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

Michael Niedermayer michaelni
Fri Nov 19 01:33:57 CET 2010

On Thu, Nov 18, 2010 at 04:12:29PM -0800, Baptiste Coudurier wrote:
> 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.

can you post that to the list so i can take a look?
from your description it sounds like a good solution

Michael     GnuPG fingerprint: 9FF2128B147EF6730BADF133611EC787040B0FAB

I have often repented speaking, but never of holding my tongue.
-- Xenocrates
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