The ratio
property of the DynamicsCompressorNode
interface Is a k-rate AudioParam
representing the amount of change, in dB, needed in the input for a 1 dB change in the output.
The ratio
property's default value is 12
and it can be set between 1
and 20
.
Syntax
var audioCtx = new AudioContext(); var compressor = audioCtx.createDynamicsCompressor(); compressor.ratio.value = 12;
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 'ratio' 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 | |||||||||||
---|---|---|---|---|---|---|---|---|---|---|---|---|
ratio | 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