[MPlayer-users] lavc vs. xvid (and improving lavc quality)

[Michael Niedermayer]

Hi

On Monday 07 June 2004 16:57, Nico Sabbi wrote:
> Michael Niedermayer wrote:
> >Hi
> >
> >On Monday 07 June 2004 08:09, D Richard Felker III wrote:
> >[...]
> >
> >>>>another solution is to get _latest_ libavcodec cvs and use
> >>>>cmp=10:subcmp=10:mbcmp=10:dia=3 but this is very new and so might not
> >>>>work as expected yet, theres also a coefficient in the code which still
> >>>>needs to be finetuned or exported
> >>>
> >>>Wow.  WOW.  Did I mention: _WOW_!  This is an _amazing_ improvement.
> >>>
> >>>You're my new deity for this week. :)
> >>
> >>WOW! What I'm impressed at is that Michael was able to please the
> >>"block whiners" so fast! :)
> >>
> >>BTW, could we have an explanation of why the "noise preserving" sse
> >>function is better?
> >
> >sure
> >
> >first ill explain what nsse is, nsse is simple the sse comparisson
> > function with an additional term added which is the difference amount of
> > the high freq noise between the compared blocks
> >so when the source material is noisy the motion estimation / macroblock
> >decision will favor noisy blocks, the trick here is that its much cheaper
> >bitrate wise to find some noisy block instead of a using a lower quantizer
> >and actually storing the exact noise
> >
> >so why does keeping the images slightly noisy help? there are at least 2
> >relatively obvious reasons
> >1. the noise masks the blocking artefacts, just try to add some noise
> > during decoding, the blocks should be less visible
> >2. when compressing some area of nearly constant color u end up with areas
> > of exactly constant color and somewhat blocky edges between colors n and
> > n+1, the motion compensation for the next frame is now limited to only a
> > few possible blocks as many motion vectors will result in the same
> > constant color or same 2 with an edge in the middle, OTOH if the image is
> > noisy then there are many more different choices for the motion
> > compensation so the image can be represented more accurately
> >
> >[...]
>
> does chroma motion work well with your last patch to sse ?
i didnt try, but it should work

[...]
-- 
Michael
level[i]= get_vlc(); i+=get_vlc();		(violates patent EP0266049)
median(mv[y-1][x], mv[y][x-1], mv[y+1][x+1]);	(violates patent #5,905,535)
buf[i]= qp - buf[i-1];				(violates patent #?)
for more examples, see http://mplayerhq.hu/~michael/patent.html
stop it, see http://petition.eurolinux.org & http://petition.ffii.org/eubsa/en