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

[Rich Felker]

On Sat, Oct 08, 2005 at 02:12:22PM -0400, Giacomo Comes wrote:
> On Sat, Oct 08, 2005 at 09:15:11AM +0200, Thomas Heuving wrote:
> > Nico Sabbi schrieb am Thu, 06 Oct 2005 10:10:04 +0200:
> > >>  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
> > 
> > that works, but I want some black borders as most DVD-Players seem
> > to cut some of the original content in order to present the material
> > on the Television. I think that's the reason why commercial content
> > tends to have black borders too (?).
> > Less complicated is
> > scale=-1:10:::::pal (or ntsc)
> > so you don't have to expand by yourself.
> > 
> > > -vf scale 720:-10,expand=720:576,harddup  to resize the width to 720
> > > and the height according to the A/R ?
> > 
> > This gives bad distortions.
> > 
> > > unnecessarily complicated
> > 
> > But it seems to be necessary to do two invokations, as I didn't find
> >  and nobody mentioned a working example of putting black borders and do
> >  a scaling in one go.
> 
> I already told you that that if you do scale-expand you can do it in one pass.
> 
> For you particular movie
> 
> -vf scale=684:547,expand=720:576  will add 5% border and

Scaling to odd height is _always_ invalid for 4:2:0 pictures. MPlayer
will do it anyway but it will make bad chroma artifacts at the edge.
Ideally you should line the borders up to mod-16 boundaries if you're
going to add borders, anyway.

Rich