2fb00f20a9
Hand tracking at 30fps was writing 126 params per frame to the C15 ring buffer (capacity 512), flooding it and starving arpeggiator noteOn/noteOff messages — causing stuck/dropped notes. Three-part fix: - Arpeggiator now runs in a dedicated Web Worker with direct SharedArrayBuffer access, bypassing the main thread entirely for note timing. Worker setInterval isn't subject to main thread jank. - RingBufferWriter uses CAS (Atomics.compareExchange) for multi-producer safety — both main thread (params) and worker (notes) write safely. - routeOutputs throttles synth parameter sends: dead-zone filter (0.2% change threshold) + rate cap (~20fps), reducing ring buffer pressure from ~3800 msg/s to ~50-100 msg/s of actual changes.
97 lines
2.3 KiB
JavaScript
97 lines
2.3 KiB
JavaScript
// Arpeggiator — plays chord progressions through the C15 engine
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// Delegates to a dedicated Web Worker for reliable timing.
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// The worker writes noteOn/noteOff directly to the SharedArrayBuffer
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// ring buffer, bypassing main thread entirely.
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export class Arpeggiator {
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constructor(bridge) {
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this.bridge = bridge;
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this._worker = null;
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this._playing = false;
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this._bpm = 120;
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this._octaves = 2;
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this._octaveOffset = 0;
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this._progression = 'I-vi-IV-V';
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}
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get progressionNames() {
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return ['I-vi-IV-V', 'I-IV-vi-V', 'i-VI-III-VII', 'I-V-vi-IV'];
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}
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get playing() { return this._playing; }
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get bpm() { return this._bpm; }
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set bpm(v) {
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this._bpm = v;
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this._send('set', { bpm: v });
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}
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get octaves() { return this._octaves; }
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set octaves(v) {
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this._octaves = v;
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this._send('set', { octaves: v });
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}
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get octaveOffset() { return this._octaveOffset; }
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set octaveOffset(v) {
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this._octaveOffset = v;
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this._send('set', { octaveOffset: v });
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}
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get progression() { return this._progression; }
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set progression(v) {
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this._progression = v;
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this._send('set', { progression: v });
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}
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_ensureWorker() {
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if (this._worker) return;
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this._worker = new Worker(
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new URL('./arpeggiator-worker.js', import.meta.url),
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{ type: 'module' }
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);
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this._worker.onmessage = (e) => {
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if (e.data.type === 'state') {
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this._playing = e.data.playing;
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}
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};
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// Pass the SharedArrayBuffer so the worker can write notes directly
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const sab = this.bridge.sharedBuffer;
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if (sab) {
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this._worker.postMessage({ type: 'init', data: { sharedBuffer: sab } });
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}
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// Sync current settings
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this._send('set', {
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bpm: this._bpm,
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octaves: this._octaves,
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octaveOffset: this._octaveOffset,
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progression: this._progression,
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});
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}
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_send(type, data) {
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if (this._worker) {
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this._worker.postMessage({ type, data });
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}
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}
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start() {
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this._ensureWorker();
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// If bridge wasn't ready when worker was created, send the buffer now
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const sab = this.bridge.sharedBuffer;
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if (sab) {
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this._worker.postMessage({ type: 'init', data: { sharedBuffer: sab } });
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}
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this._send('start');
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this._playing = true; // optimistic, worker confirms
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}
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stop() {
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this._send('stop');
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this._playing = false;
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}
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}
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