AudioContext+canvas實現音頻可視化

時間 2019-12-06

標籤 audiocontext+canvas audiocontext canvas 實現音頻可視化简体版

原文原文鏈接

1.建立AudioContext對象

AudioContext() 構造方法建立了一個新的 AudioContext 對象它表明了一個由音頻模塊連接而成的音頻處理圖, 每個模塊由 AudioNode 表示.javascript

let AudioContext = window.AudioContext || window.webkitAudioContext;
let audioContext = new AudioContext();      //實例化AudioContext對象
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2.建立AnalyserNode節點

let analyser;

analyser = audioContext.createAnalyser();
analyser.fftSize = 256;
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3.連接節點

let audioSrc = audioContext.createMediaElementSource(audio); //從audio中獲取聲音源文件
 audioSrc.connect(analyser);
 analyser.connect(audioContext.destination);
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4.AnalyserNode數據解析

let dataArray = new Uint8Array(analyser.frequencyBinCount);
 analyser.getByteFrequencyData(dataArray);
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5.requestAnimationFrame的使用

要使動畫動起來，咱們須要不斷重繪Canvas標籤裏的內容，requestAnimationFrame 能夠幫你以60fps的幀率繪製動畫。css

function render() {
    requestAnimationFrame(render);
	//...
}
requestAnimationFrame(render);
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6.瀏覽器兼容性:

瀏覽器	Chrome	Firefox	IE	Opera	Safari
支持版本	10.0	25.0	不支持	15.0	6.0

示例代碼

jshtml

let AudioContext = window.AudioContext || window.webkitAudioContext;
let audioContext = new AudioContext();
let analyser = audioContext.createAnalyser();
analyser.fftSize = 256;
analyser = audioContext.createAnalyser();

let audio = document.getElementById('audio');
let audioSrc = audioContext.createMediaElementSource(audio);
audioSrc.connect(analyser);
analyser.connect(audioContext.destination);
let canvas = document.getElementById('canvas');

let ctx = canvas.getContext("2d");
ctx.lineWidth = 2;
let grd = ctx.createLinearGradient(0, 0, 600, 0);
grd.addColorStop(0, "#00d0ff");
grd.addColorStop(1, "#eee");

let grd2 = ctx.createLinearGradient(0, 0, 600, 0);
grd2.addColorStop(0, "#fff");
grd2.addColorStop(1, "#e720ee");
let het=0;

var globalID;
function render() {
    ctx.clearRect(0, 0, canvas.width, canvas.height);
    let dataArray = new Uint8Array(analyser.frequencyBinCount);
    analyser.getByteFrequencyData(dataArray);
    ctx.beginPath();
    for (let i = 0; i < 200; i++) {
        let value = dataArray[6*i];
        ctx.fillStyle = grd;
        ctx.fillRect(i * 5, 300, 2, -value + 1);
        ctx.fillRect(i * 5, 280-value, 2, het);
        ctx.fillStyle = grd2;
        ctx.fillRect(i * 5, 300, 2, value + 1);
        ctx.fillRect(i * 5, 320+value, 2, het);
    }
    globalID=requestAnimationFrame(render);
};
globalID=requestAnimationFrame(render);


var fileChange = document.getElementById('fileChooser');
	fileChange.onchange = fileChange=(e)=>{
   if( e.target.files[0]){
	let playfile= URL.createObjectURL( e.target.files[0]);
	audio.src=playfile;
	let musicName = e.target.files[0].name.split('.')[0];
	audio.play();
	}
};
	
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htmljava

<!DOCTYPE html>
<html>
    <head>
        <meta charset="utf-8" />
        <title></title>
    </head>
    <style type="text/css">
        body{
            height: 100%;
            width: 100%;
            background-color: #3f3f3f;
        }
    </style>
    <body>
        <audio id="audio"  src="music/music.mp3">
            Your browser does not support the audio element.
        </audio>
        <canvas id="canvas" width="800" height="600" >
            Your browser does not support Canvas tag.
        </canvas>
        <input id="fileChooser" type="file" />
    </body>
	<script src="js/js.js" type="text/javascript" charset="utf-8"></script>
</html>
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示例：liazm.com/#/audioweb

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