AnalyserNode интерфейс который предоставляет частоту (frequency) в реальном времени. ЭлементAudioNode 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.

Наследование

Интерфейс унаследован от следующих родительских интерфейсов:

Constructor

AnalyserNode()

Creates a new instance of anAnalyserNode object.

Properties

Inherits properties from its parent,AudioNode.

AnalyserNode.fftSize

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

AnalyserNode.frequencyBinCountТолько 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

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 usinggetByteFrequencyData().

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 usinggetByteFrequencyData().

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,AudioNode.

AnalyserNode.getFloatFrequencyData()

Copies the current frequency data into aFloat32Array array passed into it.

AnalyserNode.getByteFrequencyData()

Copies the current frequency data into aUint8Array (unsigned byte array) passed into it.

AnalyserNode.getFloatTimeDomainData()

Copies the current waveform, or time-domain, data into aFloat32Array array passed into it.

AnalyserNode.getByteTimeDomainData()

Copies the current waveform, or time-domain, data into aUint8Array (unsigned byte array) passed into it.

Examples

Basic usage

The following example shows basic usage of anAudioContext to create anAnalyserNode, thenrequestAnimationFrame 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 ourVoice-change-O-matic demo (seeapp.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);// Get a canvas defined with ID "oscilloscope"var canvas = document.getElementById("oscilloscope");var canvasCtx = canvas.getContext("2d");// draw an oscilloscope of the current audio sourcefunction 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

Совместимость с браузерами

Смотрите также

• Using the Web Audio API