This is really cool. Have you looked at all at the constant Q transform https://en.m.wikipedia.org/wiki/Constant-Q_transform https://en.m.wikipedia.org/wiki/Co

This is really cool. Have you looked at all at the constant Q transform https://en.m.wikipedia.org/wiki/Constant-Q_transform https://en.m.wikipedia.org/wiki/Constant-Q_transform which is basically a Fourier Transform with logarithmically spaces bins so that it can be aligned with traditional musical notes. Miller Puckette (Max/Pure Data) among others, has a fast algorithm for its calculation.