[FFmpeg-devel] [PATCH] h264: factor out dequant table lookup outside loops

Andreas Öman andreas
Mon Sep 24 12:59:21 CEST 2007


the attached patch does $subj, much like what I did for
the chroma residuals earlier.

Gives about 1-2% speedup.

Note that I tried various loop-constructs for the 8x8DCT case,
but this seems to be the fastest way.

unmodified: avg: 3.737  stddev: 0.009  med: 3.736
patched:    avg: 3.642  stddev: 0.010  med: 3.638

unmodified: avg: 23.339  stddev: 0.107  med: 23.321
patched:    avg: 22.973  stddev: 0.201  med: 22.889

unmodified: avg: 10.090  stddev: 0.121  med: 10.053
patched:    avg: 9.931   stddev: 0.140  med: 9.891

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