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xaudio.synthesizer

xaudio.synthesizer creates a synth combining an oscillator with amp / filter / reverb, ADSR envelopes, and an LFO. Trigger it with press to use it for sound effects or as a simple instrument. The synthesizer's release is tied to a unit created under the current scope, so it is released together with the calling unit.

import { xnew, xaudio } from '@mulsense/xnew';

function Main(unit) {
  const synth = xaudio.synthesizer({
    oscillator: { type: 'square' },
    amp: { envelope: { amount: 0.3, ADSR: [1, 80, 0.7, 120] } },
  });

  xnew('<button>', 'play').on('click', () => synth.press('A4', '4n'));
}

Options (on creation)​

Settings passed to xaudio.synthesizer(options).

OptionTypeDescription
oscillatorobjectSound source. type (sine / triangle / square / sawtooth), plus an optional envelope (pitch modulation) and LFO.
ampobjectAmplitude envelope. envelope is required.
filterobjectOptional. type (lowpass / highpass / bandpass) and cutoff (4–8192).
reverbobjectOptional. time (0–2000ms) and mix (0–1).
bpmnumberTempo used when durations are given as note lengths (60–240). Defaults to 120.

Envelope (ADSR)​

oscillator.envelope and amp.envelope take the shape { amount, ADSR }.

  • amount — Modulation amount. For amp it is level (0–1); for oscillator it is pitch in semitones (-36 to +36).
  • ADSR — [Attack, Decay, Sustain, Release]. A / D / R are in milliseconds (0–8000), S is a 0–1 ratio.

LFO​

oscillator.LFO is { amount, type, rate }, modulating pitch periodically (amount: 0–36 semitones, rate: 1–128Hz).

Methods​

press(frequency, duration?, wait?)​

Plays a note.

  • frequency — Frequency in Hz, or a note name (e.g. 'A4').
  • duration — Note length. Milliseconds (number) or a note value ('4n', '8n', ...). With a duration the note auto-releases; without one it sustains and returns { release }, so you call release() yourself to stop it.
  • wait — Delay before the attack, in milliseconds. Useful for staggering notes into an arpeggio.
// Auto-stops (plays for a quarter note)
synth.press('C4', '4n');

// Manual stop (sounds while held)
const note = synth.press('C4');
// ... on release
note.release();

// Stagger into an arpeggio with wait
['C5', 'E5', 'G5', 'C6'].forEach((note, i) => synth.press(note, 120, i * 70));
note

The overall master volume is controlled with xaudio.volume.

Demo​

A demo where you can tweak the synth parameters.

Combining press calls lets you build game-style sound effects.