Lowest CPU utilization audio codec?

I thought about asking this question to only our Resident Linear Audio 
Codec Guru ;) but thought I'd ask everyone instead:  I was recently 
given a video and audio challenge that I'm starting work on, and it 
requires realtime audio decompression of 8-bit unsigned PCM data (think 
"sound blaster" 11KHz or 22KHz 8-bit sound here).  Lossy algorithms are 
acceptable but not required.

I thought IMA ADPCM would be the best approach, but it would only halve 
the size of the data (4-bit ADPCM vs. 8-bit PCM) and I was hoping to get 
a bit more compression...  I also recall John Ratcliffe's "adaptive 
ADPCM" that achieved between 3:1 to 6:1 for speech and was essentially 
ADPCM with multiple tables, but I've lost my Dr. Dobb's article on that 
from a decade ago.

Any suggestions?  The key focus here is realtime (ie non-complex) 
decompression -- the platform this challenge was presented for is 
extremely slow.
-- 
Jim Leonard ([email protected])
World's largest electronic gaming project:    http://www.MobyGames.com/
A delicious slice of the demoscene:        http://www.MindCandyDVD.com/
Various oldskool PC rants and ramblings:       http://www.oldskool.org/




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