It’s awesome that you are working with the Arduino – thats how I started and I think it was probably the best approach to learning about electronics. I’ve been studying for my undergraduate degree in college so I have very limited amount of time to browse the Internet which is why its been hard to get around to your question.

This project you referred to was lost in a computer crash – so I have no code to give you. But let me give you a few hints.

I used the “Minim” library for java that you can find here: http://code.compartmental.net/tools/minim/. I believe this library is now included with Processing now (the platform I used to communicate over serial to the arduino).

Minim requires an audio input, so you can either run a splitter from an ipod to your microphone port on your computer, or use some sort of software to route the sound output from your computer back as an input. I ran my software on a Mac so I used a piece of software called SoundFlowerBed.

Anyways, Minim has a BeatDetect class (seen here: http://code.compartmental.net/tools/minim/manual-beatdetect/) It was useful in the video I had but it can be pretty jumpy sometimes.

You can also use what is called a Fast Fourier Transform (FFT For short) (Minim does this too, check out their documentation.) An FFT basically takes your audio input and seperates it into frequency ranges. So basically you can tell how loud the audio is from say 0-60 Hz and compare that with the entire audio signal. From there I was able to basically look at the “jumps” produced by the bass of the music and determine if that is a beat compared to how the jumps occurred in the last say 10 seconds.

Beat detection is a fairly complex thing to do – and I never got it to really “work” half of the time. For example, a snare hit spreads across the whole frequency spectrum of hearing (20-20000Hz) so when I compared the lower frequencies to everything else, it just seems that it fit in.

I went a long way since then, and found the best effect is when you just change the intensity of the light with respect to how loud those lower frequencies are. You can see this in my video I attached of my last lighting project.

I hope this gives you some ideas, good luck with your project.

I’m completely new to this since I’m not an engineering student. I’ll try out what you told me. Thanks again.

If you wanted to actually play music via minim on the arduino would be a different story. If you wanted to interface with speakers, you could put the output from the analog output pins on the arduino through an amplifier (LM386?) and then to the speakers. I’m not sure what quality of sound you might get out of it either. If you dont have analog out, then a digital-to-analog convert -> LM386 should work as well. Thats more complicated though. Software wise, I would look at the AudioBuffer class in Minim to extract the sound data.

Good luck,
Andrew

It’s really cool that you were able to rig it up so quickly!
I’m doing a similar project but I used an Arduino Shield to play music instead. I am stuck in one part that I’m guessing you are the only one who can answer. How did you manage to send the output of beat signals to the arduino through MINIM? Did you have to code something?

Please help!

I second Joe’s request.
I’d love to see how you set this up, if that’s okay with you.
Thanks!