[vorbis] Multichannel vorbis.

[Aaron Plattner]

I managed to make a 4 channel .ogg by taking two 2-channel wavs, converting
them to raw and using a small program I wrote to interleave them, and then
using sox -c 4 to make a 4-channel .wav.  Oggenc was happy to encode that into
a 4-channel .ogg file.  It wouldn't play using the OSS driver, but the ALSA
driver played it just fine, although I found out later that it mixes the front
and back channels together when it plays, which is pretty stupid in my opinion.

As a side question, will Vorbis directly encode Dolby Digital streams somehow,
or will there be a Dolby Digital to Ambisonics stage first?  It seems to me
that since Dolby Digital is just planar audio, it should be possible to encode
it in a 3-channel Ambisonic format, although I don't know how well that would
work for movies with speech only in the front.

Aaron Plattner

On Thu, Jul 19, 2001 at 05:24:34PM +0300, Pavel Polischouk wrote:
> Hi.
> 
> I have two CDs that the artists inteded for simultaneous listening. They 
> even provide instructions on how to start two CD players with the 
> minimal time shift.
> (for those interested - the CDs are Neurosis/Times Of Grace and Tribes 
> Of Neurot/Grace)
> I've heard that Vorbis can encode multiple streams. I've already encoded 
> both albums into regular 2-channel .ogg files.
> The questions are:
> 1. How do I produce 4-channel .ogg file from 2 2-channel .oggs?
> (pointing at relevant parts of oggenc.c and ogg123.c that read/write ogg 
> blocks for each channel may be fine so I can write a simple app that 
> just reads ogg blocks from two input files and puts them into one 
> output. If I write that beast I'll contribute it back to ogg/vorbis 
> project immediately).
> or 1.1. How do I produce 4-channel .ogg from 2 2-channel .wavs if there 
> is some way of doing this without invoking gcc?
> 2. How do I play this file (say, mixing together both left and both 
> right channels as the first attempt, and using some multichannel 
> soundcard later)?
> Some suboptimal solution that I use now is to start two instances of 
> ogg123 and let esd mix the sound. Is anyone thinking about adding 
> multichannel functionality to XMMS plugin, that can mix multiple ogg 
> channels into 2 soundcard channel in a somewhat configurable way - say, 
> with 4-way balance at least? How hard is to add such an option?
> 
> Thanks,
> Pavel
> 
> 
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