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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" |
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.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 'DynamicsCompressorNode' in that specification. |
Working Draft |
Browser compatibility
Feature | Chrome | Firefox (Gecko) | Internet Explorer | Opera | Safari (WebKit) |
---|---|---|---|---|---|
Basic support | 10.0webkit | 25.0 (25.0) | No support | 15.0webkit 22 (unprefixed) |
6.0webkit |
Feature | Android | Android Webview | Firefox Mobile (Gecko) | Firefox OS | IE Mobile | Opera Mobile | Safari Mobile | Chrome for Android |
---|---|---|---|---|---|---|---|---|
Basic support | ? | (Yes) | 26.0 | 1.2 | ? | ? | ? | 33.0 |