Batch set MP4 create date metadata from filename

Question

On a Linux system, I have a bunch of MP4 files named like 20190228_155905.mp4 but with no metadata. I've previously had a similar problem with some jpg's which I solved manually with

exiv2 -M"set Exif.Photo.DateTimeOriginal 2018:09:18 20:11:04" 20180918_201104.jpg

but as far as I can see, the DateTimeOriginal is only for images, not videos. Videos that do have metadata have a Xmp.video.MediaCreateDate field that seems like what I want. I guess it contains a Unix timestamp, so I'd need a way to get the date from the filename, convert it to a Unix timestamp and set that value to Xmp.video.MediaCreateDate. Is that all correct? Or am I overcomplicating things?

Edit: If I wasn't clear, I want to set creation date metadata on mp4 files using its filename that contains the date, so that programs can sort all my media files by their metadata

Answer 1

This uses ffmpeg (sudo apt install ffmpeg to install) and works on your exact file names. It replaces your old files with new ones with the metadata set. Maybe try WITHOUT the && mv "~$f" "$f" part first:

$ for f in *.mp4; do ffmpeg -i "$f" -metadata creation_time="${f:0:4}-${f:4:2}-${f:6:2} ${f:9:2}:${f:11:2}:${f:13:2}" -codec copy "~$f" && mv "~$f" "$f"; done

Check metadata with:

$ ffprobe -v quiet 20190228_155905.mp4 -print_format json -show_entries stream=index,codec_type:stream_tags=creation_time:format_tags=creation_time