Spaces:
Sleeping
Sleeping
File size: 4,506 Bytes
4cadbaf |
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 99 100 101 102 103 104 105 106 107 108 109 110 111 112 113 114 115 116 117 118 119 120 121 122 123 124 125 126 127 128 129 130 131 132 133 134 135 136 137 138 139 140 141 142 143 144 145 146 147 148 149 150 151 152 153 154 155 156 157 158 159 160 161 162 163 164 165 166 167 168 169 170 171 172 173 174 175 176 177 178 179 180 181 182 183 184 185 |
const MIDI = require("./MIDI");
const trackDeltaToAbs = events => {
let tick = 0;
events.forEach(event => {
tick += event.deltaTime;
event.tick = tick;
});
};
const trackAbsToDelta = events => {
let lastTick = 0;
events.sort((e1, e2) => e1.tick - e2.tick).forEach(event => {
event.deltaTime = event.tick - lastTick;
lastTick = event.tick;
});
};
const sliceTrack = (track, startTick, endTick) => {
trackDeltaToAbs(track);
const events = [];
const status = {};
track.forEach(event => {
if (event.tick >= startTick && event.tick <= endTick && event.subtype !== "endOfTrack")
events.push({
...event,
tick: event.tick - startTick,
});
else if (event.tick < startTick) {
switch (event.type) {
case "meta":
status[event.subtype] = event;
break;
}
}
});
Object.values(status).forEach(event => events.push({
...event,
tick: 0,
}));
events.push({
tick: endTick - startTick,
type: "meta",
subtype: "endOfTrack",
});
trackAbsToDelta(events);
return events;
};
const sliceMidi = (midi, startTick, endTick) => ({
header: midi.header,
tracks: midi.tracks.map(track => sliceTrack(track, startTick, endTick)),
});
const TICKS_PER_BEATS = 480;
const EXCLUDE_MIDI_EVENT_SUBTYPES = [
"endOfTrack", "trackName",
"noteOn", "noteOff",
];
function encodeToMIDIData(notation, {startTime, unclosedNoteDuration = 30e+3} = {}) {
notation.microsecondsPerBeat = notation.microsecondsPerBeat || 500000;
const ticksPerBeat = TICKS_PER_BEATS;
const msToTicks = ticksPerBeat * 1000 / notation.microsecondsPerBeat;
const header = { formatType: 0, ticksPerBeat };
const track = [];
if (!Number.isFinite(startTime)) {
if (!notation.notes || !notation.notes[0])
throw new Error("encodeToMidiData: no start time specificed");
startTime = notation.notes[0].start;
}
track.push({ time: startTime, type: "meta", subtype: "copyrightNotice", text: `Composed by MusicWdigets. BUILT on ${new Date(Number(process.env.VUE_APP_BUILD_TIME)).toDateString()}` });
const containsTempo = notation.events && notation.events.find(event => event.subtype == "setTempo");
if (!containsTempo) {
track.push({ time: startTime, type: "meta", subtype: "timeSignature", numerator: 4, denominator: 4, thirtyseconds: 8 });
track.push({ time: startTime, type: "meta", subtype: "setTempo", microsecondsPerBeat: notation.microsecondsPerBeat });
}
//if (notation.correspondences)
// track.push({ time: startTime, type: "meta", subtype: "text", text: "find-corres:" + notation.correspondences.join(",") });
let endTime = startTime || 0;
if (notation.notes) {
for (const note of notation.notes) {
track.push({
time: note.start,
type: "channel",
subtype: "noteOn",
channel: note.channel || 0,
noteNumber: note.pitch,
velocity: note.velocity,
finger: note.finger,
});
endTime = Math.max(endTime, note.start);
if (Number.isFinite(unclosedNoteDuration))
note.duration = note.duration || unclosedNoteDuration;
if (note.duration) {
track.push({
time: note.start + note.duration,
type: "channel",
subtype: "noteOff",
channel: note.channel || 0,
noteNumber: note.pitch,
velocity: 0,
});
endTime = Math.max(endTime, note.start + note.duration);
}
}
}
if (notation.events) {
const events = notation.events.filter(event => !EXCLUDE_MIDI_EVENT_SUBTYPES.includes(event.data.subtype));
for (const event of events) {
track.push({
time: event.time,
...event.data,
});
endTime = Math.max(endTime, event.time);
}
}
track.push({ time: endTime + 100, type: "meta", subtype: "endOfTrack" });
track.sort(function (e1, e2) { return e1.time - e2.time; });
// append finger event after every noteOn event
track.map((event, index) => ({event, index}))
.filter(({event}) => event.subtype == "noteOn" && event.finger != null)
.reverse()
.forEach(({event, index}) => track.splice(index + 1, 0, {
time: event.time,
type: "meta",
subtype: "text",
text: `fingering(${event.finger})`,
}));
track.forEach(event => event.ticks = Math.round((event.time - startTime) * msToTicks));
track.forEach((event, i) => event.deltaTime = (event.ticks - (i > 0 ? track[i - 1].ticks : 0)));
return {header, tracks: [track]};
};
function encodeToMIDI(notation, options) {
const data = encodeToMIDIData(notation, options);
return MIDI.encodeMidiFile(data);
};
module.exports = {
sliceMidi,
encodeToMIDIData,
encodeToMIDI,
};
|