[MPlayer-users] Two-passes encoding - What happens exactly?

[Alain Barthélemy]

Le jeudi 03 juin 2004, 11:54:19 ou environ D Richard Felker III <dalias at aerifal.cx> a écrit:
> On Thu, Jun 03, 2004 at 09:36:00AM +0200, Alain Barthélemy wrote:
> > > Is that the highest resolution your tv card is capable of? I use 
> > > "width=720:height=576".
> > 
> > Normally it should be 640x480 but I made lately a quick test with resolution
> > 720x576 and it worked.
> 
> It depends on whether you have NTSC or PAL.

I have PAL thus it should be 640x480. Thanks for reminding me.

> 
> > > > -lavcopts vcodec=mpeg4:vbitrate=1800:mbd=2:acodec=mp3:v4mv -oac mp3lame
> > > MP3 from Libavcodec (acodec=mp3) or lame (-oac mp3lame)?
> > 
> > True! I was wondering myself if -ovc lavc -lavcopts ...:acodec=mp3:abitrate=96
> > or -oac mp3lame -lameopts ...:br=96 was not saying the same thing. What
> > disturbed me was that acodec and abitrate were options of -ovc (v for "video").
> 
> -lavcopts acodec and abitrate are useless unless you're using -oac
> lavc. For -oac mp3lame you use -lameopts!

Useless? OK! But you don't enligten me. I must understand that -lavcopts acodec
and abitrate are *only* useful if I have -oac mp3lame lameopts cbr:br=96. *But*
does not it do the same as -ovc lavc -lavcopts acodec=mp3:abitrate=mp3. Should
not I use one or *exclusive* the other option?


> 
> > > "-vf denoise3d=5:4:7" should give better quality than "-vf pp=tn" (But 
> > > needs more CPU-time).
> > 
> > I'm not familiar with denoise. Still learning about video compression (and still dumb).
> 
> Well don't use pp=tn. It removes noise but ADDS blocking artifacts
> which are much worse!

Thanks for this remark. I tried -vf denoise3d=5:4:7 and I did not see anything
negative. Mencoder is now "touch & try" and I am no specialist of video
compression.

Thus I keep now:

mencoder -tv driver=v4l:width=640:height=480 -ovc lavc -lavcopts
vcodec=mpeg4:vbitrate=1800:mbd=2:v4mv -oac mp3lame -lameopts cbr:br=96 -vf
crop=620:460,denoise3d=5:4:7,scale -zoom -xy 640 -sws 1 movie.avi

... till someone tells me the image will be completely distorted.

I just finished capturing a TV movie (B/W) and the movie looks normal and with
resolution 576x720, John Wayne does not look distorted.

Thanks again.

> 
> Rich

-- 
Alain Barthélemy
cassandre at bartydeux.be
http://bartydeux.be
Linux User #315631