[FFmpeg-user] Mp4 Concat Demuxer Produces Incorrect Output

[Jim Shupert]

  Would the tbn being different on these files effect the output of the concat demuxer?

I do not have a direct response to your question but I know that
one can have 2 files that are the same in every way except for 1
file a is drop frame time code
file b is Non drop time code

and those 2 files will NOT concat

in regards to your Q -my guess is - yes.  I think that explains what your seeing