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.
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:
Constructor
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).
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();
Specifications
Specification | Status | Comment |
---|---|---|
Web Audio API Определение 'AnalyserNode' в этой спецификации. |
Рекомендация |
Browser compatibility
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