[FFmpeg-devel] [RCF] lavfi aspect ratio setting path

Baptiste Coudurier baptiste.coudurier
Fri Nov 19 01:12:29 CET 2010

Hi Stefano,

On 11/18/2010 01:27 PM, Stefano Sabatini wrote:
> Hi,
> -aspect currently works by changing the PAR in the video encoder
> context and in the output stream, thus readjusting the output DAR.
> If the libavfilter is enabled, in output_packet() we have:
>      if (ist->picref->video)
>          ost->st->codec->sample_aspect_ratio = ist->picref->video->pi
> so sample_aspect_ratio is set to the value in the filtered frame,
> thus ignoring the value set with -aspect.
> Workaround for this issue is either configure with --disable-avfilter
> and use -aspect, or use the aspect filter.
> I suggest to disable the -aspect option when using libavfilter, thus
> forcing the users to employ the aspect filter. Alternatively we could
> just drop support for -aspect in favor of libavfilter, but when that
> approach made sense with the pad and crop options which were
> "polluting" the ffmpeg code with much hard-to-maintain complex code,
> this doesn't seem the case for the aspect option and I still want to
> keep that option for users which for some reason (e.g. because of the
> lavfi regressions) are using an ffmpeg compiled with
> --disable-avfilter.

First, thanks for looking into this.

I, too, would like to keep the -aspect cli option.

I have a patch in my tree that actually set the aspect at the end of 
configure_filters and disable the code you quoted above.

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