[FFmpeg-devel] [TeX] DCA subband transform

[Alexander E. Patrakov]

Hello,

recently there was a discussion whether the DCA subband transform is a
windowed MDCT or something else. The attached TeX file contains the proof
that the original obfuscated transform is in fact, up to a constant factor,
a pseudo-QMF cosine modulation ?lter bank combined with the sign ?ip of
subband inputs whose number is congruent to 1 or 2 modulo 4.

I will use this math in order to write a higher-level simplification of the
transform code, in particular, I will remove the "noidea" history buffer.

-- 
Alexander E. Patrakov
-------------- next part --------------
A non-text attachment was scrubbed...
Name: dca-transform.tex
Type: text/x-tex
Size: 15723 bytes
Desc: not available
URL: <http://lists.mplayerhq.hu/pipermail/ffmpeg-devel/attachments/20080907/f447863b/attachment.tex>