Unpacks stems into folders with cover art and separate tracks using ffmpeg

unpack_stems.sh

#!/bin/bash

#
# Extracts tracks from stems files and puts them in folders
# named after the stem filenames.
#

for stem in *.mp4
do
	name=${stem%\.*}
	echo $name

	# Create a directory
	rm -R ./"$name"
	mkdir $name

	# Album cover
	coverFilename="$name"/"$name"_cover.jpg
	echo "  - Extracting album cover to $coverFilename"
	ffmpeg -i "$stem" -an -vcodec copy "$coverFilename"

	# Audio tracks
	for trackNo in 1 2 3 4
	do
		trackFilename="$name"/"$name"_"$trackNo".m4a
		echo "  - Extracting audio track $trackNo to $trackFilename"
		ffmpeg -i $stem -map 0:$trackNo -vn "$trackFilename"
	done
done