sudo apt install libav-tools
webm to mp4
http://askubuntu.com/questions/323944/convert-webm-to-other-formats
ffmpeg -i "Jurjak - Bucuresti.webm" -qscale 0 "Jurjak - Bucuresti.mp4"
ffmpeg -fflags +genpts -i "Jurjak - Bucuresti.webm" -r 24 "Jurjak - Bucuresti1.mp4" -> change to 24 FPS
ffmpeg -i "Jurjak - Bucuresti.webm" -vf scale=-1:720 "Jurjak - Bucuresti1.mp4" -> change to 720p
mp4 to mp3
ffmpeg -i "song-name.mp4" -b:a 192K -vn "song-name.mp3"
mkv to mp3
ffmpeg -i "song-name.mkv" -b:a 192K -vn "song-name.mp3"
webm to mp3
ffmpeg -i "song-name.webm" -b:a 192K -vn "song-name.mp3"
wav to mp3
ffmpeg -i "song-name.wav" -b:a 192K -vn "song-name.mp3"
many wav to many mp3 (same dir)
for f in ./*.wav; do ffmpeg -i "$f" -b:a 192K -vn "$(basename "$f" .wav).mp3"; done