[Ffmpeg-devel] DAR and SAR FFmpeg option confusion

[Roman Shaposhnik]

Hi

On Tue, 2007-03-13 at 20:14 +0100, Michael Niedermayer wrote:
> >   I don't think its just DV, but that aside -- it seems that we've got
> > three ways of solving this issue:
> >   
> >     * as you and M?ns pointed out admitting that the DAR is 15:11 will
> >       do the trick. I guess it'll mean lots of FAQing, but that's ok
> > 
> >     * somehow make libavcodec aware that there's a smaller DISPLAY area
> >       embedded inside the coded frame. And for that area the SAR is 
> >       (obviously!) the same, but the DAR is what everybody expects it
> >       to be
> 
> there is AVFrame.pan_scan to specify display areaS though i dont see how
> that would affect the DAR disscussion

  My thinking was that if we start using those everything that has to do
with calculating SARs based on geometry and DARs could first check
for the DISPLAY geometry (perhaps that's what AVFrame.pan_scan should be
used for) and only if its not set check for the regular height and
width. That way, the math that initiated this very thread would still
work and not only that but everybody can happily use 4:3 as the DAR
instead  of some weird #s.

  Now, should I start filling AVFrame.pan_scan in DV codec ? IOW,
was introduced to handle exactly what I'm talking about here or
is it just one of those MPEG2/MPEG4 oddities ?

Thanks,
Roman.