From 074785cea106179cb3305637055ab0a009ca74f2 Mon Sep 17 00:00:00 2001 From: Peter Bengtsson Date: Tue, 8 Dec 2020 14:42:52 -0500 Subject: initial commit --- files/ru/web/api/analysernode/index.html | 183 +++++++++++++++++++++++++++++++ 1 file changed, 183 insertions(+) create mode 100644 files/ru/web/api/analysernode/index.html (limited to 'files/ru/web/api/analysernode/index.html') diff --git a/files/ru/web/api/analysernode/index.html b/files/ru/web/api/analysernode/index.html new file mode 100644 index 0000000000..13032fbbf8 --- /dev/null +++ b/files/ru/web/api/analysernode/index.html @@ -0,0 +1,183 @@ +--- +title: AnalyserNode +slug: Web/API/AnalyserNode +translation_of: Web/API/AnalyserNode +--- +

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

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AnalyserNode интерфейс который предоставляет частоту (frequency) в реальном времени.  Элемент {{domxref("AudioNode")}} который пропускает аудиопоток неизменным от ввода (input) до вывода (output), но позволяет использовать генерируемые данные, обрабатывать или создавать аудиовизуализацию.

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AnalyserNode имеет только один ввод и один вывод. Узел работает даже если вывод не подсоединен.

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

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Количество входов1
Количество выводов1 (but may be left unconnected)
Channel count mode"explicit"
Количество каналов1
Channel interpretation"speakers"
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Наследование

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Интерфейс унаследован от  следующих родительских интерфейсов:

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{{InheritanceDiagram}}

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Constructor

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{{domxref("AnalyserNode.AnalyserNode", "AnalyserNode()")}}
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Creates a new instance of an AnalyserNode object.
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Properties

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

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{{domxref("AnalyserNode.fftSize")}}
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Is an unsigned long value representing the size of the FFT (Fast Fourier Transform) to be used to determine the frequency domain.
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{{domxref("AnalyserNode.frequencyBinCount")}} {{readonlyInline}}
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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.
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{{domxref("AnalyserNode.minDecibels")}}
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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().
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{{domxref("AnalyserNode.maxDecibels")}}
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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().
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{{domxref("AnalyserNode.smoothingTimeConstant")}}
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Is a double value representing the averaging constant with the last analysis frame — basically, it makes the transition between values over time smoother.
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Methods

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

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

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

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Basic usage

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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).

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

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SpecificationStatusComment
{{SpecName('Web Audio API', '#the-analysernode-interface', 'AnalyserNode')}}{{Spec2('Web Audio API')}}
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Browser compatibility

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{{Compat("api.AnalyserNode")}}

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See also

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