This link provides code for an autocorrelation-based pitch detection algorithm but says:
Cons: Not as accurate, doesn't work for inharmonic things like musical instruments, this implementation has trouble with finding the true peak
Why is that? What implications will it have if I want to create a guitar pitch detector (let's assume that I am only working with monophonic audio for now). Is it the noise that creates those implications? I thought that musical instruments are harmonic things, not inharmonic.
Is the YIN algorithm an improvement in this aspect? If not, what does it improve?