[FFmpeg-user] Stream copy of mxf format is weird

Nicolas Gaullier nicolas.gaullier at cji.paris
Tue Jan 30 11:28:03 EET 2024


>De : ffmpeg-user <ffmpeg-user-bounces at ffmpeg.org> De la part de Syehoon Kim
>(...)
>But, I found that the new stream copied mxf file suffers from non-monotonous dts problem.
>What I found is that dts is duplicated every 3 frames.
>
>The command I used is as follows:
>  ffmpeg -i (original_mxf).mxf -codec copy (stream_copied).mxf Interestingly, if I convert the weird mxf output file to another format such as mov, or avi, it works well.

It is not very clear to me, but it seems you only inspected the output and not the input.
To start with, here is something you can try to quickly check dts/pts of your mxf input:
ffmpeg -I input.mxf  -map v -c copy -f framecrc -
You can also directly decode to void to check some non-monotonous errors: ffmpeg -i input.mxf -f null null
You can also play your input file with mpv keeping an eye on the console output messages.
You can also dump your input mxf structure with dedicated tools (bmx, mxflib).
It is not very widespread or well-known, but timestamp issues DO happen in the mxf wrapper itself.

Nicolas


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