WaveShaperNode.curve

WaveShaperNode 接口的 curve 属性是一个描述要被应用的畸变的Float32Array (en-US) 数组.

数组的中间元素被应用于每个信号数值 0， 第一个应用于信号数值 -1，最后一个应用于信号数值 1； 小于 -1 或者大于 1 的数值分别按照 -1 和 1 来处理。

如有必要， 使用线性插值计算畸变曲线的中间值。

注意: 数组的值可以是 null : 在这个情况下, 不会有畸变被应用到输入的信号上。

语法

var audioCtx = new AudioContext();
var distortion = audioCtx.createWaveShaper();
distortion.curve = myCurveDataArray; // myCurveDataArray is a Float32Array

Value

 一个 Float32Array (en-US).

示例

The following example shows basic usage of an AudioContext to create a wave shaper node. For applied examples/information, check out our Voice-change-O-matic demo (see app.js for relevant code).

Note: Sigmoid functions are commonly used for distortion curves because of their natural properties. Their S-shape, for instance, helps create a smoother sounding result. We found the below distortion curve code on Stack Overflow.

var audioCtx = new (window.AudioContext || window.webkitAudioContext)();
var distortion = audioCtx.createWaveShaper();

  ...

function makeDistortionCurve(amount) {
  var k = typeof amount === 'number' ? amount : 50,
    n_samples = 44100,
    curve = new Float32Array(n_samples),
    deg = Math.PI / 180,
    i = 0,
    x;
  for ( ; i < n_samples; ++i ) {
    x = i * 2 / n_samples - 1;
    curve[i] = ( 3 + k ) * x * 20 * deg / ( Math.PI + k * Math.abs(x) );
  }
  return curve;
};

  ...

distortion.curve = makeDistortionCurve(400);
distortion.oversample = '4x';

规范

Specification Status Comment
Web Audio API
curve		 Working Draft  

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参考链接