[MEncoder-users] new doom9 codec comparission (also questions for Doom9)

[Michael Niedermayer]

Hi

On Thu, Dec 01, 2005 at 04:40:18PM -0800, Corey Hickey wrote:
> Well, I finally went and rented The Matrix and started messing around.
> For now I'm concentrating only on mpeg4 -- I'll deal with the exciting
> part (snow) later. Also, if someone else can provide a nice windows
> binary, I'd appreciate it; I have little experience in that regard and
> probably couldn't do as well as many others on this list.
> 
> I have several questions and things to comment on.
[...]
> ------------------------------------------------------------------------
> Next, questions for mplayer people.
> 
> 1. I don't know much about postprocessing. On the encoding I'm doing
> right now, pp=ac looks a little less blocky than pp=fa. Does anyone have
> a good recommendation?

i would recommand against pp=fa its just based on filters invented by me
which are supposed to be fast and not perfect, if you want more speed try
without the dering filter (pp=ha:128:7,va) but whatever you choose
test it first, dont blindly trust my suggestion ...
also definitly try to add some noise, it might look better, something on
windows, does add noise by default, i never could figure out what part it
was (the noise was vissible with ffdshow even though it had all noise adding
filters disabled ..., but that was long ago)
if possible also test with TFT & CRT monitors (btw, doom9 which do you use,
ive seen quite some differences in artifact vissibility between CRT and TFT)
also try the newer spp based postprocessing filters if the CPU is fast enough

also see http://guru.multimedia.cx/?p=8 for some pp compaission, maybe ill
add more variants ...


[...]
> 3. I seem to recall that multithreaded encoding incurs a slight penalty
> to quality (or, at least, psnr). Do any particular lavcopts make
> multithreaded encoding better or worse? If not, I'm just going to find
> the best options I can with only one thread and, as a final step, test
> threads=2 to make sure nothing blows up.

hmm, a larger last_pred and preme=2 might help a little for the multithreading
stuff, someone could also try to do just the motion estimation or just the
bitstream encoding multithreaded (needs code change, maybe ill take a look but
dont hold your breath ...)

and maybe try multithreded decoding too

> 
> 
> ------------------------------------------------------------------------
> Last, some comments.
> 
> Right now I'm testing the following command:
> for i in 1 2 ; do
>   time mencoder ~/dumpstream/matrix.vob -aid 128 -oac copy \
> -vf crop=718:356:0:60,scale=640:272 -ovc lavc -lavcopts \
> vcodec=mpeg4:vbitrate=581:vratetol=1000:psnr:vpass=$i:mbd=2:mv0:trell:\
> cbp:precmp=2:cmp=2:subcmp=2:predia=2:dia=2:preme=2:vme=5:v4mv \
> -ofps 24000/1001
> done

dont forget to remove psnr in the final suggestion, it eats some precious cpu
time, also try NSSE maybe

[...]

-- 
Michael