https://github.com/diversen/adsr-gain-node

A simple and small nodejs module for creating an adsr gain node
https://github.com/diversen/adsr-gain-node

adsr audiocontext

Last synced: about 1 year ago
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A simple and small nodejs module for creating an adsr gain node

• Host: GitHub
• URL: https://github.com/diversen/adsr-gain-node
• Owner: diversen
• Created: 2017-07-21T14:58:20.000Z (almost 9 years ago)
• Default Branch: master
• Last Pushed: 2019-02-10T18:41:41.000Z (over 7 years ago)
• Last Synced: 2025-03-08T12:02:30.334Z (over 1 year ago)
• Topics: adsr, audiocontext
• Language: JavaScript
• Size: 40 KB
• Stars: 1
• Watchers: 2
• Forks: 0
• Open Issues: 0
• Metadata Files:
  • Readme: README.md

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README

          
# adsr-gain-node

Simple object for getting an ADSR gain node

## Install: 

    npm install --save adsr-gain-node

## Example usage

~~~js

var adsrGainNode = require('adsr-gain-node')

var audioCtx = new AudioContext();

var oscillator = audioCtx.createOscillator();

// Helper function to get new gain node

function getADSR () {

    let adsr = new adsrGainNode(audioCtx);

    adsr.setOptions({

        attackAmp: 0.001, 

        decayAmp: 0.3,

        sustainAmp: 0.7,

        releaseAmp: 0.001,

        attackTime: 1.1,

        decayTime: 0.2,

        sustainTime: 1.0, 

        releaseTime: 5.0,

        /**

         * If you are making e.g. a keyboard, then you may 

         * not auto-release the note

         * If auto release is false then

         * you should release the note using. 

         * `adsr.releaseNow()´

         */

        autoRelease: true

    });

    return adsr

}

// Begin time for gain

var nowTime = audioCtx.currentTime

// Get adsr and the gain node

// Time it to begin in current time + 5 secs

let testTime = 2

var adsr = getADSR()

var gainNode = adsr.getGainNode(nowTime + testTime );

// Connect the oscillator to the gain node

oscillator.connect(gainNode);

gainNode.connect(audioCtx.destination);

// Start

oscillator.start(nowTime + testTime);

// Stop oscillator according to the ADSR

let endTime = adsr.releaseTime() + testTime

oscillator.stop(endTime)

// On a piano you may want to release the note, when

// the key is released. 

// 

// Then you may do something like this to end the note and the gain node: 

// E.g onKeyUp: 

//     oscillator.stop(this.adsr.releaseTimeNow())

//     adsr.releaseNow()

~~~~

There is also a HTML form which can generate a web interface for 

the control of gain nodes. 

You can see it on [https://diversen.github.io/adsr-gain-node/](https://diversen.github.io/adsr-gain-node/) 

The source is [test.js](test.js)

## License

MIT © [Dennis Iversen](https://github.com/diversen)