Well you can go at this in several diferent ways… The 2 strongest and best ways are…
flashAMP or swiftmp3
With flashAMP… It gives you every frame a new sound loudness definition…
With swiftMP3 it gives you a .swf that can play the music in any type of loop and return each frame a spectrum…
I’d choose the swiftmp3 version way… That way you have mroe values to work with… I don’t have th direct link to either of these… But a simple google search will help you find them… They will give you directions on how to use each one then…
But… You would just take those values and then have a fcntion that would take those values and turn them into cool looking graphic beats.