Andrea/Andrew:

The 0030-Add-timecode-to-output-mov-mxf.patch works and introduces timecode in both mov and mxf and also in mp4 (instead it doesn't work in mkv). Thanks! I propose to put this patch in git.

It is a good idea but I tested it and it works and shows up in mediainfo BUT there is an error message that is a problem and I do not understand. Maybe Andrew can look at this as shown below where the new lines and error (codec open failed) is in BOLD as shown on the startup window.

I think this error come up even if you try ffmpeg cli on such file.... (it does not know what codec can correspond to timecode track - should it even be?)

it look harmless but may be it is not? Can you try other players (including standalone/hw if you have some of them around) on this file?

AFTER 0030
...
Cinelerra is free software, covered by the GNU General Public License,
and you are welcome to change it and/or distribute copies of it under
certain conditions. There is absolutely no warranty for Cinelerra.
...
tc: 0.000000
Render::render_single: Session finished.
** rendered 2713 frames in 7.326 secs, 370.325 fps
FFMPEG::scan: codec open failed
FFMPEG::scan:file=/tmp/junafter.mp4
audio0 pad 32 0 (32)

BEFORE 0030
...
Cinelerra is free software, covered by the GNU General Public License,
and you are welcome to change it and/or distribute copies of it under
certain conditions. There is absolutely no warranty for Cinelerra.
...
Render::render_single: Session finished.
** rendered 2713 frames in 9.759 secs, 278.000 fps
audio0 pad 32 0 (32)