The MPEG Audio Page contains information on MPEG-1, MPEG-2 and MPEG-4
audio formats: http://www.tnt.uni-hannover.de/project/mpeg/audio/.  The MPEG-4
Final Committee Draft is available online.

Jim Stevenson  writes:

> Where can I get a technical description, and the source code for the
> algorithms that do the compression and decompression?
> 
> What compression ratios can be achieved?
> 
> Is stereo treated as two mono chanels, or can we do better by encoding
> sum and difference?
> 
> Thanks.
> 

-- 
-Jarno