[Ffmpeg-devel] snow MC simplification

Michael Niedermayer michaelni
Tue Jan 17 14:43:53 CET 2006


Hi

On Tue, Jan 17, 2006 at 02:17:14PM +0100, Guillaume Poirier wrote:
> Michael Niedermayer wrote:
> > Hi
> > 
> > On Mon, Jan 16, 2006 at 03:32:08PM -0800, Loren Merritt wrote:
> > 
> >>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:
> >>vcodec=snow:vstrict=-2:cmp=1:mbcmp=1:subcmp=1:v4mv:qpel:vme=8:vqscale=<1..4>
> >>patch adds an average of +.7% bitrate, -.08 dB chroma
> >>decoding speed +24% (athlon-xp)
> >>no visible difference
> > 
> > 
> > if noone can see a difference then iam in favor of the simpler chroma MC code
> > after all humans watch videos not PSNR evaluating computers ...
> 
> Well said :)
> 
> A bit more precision about the drift to pink problem I experienced: each
> new picture drifts more and more towards pink, until probably a keyframe
> makes the color look normal once again.
> 
> Would it help if I were uploading the 300 frames sample I encoded?
> I don't remember how big it was though...

first please confirm that both encoder and player used the same snow.c
and not patched player but unpatched encoder or so

[...]

-- 
Michael





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