Possible to change mp4 audio language without writing entire file again?

[JeremyBrown]

I know how to change the audio language in mp4s but hate having to write the entire file to disk again and am looking to quicken my workflow. Does a program similar to the header editor in MKVToolNix exist but for mp4s?

[Ant_G]

you can just edit metadata with ffmpeg

this is the code to change the first audio stream language into english

ffmpeg -i "your_File_path_here.mp4" -c copy -metadata:s:a:0 language=eng "your_destination_file_path.mp4"

[JeremyBrown]

Doesn't "copy" write the whole file again? I stated that I can already do that and it's what I don't want to do.

[Ant_G]

sorry if i misunderstand the point of your "write the whole file again", i though that you simply not want to re-encode the whole file again which is take lot of time, and as for header editor, i can not recall any convenient GUI for MP4 to do that