[MPlayer-dev-eng] Unified ADPCM Decoder

Mike Melanson melanson at pcisys.net
Wed Dec 26 07:09:00 CET 2001


Hi team,
	So I didn't get as much done this weekend as I had hoped. But I
did do a bunch with ADPCM. Without any prior authorization, I've just
committed the basis of a unified ADPCM decoder. When I say "unified", I
mean "all of the ADPCM code in one place". So far, it just has a rewrite
of the IMA4 ADPCM decoder which does mono properly and almost has stereo
right, too (something that the old ima4.c didn't do). I'm still working a
kink out the stereo portion, but I'm really close; I can tell because the
sound is almost coherent on The Phantom Menace "A" trailer.

	I have the data formats in hand for both MS ADPCM and that format
0x62 I've been working with. I will implement them both in the same module
as soon as I can. I've also written a document about all of the formats
and will publish it on my CRI site as soon as I'm confident it's all
correct (i.e., I've implemented them all based on the document).

	Quick question on the audio: Am I correct in assuming that stereo
PCM samples are interleaved, LRLR...? Therefore, output[0],
output[2]...output[2n] will all be left channel, while output[2n+1] will
all be right channel?

	Thanks...
-- 
	-Mike Melanson




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