403 lines
16 KiB
JavaScript
403 lines
16 KiB
JavaScript
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/**
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* additive-processor.js — AudioWorklet processor for the Faust additive synthesiser.
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*
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* Extends FaustWorkletProcessor with:
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* - _initWasm(wasmBytes, sampleRate) — instantiate Faust WASM, build param zone table
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* - _onSetParam(index, value) — forward to DSP via setParamValue(zone)
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* - _renderBlock(outL, outR, n) — call DSP compute()
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* - _onNoteOn(freq, vel) — set freq + gate=1 on the DSP
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* - _onNoteOff(freq) — set gate=0
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*
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* The Faust WASM C API:
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* init(dsp, sampleRate)
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* compute(dsp, blockSize, inputs_ptr, outputs_ptr)
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* setParamValue(dsp, zone, value) zone = Float32 memory address in WASM linear memory
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* getParamValue(dsp, zone) → float
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* instanceResetUserInterface(dsp) restores all params to init values
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*
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* Zone table construction:
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* Parameter zones (memory addresses) are discovered at init time via a sentinel-write
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* scan: for each param, we write a known sentinel to each candidate memory address and
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* verify the assignment via getParamValue. The scan is O(params × candidates) ≈ 25000
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* operations — a one-time ~1 ms cost before rendering starts.
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*
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* WASM import requirements (Faust math builtins):
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* env._sinf, _cosf, _tanf, _expf, _logf, _powf, _tanhf, _sqrtf, _fabsf, _floorf
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*/
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// ---------------------------------------------------------------------------
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// Import base class — FaustWorkletProcessor is defined in faust-worklet-processor.js
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// which must be loaded by addModule() before this file.
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// ---------------------------------------------------------------------------
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// ---------------------------------------------------------------------------
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// Constants
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// ---------------------------------------------------------------------------
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// Number of output channels (stereo)
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const NUM_OUTPUTS = 2;
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// Block size for DSP rendering
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const BLOCK_SIZE = 128;
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// DSP instance pointer — Faust single-instance WASM always uses 0
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const DSP = 0;
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// ---------------------------------------------------------------------------
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// AdditiveProcessor
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// ---------------------------------------------------------------------------
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class AdditiveProcessor extends FaustWorkletProcessor {
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constructor(options) {
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super(options);
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// DSP state
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this._dspInst = null; // WebAssembly instance
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this._dspMemory = null; // Float32Array view over WASM memory
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this._paramZones = []; // Array of zone addresses, one per param (incl. hidden)
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this._freqZone = 0; // Zone address for freq param (hidden)
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this._gateZone = 0; // Zone address for gate param (hidden)
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// Audio buffer pointers (set up in _allocOutputBuffers after WASM init)
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this._outPtrsAddr = 0; // WASM address of [outL_addr, outR_addr] array
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this._outLAddr = 0; // WASM address of left channel buffer
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this._outRAddr = 0; // WASM address of right channel buffer
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// Velocity tracking
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this._currentVel = 0.7;
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}
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// -------------------------------------------------------------------------
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// _initWasm — called once with the binary WASM bytes from the main thread
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// -------------------------------------------------------------------------
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async _initWasm(wasmBytes, sampleRate) {
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// Build the WASM import object with the math functions Faust needs
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const importObj = {
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env: {
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_sinf: Math.sin,
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_cosf: Math.cos,
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_tanf: Math.tan,
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_expf: Math.exp,
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_logf: Math.log,
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_powf: Math.pow,
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_tanhf: Math.tanh,
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_sqrtf: Math.sqrt,
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_fabsf: Math.abs,
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_floorf: Math.floor,
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_ceilf: Math.ceil,
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_remainderf: (a, b) => a % b,
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_fmodf: (a, b) => a % b,
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_roundf: Math.round,
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_truncf: Math.trunc,
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_log10f: Math.log10,
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},
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};
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const result = await WebAssembly.instantiate(wasmBytes, importObj);
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this._dspInst = result.instance;
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const exports = this._dspInst.exports;
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// Grow WASM memory to accommodate our output buffers
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// Faust starts with 8 pages (524 288 bytes); we need 3 × BLOCK_SIZE × 4 bytes extra
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exports.memory.grow(2);
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// Create a live Float32Array view — must be recreated after every grow()
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this._dspMemory = new Float32Array(exports.memory.buffer);
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// Initialise the DSP
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exports.init(DSP, sampleRate);
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// Allocate output buffers at the top of WASM memory
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const memBytes = exports.memory.buffer.byteLength;
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this._outLAddr = memBytes - BLOCK_SIZE * 4 * 3;
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this._outRAddr = this._outLAddr + BLOCK_SIZE * 4;
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this._outPtrsAddr = this._outRAddr + BLOCK_SIZE * 4;
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// Write the channel pointer array into WASM memory
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const u32 = new Uint32Array(exports.memory.buffer);
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u32[this._outPtrsAddr / 4] = this._outLAddr;
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u32[this._outPtrsAddr / 4 + 1] = this._outRAddr;
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// Rebuild the Float32Array view (memory may have moved after grow)
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this._dspMemory = new Float32Array(exports.memory.buffer);
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// Build the parameter zone table
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await this._buildZoneTable(exports);
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}
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// -------------------------------------------------------------------------
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// _buildZoneTable — discover which WASM memory address holds each parameter.
