thanks to your script, should work for everything

[mrfragger]

for f in *.opus ; do kid3-cli -c "set title '$(printf '%n' "$f")'" "$f" ; done

or mp3, mp4, etc.

also I figured it out cuz trying to pipe python titlecase to filenames and it took me forever to figure out syntax

for f in *.opus ; do mv -i -- "$f" "$(printf '%s\n' "$f" | titlecase)" ; done

Now I combine it into one command

for f in *.opus ; do mv -i -- "$f" "$(printf '%s\n' "$f" | titlecase)" ; kid3-cli -c "set title '$(printf '%n' "$f")'" "$f" ; done