From 05493021889a6d226791aa2eb412de7becad2ace Mon Sep 17 00:00:00 2001 From: Michael Niedermayer Date: Sun, 11 May 2003 10:19:05 +0000 Subject: [PATCH] more idct_permute docs Originally committed as revision 1852 to svn://svn.ffmpeg.org/ffmpeg/trunk --- libavcodec/dsputil.h | 4 ++++ 1 file changed, 4 insertions(+) diff --git a/libavcodec/dsputil.h b/libavcodec/dsputil.h index 8643e9ac9a..138e6f42c8 100644 --- a/libavcodec/dsputil.h +++ b/libavcodec/dsputil.h @@ -240,6 +240,10 @@ typedef struct DSPContext { /** * idct input permutation. + * several optimized IDCTs need a permutated input (relative to the normal order of the reference + * IDCT) + * this permutation must be performed before the idct_put/add, note, normally this can be merged + * with the zigzag/alternate scan
* an example to avoid confusion: * - (->decode coeffs -> zigzag reorder -> dequant -> reference idct ->...) * - (x -> referece dct -> reference idct -> x)