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    DynamicsCompressorNode.attack

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    The attack property of the DynamicsCompressorNode interface is a k-rate AudioParam representing the amount of time, in seconds, required to reduce the gain by 10 dB. It defines how quickly the signal is adapted when its volume is increased.

    The attack property's default value is 0.003 and it can be set between 0 and 1.

    Syntax

    var audioCtx = new AudioContext();
var compressor = audioCtx.createDynamicsCompressor();
compressor.attack.value = 0;

    Value

    An AudioParam.

    Note: Though the AudioParam returned is read-only, the value it represents is not.

    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.value = -50;
compressor.knee.value = 40;
compressor.ratio.value = 12;
compressor.reduction.value = -20;
compressor.attack.value = 0;
compressor.release.value = 0.25;

// 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 'attack' in that specification.    		 Working Draft  

    Browser compatibility

    Feature Chrome Firefox (Gecko) Internet Explorer Opera Safari (WebKit)
    Basic support 10.0webkit 25.0 (25.0)  Not supported 15.0webkit
    22 (unprefixed)    		 6.0webkit
    Feature Android Firefox Mobile (Gecko) Firefox OS IE Mobile Opera Mobile Safari Mobile Chrome for Android
    Basic support ? 26.0 1.2 ? ? ? 33.0

    See also

    Document Tags and Contributors

    Tags: 
     Contributors to this page: fscholz, JesseTG, chrisdavidmills
     Last updated by: fscholz,