[MPlayer-dev-eng] MS-ADPCM/Stereo Works

[Mike Melanson]

On Fri, 28 Dec 2001, Michael Niedermayer wrote:

> > but they work on small, fixed-size fragments (blocks, chunks), don't?
> > so they could be decoded in parallel.
> i thought about the same ... interleave a few blocks so that mmx has only 
> independant stuff ...

	I hadn't thought of this. True, in the IMA variant, blocks are
only 32 bytes long, though there are still 64 samples to be decoded. But
they could be interleaved in such a way as to parallelize the decode of 4
separate blocks. But that's just for IMA. MS ADPCM has 256-byte blocks and
the decoder I'm working on tonight has 2048-byte blocks. Realistically,
though, I doubt that the overhead of (de-)interleaving would defeat the
purpose.

	Still, it's an interesting thought experiment, just to understand
SIMD instructions.

> >
> > but again: it was joke, nobody needs optimzation for such low-bitrate
> > simple algos... (imho)
> hmm, iirc adpcm sounds better than m$ wma

	Depends on a lot of variables, though I have a colleague who's an
audiophile (audio snob) who vehemently contends that the previous version
of WMA is superior to the current version. 

-- 
	-Mike Melanson