AnalyserNode
La interfaz AnalyserNode
representa un nodo habilitado para proveer frecuencia en tiempo real y analisis de tiempo-dominio. Es un AudioNode
que pasa el flujo de audio sin modificación desde el origen de entrada a la salida, pero, te permite obtener los datos generados, procesarlos, y crear visualizaciones de audio.
Un AnalyzerNode
tiene exactamente una entrada y una salida. El nodo trabaja incluso si la salida no se encuentra conectada.
Numero de entradas | 1 |
---|---|
Numero de salidas | 1 (puede estar desconectada) |
Modo de conteo de canal | "explicit" |
Conteo de cana | 1 |
Interpretación de canal | "speakers" |
Herencia
Esta interfaz hereda de las siguientes interfaces padre:
Propiedades
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) Read only- 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()
(en-US)- 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
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 AudioContext
(en-US) 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);
// 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
Specification | Status | Comment |
---|---|---|
Web Audio API La definición de 'AnalyserNode' en esta especificación. |
Working Draft |
Browser compatibility
Feature | Chrome | Firefox (Gecko) | Internet Explorer | Opera | Safari (WebKit) |
---|---|---|---|---|---|
Basic support | 10.0webkit (en-US) | 25.0 (25.0) | Sin soporte | 15.0 webkit (en-US) 22 |
6.0webkit (en-US) |
Feature | Android | Firefox Mobile (Gecko) | Firefox OS | IE Mobile | Opera Mobile | Safari Mobile | Chrome for Android |
---|---|---|---|---|---|---|---|
Basic support | ? | 26.0 | 1.2 | ? | ? | ? | 33.0 |