[XviD-devel] GME and Block ME

Michael Niedermayer michaelni at gmx.at
Sat Apr 19 13:21:11 CEST 2003


Hi

On Saturday 19 April 2003 08:56, Marco Al wrote:
> From: "Michael Niedermayer" <michaelni at gmx.at>
>
> > yes sounds better, ill change ffmpeg/mencoder docs to that :)
>
> Hey, since you are reading this a question :) Does your code do an optimal
> search or an M-best search?
optimal, except that only 0, level, level-1 are checked, IIRC additionaly 
checking level-2 had only a few byte lower filesize at constant quant, the 
level-2 code is there and outcommented if u want to try

for h263 quantizers a larger level difference should not be needed
the dequantized level stepsize is 2*qp and so for level-3 (!= 0) we need to 
gain at least ((2.5*2*qp)^2 - (0.5*2*qp)^2)/lambda bits where lambda is 
0.85*qp^2 as recommanded by some doc
so we need at least ((2.5*2)^2 - (0.5*2)^2)/0.85 ~ 28.2 bit and the longest 
vlc (esc3) has 30 bits and the shortest vlc is 2 bit

for mpeg style quantizers that should be true too unless the quant matrix 
contains very small coeffs but thats not the case normally

[...]

-- 
Michael
screen[y][x] ^= cursor[cy][cx];			(violates patent #4,197,590)
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


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