Created
September 22, 2012 15:00
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Convert note to frequency
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// Takes string of Note + Octave | |
// Example: | |
// var frequency = getFrequency('C3'); | |
var getFrequency = function (note) { | |
var notes = ['A', 'A#', 'B', 'C', 'C#', 'D', 'D#', 'E', 'F', 'F#', 'G', 'G#'], | |
octave, | |
keyNumber; | |
if (note.length === 3) { | |
octave = note.charAt(2); | |
} else { | |
octave = note.charAt(1); | |
} | |
keyNumber = notes.indexOf(note.slice(0, -1)); | |
if (keyNumber < 3) { | |
keyNumber = keyNumber + 12 + ((octave - 1) * 12) + 1; | |
} else { | |
keyNumber = keyNumber + ((octave - 1) * 12) + 1; | |
} | |
// Return frequency of note | |
return 440 * Math.pow(2, (keyNumber- 49) / 12); | |
}; |
Java Version
private double getFrequency(String note) {
String[] notes = {"A", "A#", "B", "C", "C#", "D", "D#", "E", "F", "F#", "G", "G#"};
int octave = note.length() == 3 ? Integer.parseInt(String.valueOf(note.charAt(2))) : Integer.parseInt(String.valueOf(note.charAt(1)));
int keyNumber = java.util.Arrays.asList(notes).indexOf(note.substring(0, note.length() - 1));
if (keyNumber < 3) {
keyNumber = keyNumber + 12 + ((octave - 1) * 12) + 1;
} else {
keyNumber = keyNumber + ((octave - 1) * 12) + 1;
}
// Return frequency of note
return 440 * Math.pow(2, (float)(keyNumber - 49) / 12);
}
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Python version