[MPlayer-users] divtc filter description

D Richard Felker III dalias at aerifal.cx
Tue Mar 1 21:26:58 CET 2005

On Tue, Mar 01, 2005 at 09:55:29PM +0200, Ville Saari wrote:
> On Mon, Feb 28, 2005 at 02:26:22AM +0300, Vladimir Mosgalin wrote:
> > In man page, there are following words in description of divtc:
> > 
> > In order to use divtc  two  pass  with two pass video encoding, you must
> > perform three passes: first divtc pass one and encoder pass one,  then
> > divtc pass  two  and encoder pass two, and finally divtc pass two and
> > encoder pass two.
> > 
> > I don't quite get it.. shouldn't it be other way around? First pass of
> > divtc with second pass of encoder makes no sense to me.
> Is that my cola or did someone else add that sentence to the manpage
> afterwards?

I did, and I drank the cola.

> Other way round is correct of course, but actually doing a redundant
> encoder pass one for the first divtc pass is waste of cpu cycles.
> I usually do it using this kind of dummy encoding:
> mencoder -vf divtc=pass=1,crop=16:16:0:0 -ovc raw -nosound -o /dev/null
> It runs very fast. Just remember to place softskip after divtc=pass2 in
> the encoding passes. Using mplayer -nosound -vo null for the first divtc
> pass may also work, but I haven't tried it.

Can you update the man page with better info on how to use 2pass with
mencoder? I just wrote the minimal to make it correct and keep naive
users from making stupid mistakes.

> It would be useful for this kind of tricks if mencoder had a null codec
> that would just drop the data and produce empty frames. The frameno
> should be pretty much like that, but it didn't work when I tried to
> use it. Unfortunately I can't remember what kind of problem I had with it.

Use -vf crop=2:2 -ovc raw :) 6 bytes per frame isn't too bad...


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