DynamicsCompressorNode

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

Browser compatibility

See also

• Using the Web Audio API