Algorithms for determining the key of an audio sample

Question

I am interested in determining the musical key of an audio sample. How would (or could) an algorithm go about trying to approximate the key of a musical audio sample?

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Answer 1

First you need a pitch detection algorithm (e.g. autocorrelation).

You can use then your pitch detection algorithm to extract the pitch over a number of short time windows. After that you would need to see which musical key the sampled pitches fit best with.