Note: As of the August 29 2014 Web Audio API spec publication, this feature has been marked as deprecated, and is soon to be replaced by Audio Workers.
The bufferSize
property of the ScriptProcessorNode
interface returns an integer representing both the input and output buffer size, in sample-frames. Its value can be a power of 2 value in the range 256
–16384
.
Syntax
var audioCtx = new AudioContext();
var scriptNode = audioCtx.createScriptProcessor(4096, 1, 1);
console.log(scriptNode.bufferSize);
Value
An integer.
Example
The following example shows basic usage of a ScriptProcessorNode
to take a track loaded via AudioContext.decodeAudioData()
, process it, adding a bit of white noise to each audio sample of the input track (buffer) and play it through the AudioDestinationNode
. For each channel and each sample frame, the scriptNode.onaudioprocess
function takes the associated audioProcessingEvent
and uses it to loop through each channel of the input buffer, and each sample in each channel, and add a small amount of white noise, before setting that result to be the output sample in each case.
Note: For a full working example, see our [[../../../../../../../mdn.github.io/webaudio-examples/script-processor-node/index|script-processor-node]] github repo (also view the source code.)
var myScript = document.querySelector('script');
var myPre = document.querySelector('pre');
var playButton = document.querySelector('button');
// Create AudioContext and buffer source
var audioCtx = new AudioContext();
source = audioCtx.createBufferSource();
// Create a ScriptProcessorNode with a bufferSize of 4096 and a single input and output channel
var scriptNode = audioCtx.createScriptProcessor(4096, 1, 1);
console.log(scriptNode.bufferSize);
// load in an audio track via XHR and decodeAudioData
function getData() {
request = new XMLHttpRequest();
request.open('GET', 'viper.ogg', true);
request.responseType = 'arraybuffer';
request.onload = function() {
var audioData = request.response;
audioCtx.decodeAudioData(audioData, function(buffer) {
myBuffer = buffer;
source.buffer = myBuffer;
},
function(e){"Error with decoding audio data" + e.err});
}
request.send();
}
// Give the node a function to process audio events
scriptNode.onaudioprocess = function(audioProcessingEvent) {
// The input buffer is the song we loaded earlier
var inputBuffer = audioProcessingEvent.inputBuffer;
// The output buffer contains the samples that will be modified and played
var outputBuffer = audioProcessingEvent.outputBuffer;
// Loop through the output channels (in this case there is only one)
for (var channel = 0; channel < outputBuffer.numberOfChannels; channel++) {
var inputData = inputBuffer.getChannelData(channel);
var outputData = outputBuffer.getChannelData(channel);
// Loop through the 4096 samples
for (var sample = 0; sample < inputBuffer.length; sample++) {
// make output equal to the same as the input
outputData[sample] = inputData[sample];
// add noise to each output sample
outputData[sample] += ((Math.random() * 2) - 1) * 0.2;
}
}
}
getData();
// wire up play button
playButton.onclick = function() {
source.connect(scriptNode);
scriptNode.connect(audioCtx.destination);
source.start();
}
// When the buffer source stops playing, disconnect everything
source.onended = function() {
source.disconnect(scriptNode);
scriptNode.disconnect(audioCtx.destination);
}
Specifications
Specification | Status | Comment |
Web Audio APIThe definition of 'bufferSize' 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.
Update compatibility data on GitHub
Desktop | Mobile | |||||||||||
---|---|---|---|---|---|---|---|---|---|---|---|---|
|
Chrome Full support 14 Full support 14 Prefixed' Implemented with the vendor prefix: webkit |
Edge
Full support 12 |
Firefox
Full support 25 |
IE
No support No |
Opera Full support 22 Full support 22 Full support 15 Prefixed' Implemented with the vendor prefix: webkit |
Safari Full support 6 Full support 6 Prefixed' Implemented with the vendor prefix: webkit |
WebView Android
Full support Yes |
Chrome Android
Full support Yes |
Firefox Android
Full support 25 |
Opera Android Full support 22 Full support 22 Full support 14 Prefixed' Implemented with the vendor prefix: webkit |
Safari iOS Full support 6 Full support 6 Prefixed' Implemented with the vendor prefix: webkit |
Samsung Internet Android
Full support Yes |
Legend
- Full support
- Full support
- No support
- No support
- Deprecated. Not for use in new websites.'
- Deprecated. Not for use in new websites.
- Requires a vendor prefix or different name for use.'
- Requires a vendor prefix or different name for use.
See also
ScriptProcessorNode.bufferSize by Mozilla Contributors is licensed under CC-BY-SA 2.5.