AudioContext.createAnalyser()

AudioContextcreateAnalyser()方法能创建一个AnalyserNode,可以用来获取音频时间和频率数据,以及实现数据可视化。

注意:关于该节点的更多信息,请查看AnalyserNode

语法

var audioCtx = new AudioContext();
var analyser = audioCtx.createAnalyser();

返回值

AnalyserNode对象

例子

下面的例子展示了AudioContext创建分析器节点的基本用法,然后用requestAnimationFrame()来反复获取时域数据,并绘制出当前音频输入的“示波器风格”输出。更多完整例子请查看Voice-change-O-matic demo (中app.js的128–205行代码)

var audioCtx = new (window.AudioContext || window.webkitAudioContext)();
var analyser = audioCtx.createAnalyser();

  ...

analyser.fftSize = 2048;
var bufferLength = analyser.fftSize;
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();

规范

Specification Status Comment
Web Audio API
createAnalyser()
Working Draft  

浏览器兼容性

We're converting our compatibility data into a machine-readable JSON format. This compatibility table still uses the old format, because we haven't yet converted the data it contains. Find out how you can help! (en-US)
Feature Chrome Firefox (Gecko) Internet Explorer Opera Safari (WebKit)
Basic support 10.0webkit (en-US) 25.0 (25.0)  未实现 15.0webkit (en-US)
22
6.0webkit (en-US)
Feature Android Firefox Mobile (Gecko) Firefox OS IE Mobile Opera Mobile Safari Mobile Chrome for Android
Basic support ? 26.0 1.2 ? ? ? 33.0

另见