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
|
// MQ Synthesizer
// Replica oscillator bank for sinusoidal synthesis, plus two-pole resonator mode
// Evaluate cubic bezier curve at time t
function evalBezier(curve, t) {
const dt = curve.t3 - curve.t0;
if (dt <= 0) return curve.v0;
let u = (t - curve.t0) / dt;
u = Math.max(0, Math.min(1, u));
const u1 = 1.0 - u;
return u1*u1*u1 * curve.v0 +
3*u1*u1*u * curve.v1 +
3*u1*u*u * curve.v2 +
u*u*u * curve.v3;
}
// Deterministic LCG PRNG
function randFloat(seed, min, max) {
seed = (1664525 * seed + 1013904223) % 0x100000000;
return min + (seed / 0x100000000) * (max - min);
}
// Synthesize audio from MQ partials
// partials: array of {freqCurve, ampCurve, replicas?, resonator?}
// replicas: {offsets, decay_alpha, jitter, spread_above, spread_below}
// resonator: {enabled, r, gainComp} — two-pole resonator mode per partial
// integratePhase: true = accumulate 2π*f/SR per sample (correct for varying freq)
// false = 2π*f*t (simpler, only correct for constant freq)
// options.k1: LP coefficient in (0,1] — omit to bypass
// options.k2: HP coefficient in (0,1] — omit to bypass
function synthesizeMQ(partials, sampleRate, duration, integratePhase = true, options = {}) {
const numSamples = Math.floor(sampleRate * duration);
const pcm = new Float32Array(numSamples);
const jitterMult = options.disableJitter ? 0 : 1;
const spreadMult = options.disableSpread ? 0 : 1;
const defaultReplicas = {
offsets: [1.0],
decay_alpha: 0.1,
jitter: 0.05,
spread_above: 0.02,
spread_below: 0.02
};
// Pre-build per-partial configs with fixed spread/jitter and phase accumulators
const configs = [];
for (let p = 0; p < partials.length; ++p) {
const partial = partials[p];
const fc = partial.freqCurve;
const ac = partial.ampCurve;
if ((partial.resonator && partial.resonator.enabled) || options.forceResonator) {
// --- Two-pole resonator mode ---
// Driven by band-limited noise scaled by amp curve.
// r controls pole radius (bandwidth): r→1 = narrow, r→0 = wide.
// gainNorm = sqrt(1 - r²) normalises steady-state output power to ~A.
const res = partial.resonator || {};
const r = res.r != null ? Math.min(0.9999, Math.max(0, res.r)) : 0.995;
const gainComp = res.gainComp != null ? res.gainComp : 1.0;
const gainNorm = Math.sqrt(Math.max(0, 1.0 - r * r));
configs.push({
mode: 'resonator',
fc, ac,
r, gainComp, gainNorm,
y1: 0.0, y2: 0.0,
noiseSeed: ((p * 1664525 + 1013904223) & 0xFFFFFFFF) >>> 0
});
} else {
// --- Sinusoidal (replica) mode ---
const rep = partial.replicas != null ? partial.replicas : defaultReplicas;
const offsets = rep.offsets != null ? rep.offsets : [1.0];
const decay_alpha = rep.decay_alpha != null ? rep.decay_alpha : 0.0;
const jitter = rep.jitter != null ? rep.jitter : 0.0;
const spread_above = rep.spread_above != null ? rep.spread_above : 0.0;
const spread_below = rep.spread_below != null ? rep.spread_below : 0.0;
const replicaData = [];
for (let r = 0; r < offsets.length; ++r) {
const spread = spreadMult * randFloat(p * 67890 + r * 999, -spread_below, spread_above);
const initPhase = randFloat(p * 67890 + r, 0.0, 1.0) * (jitter * jitterMult) * 2.0 * Math.PI;
replicaData.push({ratio: offsets[r], spread, phase: initPhase});
}
configs.push({ mode: 'sinusoid', fc, ac, decay_alpha, replicaData });
}
}
for (let i = 0; i < numSamples; ++i) {
const t = i / sampleRate;
let sample = 0.0;
for (let p = 0; p < configs.length; ++p) {
const cfg = configs[p];
const {fc, ac} = cfg;
if (cfg.mode === 'resonator') {
if (t < fc.t0 || t > fc.t3) { cfg.y1 = 0.0; cfg.y2 = 0.0; continue; }
const f0 = evalBezier(fc, t);
const A = evalBezier(ac, t);
const omega = 2.0 * Math.PI * f0 / sampleRate;
const b1 = 2.0 * cfg.r * Math.cos(omega);
// LCG noise excitation (deterministic per-partial)
cfg.noiseSeed = (Math.imul(1664525, cfg.noiseSeed) + 1013904223) >>> 0;
const noise = cfg.noiseSeed / 0x100000000 * 2.0 - 1.0;
const x = A * cfg.gainNorm * noise;
const y = b1 * cfg.y1 - cfg.r * cfg.r * cfg.y2 + x;
cfg.y2 = cfg.y1;
cfg.y1 = y;
sample += y * cfg.gainComp;
} else {
if (t < fc.t0 || t > fc.t3) continue;
const f0 = evalBezier(fc, t);
const A0 = evalBezier(ac, t);
const {decay_alpha, replicaData} = cfg;
for (let r = 0; r < replicaData.length; ++r) {
const rep = replicaData[r];
const f = f0 * rep.ratio * (1.0 + rep.spread);
const A = A0 * Math.exp(-decay_alpha * Math.abs(f - f0));
let phase;
if (integratePhase) {
rep.phase += 2.0 * Math.PI * f / sampleRate;
phase = rep.phase;
} else {
phase = 2.0 * Math.PI * f * t + rep.phase;
}
sample += A * Math.sin(phase);
}
}
}
pcm[i] = sample;
}
// Post-synthesis filters (applied before normalization)
// LP: y[n] = k1*x[n] + (1-k1)*y[n-1] — options.k1 in (0,1], omit to bypass
// HP: y[n] = k2*(y[n-1] + x[n] - x[n-1]) — options.k2 in (0,1], omit to bypass
if (options.k1 != null) {
const k1 = Math.max(0, Math.min(1, options.k1));
let y = 0.0;
for (let i = 0; i < numSamples; ++i) {
y = k1 * pcm[i] + (1.0 - k1) * y;
pcm[i] = y;
}
}
if (options.k2 != null) {
const k2 = Math.max(0, Math.min(1, options.k2));
let y = 0.0, xp = 0.0;
for (let i = 0; i < numSamples; ++i) {
const x = pcm[i];
y = k2 * (y + x - xp);
xp = x;
pcm[i] = y;
}
}
// Normalize
let maxAbs = 0;
for (let i = 0; i < numSamples; ++i) maxAbs = Math.max(maxAbs, Math.abs(pcm[i]));
if (maxAbs > 1.0) {
for (let i = 0; i < numSamples; ++i) pcm[i] /= maxAbs;
}
return pcm;
}
|
