[FFmpeg-devel] [PATCH] Fix VP3 dequantization matrices when an IDCT permutation is used

David Conrad lessen42
Wed Sep 17 07:07:47 CEST 2008


Hi,

It appears that the reason why the VP3 SSE/MMX IDCTs weren't bitexact  
to the C version was because the dct coefficients weren't being  
dequantized correctly when a permutation was needed. The coefficients  
are permutated correctly in unpack_vlcs() but the dequantization  
matrices are built assuming no permutation. This fix allows both the  
SSE2 and MMX IDCTs produce bitexact output for the VP3 and Theora  
samples I have.

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