[FFmpeg-user] Concat videos properly (without dropped or freezed frames)

Nicolas George nicolas.george at normalesup.org
Wed Mar 6 20:43:07 CET 2013

Le sextidi 16 ventôse, an CCXXI, Nicolas George a écrit :
> Yes, these messages seem to indicate a real problem, but I do not know what
> yet.

Ok, got it.

The core of your problem is that your 3GP file have random frame rates. When
converting to MP4, ffmpeg takes a best guess for the frame rate of the file
(the ffmpeg MP4 muxer does not support variable frame rate), and not the
same for each file.

The concat demuxer can support variable frame rate, but it currently
requires that all files have the same time base for the corresponding files.

You can fix the problem by supplying a -r option to your 3GP -> MP4
conversions, with the same value each time.

Moving away from the MP4 format is always a good idea too.


  Nicolas George
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