libavcodec settings tested

[TactX]

Rémi Guyomarch has done a quite big comparison of different settings for the libavcodec MPEG-4.

His tests are based on the PSNR values of the output files, encoded with different settings and a combinations of those.

Have a look at it here (http://rguyom.ath.cx/). It's very intersting, even if you don't use libavcodec.

[Rrrough]

interesting page, definetly.
libavcodec is getting better and better, and it's VERY fast under Linux and transcode.
unfortunately Moritz Bunkus, who made the transcode FFMPEG export module configurable, has discontinued his work on the module.
that means, evolutionary leaps like QPEL and trellis quantization aren't accessible :(
hopefully someone will continue this great work...

cheers

[TactX]

Well, you can still use mencoder to access advanced features like qpel, trell, blabla....

And mencoder is faster.

[Rrrough]

And mencoder is faster. hmmm, not for me. but then, I haven't done too much with mencoder yet.
and I have to admit that I like dvd::rip as a frontend, I haven't come across one for mencoder.

cheers

[TactX]

There is KMencoder (with the evil K for KDE :D). I have not tested it and propably will never. I'm doing my encodings with mencoder only (and AVIdemux for muxing things sometimes).
I have a default "script" for mencoder, where I simply change the parameters.

Mencoder is really not faster for you? Compiled yourself?

EDIT: I forgot to mention AcidRip. Did not test it, too.

[Rrrough]

Mencoder is really not faster for you? Compiled yourself? yep, compiled myself, both latest versions. I think it's the resize method, as said I haven't tried too much with mencoder, I mainly compiled it to have the fabulous mplayer. with transcode there's lanczos3 and fast resize (bilinear?). fast resize comes also with good quality. and it's straight YV12.
what settings do u use in your default script ?

cheers

[TactX]

Mencoder does straight yv12 resizing, too.

This is a default script for the Matrix where I'm playing around with libavcodecs settings atm.

******
mencoder temp.vob -vop scale=640:256,crop=716:416:2:80 -o pass1.avi -nosound -ovc lavc -lavcopts vcodec=mpeg4:vbitrate=632389:vrc_override=186190,196160,-400:vhq:v4mv:precmp=2:cmp=2:subcmp=2:vb_qfactor=1.25:vb_qoffset=0.6:vmax_b_frames=1:trell:vpass=1
mencoder temp.vob -vop scale=640:256,crop=716:416:2:80 -o pass2.avi -nosound -ovc lavc -lavcopts vcodec=mpeg4:vbitrate=632389:vrc_override=186190,196160,-400:vhq:v4mv:precmp=2:cmp=2:subcmp=2:vb_qfactor=1.25:vb_qoffset=0.6:vmax_b_frames=1:trell:vpass=2
******

Note: these settings are _not_ fast, but the quality is great as far as I can say...

[Rrrough]

ok, you are right. just fiddled around w/ mencoder a bit more (especially w/ crop/resize...) and used similar settings like you.
the speed impact isn't too big, the quality increase is GREAT.
lavc -R-O-C-K-S- !

cheers

[TactX]

Originally posted by Rrrough
...the quality increase is GREAT.
lavc -R-O-C-K-S- !

I can confirm that. My Matrix-test (with the settings above) has just finished and the quality is simply great!

It really rocks...

[Rrrough]

btw. I found a nice way to encode a whole dvd-rip other than
cat /space/*vob | (as described on Moritz' page)

I'm using

mencoder -dvd 1 -dvd-device /mnt/reiserfs/fear ...

where the directory contains all vobs and related ifo's.

the advantage is that you still can use -ss

cheers

[TactX]

Hmmm, I used to do "mplayer -dvd 1 -dumpstream" for that....
This creates a file called stream.dump (you specify another name of course) and I still have access to the subs and stuff.

What's the difference then (besides the ifos I don't need)?

[Rrrough]

never done that before... I was just following Moritz' page.
so there are many other ways...
can you still play back the streamdump-file ?

cheers

[TactX]

Originally posted by Rrrough
can you still play back the streamdump-file ?
Of course you can ;)

[Rrrough]

UPDATE :

Tilmann Bitterberg updated the transcode ffmpeg export module, including the same ffmpeg version as mplayer/mencoder 0.90rc5.
the usage of ffmpeg.cfg is very easy.

get the latest snapshot from his website here (http://www.zebra.fh-weingarten.de/~transcode/pre/).

cheers