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Real Time Pitch Tracking

Posted on 2021-05-23 12:00

Notes

Yin

I'm a long-time Yin user, but the algorithm seems to have some serious limitations for realtime use in an embedded enviroment:

The algorithm is block-based and inherently latent
The fast version of the algorithm requires an FFT on every block
In my experiments the algorthm slows to a crawl with a large tau_max, so detecting pitches lower than ~70-80hz seems to have a pretty big impact on performance.

Extended Complex Kalman Filter

2017 dafx paper

Das Orchisama, Chris Chafe and JOS to the rescue maybe?

This algorithm is designed for low-latency real time use, and computes a pitch estimate on every sample instead of every frame like Yin.
It still requires an FFT on every block, although there is a note about some mitigations in the paper...
Seems to perform much better than Yin: much more stable and tracks fast moment more easily

Bell Labs Hardware Implementation

1976 IEEE paper: J Dubnowski, R Schafer, L Rabiner. Real-time digital hardware pitch detector

Is this something? They call this "high-quality" but that's in 1976. Maybe it's just a basic autocorrelation approach? (EG what Yin attempts to improve on...)

I'll have to track down access, I'm curious...

MPM / Tartini

200? paper: Philip McLeod & Geoff Wyvill. A Smarter Way To Find Pitch

The "clarity" param is interesting.
Also requires an FFT.
Is optimized to use small block sizes though, so latency should be lower... but then you're doing that many more FFTs a second...

The primary author's PhD thesis (1980) looks like a fantastic introduction to the literature (also discussions of wavelet analysis & LPC!)

Reading Notes

Comparison of Pitch Trackers for Real Time Guitar Effects