[FFmpeg-user] Possible feature additions for concatenating video files

Carl Eugen Hoyos cehoyos at ag.or.at
Thu Jan 5 00:45:59 CET 2012

 <dg1727 <at> hushmail.com> writes:

> A.  An option in FFmpeg to assume that the input file is correct 
> (audio and video have the same duration) except that only the video-
> FPS field is wrong.  This option would change only the video-FPS 
> field to make the computed video duration match the audio duration. 
>  Preferably, this option could be given to the "ffmpeg" command in 
> the FLV-to-MP4 step listed above.

If I understand that correctly, FFmpeg miscalculates (or misdetects) the video
(or audio) duration in one of your samples, and the result of your initial
ffmpeg -i input -acodec copy -vcodec copy call results in an out-of-sync file.
If that is correct, please provide a sample.

Carl Eugen

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