From 218934fa2ed1c702a6d3923d2aa2cc6b43c48684 Mon Sep 17 00:00:00 2001 From: Peter Bengtsson Date: Tue, 8 Dec 2020 14:43:23 -0500 Subject: initial commit --- .../analysernode/getbytefrequencydata/index.html | 149 ++++++++++++++ files/zh-tw/web/api/analysernode/index.html | 226 +++++++++++++++++++++ 2 files changed, 375 insertions(+) create mode 100644 files/zh-tw/web/api/analysernode/getbytefrequencydata/index.html create mode 100644 files/zh-tw/web/api/analysernode/index.html (limited to 'files/zh-tw/web/api/analysernode') diff --git a/files/zh-tw/web/api/analysernode/getbytefrequencydata/index.html b/files/zh-tw/web/api/analysernode/getbytefrequencydata/index.html new file mode 100644 index 0000000000..d6b226dd8f --- /dev/null +++ b/files/zh-tw/web/api/analysernode/getbytefrequencydata/index.html @@ -0,0 +1,149 @@ +--- +title: AnalyserNode.getByteFrequencyData() +slug: Web/API/AnalyserNode/getByteFrequencyData +translation_of: Web/API/AnalyserNode/getByteFrequencyData +--- +

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

+ +
+

{{ domxref("AnalyserNode") }} 介面的 getByteFrequencyData() 方法會將當前的頻率資料複製到 {{domxref("Uint8Array")}} （無號 byte 陣列）。

+ +

如果陣列的元素數目比 {{domxref("AnalyserNode.frequencyBinCount")}} 少的話，多餘的元素會被 drop 掉。如果比需要的少的話，多餘的元素會被忽略。

+
+ +

語法

+ +
var audioCtx = new AudioContext();
+var analyser = audioCtx.createAnalyser();
+var dataArray = new Uint8Array(analyser.frequencyBinCount); // Uint8Array 應該要和 frequencyBinCount 等長
+analyser.getByteFrequencyData(dataArray); // 將 getByteFrequencyData() 回傳的資料放進 Uint8Array
+
+ +

回傳值

+ +

{{domxref("Uint8Array")}}。

+ +

範例

+ +

下面的範例顯示出 {{domxref("AudioContext")}} 用於建立一個 AnalyserNode 的基本用法，然後 {{domxref("window.requestAnimationFrame()", "requestAnimationFrame")}} 以及 {{htmlelement("canvas")}} 用來重複收集當前聲音輸入的頻率資料並在 "winamp bargraph style" 畫出輸出。若要知道更完整的範例或是資訊，請參考 Voice-change-O-matic demo （看 app.js 第 128–205 行 會有相關的程式碼）。

+ +
var audioCtx = new (window.AudioContext || window.webkitAudioContext)();
+var analyser = audioCtx.createAnalyser();
+
+  ...
+
+analyser.fftSize = 256;
+var bufferLength = analyser.frequencyBinCount;
+console.log(bufferLength);
+var dataArray = new Uint8Array(bufferLength);
+
+canvasCtx.clearRect(0, 0, WIDTH, HEIGHT);
+
+function draw() {
+  drawVisual = requestAnimationFrame(draw);
+
+  analyser.getByteFrequencyData(dataArray);
+
+  canvasCtx.fillStyle = 'rgb(0, 0, 0)';
+  canvasCtx.fillRect(0, 0, WIDTH, HEIGHT);
+
+  var barWidth = (WIDTH / bufferLength) * 2.5;
+  var barHeight;
+  var x = 0;
+
+  for(var i = 0; i < bufferLength; i++) {
+    barHeight = dataArray[i];
+
+    canvasCtx.fillStyle = 'rgb(' + (barHeight+100) + ',50,50)';
+    canvasCtx.fillRect(x,HEIGHT-barHeight/2,barWidth,barHeight/2);
+
+    x += barWidth + 1;
+  }
+};
+
+draw();
+ +

參數

+ +
+
陣列
+
頻率定義域會被複製進去的 {{domxref("Uint8Array")}} 。
+
+ +

規範

+ + + + + + + + + + + + + + +
規範狀態Comment
{{SpecName('Web Audio API', '#widl-AnalyserNode-getByteFrequencyData-void-Uint8Array-array', 'getByteFrequencyData()')}}{{Spec2('Web Audio API')}} 
+ +

瀏覽器支援度

+ +
{{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")}}
+
+ +
+ + + + + + + + + + + + + + + + + + + + + + + +
FeatureAndroidFirefox Mobile (Gecko)Firefox OSIE MobileOpera MobileSafari MobileChrome for Android
Basic support{{CompatUnknown}}26.01.2{{CompatUnknown}}{{CompatUnknown}}{{CompatUnknown}}33.0
+
+ +

參看

+ + diff --git a/files/zh-tw/web/api/analysernode/index.html b/files/zh-tw/web/api/analysernode/index.html new file mode 100644 index 0000000000..875993cea9 --- /dev/null +++ b/files/zh-tw/web/api/analysernode/index.html @@ -0,0 +1,226 @@ +--- +title: AnalyserNode +slug: Web/API/AnalyserNode +tags: + - API + - AnalyserNode + - Interface + - NeedsTranslation + - Reference + - TopicStub + - Web Audio API +translation_of: Web/API/AnalyserNode +--- +

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

+ +

The AnalyserNode interface represents a node able to provide real-time frequency and time-domain analysis information. It is an {{domxref("AudioNode")}} that passes the audio stream unchanged from the input to the output, but allows you to take the generated data, process it, and create audio visualizations.

