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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 "explicit"
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 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 API
The definition of 'DynamicsCompressorNode' in that specification.
Working Draft  

Browser compatibility

Update compatibility data on GitHub
DesktopMobile
ChromeEdgeFirefoxInternet ExplorerOperaSafariAndroid webviewChrome for AndroidEdge MobileFirefox for AndroidOpera for AndroidiOS SafariSamsung Internet
Basic supportChrome Full support 14Edge Full support YesFirefox Full support 25IE No support NoOpera Full support 15Safari Full support 6WebView Android Full support YesChrome Android Full support 18Edge Mobile Full support YesFirefox Android Full support 26Opera Android Full support 15Safari iOS ? Samsung Internet Android Full support Yes
DynamicsCompressorNode() constructorChrome Full support 55
Notes
Full support 55
Notes
Notes Before Chrome 59, the default values were not supported.
Edge ? Firefox Full support 53IE No support NoOpera Full support 42Safari ? 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.
Edge Mobile ? Firefox Android Full support 53Opera Android Full support 42Safari iOS ? Samsung Internet Android Full support 6.0
attackChrome Full support 14Edge Full support 12Firefox Full support 25IE No support NoOpera Full support 15Safari Full support 6WebView Android Full support YesChrome Android Full support 18Edge Mobile Full support YesFirefox Android Full support 26Opera Android Full support 15Safari iOS ? Samsung Internet Android Full support Yes
kneeChrome Full support 14Edge Full support 12Firefox Full support 25IE No support NoOpera Full support 15Safari Full support 6WebView Android Full support YesChrome Android Full support 18Edge Mobile Full support YesFirefox Android Full support 26Opera Android Full support 15Safari iOS ? Samsung Internet Android Full support Yes
ratioChrome Full support 14Edge Full support 12Firefox Full support 25IE No support NoOpera Full support 15Safari Full support 6WebView Android Full support YesChrome Android Full support 18Edge Mobile Full support YesFirefox Android Full support 26Opera Android Full support 15Safari iOS ? Samsung Internet Android Full support Yes
reductionChrome Full support 14
Notes
Full support 14
Notes
Notes Before version 52, this was an AudioParam..
Edge Full support 12Firefox Full support 25IE No support NoOpera Full support 15Safari Full support 6WebView 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..
Edge Mobile Full support YesFirefox Android Full support 26Opera Android Full support 15Safari iOS ? Samsung Internet Android Full support Yes
releaseChrome Full support 14Edge Full support 12Firefox Full support 25IE No support NoOpera Full support 15Safari Full support 6WebView Android Full support YesChrome Android Full support 18Edge Mobile Full support YesFirefox Android Full support 26Opera Android Full support 15Safari iOS ? Samsung Internet Android Full support Yes
thresholdChrome Full support 14Edge Full support 12Firefox Full support 25IE No support NoOpera Full support 15Safari Full support 6WebView Android Full support YesChrome Android Full support 18Edge Mobile Full support YesFirefox Android Full support 26Opera Android Full support 15Safari iOS ? Samsung Internet Android Full support Yes

Legend

Full support  
Full support
No support  
No support
Compatibility unknown  
Compatibility unknown
See implementation notes.
See implementation notes.

See also

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