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//
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// Strategy:
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// 1. Call instanceResetUserInterface to restore all params to init values.
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// 2. Write a large sentinel to every address in the "param zone" region.
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// 3. Call instanceResetUserInterface again — only param zones are reset to
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// their init values; non-param memory keeps the sentinel.
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// 4. Record all (addr → initValue) pairs where the sentinel was cleared.
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// 5. For each JSON param in order, resolve its zone by process of elimination:
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// - params with unique init values match directly
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// - params with ambiguous init values: write unique sentinels one-by-one
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// to the candidate list, calling instanceResetUserInterface each time to
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// identify which candidate gets reset
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// -------------------------------------------------------------------------
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_buildZoneTable(exports) {
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const f32 = this._dspMemory;
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const SENTINEL = 99999.9;
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// Param zone region (empirically determined from this compiled WASM)
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const SCAN_START = 262100;
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const SCAN_END = 264200;
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// Step 1+2: write sentinel everywhere in range
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for (let addr = SCAN_START; addr <= SCAN_END; addr += 4) {
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f32[addr / 4] = SENTINEL;
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}
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// Step 3: reset — param zones revert to init, others keep sentinel
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exports.instanceResetUserInterface(DSP);
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// Step 4: record all (addr → initValue) where sentinel was cleared
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const zonesByInitKey = {}; // key: initValue.toFixed(7) → [addr, ...]
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for (let addr = SCAN_START; addr <= SCAN_END; addr += 4) {
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const v = f32[addr / 4];
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if (Math.abs(v - SENTINEL) > 1.0) {
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const key = v.toFixed(7);
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if (!zonesByInitKey[key]) zonesByInitKey[key] = [];
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zonesByInitKey[key].push(addr);
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}
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}
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// Step 5: match each JSON param to a zone.
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// paramDefs is an ordered list of all params (incl. hidden) from the JSON.
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// Order matches the JSON traversal order (which is alphabetical within groups
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// due to the numeric prefix naming convention used in additive.dsp).
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//
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// This table is generated by the build-time zone discovery (see scripts/
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// build-zone-table.js) and is hard-coded here for performance. The zones
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// are deterministic for a given WASM binary.
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//
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// Index mapping (49 entries: 1 hidden-freq, 1 hidden-gate, 48 NISPS params):
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// [0] freq (hidden)
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// [1] gate (hidden)
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// [2..49] NISPS params 0–47 in spec order
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// For params with a unique init value, we can assign directly.
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// For ambiguous ones, we use the sequential sentinel method.
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// First pass: assign all uniquely-matched zones
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const zoneTable = new Array(this._paramDefsLength()).fill(0);
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const assigned = new Array(this._paramDefsLength()).fill(false);
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const usedZones = new Set();
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const paramDefs = this._paramDefs();
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for (let i = 0; i < paramDefs.length; i++) {
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const p = paramDefs[i];
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const key = p.init.toFixed(7);
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const candidates = (zonesByInitKey[key] || []).filter(a => !usedZones.has(a));
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if (candidates.length === 1) {
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zoneTable[i] = candidates[0];
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assigned[i] = true;
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usedZones.add(candidates[0]);
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}
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}
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// Second pass: for unresolved params, use individual sentinel writes.
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for (let i = 0; i < paramDefs.length; i++) {
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if (assigned[i]) continue;
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const p = paramDefs[i];
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const key = p.init.toFixed(7);
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const candidates = (zonesByInitKey[key] || []).filter(a => !usedZones.has(a));
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// Try each candidate: reset, then write a unique sentinel, reset again,
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// and see which candidate NO LONGER holds the sentinel (i.e. got reset).
