I can spend hours sitting and watching an iTunes visualizer. I sit mesmerized by the swirling colors, imagining that the visualizer knows every detail about the song; that changes in color or pattern that happen to coincide with changes in the music are intentional. However, this usually isn't the case. The best visualizers I've seen can, at best, detect a drastic change in overall average volume, but that's it.
Eventually I hope to be able to make a visualizer that provides much more direct feedback based on the music, but that's a long way off, as the code would be very advanced.
To make my visualizer, I used a graphic design program for the mac called Quartz Composer, which is basically pd for video. So all the experience I got with pd in this class paid off! I wouldn't have been able to do it without that experience.
This project is my first attempt at a visualizer. It's very simple: the visualizer displays a record player, a cd player, or an ipod depending on the era of the music you are listening to. The background brightens or darkens based on the overall volume of the music. Also, the user can move around the camera with asdw controls, which provides a degree of interactivity that i've yet to see in a visualizer.
Next quarter I plan to make a much more advanced, and hopefully highly interactive, visualizer.