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livetrax/share/web_surfaces/builtin/mixer/toolkit/implements/notes.js

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2020-06-21 17:29:27 -04:00
/*
* This file is part of Toolkit.
*
* Toolkit is free software; you can redistribute it and/or
* modify it under the terms of the GNU General Public
* License as published by the Free Software Foundation; either
* version 3 of the License, or (at your option) any later version.
*
* Toolkit is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
* Lesser General Public License for more details.
*
* You should have received a copy of the GNU General
* Public License along with this program; if not, write to the
* Free Software Foundation, Inc., 51 Franklin Street, Fifth Floor,
* Boston, MA 02110-1301 USA
*/
"use strict";
(function(w, TK){
var notes = [ "C", "C#", "D", "D#", "E", "F", "F#", "G", "G#", "A", "A#", "B" ];
TK.Notes = TK.class({
/**
* TK.Notes converts between frequencies, MIDI notes
* and note names.
*
* @mixin TK.Notes
*/
_class: "Notes",
/**
* Returns a note name for a MIDI note number.
*
* @method TK.Notes#midi2note
*
* @param {int} note - The MIDI note to translate.
*
* @returns {string} note - The name of the note.
*/
midi2note: function (num) {
return notes[num % 12] + parseInt(num / 12);
},
/**
* Returns a frequency of a MIDI note number.
*
* @method TK.Notes#midi2freq
*
* @param {int} note - The MIDI note to translate.
*
* @returns {number} frequency - The frequency of the MIDI number.
*/
midi2freq: function (num, base) {
base |= 440;
return Math.pow(2, (num - 69) / 12) * base;
},
/**
* Returns a MIDI note number for a frequency.
*
* @method TK.Notes#freq2midi
*
* @param {number} frequency - The frequency to translate.
* @param {number} [base] - The frequency of A440.
*
* @returns {int} number - The MIDI number of the frequency.
*/
freq2midi: function (freq, base) {
base |= 440;
var f2 = Math.log2(freq / base);
return Math.max(0, Math.round(12 * f2 + 69));
},
/**
* Returns the percents a frequency misses a real note by.
*
* @method TK.Notes#freq2cents
*
* @param {number} frequency - The frequency to translate.
* @param {number} [base] - The frequency of A440.
*
* @returns {number} cents - The percent of the difference to the next full note.
*/
freq2cents: function (freq, base) {
base |= 440;
var f2 = Math.log2(freq / base);
f2 *= 1200;
f2 %= 100;
return (f2 < -50) ? 100 + f2 : (f2 > 50) ? -(100 - f2) : f2;
},
/**
* Returns a note name for a frequency.
*
* @method TK.Notes#freq2note
*
* @param {number} frequency - The frequency to translate.
* @param {number} [base] - The frequency of A440.
*
* @returns {string} note - The name of the note.
*/
freq2note: function (freq, base) {
base |= 440;
return this.midi2note(this.freq2midi(freq, base));
}
});
})(this, this.TK);