[MPlayer-users] AVI->DVD: Problem understanding expand and scale

[Giacomo Comes]

On Thu, Oct 06, 2005 at 10:10:04AM +0200, Nico Sabbi wrote:
> Thomas Heuving wrote:
> 
> >Hello,
> >
> >I'm new to mplayer and have a problem in converting from AVI to DVD.
> >I've read
> >http://www.mplayerhq.hu/DOCS/HTML/en/menc-feat-vcd-dvd.html
> >and afterwards tried to convert a AVI (640:368, ratio 1.74:1) to PAL-DVD.
> >Here's my commandline:
> > mencoder -oac lavc -ovc lavc -of mpeg -mpegopts format=dvd -vf
> > expand=672:378:16:4,dsize=16/9,scale=720:576,harddup
> > -lavcopts aspect=16/9:acodec=ac3:abitrate=192:vcodec=mpeg2video:
> > vrc_buf_size=1835:vrc_maxrate=9800:vbitrate=5000:keyint=18
> > -o test.mpg -endpos 100 my.avi
> 
> why not simply -vf scale=-1:-10,expand=720:576,harddup
> to keep the original width, or
> -vf scale 720:-10,expand=720:576,harddup  to resize the width to 720
> and the height according to the A/R ?
> 
> >and then
> > mencoder -oac lavc -ovc lavc -of mpeg -mpegopts format=dvd -vf
> > scale=720:576,harddup
> > -lavcopts aspect=16/9:acodec=ac3:abitrate=192:vcodec=mpeg2video:
> > vrc_buf_size=1835:vrc_maxrate=9800:vbitrate=5000:keyint=18
> > -o test2.mpg -endpos 100 test.mpg
> >
> >all looks fine.
> 
> keyint is 15 for PAL (although I use 25), and you had better add mbd=2
> 
> >What's wrong with my approach? What's different in

The approach is correct in theory, but in practice does not work all 
the times because there is a bug somewhere.
I know for sure that doing expand-scale expose the bug.
If you do scale-expand with one invocation everything works as expected.

Giacomo

> >doing the conversions in two invocations of mencoder?
> >
> >Best regards
> 
> unnecessarily complicated