[FFmpeg-devel] [PATCH] ffv1: more than 8 bit per RGB channel

Georg Lippitsch georg.lippitsch at gmx.at
Thu Aug 23 16:10:49 CEST 2012

Am 22.08.2012, 23:52 Uhr, schrieb Michael Niedermayer <michaelni at gmx.at>:

> also what effect does this has on en/decoding speed of 8/8/8 rgb ?
> (that is once it works again)

As you suggested, I did some measurements adding a timer around the loop  
in encode/decode_rgb_frame.
It turned out that the if() did not really hurt, but the encode_line(s, w,  
sample[p], (p+1)/2, bits+1) caused a huge speed penalty (nearly 5%).

So, I suggest going different branches depending on bit depth, as I do in  
the latest version of my patch

The speed result is a bit weird though, because it even uses slightly less  
cycles than in the original code:

Original: 4758587630 decicycles in rgb_frame, 64 runs, 0 skips
My patch: 4757414280 decicycles in rgb_frame, 64 runs, 0 skips



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