Web/API/DynamicsCompressorNode

The DynamicsCompressorNode interface provides a compression effect, which lowers the volume of the loudest parts of the signal in order to help prevent clipping and distortion that can occur when multiple sounds are played and multiplexed together at once. This is often used in musical production and game audio. DynamicsCompressorNode is an AudioNode that has exactly one input and one output; it is created using the AudioContext.createDynamicsCompressor() method.

Number of inputs	`1`
Number of outputs	`1`
Channel count mode	`"clamped-max"`
Channel count	`2`
Channel interpretation	`"speakers"`

Constructor

DynamicsCompressorNode(): Creates a new instance of an DynamicsCompressorNode object.

Properties

Inherits properties from its parent, AudioNode.

DynamicsCompressorNode.threshold Read only: Is a k-rate AudioParam representing the decibel value above which the compression will start taking effect.
DynamicsCompressorNode.knee Read only: Is a k-rate AudioParam containing a decibel value representing the range above the threshold where the curve smoothly transitions to the compressed portion.
DynamicsCompressorNode.ratio Read only: Is a k-rate AudioParam representing the amount of change, in dB, needed in the input for a 1 dB change in the output.
DynamicsCompressorNode.reduction Read only: Is a float representing the amount of gain reduction currently applied by the compressor to the signal.
DynamicsCompressorNode.attack Read only: Is a k-rate AudioParam representing the amount of time, in seconds, required to reduce the gain by 10 dB.
DynamicsCompressorNode.release Read only: Is a k-rate AudioParam representing the amount of time, in seconds, required to increase the gain by 10 dB.

Methods

No specific methods; inherits methods from its parent, AudioNode.

Example

The below code demonstrates a simple usage of createDynamicsCompressor() to add compression to an audio track. For a more complete example, have a look at our [[../../../../../../mdn.github.io/webaudio-examples/compressor-example/index|basic Compressor example]] (view the source code).

// Create a MediaElementAudioSourceNode
// Feed the HTMLMediaElement into it
var source = audioCtx.createMediaElementSource(myAudio);

// Create a compressor node
var compressor = audioCtx.createDynamicsCompressor();
compressor.threshold.setValueAtTime(-50, audioCtx.currentTime);
compressor.knee.setValueAtTime(40, audioCtx.currentTime);
compressor.ratio.setValueAtTime(12, audioCtx.currentTime);
compressor.attack.setValueAtTime(0, audioCtx.currentTime);
compressor.release.setValueAtTime(0.25, audioCtx.currentTime);

// connect the AudioBufferSourceNode to the destination
source.connect(audioCtx.destination);

button.onclick = function() {
  var active = button.getAttribute('data-active');
  if(active == 'false') {
    button.setAttribute('data-active', 'true');
    button.innerHTML = 'Remove compression';

    source.disconnect(audioCtx.destination);
    source.connect(compressor);
    compressor.connect(audioCtx.destination);
  } else if(active == 'true') {
    button.setAttribute('data-active', 'false');
    button.innerHTML = 'Add compression';

    source.disconnect(compressor);
    compressor.disconnect(audioCtx.destination);
    source.connect(audioCtx.destination);
  }
}

Specifications

Specification	Status	Comment
Web Audio APIThe definition of 'DynamicsCompressorNode' in that specification.	Working Draft

Browser compatibility

Update compatibility data on GitHub

	Desktop						Mobile
	Chrome	Edge	Firefox	Internet Explorer	Opera	Safari	Android webview	Chrome for Android	Firefox for Android	Opera for Android	Safari on iOS	Samsung Internet
`DynamicsCompressorNode`	Chrome Full support 14	Edge Full support 12	Firefox Full support 25	IE No support No	Opera Full support 15	Safari Full support 6	WebView Android Full support Yes	Chrome Android Full support 18	Firefox Android Full support 26	Opera Android Full support 14	Safari iOS Full support Yes	Samsung Internet Android Full support 1.0
`DynamicsCompressorNode()` constructor	Chrome Full support 55 Notes' Full support 55 Notes' Notes' Before Chrome 59, the default values were not supported.	Edge Full support 79	Firefox Full support 53	IE No support No	Opera Full support 42	Safari No support No	WebView Android Full support 55 Notes' Full support 55 Notes' Notes' Before version 59, the default values were not supported.	Chrome Android Full support 55 Notes' Full support 55 Notes' Notes' Before Chrome 59, the default values were not supported.	Firefox Android Full support 53	Opera Android Full support 42	Safari iOS No support No	Samsung Internet Android Full support 6.0 Notes' Full support 6.0 Notes' Notes' Before Samsung Internet 7.0, the default values were not supported.
`attack`	Chrome Full support 14	Edge Full support 12	Firefox Full support 25	IE No support No	Opera Full support 15	Safari Full support 6	WebView Android Full support Yes	Chrome Android Full support 18	Firefox Android Full support 26	Opera Android Full support 14	Safari iOS Full support Yes	Samsung Internet Android Full support 1.0
`knee`	Chrome Full support 14	Edge Full support 12	Firefox Full support 25	IE No support No	Opera Full support 15	Safari Full support 6	WebView Android Full support Yes	Chrome Android Full support 18	Firefox Android Full support 26	Opera Android Full support 14	Safari iOS Full support Yes	Samsung Internet Android Full support 1.0
`ratio`	Chrome Full support 14	Edge Full support 12	Firefox Full support 25	IE No support No	Opera Full support 15	Safari Full support 6	WebView Android Full support Yes	Chrome Android Full support 18	Firefox Android Full support 26	Opera Android Full support 14	Safari iOS Full support Yes	Samsung Internet Android Full support 1.0
`reduction`	Chrome Full support 14 Notes' Full support 14 Notes' Notes' Before version 52, this was an `AudioParam.`.	Edge Full support 12	Firefox Full support 25	IE No support No	Opera Full support 15	Safari Full support 6	WebView Android Full support Yes Notes' Full support Yes Notes' Notes' Before version 52, this was an `AudioParam.`.	Chrome Android Full support 18 Notes' Full support 18 Notes' Notes' Before version 52, this was an `AudioParam.`.	Firefox Android Full support 26	Opera Android Full support 14	Safari iOS Full support Yes	Samsung Internet Android Full support 1.0 Notes' Full support 1.0 Notes' Notes' Before Samsung Internet 6.0, this was an `AudioParam.`.
`release`	Chrome Full support 14	Edge Full support 12	Firefox Full support 25	IE No support No	Opera Full support 15	Safari Full support 6	WebView Android Full support Yes	Chrome Android Full support 18	Firefox Android Full support 26	Opera Android Full support 14	Safari iOS Full support Yes	Samsung Internet Android Full support 1.0
`threshold`	Chrome Full support 14	Edge Full support 12	Firefox Full support 25	IE No support No	Opera Full support 15	Safari Full support 6	WebView Android Full support Yes	Chrome Android Full support 18	Firefox Android Full support 26	Opera Android Full support 14	Safari iOS Full support Yes	Samsung Internet Android Full support 1.0

Legend

Full support: Full support
No support: No support
See implementation notes.': See implementation notes.