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

[Alain Barthélemy]

Le Tuesday 01 June 2004, 13:54:36 ou environ D Richard Felker III <dalias at aerifal.cx> a écrit:
> On Tue, Jun 01, 2004 at 11:50:33AM +0200, Alain Barthélemy wrote:
> > > >Normally I should have a better (re-)encoding.
> > > 
> > > ...depends on what you mean by "better". The end result will be
> > > lower-quality than the original, inevitably because of the transcoding
> > > process; the only possible advantages are A) potentially smaller
> > > filesize and B) it will use lavc's codec rather than whatever it had
> > > before, which may constitute an improvement in compression capability.
> > 
> > Thus two-passes encoding is only useful if you want to change the vbitrate and
> > other lavcopts options. I suppose that to change the video filtering (-vf
> > crop..,scale, -zoom -xy..), one pass is enough with mencoder -oac copy -ovc
> > copy -vf crop,etc.... Confirm/Don't confirm?
> 
> No, you misunderstand entirely. With -ovc copy you don't reencode at
> all, you just remux the stream that was already there. On the other
> hand, if you ARE encoding, you should always use 2pass mode. With just
> 1 pass, results will be horrible during high-action scenes.
> 
> Rich

No I did not misunderstand entirely (just a bit). Thus I understood well that I
had to use two-pass mode if I wanted to crop a movie.

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