Jasima/musicbox
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Independent sequencers allow for mismatched measure lengths

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This commit is contained in:
Will Greenberg 2021-01-12 21:13:10 -08:00
parent 34d07d363e
commit 13c87ce547
2 changed files with 60 additions and 78 deletions
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1
index.html
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@ -8,6 +8,7 @@ textarea {
}
</style>
</head>
<span id='status'>loading samples...</span><br>
<textarea id='beats'></textarea>
<textarea id='piano'></textarea>
</html>

137
musicbox.js
View file

@ -12,19 +12,26 @@ function createBufferSource(ctx, buffer) {
return source;
}
class PianoSequencer {
class Piano {
constructor(notes) {
// load 3 octaves of the given notes
this.notes = crossProduct(notes, '345');
this.input = '';
this.lowOctave = 'qwertyu';
this.midOctave = 'asdfghj';
this.highOctave = 'zxcvbnm';
}
async init(ctx) {
this.ff = await loadNotes(ctx, 'ff', this.notes);
this.mf = await loadNotes(ctx, 'mf', this.notes);
this.ff = await this.loadNotes(ctx, 'ff', this.notes);
this.mf = await this.loadNotes(ctx, 'mf', this.notes);
}
async loadNotes(ctx, volume, notes) {
return await Promise.all(notes.map(async (note) => {
const path = `samples/piano/${volume}/${note}.mp3`;
const buffer = await loadBuffer(ctx, path);
return createBufferSource(ctx, buffer);
}));
}
parseLine(line) {
@ -51,9 +58,8 @@ class PianoSequencer {
}
}
class BeatSequencer {
class Beats {
cosntructor() {
this.input = '';
}
async init(ctx) {
@ -72,37 +78,20 @@ class BeatSequencer {
}
class Sequencer {
constructor(piano, beats) {
this.piano = piano;
this.beats = beats;
this.pianoSequences = [];
this.beatsSequences = [];
constructor(instrument) {
this.instrument = instrument;
this.sequences = [];
this.idx = 0;
}
toBase64() {
const json = JSON.stringify({
piano: this.piano.input,
beats: this.beats.input,
});
return btoa(json);
}
buildSequence(instrument, input) {
instrument.input = input;
return input.split('\n').map(line => instrument.parseLine(line));
}
length() {
return this.pianoSequences.map(a => a.length)
.concat(this.beatsSequences.map(a => a.length))
return this.sequences.map(a => a.length)
.reduce((a, b) => Math.max(a, b), 0);
}
play() {
step() {
const length = this.length();
if (length === 0) {
console.log('empty');
return;
}
@ -110,29 +99,16 @@ class Sequencer {
this.idx = 0;
}
this.pianoSequences.map(a => a[this.idx])
.concat(this.beatsSequences.map(a => a[this.idx]))
this.sequences.map(a => a[this.idx])
.filter(maybeBuf => !!maybeBuf)
.forEach(buf => cloneBuf(buf).start());
.forEach(buf => createBufferSource(buf.context, buf.buffer).start());
this.idx++;
}
updatePiano(input) {
this.pianoSequences = this.buildSequence(this.piano, input);
console.log(this.pianoSequences);
update(input) {
this.sequences = input.split('\n')
.map(line => this.instrument.parseLine(line));
}
updateBeats(input) {
this.beatsSequences = this.buildSequence(this.beats, input);
console.log(this.beatsSequences);
}
}
async function loadNotes(ctx, volume, notes) {
return await Promise.all(notes.map(async (note) => {
const buffer = await loadBuffer(ctx, `samples/piano/${volume}/${note}.mp3`);
return createBufferSource(ctx, buffer);
}));
}
async function loadBeats(ctx, letters) {
@ -143,35 +119,36 @@ async function loadBeats(ctx, letters) {
}));
}
function setupSequencer(piano, beats) {
const sequencer = new Sequencer(piano, beats);
const pianoTextbox = document.getElementById('piano');
const beatsTextbox = document.getElementById('beats');
if (window.location.hash.length > 0) {
const base64 = window.location.hash.slice(1);
try {
const json = JSON.parse(atob(base64));
pianoTextbox.value = json.piano;
beatsTextbox.value = json.beats;
} catch(e) {
console.log(`invalid sequence ${base64}: ${e}`);
}
}
sequencer.updatePiano(pianoTextbox.value);
sequencer.updateBeats(beatsTextbox.value);
pianoTextbox.addEventListener('input', e => {
sequencer.updatePiano(e.target.value);
window.location.hash = sequencer.toBase64();
});
beatsTextbox.addEventListener('input', e => {
sequencer.updateBeats(e.target.value);
window.location.hash = sequencer.toBase64();
function setupSequencer(instrument, name) {
const sequencer = new Sequencer(instrument);
const textbox = document.getElementById(name);
sequencer.update(textbox.value);
textbox.addEventListener('input', e => {
sequencer.update(e.target.value);
setHash();
});
return sequencer;
}
function cloneBuf(note) {
return createBufferSource(note.context, note.buffer);
function setHash() {
const state = JSON.stringify({
piano: document.getElementById('piano').value,
beats: document.getElementById('beats').value,
});
window.location.hash = btoa(state);
}
function loadHash() {
if (window.location.hash.length > 0) {
const base64 = window.location.hash.slice(1);
try {
const json = JSON.parse(atob(base64));
document.getElementById('piano').value = json.piano;
document.getElementById('beats').value = json.beats;
} catch(e) {
console.log(`invalid sequence ${base64}: ${e}`);
}
}
}
function crossProduct(a, b) {
@ -179,16 +156,20 @@ function crossProduct(a, b) {
}
window.addEventListener('load', async () => {
loadHash();
const ctx = new AudioContext();
const piano = new PianoSequencer('CDEFGAB');
const beats = new BeatSequencer();
console.log('loading...');
const piano = new Piano('CDEFGAB');
const beats = new Beats();
await piano.init(ctx);
await beats.init(ctx);
console.log('done');
const sequencer = setupSequencer(piano, beats);
document.getElementById('status').remove();
const pianoSequencer = setupSequencer(piano, 'piano');
const beatsSequencer = setupSequencer(beats, 'beats');
const bpm = 120;
const bpm = 240;
const msPerBeat = (1 / bpm) * 60 * 1000;
setInterval(() => sequencer.play(), msPerBeat);
setInterval(() => {
pianoSequencer.step();
beatsSequencer.step();
}, msPerBeat);
});