strudel-docker/packages/webaudio/synth.mjs

import { fromMidi, toMidi } from '@strudel.cycles/core';
import { setSound } from './webaudio.mjs';
import { getOscillator, gainNode, getADSR } from './helpers.mjs';

export function loadSynthSounds() {
  ['sine', 'square', 'triangle', 'sawtooth'].forEach((wave) => {
    setSound(wave, ({ hap, duration, t }) => {
      // destructure adsr here, because the default should be different for synths and samples
      const { attack = 0.001, decay = 0.05, sustain = 0.6, release = 0.01 } = hap.value;
      let { n, note, freq } = hap.value;
      // with synths, n and note are the same thing
      n = note || n || 36;
      if (typeof n === 'string') {
        n = toMidi(n); // e.g. c3 => 48
      }
      // get frequency
      if (!freq && typeof n === 'number') {
        freq = fromMidi(n); // + 48);
      }
      // maybe pull out the above frequency resolution?? (there is also getFrequency but it has no default)
      // make oscillator
      const o = getOscillator({ t, s: wave, freq, duration, release });
      // chain.push(o);
      // level down oscillators as they are really loud compared to samples i've tested
      //chain.push(gainNode(0.3));
      const g = gainNode(0.3);
      // TODO: make adsr work with samples without pops
      // envelope
      const adsr = getADSR(attack, decay, sustain, release, 1, t, t + duration);
      //chain.push(adsr);
      return o.connect(g).connect(adsr);
    });
  });
}