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Old 11 November 2016, 14:00   #73
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Join Date: Jun 2010
Location: PL
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Originally Posted by meynaf View Post
There would be some speed gain but not very much because current YCbCr conversion is normally quite optimal and so this conversion doesn't really play a major role on overall decode time (i know for jpeg still images but for video it's just a guess, though). For a coarse estimate i'd say something like 10% gain.

I don't think it can be easily tested because YCgCo isn't supported in MPEG-1 (only format supported by Riva).
For this MPEG-4 support has to be added (but h.264 would be a lot more cpu intensive).

MPEG-1 fully support YCgCo (just set matrix coefficient as 8 - normally it is reserved for future use in MPEG-1 and MPEG-2 but it is fully specified for H.264 and H.265 - problem is that nobody use MPEG-1 so it is uncommon practice to use YCgCo as it is not popular even nowadays but Amiga have limited processing capabilities so any gain is valuable (as every pixel need to be converted from YCbCr to RGB and later to Amiga HW limitations).
Side to this Intra frame formats should be less intensive especially H.264 (without CABAC and deblocking loop which takes like 50 - 60% of decoder processing power).
I can made streams for testing if this is a problem.
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