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.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 'attack' in that specification. |
Working Draft |
Browser compatibility
The compatibility table on this page is generated from structured data. If you'd like to contribute to the data, please check out https://github.com/mdn/browser-compat-data and send us a pull request.
Desktop | Mobile | |||||||||||
---|---|---|---|---|---|---|---|---|---|---|---|---|
attack | Chrome Full support 14 | Edge Full support 12 | Firefox Full support 25 | IE No support No | Opera Full support 15 | Safari Full support 6 | WebView Android Full support Yes | Chrome Android Full support 18 | Firefox Android Full support 26 | Opera Android Full support 14 | Safari iOS Full support Yes | Samsung Internet Android Full support 1.0 |
Legend
- Full support
- Full support
- No support
- No support