AudioBuffer
La interfaz AudioBuffer
representa un pequeño recurso de audio que se almacena en memoria, creado a partir de un archivo de audio usando el método AudioContext.decodeAudioData()
(en-US), o de datos en bruto con el método AudioContext.createBuffer()
(en-US). Una véz cargado en AudioBuffer, el audio puede ser reproducido pasandolo en el método AudioBufferSourceNode
(en-US).
Objetos de este tipo son diseñados para almacenar pequeños trozos de audio, normalmente menos de 45 segundos. Para audios más extensos, los objectos implementan MediaElementAudioSourceNode
(en-US) que es más adecuado. El buffer contiene data en el siguiente formado: non-interleaved IEEE754 32-bit linear PCM with a nominal range between -1
and +1
, that is, 32bits floating point buffer, with each samples between -1.0 and 1.0. If the AudioBuffer
has multiple channels, they are stored in separate buffer.
Constructor
AudioBuffer()
(en-US)-
Crea y retorna una nueva instancia de
AudioBuffer
Propiedades
AudioBuffer.sampleRate
(en-US) Read only-
Returns a float representing the sample rate, in samples per second, of the PCM data stored in the buffer.
AudioBuffer.length
(en-US) Read only-
Returns an integer representing the length, in sample-frames, of the PCM data stored in the buffer.
AudioBuffer.duration
(en-US) Read only-
Returns a double representing the duration, in seconds, of the PCM data stored in the buffer.
AudioBuffer.numberOfChannels
(en-US) Read only-
Returns an integer representing the number of discrete audio channels described by the PCM data stored in the buffer.
Métodos
AudioBuffer.getChannelData()
(en-US)-
Returns a
Float32Array
(en-US) containing the PCM data associated with the channel, defined by thechannel
parameter (with0
representing the first channel). AudioBuffer.copyFromChannel()
(en-US)-
Copies the samples from the specified channel of the
AudioBuffer
to thedestination
array. AudioBuffer.copyToChannel()
(en-US)-
Copies the samples to the specified channel of the
AudioBuffer
, from thesource
array.
Ejemplo
El siguiente ejemplo muestra como se crea un AudioBuffer
y rellena con un sonido blanco aleatorio. Puedes encontrar el código completo en nuestro repositorio: webaudio-examples; y una versión disponible: running live
js
var audioCtx = new (window.AudioContext || window.webkitAudioContext)();
// Create an empty three-second stereo buffer at the sample rate of the AudioContext
var myArrayBuffer = audioCtx.createBuffer(
2,
audioCtx.sampleRate * 3,
audioCtx.sampleRate,
);
// Fill the buffer with white noise;
// just random values between -1.0 and 1.0
for (var channel = 0; channel < myArrayBuffer.numberOfChannels; channel++) {
// This gives us the actual array that contains the data
var nowBuffering = myArrayBuffer.getChannelData(channel);
for (var i = 0; i < myArrayBuffer.length; i++) {
// Math.random() is in [0; 1.0]
// audio needs to be in [-1.0; 1.0]
nowBuffering[i] = Math.random() * 2 - 1;
}
}
// Get an AudioBufferSourceNode.
// This is the AudioNode to use when we want to play an AudioBuffer
var source = audioCtx.createBufferSource();
// set the buffer in the AudioBufferSourceNode
source.buffer = myArrayBuffer;
// connect the AudioBufferSourceNode to the
// destination so we can hear the sound
source.connect(audioCtx.destination);
// start the source playing
source.start();
Especificaciones
Specification |
---|
Web Audio API # AudioBuffer |
Compatibilidad con navegadores
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