AudioBuffer.getChannelData()

 AudioBuffer 接口的getChannelData()方法返回一Float32Array (en-US) ,其中包含与通道关联的PCM数据,通道参数定义(0表示第一个通道)。

语法

var myArrayBuffer = audioCtx.createBuffer(2, frameCount, audioCtx.sampleRate);
var nowBuffering = myArrayBuffer.getChannelData(channel);

参数

channel
channel属性是要获取特定通道数据的索引。0代表第一个通道。 如果索引值大于或等于AudioBuffer.numberOfChannels, 会抛出一个索引大小异常(INDEX_SIZE_ERR )的错误。

返回值

 Float32Array (en-US).

例子

在下例中,我们创建一个2秒钟的缓冲区,用白噪声填充它,然后通过AudioBufferSourceNode来播放它. 评论应该会清楚的解释发生的事情。 你也可以实时运行代码,或者查看源代码

var audioCtx = new (window.AudioContext || window.webkitAudioContext)();
var button = document.querySelector('button');
var pre = document.querySelector('pre');
var myScript = document.querySelector('script');

pre.innerHTML = myScript.innerHTML;

// Stereo
var channels = 2;
// Create an empty two second stereo buffer at the
// sample rate of the AudioContext
var frameCount = audioCtx.sampleRate * 2.0;

var myArrayBuffer = audioCtx.createBuffer(2, frameCount, audioCtx.sampleRate);

button.onclick = function() {
  // Fill the buffer with white noise;
  //just random values between -1.0 and 1.0
  for (var channel = 0; channel < channels; channel++) {
   // This gives us the actual ArrayBuffer that contains the data
   var nowBuffering = myArrayBuffer.getChannelData(channel);
   for (var i = 0; i < frameCount; 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();
}

Specification

Specification Status Comment
Web Audio API
getChannelData
Working Draft  

Browser compatibility

BCD tables only load in the browser

See also