I have been developing(with limited success)a patch to send MIDI controller data and note ON/OFF/velocity based on the dynamics of 2 or 3 frequency ranges(Kick,Snare,Hi-Hat). The problem I'm having is in the process of filtering the incoming audio. I consider myself to be quite an audio geek but when it comes to the internal workings of filters and the math behind them, I'm pretty clueless. I can't seem to build a good adjustable band-pass filter, just a bunch of resonant noise. So I am wondering if anyone has had success with accurate filtering or if anyone has tried to make a similar patch. I even be willing to compensate anyone that has a working example of this. I've been working on this for a while and it seems I've hit a wall with it. Unfortunately I really need to make this work soon. Any information is sincerely appreciated.
(If anyone is interested in my flawed approach, I've attached the text version of my filter)