[FFmpeg-user] Loss of mp4 metadata when copying

Andrew Brezovsky abrezovsky at gmail.com
Thu Jan 16 04:43:47 EET 2020

I have been trying to modify the handler_name metadata field of an audio
stream in a video file within an mp4 container.
However, ffmpeg seems to be discarding the handler_name field and replacing
it with a generic "SoundHandler" value.
While the values in the input and output read-outs are correct, at the end
of the copy I see "[mp4 @ 0x558cdfba2000] Unknown hldr_type for text,
writing dummy values".

Here is the command I'm trying to use:
ffmpeg -i mystery_source.mp4 -map 0 -map_metadata 0 -c copy -metadata:s:a:0
handler_name="Stereo" mystery.mp4

Here is the output: https://pastebin.com/r8kgt7Ny

I am trying to change these as I forgot to modify the name of the audio
stream when transcoding with HandBrake. I am trying to avoid re-encoding
the file just to rename the audio track (so it appears correctly in
programs such as VLC).
Thanks for any help.

Andrew Brezovsky
abrezovsky at gmail.com

More information about the ffmpeg-user mailing list