+ +

An AnalyzerNode has exactly one input and one output. The node works even if the output is not connected.

+ +

Without modifying the audio stream, the node allows to get the frequency and time-domain data associated to it, using a FFT.

+ + + + + + + + + + + + + + + + + + + + + + + + +
Number of inputs1
Number of outputs1 (but may be left unconnected)
Channel count mode"explicit"
Channel count1
Channel interpretation"speakers"
+ +

Inheritance

+ +

This interface inherits from the following parent interfaces:

+ +

{{InheritanceDiagram}}

+ +

Properties

+ +

Inherits properties from its parent, {{domxref("AudioNode")}}.

+ +
+
{{domxref("AnalyserNode.fftSize")}}
+
Is an unsigned long value representing the size of the FFT (Fast Fourier Transform) to be used to determine the frequency domain.
+
{{domxref("AnalyserNode.frequencyBinCount")}} {{readonlyInline}}
+
Is an unsigned long value half that of the FFT size. This generally equates to the number of data values you will have to play with for the visualization.
+
{{domxref("AnalyserNode.minDecibels")}}
+
Is a double value representing the minimum power value in the scaling range for the FFT analysis data, for conversion to unsigned byte values — basically, this specifies the minimum value for the range of results when using getByteFrequencyData().
+
{{domxref("AnalyserNode.maxDecibels")}}
+
Is a double value representing the maximum power value in the scaling range for the FFT analysis data, for conversion to unsigned byte values — basically, this specifies the maximum value for the range of results when using getByteFrequencyData().
+
{{domxref("AnalyserNode.smoothingTimeConstant")}}
+
Is a double value representing the averaging constant with the last analysis frame — basically, it makes the transition between values over time smoother.
+
+ +

Methods

+ +

Inherits methods from its parent, {{domxref("AudioNode")}}.

+ +
+
{{domxref("AnalyserNode.getFloatFrequencyData()")}}
+
Copies the current frequency data into a {{domxref("Float32Array")}} array passed into it.
+
+ +
+
{{domxref("AnalyserNode.getByteFrequencyData()")}}
+
Copies the current frequency data into a {{domxref("Uint8Array")}} (unsigned byte array) passed into it.
+
+ +
+
{{domxref("AnalyserNode.getFloatTimeDomainData()")}}
+
Copies the current waveform, or time-domain, data into a {{domxref("Float32Array")}} array passed into it.
+
{{domxref("AnalyserNode.getByteTimeDomainData()")}}
+
Copies the current waveform, or time-domain, data into a {{domxref("Uint8Array")}} (unsigned byte array) passed into it.
+
+ +

Examples

+ +
+

Note: See the guide Visualizations with Web Audio API for more information on creating audio visualizations.

+
+ +

Basic usage

+ +

The following example shows basic usage of an {{domxref("AudioContext")}} to create an AnalyserNode, then {{domxref("window.requestAnimationFrame()","requestAnimationFrame")}} and {{htmlelement("canvas")}} to collect time domain data repeatedly and draw an "oscilloscope style" output of the current audio input. For more complete applied examples/information, check out our Voice-change-O-matic demo (see app.js lines 128–205 for relevant code).

+ +
var audioCtx = new (window.AudioContext || window.webkitAudioContext)();
+var analyser = audioCtx.createAnalyser();
+
+  ...
+
+analyser.fftSize = 2048;
+var bufferLength = analyser.frequencyBinCount;
+var dataArray = new Uint8Array(bufferLength);
+analyser.getByteTimeDomainData(dataArray);
+
+// draw an oscilloscope of the current audio source
+
+function draw() {
+
+      drawVisual = requestAnimationFrame(draw);
+
+      analyser.getByteTimeDomainData(dataArray);
+
+      canvasCtx.fillStyle = 'rgb(200, 200, 200)';
+      canvasCtx.fillRect(0, 0, WIDTH, HEIGHT);
+
+      canvasCtx.lineWidth = 2;
+      canvasCtx.strokeStyle = 'rgb(0, 0, 0)';
+
+      canvasCtx.beginPath();
+
+      var sliceWidth = WIDTH * 1.0 / bufferLength;
+      var x = 0;
+
+      for(var i = 0; i < bufferLength; i++) {
+
+        var v = dataArray[i] / 128.0;
+        var y = v * HEIGHT/2;
+
+        if(i === 0) {
+          canvasCtx.moveTo(x, y);
+        } else {
+          canvasCtx.lineTo(x, y);
+        }
+
+        x += sliceWidth;
+      }
+
+      canvasCtx.lineTo(canvas.width, canvas.height/2);
+      canvasCtx.stroke();
+    };
+
+    draw();
+ +

Specifications

+ + + + + + + + + + + + + + +
SpecificationStatusComment
{{SpecName('Web Audio API', '#the-analysernode-interface', 'AnalyserNode')}}{{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		6.0{{property_prefix("webkit")}}
+
+ +
+ + + + + + + + + + + + + + + + + + + + + + + +
FeatureAndroidFirefox Mobile (Gecko)Firefox OSIE MobileOpera MobileSafari MobileChrome for Android
Basic support{{CompatUnknown}}26.01.2{{CompatUnknown}}{{CompatUnknown}}{{CompatUnknown}}33.0
+
+ +

See also

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