ffmpeg -i file.mp3 -af pan="stereo|c0=c0|c1=-1*c1" -ac 1 novocal/file.mp3
ffmpeg -i novocal/file.mp3 -af "bass=g=6:f=100:w=0.5" bassboost/file.mp3
ffmpeg -i novocal/file.mp3 -i file.mp3 -filter_complex "[0:a]volume=1.0[a0];[1:a]volume=0.3[a1];[a0][a1]amix=inputs=2[a]" -map "[a]" done/file.mp3
ffmpeg -i $file -i mix/$file -map 0:v -map 1:a -map_metadata 0 -map_metadata:s:a 0:s:a -c: copy done/$file
original song copies at /Volumes/sneakernet/karaoke
for file in *.mp3
do
ffmpeg -i $file -af pan="stereo|c0=c0|c1=-1*c1" -ac 1 novocal/$file;
ffmpeg -i novocal/$file -af "bass=g=6:f=100:w=0.5" bassboost/$file;
ffmpeg -i novocal/$file -i $file -filter_complex "[0:a]volume=1.0[a0];[1:a]volume=0.3[a1];[a0][a1]amix=inputs=2[a]" -map "[a]" mix/$file;
ffmpeg -i $file -i mix/$file -map 0:v -map 1:a -map_metadata 0 -map_metadata:s:a 0:s:a -c: copy done/$file
done