sracer@media-lab.MEDIA.MIT.EDU (Andy Hong ) (11/21/90)
Does anyone have Motorola 56000 code for real-time pitch-tracking? Specifically, I'm hoping to determine the pitch of the acoustic signal from a cello in real-time--as part of a live performance. Originally, we weren't planning to dedicate too many person-hours into this project--hoping instead to just purchase a pitch-tracking system. We tested a number of off-the-shelf pitch trackers, including Zeta's Cello Retropak, various ivl pitch-to-midi converters, and the Roland CP-40. None of them was acceptable. For the moment, we've implemented an algorithm to look for max peaks and to measure the distance between these peaks. (A bowed instrument has a characteristic waveform with a big peak that corresponds to the bow "grabbing" the string and many little peaks resulting from the bow "slipping/dragging" the string.) This works great for *clean* signals, but it isn't too reliable when the signal has many harmonics or changes amplitude quickly (when the "slip/drag" peaks are close to the size of the main "grab" peak). Any suggestions? Thanks in advance. I will post a summary of all the responses I get. --Andy Hong, MIT Media Lab's Music & Cognition Group -- skate safe. andy.