> I'm not sure, haven't checked this much, but when I looked at the lame-mdct
> code last summer, I found your MDCT-code much like the "Lee's Fast DCT
> algorithm" I first found on
> http://pentium.intel.com/drg/mmx/appnotes/ap528.htm
I don't even *understand* lee's algorithm :) too much asm.
Anyway, lee is talking about DCT's which are used in MPEG video and JPEG coding.
These are different from mdct transform used in mpeg audio coding.
The MDCT is more than just a "modified" DCT. The DCT is a block transform and
the MDCT is a lapped orthogonal transform. Malvar explains it much better than
I :)
lame's MDCT was unrolled by hand over about 3 days of intense pattern finding
in the trig patterns.
There must be a better way of doing it though. I guess there's a way very
similar to the MDCT via an FFT, but that doesn't require the pre- and post-
twiddle. [probably like sporer's]
later
mike
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