From c058fa0fb22dc40ef0225b21a97578cddd0aaffa Mon Sep 17 00:00:00 2001 From: Florian Merz Date: Thu, 11 Feb 2021 14:51:05 +0100 Subject: unslug ru: move --- .../baseaudiocontext/decodeaudiodata/index.html | 220 +++++++++++++++++++++ 1 file changed, 220 insertions(+) create mode 100644 files/ru/web/api/baseaudiocontext/decodeaudiodata/index.html (limited to 'files/ru/web/api/baseaudiocontext/decodeaudiodata') diff --git a/files/ru/web/api/baseaudiocontext/decodeaudiodata/index.html b/files/ru/web/api/baseaudiocontext/decodeaudiodata/index.html new file mode 100644 index 0000000000..faae982eae --- /dev/null +++ b/files/ru/web/api/baseaudiocontext/decodeaudiodata/index.html @@ -0,0 +1,220 @@ +--- +title: AudioContext.decodeAudioData() +slug: Web/API/AudioContext/decodeAudioData +tags: + - API +translation_of: Web/API/BaseAudioContext/decodeAudioData +--- +

{{ APIRef("Web Audio API") }}

+ +
+

The decodeAudioData() method of the {{ domxref("AudioContext") }} Interface is used to asynchronously decode audio file data contained in an {{domxref("ArrayBuffer")}}. In this case the ArrayBuffer is usually loaded from an {{domxref("XMLHttpRequest")}}'s response attribute after setting the responseType to arraybuffer. The decoded AudioBuffer is resampled to the AudioContext's sampling rate, then passed to a callback or promise.

+
+ +

This is the preferred method of creating an audio source for Web Audio API from an audio track.

+ +

Syntax

+ +

Older callback syntax:

+ +
audioCtx.decodeAudioData(audioData, function(decodedData) {
+  // use the dec​oded data here
+});
+ +

Newer promise-based syntax:

+ +
audioCtx.decodeAudioData(audioData).then(function(decodedData) {
+  // use the decoded data here
+});
+ +

Example

+ +

In this section we will first cover the older callback-based system and then the newer promise-based syntax.

+ +

Older callback syntax

+ +

In this example, the getData() function uses XHR to load an audio track, setting the responseType of the request to arraybuffer so that it returns an array buffer as its response that we then store in the audioData variable . We then pass this buffer into a decodeAudioData() function; the success callback takes the successfully decoded PCM data, puts it into an {{ domxref("AudioBufferSourceNode") }} created using {{ domxref("AudioContext.createBufferSource()") }}, connects the source to the {{domxref("AudioContext.destination") }} and sets it to loop.

+ +

The buttons in the example simply run getData() to load the track and start it playing, and stop it playing, respectively. When the stop() method is called on the source, the source is cleared out.

+ +
+

Note: You can run the example live (or view the source.)

+
+ +
// define variables
+
+var audioCtx = new (window.AudioContext || window.webkitAudioContext)();
+var source;
+
+var pre = document.querySelector('pre');
+var myScript = document.querySelector('script');
+var play = document.querySelector('.play');
+var stop = document.querySelector('.stop');
+
+// use XHR to load an audio track, and
+// decodeAudioData to decode it and stick it in a buffer.
+// Then we put the buffer into the source
+
+function getData() {
+  source = audioCtx.createBufferSource();
+  var request = new XMLHttpRequest();
+
+  request.open('GET', 'viper.ogg', true);
+
+  request.responseType = 'arraybuffer';
+
+
+  request.onload = function() {
+    var audioData = request.response;
+
+    audioCtx.decodeAudioData(audioData, function(buffer) {
+        source.buffer = buffer;
+
+        source.connect(audioCtx.destination);
+        source.loop = true;
+      },
+
+      function(e){"Error with decoding audio data" + e.err});
+
+  }
+
+  request.send();
+}
+
+// wire up buttons to stop and play audio
+
+play.onclick = function() {
+  getData();
+  source.start(0);
+  play.setAttribute('disabled', 'disabled');
+}
+
+stop.onclick = function() {
+  source.stop(0);
+  play.removeAttribute('disabled');
+}
+
+
+// dump script to pre element
+
+pre.innerHTML = myScript.innerHTML;
+ +

New promise-based syntax

+ +
ctx.decodeAudioData(compressedBuffer).then(function(decodedData) {
+ // use the decoded data here
+});
+ +

Parameters

+ +
+
ArrayBuffer
+
An ArrayBuffer containing the audio data to be decoded, usually grabbed from an {{domxref("XMLHttpRequest")}}'s response attribute after setting the responseType to arraybuffer.
+
DecodeSuccessCallback
+
A callback function to be invoked when the decoding successfully finishes. The single argument to this callback is an AudioBuffer representing the decoded PCM audio data. Usually you'll want to put the decoded data into an {{domxref("AudioBufferSourceNode")}}, from which it can be played and manipulated how you want.
+
DecodeErrorCallback
+
An optional error callback, to be invoked if an error occurs when the audio data is being decoded.
+
+ +

Returns

+ +

An {{domxref("AudioBuffer") }} representing the decoded PCM audio data.

+ +

Specifications

+ + + + + + + + + + + + + + +
SpecificationStatusComment
{{SpecName('Web Audio API', '#widl-AudioContext-decodeAudioData-Promise-AudioBuffer--ArrayBuffer-audioData-DecodeSuccessCallback-successCallback-DecodeErrorCallback-errorCallback', 'decodeAudioData()')}}{{Spec2('Web Audio API')}} 
+ +

Browser compatibility

+ +
{{CompatibilityTable}}
+ +
+ + + + + + + + + + + + + + + + + + + + + + + + + + + +
FeatureChromeFirefox (Gecko)Internet ExplorerOperaSafari (WebKit)
Basic support{{CompatChrome(10.0)}}{{property_prefix("webkit")}}{{CompatGeckoDesktop(25.0)}} {{CompatNo}}15.0{{property_prefix("webkit")}}
+ 22 (unprefixed)		6.0{{property_prefix("webkit")}}
Promise-based syntax{{CompatChrome(49.0)}}{{CompatVersionUnknown}}{{CompatNo}}{{CompatVersionUnknown}}{{CompatNo}}
+
+ +
+ + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + +
FeatureAndroidAndroid WebviewFirefox Mobile (Gecko)Firefox OSIE MobileOpera MobileSafari MobileChrome for Android
Basic support{{CompatUnknown}}{{CompatVersionUnknown}}26.01.2{{CompatUnknown}}{{CompatUnknown}}{{CompatUnknown}}{{CompatChrome(33.0)}}
Promise-based syntax{{CompatUnknown}}{{CompatChrome(49.0)}}{{CompatVersionUnknown}}{{CompatVersionUnknown}}{{CompatNo}}{{CompatUnknown}}{{CompatUnknown}}{{CompatChrome(49.0)}}
+
+ +

See also

+ + -- cgit v1.2.3-54-g00ecf