I used Processing a lot back in 2010/2011 and i’m glad to see its grown and improved so much. Its a great tool. I first came across it after watching a music video someone had made using Processing. Here is the link. The video was made by Rober Hodgin(Thanks hamoid for the info) and the song is Radiohead - Weird Fishes/Arpeggi.
Its an incredible piece of art. This inspired me to make something of my own, but I wanted an active visualizer instead of the choreographed style of the video above. I started using processing, then did some digging and found the MINIM library. After playing with that I eventually created some really cool(at least I thought so) visual effects that react on the fly to music based on different frequency ranges. Here is a video of my favorite one. The music is Seven by Ratatat.
If anyone has similar projects or interests id be glad to chat and get back into this stuff.