The light chaser project consists of a few small projects. The first was a control box with a programable chip within which was put together by a friend of mine as a Christmas present for me. The instructions for creating this controller box can be found here, as originally posted (at least where I first heard of it) on slashdot.
The next project that I had required making the serial "cable" to connect the controller box to a (my) computer. I purchased two RJ-45 to DB9 connectors and wired them so that I could use them with any straight through ethernet cable. I may buy some RJ-11 to DB9 connectors though, so that I can make it use regular phone cable (cheap!) for running larger distances than my nice CAT5.
After I got that working, and was able to test that I was getting good outputs from the Molex connectors for the lights, I worked on building an electrical outlet box to plug the Christmas lights into, instead of cutting their cords and connecting them directly to the molex plug. This worked out pretty well, and then I realized that there were two sets of four that were separately controlled (as opposed to one set of four and a duplicate set). So, I've created a second of these boxes as well. They're not quite finished, as I need to find one of the outlet plate covers and also need to get some wire wrap to keep the five wires (for each box) together.
Now, I've basically been using the winamp plugin from the website that shows how to build the controller box. I only have 7 strands of lights though, but here's what it looks like so far in winamp. I'm not terribly satisfied with the beat detection in winamp though, so I have been doing some research into other beat detection methods. I finally ran across one mp3 player in Linux that does beat detection, called DJ Krazy. I'm even less satisfied with their beat detection, but it did give me a chance to try out my program for writing the control signal out to the lights which worked pretty well.
I've been doing a little bit of research on beat detection and found an interesting article that talks about using Discrete Wavelet Transforms to detect beats. I'm hoping that I will be able to use this to my advantage, though I suppose it's yet to be seen. My main worry is that I won't be able to do the transforms and beat detections in real-time.
I've finally got the "hardware" side of things pretty much finished. I've got the outlets done which can be seen here, here, and here. Also, there's a picture of the pieces as I'm putting them together as well.
Finally, for those who are curious (or even if you're not -- tough), I'm using the Forever Bright LED Christmas lights in these examples. These were also linked from Slashdot before Christmas. I found a few sets at a local Albertson's just before and after Christmas (After Christmas Sales!).