Simple JavaScript synthesizer using Web Audio.
Design
There are three oscillators which output to a basic attack/decay/sustain envelope, followed by an optional lowpass filter.
Usage
There's only one function, SimpleJSSynth, and it creates an AudioNode and connects it to the
destination with the given synth options:
// where <type> can be one of: 'sine' | 'square' | 'triangle' | 'sawtooth' var node = SimpleJSSynth( audioContext.destination, // the destination { // oscillator 1 osc1type: <type>, // type of wave osc1vol : 0 to 1, // oscillator volume (linear) osc1tune: 0, // relative tuning (semitones) // oscillator 2 osc2type: <type>, // type of wave osc2vol : 0 to 1, // oscillator volume (linear) osc2tune: 0, // relative tuning (semitones) // oscillator 3 osc3type: <type>, // type of wave osc3vol : 0 to 1, // oscillator volume (linear) osc3tune: 0, // relative tuning (semitones) // envelope attack : 0 to inf, // attack time (seconds) decay : 0 to inf, // decay time (seconds) sustain : 0 to 1 // sustain (fraction of max vol) susdecay: 0 to inf, // decay during sustain (seconds) // filter cutoff : 0, // lowpass cutoff (relative semitones to root) } );
The returned AudioNode object has a few extra methods for triggering the note:
// start playing the synth at frequency `freq` and volume `vol` node.noteOn(freq, vol); // while the synth is playing, bend the note +- `semitones` node.bend(semitones); // turn the note off node.noteOff(); // see if the synth is silent and ready for a new note to play node.isReady(); // stop all sound immediately node.stop(); // destroy a synth permanently (disconnect and stop all sound) node.destroy();
Example
Look at the source code of the demo. I've tried to keep it well commented.