maia-util can be used to provide estimates of the key of music content. It implements the Krumhansl-Schmuckler key-finding algorithm (Krumhansl, 1990).
Example
Suppose we have the crotchet notes A4, C5, F4, followed by quavers E4, G#4. The
key estimate should be A minor. The point set ps below represents these notes,
with first dimension of ontime, second dimension of MIDI note number, and third
dimension of duration.
The key of the associated notes can be estimated using the function
fifth_steps_mode. The first element of the output variable fsm is the
string "A minor".
var mu = require('maia-util');
var ps = [[0, 69, 1], [1, 72, 1], [2, 65, 1], [3, 64, 0.5], [3.5, 68, 0.5]];
var fsm = mu.fifth_steps_mode(
ps,
mu.krumhansl_and_kessler_key_profiles
);
console.log("fsm:", fsm);
For interactive versions, see this JSFiddle example or this RunKit example.
References
- Krumhansl, C. L. (1990). Cognitive foundations of musical pitch. Oxford University Press.