it just compare a frame and the "frame-1 frame", and evaluate the number of changed pixels
then convert it in 0-255 and send it to a control change (on/off if >threshold, or a scaling between 0-127)
if i remember well, the midi mapping is not optimal. I will made a more efficient later.
Thanks for this patch, I found this tracks quite well in my situation but I'm not getting the correct data out, too many note ons and the volume of the note is difficult to attach to other devices, maybe you could help me out to get the data from this patch I need? One note on and a mappable parameter, or even sending OSC events out would be great..