https://github.com/mmckegg/adsr

UNMAINTAINED: Attack, decay, sustain, release envelope for automating Web Audio API AudioParams.
https://github.com/mmckegg/adsr

Last synced: 3 months ago
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UNMAINTAINED: Attack, decay, sustain, release envelope for automating Web Audio API AudioParams.

• Host: GitHub
• URL: https://github.com/mmckegg/adsr
• Owner: mmckegg
• Archived: true
• Created: 2014-02-09T10:11:50.000Z (over 10 years ago)
• Default Branch: master
• Last Pushed: 2016-07-13T22:52:24.000Z (over 8 years ago)
• Last Synced: 2024-06-30T14:27:46.972Z (4 months ago)
• Language: JavaScript
• Homepage:
• Size: 10.7 KB
• Stars: 30
• Watchers: 3
• Forks: 1
• Open Issues: 1
• Metadata Files:
  • Readme: README.md

Awesome Lists containing this project

• awesome-javascript-audio - adsr - attack, delay, sustain, release envelopes (Sound editing / ADSR envelopes)

README

        
adsr

===

Attack, decay, sustain, release envelope for automating Web Audio API AudioParams.

## Status: Unmaintained

Check out https://github.com/itsjoesullivan/envelope-generator, which is a much better implementation :)

## Install

```bash

$ npm install adsr

```

## API

```js

var ADSR = require('adsr')

```

### ADSR(audioContext)

Returns an ADSR ModulatorNode instance.

### node.attack (get/set)

Attack time in seconds.

### node.decay (get/set)

Decay time in seconds.

### node.sustain (get/set)

Decimal representing what multiple of initial value to hold at in sustain portion of envelope.

### node.release (get/set)

Release time in seconds.

### node.value ([AudioParam](https://developer.mozilla.org/en-US/docs/Web/API/AudioParam))

The target value of the attack portion of envelope. Defaults to 1.

### node.startValue (AudioParam)

The start value which will ramp to `node.value` over time specified by `node.attack`. Defaults to 0.

### node.endValue (AudioParam)

The final value which will be ramped to over time specified by `node.release`. Defaults to 0.

### node.connect(destinationAudioParam)

Connect the modulator to the desired destination audio param.

### node.disconnect()

Disconnect from any target AudioParams and reset to `node.value`.

### node.start(at)

Trigger the attack-decay-sustain portion of the envelope at the specified time relative to audioContext.currentTime.

This can only be called once. Create additional instances of ADSR for multiple events.

### node.stop(at, isTarget)

Specify the time to start the release portion of the envelope. Or if `isTarget === true`, the time the release portion should complete by.

Returns the time that the release portion will complete by (this can be used to decide when to stop the source AudioNode)

## Example

```js

var audioContext = new AudioContext()

var oscillator = audioContext.createOscillator()

var gain = audioContext.createGain()

oscillator.connect(gain)

gain.connect(audioContext.destination)

var envelopeModulator = ADSR(audioContext)

gain.gain.value = 0 // set base value to 0 as modulators add to existing value

envelopeModulator.connect(gain.gain)

envelopeModulator.attack = 0.01 // seconds

envelopeModulator.decay = 0.4 // seconds

envelopeModulator.sustain = 0.6 // multiply gain.gain.value

envelopeModulator.release = 0.4 // seconds

envelopeModulator.value.value = 2 // value is an AudioParam

envelopeModulator.start(audioContext.currentTime)

oscillator.start(audioContext.currentTime)

var stopAt = envelopeModulator.stop(audioContext.currentTime + 1)

oscillator.stop(stopAt)

```