Simple script to convert jpg files into base64 blobs suitable for attaching to ogg image files as metadata_block_picture
Runs in bash, no known dependencies, simply uses what come on a standard Linux install
The image width/height determination method feels fragile, but it seems to work so far.
Follows the format outlined by ogg creators
https://xiph.org/flac/format.html#metadata_block_picture
With credit to Biapy
https://superuser.com/questions/169151/embed-album-art-in-ogg-through-command-line-in-linux
Example usage: This produces cover.base64 blob
$ ogg-image-blobber.sh cover.jpg
This attaches the blob to an ogg file
$ ffmpeg -i file.ogg -metadata "metadata_block_picture=$(cat cover.base64)" new.ogg