ffmpeg - output metadata, add/remove modification then add it to the video

[kalemvar1]

It is possible to export the full metadata from a video/audio .mp4 (in .txt probably) then modify it to add or remove some tag and upload it back to the video ?

Thanks for your help

kalemvar1

[Budman1]

ffmpeg -i in.mp4 -f ffmetadata in.txt
exiftool in.mp4 >a.txt
ffprobe -show_frames "in.mp4" >B.txt

The above Will all Output MetaData to a text file. The problem is that they all do it differently and the Designations are not always the same for each metadata tag.
Further complicating this is the fact that the writing programs also have there own designations for the metadata tags.

The easiest way is to use ffmpeg to copy all Metadata from source file to the destination file and add the new or changed data.

Adding Encoded/Tagged dates to a video without them:
ffmpeg -i test.mp4 -map_metadata 0 -metadata creation_time="2020-07-30 12:59:20" -c copy C.mp4
Removing Encoded/Tagged dates:
ffmpeg -i test.mp4 -map_metadata 0 -metadata creation_time="" -c copy C.mp4

It is necessry to use the metadata "key=XXXX" format; The recognized list of formats is as listed for mp4:
"title"
"author"
"album_artist"
"album"
"grouping"
"composer"
"year"
"track"
"comment"
"genre"
"copyright"
"description"
"synopsis"
"show"
"episode_id"
"network"
"lyrics"
"creation_time" (Sets both Encoded and aTagged dates in metadata)

[kalemvar1]

Thanks for reply, that's explain a lot.

would it be possible to add "bitrate" or "maximum bitrate" within metadata (for a video that don't have one or both listed) or we are limited to only the list you described ?

[Budman1]

Wouldnt do much good sonce you would be telling a 200k bps video that it is 400k. Only way to do that is recode. Bitrate and other is used by codec so lying to it would not be good. If you notice the list of mp4 allowed keys are not needed to have a valid video.

Different formats use different allowable keys. The above list is the only ones i know are allowed for mp4.

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