From 33058f2b292b3a581333bdfb21b8f671898c5060 Mon Sep 17 00:00:00 2001 From: Peter Bengtsson Date: Tue, 8 Dec 2020 14:40:17 -0500 Subject: initial commit --- .../audiocontext/createscriptprocessor/index.html | 199 +++++++++++++++++++++ 1 file changed, 199 insertions(+) create mode 100644 files/zh-cn/web/api/audiocontext/createscriptprocessor/index.html (limited to 'files/zh-cn/web/api/audiocontext/createscriptprocessor') diff --git a/files/zh-cn/web/api/audiocontext/createscriptprocessor/index.html b/files/zh-cn/web/api/audiocontext/createscriptprocessor/index.html new file mode 100644 index 0000000000..7e505bc06a --- /dev/null +++ b/files/zh-cn/web/api/audiocontext/createscriptprocessor/index.html @@ -0,0 +1,199 @@ +--- +title: AudioContext.createScriptProcessor() +slug: Web/API/AudioContext/createScriptProcessor +translation_of: Web/API/BaseAudioContext/createScriptProcessor +--- +

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

+ +
+

{{ domxref("AudioContext") }} 接口的createScriptProcessor() 方法创建一个{{domxref("ScriptProcessorNode")}} 用于通过JavaScript直接处理音频.

+
+ +

语法

+ +
var audioCtx = new AudioContext();
+myScriptProcessor = audioCtx.createScriptProcessor(bufferSize, numberOfInputChannels, numberOfOutputChannels);
+ +

参数

+ +
+
bufferSize
+
缓冲区大小，以样本帧为单位。具体来讲，缓冲区大小必须是下面这些值当中的某一个: 256, 512, 1024, 2048, 4096, 8192, 16384. 如果不传，或者参数为0，则取当前环境最合适的缓冲区大小, 取值为2的幂次方的一个常数，在该node的整个生命周期中都不变.
+
该取值控制着audioprocess事件被分派的频率，以及每一次调用多少样本帧被处理. 较低bufferSzie将导致一定的延迟。较高的bufferSzie就要注意避免音频的崩溃和故障。推荐作者不要给定具体的缓冲区大小，让系统自己选一个好的值来平衡延迟和音频质量。
+
numberOfInputChannels
+
值为整数，用于指定输入node的声道的数量，默认值是2，最高能取32.
+
numberOfOutputChannels
+
值为整数，用于指定输出node的声道的数量，默认值是2，最高能取32.
+
+ +
+

重要: Webkit (version 31)要求调用这个方法的时候必须传入一个有效的bufferSize .

+
+ +
+

注意: numberOfInputChannels和numberOfOutputChannels的值不能同时为0，二者同时为0是无效的

+
+ +

返回

+ +

A {{domxref("ScriptProcessorNode")}}.

+ +

示例

+ +

下面的例子展示了一个ScriptProcessorNode的基本用法，数据源取自 {{ domxref("AudioContext.decodeAudioData") }}, 给每一个音频样本加一点白噪声，然后通过{{domxref("AudioDestinationNode")}}播放(其实这个就是系统的扬声器)。 对于每一个声道和样本帧，在把结果当成输出样本之前，scriptNode.onaudioprocess方法关联audioProcessingEvent ，并用它来遍历每输入流的每一个声道，和每一个声道中的每一个样本，并添加一点白噪声。

+ +
+

注意: 完整的示例参照 script-processor-node github (查看源码 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);
+}
+
+ +

规范

+ + + + + + + + + + + + + + +
SpecificationStatusComment
{{SpecName('Web Audio API', '#widl-AudioContext-createScriptProcessor-ScriptProcessorNode-unsigned-long-bufferSize-unsigned-long-numberOfInputChannels-unsigned-long-numberOfOutputChannels', 'createScriptProcessor')}}{{Spec2('Web Audio API')}}
+ +

浏览器兼容性

+ +
{{CompatibilityTable}}
+ +
+ + + + + + + + + + + + + + + + + + + + + +
FeatureChromeEdgeFirefox (Gecko)Internet ExplorerOperaSafari (WebKit)
Basic support{{CompatChrome(10.0)}}{{property_prefix("webkit")}}{{CompatVersionUnknown}}{{CompatGeckoDesktop(25.0)}} {{CompatNo}}15.0{{property_prefix("webkit")}}
+ 22 (unprefixed)		6.0{{property_prefix("webkit")}}
+
+ +
+ + + + + + + + + + + + + + + + + + + + + + + + + +
FeatureAndroidEdgeFirefox Mobile (Gecko)Firefox OSIE MobileOpera MobileSafari MobileChrome for Android
Basic support{{CompatUnknown}}{{CompatVersionUnknown}}26.01.2{{CompatUnknown}}{{CompatUnknown}}{{CompatUnknown}}33.0
+
+ +

See also

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