File size: 3,424 Bytes
af6912c |
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 66 67 68 69 70 71 72 73 74 75 76 77 78 79 80 81 82 83 84 85 86 87 88 89 90 91 92 93 94 95 96 97 98 99 100 101 102 103 104 105 106 107 108 109 110 111 112 113 114 115 116 |
// abc_midi_create.js: Turn a linear series of events into a midi file.
var rendererFactory = require('../synth/abc_midi_renderer');
var create;
(function() {
"use strict";
var baseDuration = 480*4; // nice and divisible, equals 1 whole note
create = function create(abcTune, options) {
if (options === undefined) options = {};
var commands = abcTune.setUpAudio(options);
var midi = rendererFactory();
var title = abcTune.metaText ? abcTune.metaText.title : undefined;
if (title && title.length > 128) title = title.substring(0, 124) + '...';
var key = abcTune.getKeySignature();
var time = abcTune.getMeterFraction();
// MAE 7 July 2024 - Fix for */8 meter tempos
var tempo = commands.tempo;
var beatsPerSecond = tempo / 60;
// Fix tempo for */8 meters
if (time.den == 8){
// Compute the tempo based on the actual milliseconds per measure, scaled by the number of eight notes and halved to get tempo in bpm.
var msPerMeasure = abcTune.millisecondsPerMeasure();
tempo = (60000 / (msPerMeasure/time.num)) / 2;
beatsPerSecond = tempo/60;
}
//var beatLength = abcTune.getBeatLength();
midi.setGlobalInfo(tempo, title, key, time);
for (var i = 0; i < commands.tracks.length; i++) {
midi.startTrack();
var notePlacement = {};
for (var j = 0; j < commands.tracks[i].length; j++) {
var event = commands.tracks[i][j];
switch (event.cmd) {
case 'text':
midi.setText(event.type, event.text);
break;
case 'program':
var pan = 0;
if (options.pan && options.pan.length > i)
pan = options.pan[i];
if (event.instrument === 128) {
// If we're using the percussion voice, change to Channel 10
midi.setChannel(9, pan);
midi.setInstrument(0);
} else {
midi.setChannel(event.channel, pan);
midi.setInstrument(event.instrument);
}
break;
case 'note':
var gapLengthInBeats = event.gap * beatsPerSecond;
var start = event.start;
// The staccato and legato are indicated by event.gap.
// event.gap is in seconds but the durations are in whole notes.
var end = start + event.duration - gapLengthInBeats;
if (!notePlacement[start])
notePlacement[start] = [];
notePlacement[start].push({ pitch: event.pitch, volume: event.volume, cents: event.cents });
if (!notePlacement[end])
notePlacement[end] = [];
notePlacement[end].push({ pitch: event.pitch, volume: 0 });
break;
default:
console.log("MIDI create Unknown: " + event.cmd);
}
}
addNotes(midi, notePlacement, baseDuration);
midi.endTrack();
}
return midi.getData();
};
function addNotes(midi, notePlacement, baseDuration) {
var times = Object.keys(notePlacement);
for (var h = 0; h < times.length; h++)
times[h] = parseFloat(times[h]);
times.sort(function(a,b) {
return a - b;
});
var lastTime = 0;
for (var i = 0; i < times.length; i++) {
var events = notePlacement[times[i]];
if (times[i] > lastTime) {
var distance = (times[i] - lastTime) * baseDuration;
midi.addRest(distance);
lastTime = times[i];
}
for (var j = 0; j < events.length; j++) {
var event = events[j];
if (event.volume) {
midi.startNote(event.pitch, event.volume, event.cents);
} else {
midi.endNote(event.pitch);
}
}
}
}
})();
module.exports = create;
|