gibberish-dsp/js/envelopes/adsr.js

Gibberish is designed to be an optimized API for audio synthesis using per-sample techniques.

const ugen = require( '../ugen.js' ),
      g = require( 'genish.js' )

module.exports = function( Gibberish ) {

  const ADSR = function( argumentProps ) {
    const adsr  = Object.create( ugen ),
          attack  = g.in( 'attack' ),
          decay   = g.in( 'decay' ),
          sustain = g.in( 'sustain' ),
          release = g.in( 'release' ),
          sustainLevel = g.in( 'sustainLevel' )

    const props = Object.assign( {}, ADSR.defaults, argumentProps )

    Object.assign( adsr, props )

    const graph = g.adsr( 
      attack, decay, sustain, sustainLevel, release, 
      { triggerRelease: props.triggerRelease, shape:props.shape, alpha:props.alpha } 
    )

    adsr.trigger = graph.trigger
    adsr.advance = graph.release

    const __out = Gibberish.factory( adsr, graph, ['envelopes','ADSR'], props )

    return __out 
  }

  ADSR.defaults = { 
    attack:22050, 
    decay:22050, 
    sustain:44100, 
    sustainLevel:.6, 
    release: 44100, 
    triggerRelease:false,
    shape:'exponential',
    alpha:5 
  } 

  return ADSR
}