Here's a video of it in action:
I use an FFT is used to find the energy at different frequencies. What I'm displaying is kind of like a histogram of the frequencies. Content at high frequencies makes the right-most light turn on, and content at low frequencies makes the left-most light turn on.
I've posted the source at GitHub, released under the GPLv3.
WaveAudio
I've been writing a C# sound library called WaveAudio. I'm sure there are many other libraries, but I'm writing this one from scratch for fun. It's great to be able to write something quick like:New feature: based on some information from Wikipedia, WaveAudio can now detect pitch using autocorrelation pitch detection. I've tested it when singing, and it does work. I've posted the source along with unit tests at GitHub, released under the GPLv3.