ffmpeg metadata copy (all)

Question

Hope you are having a wonderful day,

I come with question related to FFMPEG and copying metadata.

So my output file got just some of metadata, but not all of them, even if my.txt contains them.

currently using -map_metadata 0:g as i read somewhere here it is supposed to copy everything. I tried few others but none are working.

I make everything in bat file so this is part of "for" loop:

ffmpeg -i "%%A" -f ffmetadata metadata.txt -f rawvideo -y NUL

and then

ffmpeg -i "%%A" -f ffmetadata -i metadata.txt -c copy -map_metadata 0:g -movflags +faststart "%output%\%%~nAtag.mov"

Now, I get from metadata title, author, but I do not get field "description". So not ALL the data is copied. Do you know how to basically copy these metadata from file to another (absolutely all of them?

PS -metadata description="TESTESTTEST" seems to work only on mp4 files, not mov files

Answer 1

For mov & mp4 containers, custom tags can be written if -movflags use_metadata_tags is added.
See Gyan answer

Answer 2

For a non-ffmpeg solution, exiftool can be used to copy metadata in MP4/Mov files with this command
exiftool -TagsFromFile source.mp4 -All:All target.mp4

Batch processing can be done with this command, assuming the files are the same name
exiftool -TagsFromFile /path/to/sources/%F -All:All /path/to/targets/

These commands creates backup files. Add-overwrite_original to suppress the creation of backup files.