Grumpy_Mike:
In a consistent manor with what?
As in does does voltage correlate to decibels or tone or anything like that? I forgot about amplitude; can the Arduino measure that?
I guess I'll try to give an example here. Say a song is playing, and at one point, it's really soft/quiet relative to the rest of the song, and kind of slow. At that point, I would want the LEDs to light up at maybe 30% power and at say 3 flashes per second. Then the song picks up and is now faster and louder, so I would want the LEDs to light up at like 90% power and at 5 flashes per second.
The numbers are totally arbitrary and I can handle the coding, I just don't know what kind of data I would have to work with, what that data would represent in the song (like voltage corresponding to decibels or something), and how exactly I would get the music from the computer to the Arduino.