[Mplayer-advusers] Multichannel Vorbis Playback Possible?

[Joerg Sauer]

On Saturday 06 April 2002 20:38, Arpi wrote:

> more than 2 (stereo) channel in a single stream, or multiple audio streams
> (for example english and hungarian audio) in a .avi/.ogg file ?

More than two channels in one audio stream. Ie, real multichannel surround 
audio just like the AC3 on the DVD but greatly reduced in size and therefore 
more suitable for being stored in CD-R.

> i've never seen too lot files with vorbis audio, and all of them were with
> single stream with stereo 2ch audio.
> anyway in theory it may work - the vorbis decoder in mplayer passes the
> channel number, doesn't matter how many channels it has

It _does_ seem to be a relatively hot topic in the DivX scene. What I mean 
is, people have just begun experimenting with this. It is far from widespread 
at the moment but to me it seems like it's one of the next logical steps in 
the quest for condensing a DVD down to the size of one or two CD-Rs while 
preserving as much of its features and quality.

Multichannel audio cards are getting cheap (and therefore widespread) and 
more and more movies with AC3 sound in the AVI are being released. They are 
nice because they have true multichannel sound but they are just too big!

Most complex AC3 is encoded at 448 kbit/s. With Vorbis you could probably go 
as low as 256 kbit/s for a 5.1 track (if you use some tricks like for example 
a 'phantom center'). This is a significant reduction in total bitrate I think 
and probably just enough to make multichannel 1-CD rips possible in many 
cases.

> upload samples if you have files unplayable, i'll check

I will try to get hold of some multichannel material. There are definitely 
some audio only files out there and I guess that with the new support for 
audio files in mplayer that this should be enough for testing, shouldn't it?

Joerg