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adding linear and exponential envelope for fm synthesis

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This commit is contained in:
Raphael Forment 2023-08-29 17:25:27 +02:00
parent c87c3c6672
commit c3cd5d08c9
2 changed files with 44 additions and 14 deletions
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13
packages/superdough/helpers.mjs
View File

@ -39,6 +39,19 @@ export const getEnvelope = (attack, decay, sustain, release, velocity, begin) =>
};
};
export const getExpEnvelope = (attack, decay, velocity, begin) => {
const gainNode = getAudioContext().createGain();
gainNode.gain.setValueAtTime(0.0001, begin);
gainNode.gain.exponentialRampToValueAtTime(velocity, begin + attack);
gainNode.gain.exponentialRampToValueAtTime(0.0001, begin + attack + decay);
return {
node: gainNode,
stop: (t) => {
gainNode.gain.exponentialRampToValueAtTime(0.0001, t + decay);
},
};
};
export const getADSR = (attack, decay, sustain, release, velocity, begin, end) => {
const gainNode = getAudioContext().createGain();
gainNode.gain.setValueAtTime(0, begin);

45
packages/superdough/synth.mjs
View File

@ -1,8 +1,22 @@
import { midiToFreq, noteToMidi } from './util.mjs';
import { registerSound, getAudioContext } from './superdough.mjs';
import { getOscillator, gainNode, getEnvelope } from './helpers.mjs';
import { getOscillator, gainNode, getEnvelope, getExpEnvelope } from './helpers.mjs';
const fm = (osc, harmonicityRatio, modulationIndex, wave) => {
/*
* This function helps to setup a modulator for FM Synthesis
* @returns a modulator
*/
const carrfreq = osc.frequency.value;
const modfreq = carrfreq * harmonicityRatio;
const modgain = modfreq * modulationIndex;
return mod(modfreq, modgain, wave);
};
const mod = (freq, range = 1, type) => {
/*
* This function creates an oscillator
*/
const ctx = getAudioContext();
const osc = ctx.createOscillator();
osc.type = type;
@ -13,12 +27,6 @@ const mod = (freq, range = 1, type) => {
return { node: g, stop: (t) => osc.stop(t) };
};
const fm = (osc, harmonicityRatio, modulationIndex, wave) => {
const carrfreq = osc.frequency.value;
const modfreq = carrfreq * harmonicityRatio;
const modgain = modfreq * modulationIndex;
return mod(modfreq, modgain, wave);
};
export function registerSynthSounds() {
['sine', 'square', 'triangle', 'sawtooth'].forEach((wave) => {
@ -33,6 +41,12 @@ export function registerSynthSounds() {
release = 0.01,
fmh: fmHarmonicity = 1,
fmi: fmModulationIndex,
fmenv: fmEnvelopeType = 'linear',
fmattack: fmAttack = 0.001,
fmdecay: fmDecay = 0.2,
fmsustain: fmSustain = 0.001,
fmrelease: fmRelease = 0.1,
fmvelocity: fmVelocity = 1,
fmwave: fmWaveform = 'sine'
} = value;
let { n, note, freq } = value;
@ -49,14 +63,17 @@ export function registerSynthSounds() {
// make oscillator
const { node: o, stop } = getOscillator({ t, s: wave, freq });
let stopFm;
let stopFm, fmEnvelope;
if (fmModulationIndex) {
const { node: modulator, stop } = fm(
o, fmHarmonicity,
fmModulationIndex,
fmWaveform
);
modulator.connect(o.frequency);
const { node: modulator, stop } = fm( o, fmHarmonicity, fmModulationIndex, fmWaveform);
fmEnvelope = getEnvelope(fmAttack, fmDecay, fmSustain, fmRelease, fmVelocity, t);
if (fmEnvelopeType === "exp") {
fmEnvelope = getExpEnvelope(fmAttack, fmDecay, fmVelocity, t);
fmEnvelope.node.maxValue = fmModulationIndex * 2;
fmEnvelope.node.minValue = 0.00001;
}
modulator.connect(fmEnvelope.node);
fmEnvelope.node.connect(o.frequency);
stopFm = stop;
}
const g = gainNode(0.3);