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
-
Is an unsigned long value representing the size of the FFT (Fast Fourier Transform) to be used to determine the frequency domain.
AnalyserNode.frequencyBinCount
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
-
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
-
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
-
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 a
Float32Array
array passed into it.
AnalyserNode.getByteFrequencyData()
-
Copies the current frequency data into a
Uint8Array
(unsigned byte array) passed into it.
AnalyserNode.getFloatTimeDomainData()
-
Copies the current waveform, or time-domain, data into a
Float32Array
array passed into it. AnalyserNode.getByteTimeDomainData()
-
Copies the current waveform, or time-domain, data into a
Uint8Array
(unsigned byte array) passed into it.
Examples
Nota: 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);
// 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();
Especificaciones
Specification |
---|
Web Audio API # AnalyserNode |
Compatibilidad con navegadores
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