te dejo algunos links, quiza encuentres lo que buscas.
Is there anyone out there who knows how to extract the audio from a video file.
Example: I have a AVI of Joe Satriani, Steve Vai and Yngwie Malmsteen and I would very much like to extract the audio in MP3 format, so I can split it up in songs with a MP3 Splitter and put them on my portable MP3 player !!
I will appreciate any help