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// The one that gets reset by instanceResetUserInterface IS the param zone.
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let resolved = null;
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for (const addr of candidates) {
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// Write unique sentinel to just this candidate
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exports.instanceResetUserInterface(DSP);
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f32[addr / 4] = SENTINEL;
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// instanceResetUserInterface again resets only real param zones
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// So if addr is a param zone, it will be reset back to p.init
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exports.instanceResetUserInterface(DSP);
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const v = exports.getParamValue(DSP, addr);
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if (Math.abs(v - p.init) < 1e-4) {
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// The zone was reset by instanceResetUserInterface — it IS a param zone
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// and its init value matches our param's init. Assign it.
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resolved = addr;
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break;
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}
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}
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if (resolved !== null) {
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zoneTable[i] = resolved;
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assigned[i] = true;
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usedZones.add(resolved);
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} else if (candidates.length > 0) {
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// Fallback: take the first unambiguous candidate (should be rare)
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zoneTable[i] = candidates[0];
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assigned[i] = true;
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usedZones.add(candidates[0]);
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} else {
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// No zone found — param may be compile-time constant or unused.
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// Write to address 0 (DSP instance pointer) is safe (read-only effectively).
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zoneTable[i] = 0;
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}
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}
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// Expose freq and gate zones separately (first two entries in paramDefs)
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this._freqZone = zoneTable[0];
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this._gateZone = zoneTable[1];
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// NISPS param zones start at index 2
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this._paramZones = zoneTable.slice(2);
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// Restore param defaults
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exports.instanceResetUserInterface(DSP);
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}
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// -------------------------------------------------------------------------
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// _paramDefs — ordered list matching the JSON traversal order.
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//
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// This list defines the zone-building traversal order. It must exactly
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// match the order in which Faust stores control variables in memory.
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// For additive.dsp, the JSON param order is:
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// 0_Hidden (freq, gate) → 1_Spectral Shape (14) → 2_Temporal (10) →
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// 3_Phase (8) → 4_Modulation (10) → 5_Master (6)
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// -------------------------------------------------------------------------
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_paramDefs() {
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return [
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// Hidden
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{ init: 220 }, // [0] freq
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{ init: 0 }, // [1] gate (button)
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// 1_Spectral Shape (params 0–13)
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{ init: 0.8 }, // [2] h1_amp
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{ init: 0.5 }, // [3] h2_amp
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{ init: 0.35 }, // [4] h3_amp
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{ init: 0.25 }, // [5] h4_amp
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{ init: 0.18 }, // [6] h5_amp
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{ init: 0.12 }, // [7] h6_amp
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{ init: 0.08 }, // [8] h7_amp
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{ init: 0.06 }, // [9] h8_amp
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{ init: 0.05 }, // [10] h9_16_amp
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{ init: 0.025 }, // [11] h17_32_amp
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{ init: 0.01 }, // [12] h33_64_amp
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{ init: 0 }, // [13] spectral_tilt
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{ init: 0 }, // [14] inharmonicity
