AnalyserNode
============

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

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

![Without modifying the audio stream, the node allows to get the frequency and time-domain data associated to it, using a FFT.](/ru/docs/Web/API/AnalyserNode/fttaudiodata_en.svg)


|  |  |
| --- | --- |
| Количество входов | `1` |
| Количество выводов | `1` (but may be left unconnected) |
| Channel count mode | `"explicit"` |
| Количество каналов | `1` |
| Channel interpretation | `"speakers"` |

Наследование
------------

Интерфейс унаследован от следующих родительских интерфейсов:

EventTarget

AudioNode

AnalyserNodeConstructor
-----------

`AnalyserNode()` (en-US)

Creates a new instance of an `AnalyserNode` object.

Properties
----------

*Inherits properties from its parent, `AudioNode`*.

`AnalyserNode.fftSize` (en-US)

Is an unsigned long value representing the size of the FFT (Fast Fourier Transform) to be used to determine the frequency domain.

`AnalyserNode.frequencyBinCount` (en-US) Только для чтения 

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.

`AnalyserNode.minDecibels` (en-US)

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()`.

`AnalyserNode.maxDecibels` (en-US)

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()`.

`AnalyserNode.smoothingTimeConstant` (en-US)

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, `AudioNode`*.

`AnalyserNode.getFloatFrequencyData()` (en-US)

Copies the current frequency data into a `Float32Array` (en-US) array passed into it.

`AnalyserNode.getByteFrequencyData()`

Copies the current frequency data into a `Uint8Array` (en-US) (unsigned byte array) passed into it.

`AnalyserNode.getFloatTimeDomainData()` (en-US)

Copies the current waveform, or time-domain, data into a `Float32Array` (en-US) array passed into it.

`AnalyserNode.getByteTimeDomainData()` (en-US)

Copies the current waveform, or time-domain, data into a `Uint8Array` (en-US) (unsigned byte array) passed into it.

Examples
--------

**Примечание:** 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 `AudioContext` to create an `AnalyserNode`, then `requestAnimationFrame` and `<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).


```js
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);

// Get a canvas defined with ID "oscilloscope"
var canvas = document.getElementById("oscilloscope");
var canvasCtx = canvas.getContext("2d");

// draw an oscilloscope of the current audio source

function draw() {
  requestAnimationFrame(draw);

  analyser.getByteTimeDomainData(dataArray);

  canvasCtx.fillStyle = "rgb(200, 200, 200)";
  canvasCtx.fillRect(0, 0, canvas.width, canvas.height);

  canvasCtx.lineWidth = 2;
  canvasCtx.strokeStyle = "rgb(0, 0, 0)";

  canvasCtx.beginPath();

  var sliceWidth = (canvas.width \* 1.0) / bufferLength;
  var x = 0;

  for (var i = 0; i < bufferLength; i++) {
    var v = dataArray[i] / 128.0;
    var y = (v \* canvas.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();
```

Спецификации
------------

| Specification |
| --- |
| Web Audio API # AnalyserNode |

Совместимость с браузерами
--------------------------

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See also
--------

* Using the Web Audio API (en-US)