only stereo (and only the front left and right channels of the 5.1 sound track) on the digital connection. Just does not add up.

On the other hand I can't really hear any difference between the analog connection using stereo material so other than the z-5500 maybe having a better decoder than the sound card it may not really be an issue. But I am dissapointed that I spent additional money on a digital cable and the whole set up does not work the way it should.

I will give mplayer another shot but I am not expecting it to work either.

madman2003 · Apprentice Joined: 20 Feb 2005 Posts: 178

spdif can transport 2ch pcm audio, dolby digital, dts. Plain 5 channel audio from alsa is just not supported. (too much data) For movies with dolby digital or dts you can try to use passtrough.

zhark · n00b Joined: 26 Feb 2006 Posts: 29

Same problem here with amd64, alsa and nforce4 mainboard. Only stereo out on the spdif. Have tried to use passthrough on it with VLC (dts sound), but no luck.