[Ffmpeg-devel] DAR and SAR FFmpeg option confusion

Michael Niedermayer michaelni
Tue Mar 13 01:01:41 CET 2007


Hi

On Mon, Mar 12, 2007 at 11:22:00AM -0700, Roman Shaposhnik wrote:
> Hi,
> 
> On Mon, 2007-03-12 at 15:32 +0000, Robert Swain wrote:
> > > i'm not sure the one in utils.c should exist (if it is triggered, i'm
> > > not sure it will lead to a good behavior)...
> > > to verify this, you can try to use -vaspect option, which should use the
> > > option in utils.c, and not the one in ffmpeg.c
> > > there must also be a static in ffmepg.c to handle the aspect ratio,
> > > which you should not use to set encoder param if you use -vaspect, too...
> > 
> > I'm encoding to x264 and I wrote the code in libavcodec/x264.c to use:
> > 
> > 192:    x4->params.vui.i_sar_width = avctx->sample_aspect_ratio.num;
> > 193:    x4->params.vui.i_sar_height = avctx->sample_aspect_ratio.den;
> > 
> > I haven't done any print debugging but looking at the SAR reported by x264, 
> > these values are not affected by -vaspect, grepping for vaspect in the code 
> > returns no results and it isn't documented anywhere yet ffmpeg doesn't report 
> > any unrecognised option error. :/
> 
>   I have the same issue with DV (not being able to use SAR for real) so
> if you ever figure this out -- there'll be at least two clients for the
> functionality.

-aspect should set DAR, DAR + width and height -> SAR if this doesnt work
its a bug

[...]

-- 
Michael     GnuPG fingerprint: 9FF2128B147EF6730BADF133611EC787040B0FAB

Everything should be made as simple as possible, but not simpler.
-- Albert Einstein
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