AudioBuffer.getChannelData()

Baseline Widely available

This feature is well established and works across many devices and browser versions. It’s been available across browsers since April 2021.

AudioBuffer 接口的 getChannelData() 方法返回一Float32Array ，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

js
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.

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。

js
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
Web Audio API
# dom-audiobuffer-getchanneldata

Browser compatibility

BCD tables only load in the browser

See also