Broken copying for XAVC-L

[PhillipBarnett]

Doing a straight copy of Sony XAVC-L media produces jittery output file, dropping every third frame.
How to reproduce:
Sample Sony XAVC-L 50 file on a Ubuntu 20.04.2 LTS 64 bit machine, with a fresh compilation of ffmpeg. Copy the file as below. Play back output file with ffplay - video looks bad. Use ffmpeg -f framemd5 to check the copy against the original - there are significant differences, frames are being dropped.

I have sample files to upload, but the ftp server upload.ffmpeg.org is not allowing me access - ńetwork unreachable´

% ffmpeg -i input.mxf -c copy -map 0 output.mxf
ffmpeg version N-103614-g441b292592
built on 14 Sept 2021

Patches should be submitted to the ffmpeg-devel mailing list and not this bug tracker.

[PhillipBarnett]

Here is a diagrammatic look at a comparison of the framemd5 of the source and the copy, with the start of the hash of the first few video frames (ignoring audio and data)

Frame Original Copy

0 a161... dropped
1 a76f... a161..
2 2f06... a76f ...
3 ec60... dropped
4 512c... ec60...
5 c59d... 512c ...
6 b239... dropped
7 0d0d... b239...

[PhillipBarnett]

ffmpeg log file creating the copy

[PhillipBarnett]

Framemd5 of source file

[PhillipBarnett]

Framemd5 of copy file

[PhillipBarnett]

Very short segment of source material

[Tomas Härdin]

This also happens with the mov muxer. The original files have ptses like so (video only):

0,1,2,3,4,5,6,8

Note the lack of pts=7. When muxed as mxf I get:

1,2,4,5,7

and when muxed as mov:

2,3,4,5,6,8

Why this happens I'm not sure, but it's certainly not limited to mxfenc. Marking as reproduced.