Can someone tell me, what software I have to install to play and encode DivX movies with OGG sound?

well you will need to encode your video using whatever method you choose. The audio you will have to do in Vorbis, of course. The tool you will need to combine the 2 into an Ogg file is Koepi's OggMux, www.roeder.goe.net/~koepi/

To playback these files you will need Tobias' DirectShow filters, http://tobias.everwicked.com

You don't want Ogg sound, you want Vorbis sound.

Ogg is a container format, like AVI, Quicktime, etc.
Vorbis is an audio format, usually wrapped in Ogg.

Some time ago, people tried to put Vorbis audio inside AVIs. This would have worked, but for deficiencies in MS's implementation of AVI. As a consequence, AVIs with Vorbis audio are basically unplayable in Windows (although they may work if you don't seek or pause).

Because the AVI file format is so limited, people have been searching for replacements. There's the well designed but patented to hell MP4 format (which will become a commercial standard soon), the Ogg container format (which is very good at containing for streaming, but not so good for some other uses), and a scheme called MCF currently in development specifically designed to be a Movie Container Format.

http://www.doom9.org/ogg.htm is a very good guide to encoding into Ogg (or .OGM, as the Windows people seem to like to call OGg Movies).

... which has a working muxer for audio and subtitles thanks to robux4 now ( but no video or parser yet )... and i have to leave to China again now, as its going to be exciting ...

What are these other things the OGG container format isn't good at?

There have only been one or two small difficiencies for OGG containers so far. People wanting to use the original DVD AC3 sound as far as I know can't play it from inside OGGs yet or set the delay for the audio. But If they are wanting to do that they should stick to AVI for now. The other problem ATM is the way Divx 5.0.1 handles B frames. They work ok in AVI, but when you put em in OGG people have reported corrupt frames and the just downright crash for me. Nothng of the sort happens with any version previous to 5.0.1. Other thatn that it is all good and getting better.

Perhaps a "wrapper" stream fro AC3 could be defined that adds a header to the AC3 stream, to set delays etc.
I don't know how the synching fromwork in ogg works.

Delays are supported just fine in OGG. It is just not implimented ATM.

Well this would be interesting and has been brought up before. The problem is that the AC3 stream can't be molested in the least bit if your amp is to detect it properly.

It's non-sense but I was hoping for an AC3 wrapper around a 5.1 Vorbis file:D

Hmm, but you could still wrap it in such a way a raw stream could be extracted. Even if you just add a header with the delay, then chop it off when you want to send it to the amp. Of course, the delay problem seems to be moot, just requiring implementation.