[FFmpeg-devel] [PATCH] Simplify IMDCT in dca.c

Benjamin Larsson banan
Sat Aug 30 11:40:35 CEST 2008

Michael Niedermayer wrote:
> Hi
> patch below replaces the duplicated IMDCT in dca.c by the standard one.
> code is faster, simpler nicer, ....
> yes the QMF of dca is a windowed IMDCT

One part of the IMDCT is a timedomain overlap by the synthesis window. I
couldn't find one in the patch thus I currently don't agree with the
IMDCT claim. I'm not really sure but I think ff_imdct_half is more like
a DCT-IV. That being said patch ok (with the alignment fixes). And
thanks for optimizing the code.

Benjamin Larsson

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