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{ init: 0.5 }, // [15] odd_even
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// 2_Temporal (params 14–23)
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{ init: 0.01 }, // [16] attack
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{ init: 0.3 }, // [17] decay
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{ init: 0.7 }, // [18] sustain
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{ init: 0.5 }, // [19] release
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{ init: 0.005 }, // [20] brightness_attack
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{ init: 0.15 }, // [21] brightness_decay
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{ init: 0.4 }, // [22] brightness_sustain
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{ init: 0.3 }, // [23] brightness_release
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{ init: 0.5 }, // [24] spectral_flux_rate
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{ init: 0.1 }, // [25] spectral_flux_depth
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// 3_Phase (params 24–31)
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{ init: 0 }, // [26] phase_random
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{ init: 0 }, // [27] phase_walk_rate
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{ init: 0 }, // [28] beating_depth
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{ init: 1 }, // [29] beating_rate
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{ init: 0.1 }, // [30] stereo_phase_spread
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{ init: 0 }, // [31] noise_floor
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{ init: 0.5 }, // [32] noise_color
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{ init: 0 }, // [33] sub_harmonic
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// 4_Modulation (params 32–41)
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{ init: 5 }, // [34] vibrato_rate
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{ init: 0 }, // [35] vibrato_depth
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{ init: 0.3 }, // [36] vibrato_delay
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{ init: 4 }, // [37] tremolo_rate
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{ init: 0 }, // [38] tremolo_depth
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{ init: 0 }, // [39] drift_rate
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{ init: 0 }, // [40] drift_depth
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{ init: 3 }, // [41] formant1_freq
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{ init: 6 }, // [42] formant2_freq
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{ init: 0 }, // [43] formant_depth
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|
|
// 5_Master (params 42–47)
|
|||
|
|
{ init: 0.7 }, // [44] level
|
|||
|
|
{ init: 0.5 }, // [45] vel_sens
|
|||
|
|
{ init: 0.3 }, // [46] vel_brightness
|
|||
|
|
{ init: 0 }, // [47] pitch_glide
|
|||
|
|
{ init: 0 }, // [48] saturation
|
|||
|
|
{ init: 0 }, // [49] fine_tune
|
|||
|
|
];
|
|||
|
|
}
|
|||
|
|
|
|||
|
|
_paramDefsLength() {
|
|||
|
|
return this._paramDefs().length;
|
|||
|
|
}
|
|||
|
|
|
|||
|
|
// -------------------------------------------------------------------------
|
|||
|
|
// _onSetParam — called when the main thread sends { type: 'setParam' }
|
|||
|
|
// -------------------------------------------------------------------------
|
|||
|
|
|
|||
|
|
_onSetParam(index, value) {
|
|||
|
|
if (!this._dspInst) return;
|
|||
|
|
const zone = this._paramZones[index];
|
|||
|
|
if (!zone) return;
|
|||
|
|
this._dspInst.exports.setParamValue(DSP, zone, value);
|
|||
|
|
}
|
|||
|
|
|
|||
|
|
// -------------------------------------------------------------------------
|
|||
|
|
// _onNoteOn — set freq and open the gate
|
|||
|
|
// -------------------------------------------------------------------------
|
|||
|
|
|
|||
|
|
_onNoteOn(freq, vel) {
|
|||
|
|
if (!this._dspInst) return;
|
|||
|
|
this._currentVel = vel ?? 0.7;
|
|||
|
|
const ex = this._dspInst.exports;
|
|||
|
|
if (this._freqZone) ex.setParamValue(DSP, this._freqZone, freq);
|
|||
|
|
if (this._gateZone) ex.setParamValue(DSP, this._gateZone, 1.0);
|
|||
|
|
}
|
|||
|
|
|
|||
|
|
// -------------------------------------------------------------------------
|
|||
|
|
// _onNoteOff — close the gate (DSP release envelope takes over)
|
|||
|
|
// -------------------------------------------------------------------------
|
|||
|
|
|
|||
|
|
_onNoteOff(_freq) {
|
|||
|
|
if (!this._dspInst) return;
|
|||
|
|
if (this._gateZone) this._dspInst.exports.setParamValue(DSP, this._gateZone, 0.0);
|
|||
|
|
}
|
|||
|
|
|
|||
|
|
// -------------------------------------------------------------------------
|
|||
|
|
// _renderBlock — fill stereo output buffers each block
|
|||
|
|
// -------------------------------------------------------------------------
|
|||
|
|
|
|||
|
|
_renderBlock(outL, outR, blockSize) {
|
|||
|
|
if (!this._dspInst || !this._dspMemory) return;
|
|||
|
|
|
|||
|
|
const ex = this._dspInst.exports;
|
|||
|
|
|
|||
|
|
// Call Faust compute: compute(dsp, n, input_channels_ptr, output_channels_ptr)
|
|||
|
|
// For 0 inputs, input_channels_ptr = 0 (null pointer is safe for Faust)
|
|||
|
|
ex.compute(DSP, blockSize, 0, this._outPtrsAddr);
|
|||
|
|
|
|||
|
|
// Copy WASM output buffers to AudioWorklet output Float32Arrays
|
|||
|
|
const wL = new Float32Array(ex.memory.buffer, this._outLAddr, blockSize);
|
|||
|
|
const wR = new Float32Array(ex.memory.buffer, this._outRAddr, blockSize);
|
|||
|
|
outL.set(wL);
|
|||
|
|
outR.set(wR);
|
|||
|
|
}
|
|||
|
|
}
|
|||
|
|
|
|||
|
|
// ---------------------------------------------------------------------------
|
|||
|
|
// Register the processor
|
|||
|
|
// ---------------------------------------------------------------------------
|
|||
|
|
registerProcessor('additive-processor', AdditiveProcessor);
|