MP3

From wav

lame -h -v -B 192 in.wav out.mp3

To wav

mpg123 --stereo -w out.wav in.mp3
mplayer -ao pcm:fast:waveheader:file=in.wav -vo null -vc null in.opus

split

Split MP3 into nt (for example N=10) tracks, based on silence:

mp3splt -s -p nt=10 in.mp3