I know there are better places to ask this, but there's been a fair amount of
signal processing talk around here in recent history, and everything I google
comes up with patents and microprocessor talk.

The basic situation is that I want to program a piano tuner (we'll see about
having the guts to tune the thing).  It didn't take more than a couple hours to
write a c program that takes audio input, FFT's it, and tells you the closest
pitch.  The problem is the frequency resolution.  I essentially get the refresh
rate for resolution, e.g. 10 updates per second -> 10 Hz resolution.  This
resolution won't cut it.  G#4 is 415.3 Hz, A4 is 440 Hz, and A#4 is 466.164 Hz,
so you can see what I'm up against.  Here are my ideas:

1) Zero-pad the data pre-fft.  (I'm not sure whether this actually improves the
quality of the information.)

2) Use a feedback loop to control the frequency of a test wave.  (I don't know
what the controller should look like.)

3) FFT.  Locate max.  Band-pass.  Inverse-fft.  Count zero-crossings?  (Not
robust for noisy signals?)

As I said, my lack of knowledge in this area makes it difficult to locate the
relevant resources.  Does anyone know of a feedback loop or other more
sophisticated tools for this purpose?

 - Ricky

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