Waves

i was wondering how i could make an equalizer? like in the volume thing in windows..if you play a wav or mp3 and look at the Wave vollume, there is a bar moving up and down..what do i need to do that?..i need to know how to get the waves from teh song that plays..then i want to output it to a LED board..(thats no problem.
thanks

you must follow the data stream and get the amplitude (I have no idea how wav or mp3 files are organized). The amplitude is equivalent to the current volume. I think you can use that.