Moving this topic to its due place.
I took up the subject in the middle of the thread started by mattblack, regarding the analysis of a sound wave in several bands, so that he could milk out different midi information from each slice. He was going for visuals (the guy is in Coldcut!!!!).
Then I had the idea of using my dj mixer as a midi controller, using pretty much the same principle: feed two channels in the mixer with different sine waves and have them translated somehow into midi information.
This is what I have so far, simple as a newbie would do it:
The volume fader now convert to midi (0-127), and instead of using two different sine waves, I just sent one signal to the left channel and the other to the right. The whole processing is done like this, in parallel.
The output of the mixer is fed into the AUX input of my soundcard (it took me a while to realize the MIC input was mono!)
I still kept the sines far apart - the original idea - in their frequencies (200hz and 2khz), but I don't see any use now that the signal is separated like that. The crossfading works neatly.
I can't find the specs for my gemini mixer, or else i would have made three separate bands (cloning the specs) and send them to each channel, so that the eq knobs could be hacked into sending midi info, too. That would make the whole rig more than 2 faders!!
I ran into a lot of noise, and it takes some calibration.
The latency in PD had to go to 256ms so that it wouldn't go crazy as Ableton started, which makes the response laggy, in the end. Also (and most annoying of all) I don't know how to make the numbers calm down. Is there a way of rounding them down? They stay put in 127, for instance, but the decimals are always moving (like from 127.21 to 127.98)
And there's stuff I left undeleted so that I can go on experimenting.
My first patch, after all. And as a proof of concept, IT WORKS!
Any ideas, comments, suggestions, just shoot!
Oh, and thanks for the tips, hardoff!