js的MediaRecorder录音录视频方法笔记

   /**
   * 录音举例说明
   * https://www.cnblogs.com/zaijin-yang/p/17306578.html
   * 通过 web 录制视频（摄像头）并上传
   * https://cloud.tencent.com/developer/article/1818977?areaId=106001
   * 视频录制基础知识-MediaRecorder
   * https://www.jianshu.com/p/ad7dfd50880e
   */

import React, { useState, useEffect } from 'react'   var mediaRecorder var stream var chunks = [] export default function App() {   return (     <MyRecord />   ); }  function MyRecord() {   var [fileSize, setFileSize] = useState(0)   var [url, setUrl] = useState(null)   /**    * 录音举例说明    * https://www.cnblogs.com/zaijin-yang/p/17306578.html    * 通过 web 录制视频（摄像头）并上传    * https://cloud.tencent.com/developer/article/1818977?areaId=106001    * 视频录制基础知识-MediaRecorder    * https://www.jianshu.com/p/ad7dfd50880e    */    async function initRecord() {     //stream = await navigator.mediaDevices.getUserMedia({ audio: true })     try {       stream = await navigator.mediaDevices.getUserMedia({ video: { facingMode: 'environment' } })       // const videoElement = document.querySelector('video');       // videoElement.srcObject = stream;       //通过调用getUserMedia方法获取摄像头的实时视频流，并将其赋值给srcObject属性，从而在网页上显示实时视频。       //src适用于加载已有的静态视频文件。       //srcObject适用于处理实时视频流，比如从摄像头捕获到的视频。       mediaRecorder = new MediaRecorder(stream);       mediaRecorder.ondataavailable = event => {         if (event.data.size > 0) {           console.log('======ondataavailable事件触发,chunks.length:', chunks.length);           setFileSize(event.data.size)           chunks.push(event.data); // 将数据块追加到 chunks 数组中           }       };       mediaRecorder.onstop = () => {         console.log('======按下了停止录音键', mediaRecorder.mimeType);         const blob = new Blob(chunks, { type: mediaRecorder.mimeType }); // 将数据块转换为 Blob           // 此时你可以使用 blob 对象，比如上传到服务器或保存到本地文件         console.log('Blob created:', blob.size);         const url = URL.createObjectURL(blob); //创建新的URL表示指定的blob对象         const audio = document.getElementById("aaaa"); //创建标签         audio.src = url;         //销毁视频,释放资源URL.revokeObjectURL(url)       }     } catch (e) {       console.log('用户禁止了摄像头权限')     }   }   function startRecord() {     chunks = []     mediaRecorder.start();   }   function stopRecord() {     /**     *   mediaRecorder.state返回当前状态 (闲置中，录制中或者暂停 ) (inactive, recording, or paused.)     */     if (mediaRecorder.state === "recording") {       mediaRecorder.stop();     }   }   function destroyRecord() {     // 终止流（这可以让浏览器上正在录音的标志消失掉）     stream.getTracks().forEach(track => track.stop());     stream = null;   }   function pauseRecord() {     mediaRecorder.pause();   }   function resumeRecord() {     mediaRecorder.resume();   }    var ss = { fontSize: '20px', margin: '10px' }   return (     <div>       <video id="aaaa" controls playsInline style={{ width: '300px', height: '200px' }}></video>       <h3>文件大小:{fileSize}</h3>       <button style={ss} onClick={initRecord}>初始化录音</button>       <button style={ss} onClick={startRecord}>开始录音</button>       <button style={ss} onClick={stopRecord}>停止录音</button>       <button style={ss} onClick={destroyRecord}>销毁录音</button>       <button style={ss} onClick={pauseRecord}>暂停录音</button>       <button style={ss} onClick={resumeRecord}>恢复录制</button>     </div >   ); }