[FFmpeg-user] aspect ratio changes in the middle of the stream

Tim Nicholson nichot20 at yahoo.com
Fri Sep 6 13:27:58 CEST 2013

On 06/09/13 12:05, Carl Eugen Hoyos wrote:
> Michael Kasch - SmartCast <kasch <at> smartcast.de> writes:
>> ffmpeg  -y -i test.ts  -vf "yadif, scale=iw*sar:ih ,
>> pad=max(iw\,ih*(16/9)):ow/(16/9):(ow-iw)/2:(oh-ih)/2" 
>> -aspect 16:9 test.mp4
>> But often I have the situation that the ratio changes 
>> in the middle of a stream. 4:3 Film with 16:9
>> commercials, or first 4:3 and next show 16:9. Is there 
>> a solution to get ffmpeg or x264 to recheck the aspect
>> ratio every i-frame?
> (Why only I-frames?)
> The way I understand your question is that in some 
> circumstances, output videos do not look the way 
> you want them.
> If this is correct, please post the command line you 
> used together with complete, uncut console output for 
> such a failing case.
> Carl Eugen
> [..]

MAy broadcast .ts streams set aspect ratio on a frame by frame basis,
the question is how to get ffmpeg to do the same. So that playing over
aspect ratio transitions does not lead to distored pictures.


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