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    AudioContext.createDynamicsCompressor()

    The createDynamicsCompressor() method of the AudioContext Interface is used to create a DynamicsCompressorNode, which can be used to apply compression to an audio signal.

    Compression lowers the volume of the loudest parts of the signal and raises the volume of the softest parts. Overall, a louder, richer, and fuller sound can be achieved. It is especially important in games and musical applications where large numbers of individual sounds are played simultaneously, where you want to control the overall signal level and help avoid clipping (distorting) of the audio output.

    Syntax

    var audioCtx = new AudioContext();
    var compressor = audioCtx.createDynamicsCompressor();

    Returns

    A DynamicsCompressorNode.

    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 'createDynamicsCompressor()' 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

    Contributors to this page: teoli, chrisdavidmills
    Last updated by: teoli,