[Ffmpeg-devel] snow MC simplification

Loren Merritt lorenm
Tue Jan 17 00:32:08 CET 2006

On Mon, 16 Jan 2006, Guillaume POIRIER wrote:
> On 1/8/06, Michael Niedermayer <michaelni at gmx.at> wrote:
>> Snow currently uses the h.264 luma MC functions if possible and if not
>> (1/8 pel) then its own MC functions (mc_block())
>> the result is that mc_block() is only used for some chroma blocks if qpel is
>> enabled, so it would be nice if we could et rid of it, the attached patch
>> does that, but it needs testing (encode stuff with and without and view with
>> the respective player with and without the patch)
>> if anyone has other ideas on how this can be simplified then dont hesitate
>> to reply ...
> I don't know if that was intended, but that patch fixed a chroma bug,
> as you may notice it on those 2 screenshots:
> vanilla version:
> http://tuxrip.free.fr/transperl/MPlayer/The%20Player%20-%20vanilla.png
> snow_MC_simplification patched version:
> http://tuxrip.free.fr/transperl/MPlayer/The%20Player%20snow_MC_simplification.png
> So either a recent commit broke snow, or just just fixed a
> longstanding bug... Anyway, that's good stuff!

I see such artifacts when mixing an encode with the patch and mplayer 
without it, or vice versa.

My results:
patch adds an average of +.7% bitrate, -.08 dB chroma
decoding speed +24% (athlon-xp)
no visible difference

--Loren Merritt

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