55bf1b5d48
Adds the Faust DSP toolchain infrastructure: placeholder additive and FM DSP files, build.sh (faust -lang wasm per .dsp), faustJsonToParamMeta() to convert Faust JSON UI trees into the standard paramMeta format, FaustEngineBase (SynthEngine subclass wiring init/setParam/noteOn/noteOff through AudioWorklet messages), and FaustWorkletProcessor base class for concrete engine processors.
138 lines
4.5 KiB
JavaScript
138 lines
4.5 KiB
JavaScript
/**
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* faust-worklet-processor.js — Base AudioWorklet processor for Faust WASM engines
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*
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* This file must be loaded via audioContext.audioWorklet.addModule() before
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* creating a FaustWorkletNode. It runs in AudioWorkletGlobalScope.
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*
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* Each Faust engine subclasses FaustWorkletProcessor and overrides:
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* - static get processorName() — returns the unique processor name string
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* - _initWasm(wasmBytes, sampleRate) — initialises the Faust WASM instance
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* - _renderBlock(outputL, outputR, blockSize) — fills output buffers per block
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*
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* Message protocol (port.postMessage from main thread):
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* { type: 'init', wasmBytes: ArrayBuffer, sampleRate: number }
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* { type: 'setParam', index: number, value: number }
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* { type: 'noteOn', freq: number, vel: number }
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* { type: 'noteOff', freq: number }
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*
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* Replies from worklet to main thread:
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* { type: 'ready' }
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* { type: 'error', message: string }
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*/
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class FaustWorkletProcessor extends AudioWorkletProcessor {
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constructor(options) {
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super(options);
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this._ready = false;
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this._paramValues = {}; // index → current value (raw Faust units)
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this.port.onmessage = (e) => this._handleMessage(e.data);
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}
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// ---------------------------------------------------------------------------
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// Message handler (runs in worklet thread)
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// ---------------------------------------------------------------------------
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_handleMessage(msg) {
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if (!msg || !msg.type) return;
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switch (msg.type) {
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case 'init':
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this._initWasm(msg.wasmBytes, msg.sampleRate || sampleRate)
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.then(() => {
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this._ready = true;
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this.port.postMessage({ type: 'ready' });
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})
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.catch((err) => {
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this.port.postMessage({ type: 'error', message: String(err) });
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});
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break;
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case 'setParam':
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this._paramValues[msg.index] = msg.value;
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this._onSetParam(msg.index, msg.value);
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break;
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case 'noteOn':
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this._onNoteOn(msg.freq, msg.vel);
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break;
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case 'noteOff':
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this._onNoteOff(msg.freq);
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break;
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default:
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console.warn('[FaustWorkletProcessor] Unknown message type:', msg.type);
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}
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}
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// ---------------------------------------------------------------------------
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// AudioWorkletProcessor interface
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// ---------------------------------------------------------------------------
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process(_inputs, outputs, _params) {
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if (!this._ready) return true;
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const out = outputs[0];
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const blockSize = out[0]?.length ?? 128;
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const outL = out[0] ?? new Float32Array(blockSize);
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const outR = out[1] ?? new Float32Array(blockSize);
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this._renderBlock(outL, outR, blockSize);
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return true; // keep processor alive
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}
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// ---------------------------------------------------------------------------
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// Subclass API — override these in concrete engine processors
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// ---------------------------------------------------------------------------
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/**
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* Initialise the WASM module. Called once with the raw bytes and sample rate.
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* Must return a Promise that resolves when the engine is ready to render.
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*
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* @param {ArrayBuffer} wasmBytes
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* @param {number} sampleRate
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* @returns {Promise<void>}
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*/
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async _initWasm(_wasmBytes, _sampleRate) {
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// Default no-op: subclasses that don't use WASM can override _renderBlock only.
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}
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/**
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* Called when a parameter value changes. Override to forward to DSP.
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* @param {number} index Param index (matches paramMeta order)
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* @param {number} value Raw value in Faust units
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*/
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_onSetParam(_index, _value) {}
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/**
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* Called on note-on.
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* @param {number} freq Hz
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* @param {number} vel 0–1
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*/
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_onNoteOn(_freq, _vel) {}
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/**
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* Called on note-off.
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* @param {number} freq Hz
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*/
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_onNoteOff(_freq) {}
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/**
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* Fill a single audio block. Called from process() every 128 samples.
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* Both arrays are pre-allocated Float32Arrays of length blockSize.
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*
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* @param {Float32Array} outL Left channel output buffer (write to this)
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* @param {Float32Array} outR Right channel output buffer (write to this)
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* @param {number} blockSize
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*/
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_renderBlock(_outL, _outR, _blockSize) {
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// Default: silence — override in subclass
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}
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}
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// Note: registerProcessor() is called by each concrete engine file, not here,
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// because each engine has its own processor name.
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// Subclass files should end with:
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// registerProcessor('my-engine-processor', MyEngineProcessor);
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