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

[D Richard Felker III]

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