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janus.js video root 基础实例

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Janus项目附带实例里有很多业务代码，初学无法抓住重点。
这个例子仅仅包含可以完成一个多人视频会议的最基本的代码。
可查看注释和console输出，快速了解基本流程

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<!-- index.html -->
<!doctype html>
<html lang="zh-CN">
<head>
    <meta charset="UTF-8">
    <meta name="viewport"
          content="width=device-width, user-scalable=no, initial-scale=1.0, maximum-scale=1.0, minimum-scale=1.0">
    <meta http-equiv="X-UA-Compatible" content="ie=edge">
    <title>Document</title>
</head>
<body>
<button id="start">Start</button>
<div id="localVideoWarp">
    <div>localVideo</div>
</div>
<div id="remoteVideoWarp">
    <div>remoteVideos</div>
</div>

<script type="text/javascript" src="cdnjs/adapter.min.js"></script>
<script type="text/javascript" src="cdnjs/jquery.min.js"></script>
<script type="text/javascript" src="janus.js"></script>
<script type="text/javascript" src="test.js"></script>

</body>
</html>
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// test.js

// TODO 服务器已创建好的房间ID
const roomId = 0000;
// 一个随机字符串，可以用来归类来自同一个用户的所有handle
const opaqueId = Janus.randomString(20);
// 本地音视频流
let localStream;
// janus 实例
let janus;
// TODO server地址
const server = 'wss://xxxxx';

// 如果房间配置中require_pvtid===true, 则privateId在订阅流时必须提供该ID
let privateId;
// 发送的远端的字符串，可以传递一些信息，如（用户名，json字符串等）
const display = 'display';
// 用户ID，需保持唯一
const uid = Date.now();

// 本地用户video room handle
let localVideoRoomHandle;
// 远端用户video room handle
const remoteVMHandles = [];

console.log('Janus init start.');
Janus.init({
  // debug: 'all',
  callback() {
    console.log('Janus init success.');

    $('#start').click(async () => {
      localStream = await navigator.mediaDevices.getUserMedia({audio: true, video: true});
      console.log('mediaDevices.getUserMedia success. localStream: ', localStream);
      addLocalVideo(localStream);

      console.log('Create janus instance start.');
      janus = new Janus({
        server,
        iceServers: [{urls: 'stun:stun.stunprotocol.org'}],
        success() {
          console.log('Create janus instance success. janus:', janus);

          console.log('Attach video room plugin start.');
          janus.attach({
            plugin: 'janus.plugin.videoroom',
            opaqueId,
            success(pluginHandle) {
              localVideoRoomHandle = pluginHandle;
              console.log('Attach video room plugin success. localVideoRoomHandle: ', localVideoRoomHandle);
              join();
            },
            onmessage: function(msg, jsep) {
              const event = msg['videoroom'];
              switch (event) {
                case 'joined': {

                  const {id, private_id} = msg;
                  privateId = private_id;
                  console.log('Join video room success. ', `id: ${id} privateId: ${privateId}`);

                  // 发布流
                  publish();

                  // 如果有远端流。订阅
                  if (msg['publishers']) {
                    for (const publisher of msg['publishers']) {
                      subscribe(publisher.id, publisher.display, publisher.audio, publisher.video);
                    }
                  }

                  break;
                }
                case 'event': {
                  // 如果有远端流。订阅
                  if (msg['publishers']) {
                    for (const publisher of msg['publishers']) {
                      subscribe(publisher.id, publisher.display, publisher.audio, publisher.video);
                    }
                  }
                  break;
                }

              }

              // 协商
              if (jsep) {
                localVideoRoomHandle.handleRemoteJsep({jsep});
              }
            },
            error(err) {
              console.error(err);
            },
          });
        },
        error(error) {
          console.error(error);
        },
        destroyed() {
          console.log('destroyed');
        },
      });
    });
  },
});

function join() {
  console.log('Join video room start.');
  var register = {
    request: 'join',
    room: roomId,
    ptype: 'publisher',
    id: uid,
    display: display,
  };
  localVideoRoomHandle.send({message: register});
}

function publish() {
  console.log('Publish video room start.');
  localVideoRoomHandle.createOffer({
    media: {
      audioRecv: false,
      videoRecv: false,
      audioSend: true,
      videoSend: true,
    },
    success(jsep) {
      var publish = {request: 'configure', audio: true, video: true};
      localVideoRoomHandle.send({message: publish, jsep: jsep});
    },
  });
}

function subscribe(id, display, audio, video) {
  console.log('subscribe start. params:', id, display, audio, video);
  let remoteHandle;
  janus.attach(
    {
      plugin: 'janus.plugin.videoroom',
      opaqueId,
      success: function(pluginHandle) {
        remoteHandle = pluginHandle;
        const subscribe = {
          request: 'join',
          room: roomId,
          ptype: 'subscriber',
          feed: id,
          private_id: privateId,
        };
        remoteHandle.videoCodec = video;
        remoteHandle.send({message: subscribe});
        console.log('remoteHandle:', remoteHandle);
        remoteVMHandles.push(remoteHandle);
      },
      onmessage(msg, jsep) {
        var event = msg['videoroom'];
        if (jsep) {
          Janus.debug('Handling SDP as well...', jsep);
          remoteHandle.createAnswer(
            {
              jsep: jsep,
              media: {audioSend: false, videoSend: false},	// We want recvonly audio/video
              success: function(jsep) {
                var body = {request: 'start', room: roomId};
                remoteHandle.send({message: body, jsep: jsep});
              },
            });
        }
      },
      onremotestream: function(stream) {
        addRemoteVideo(stream, remoteHandle);
      },
    });
}

function addLocalVideo(stream) {
  const videoEle = document.createElement('video');
  videoEle.srcObject = stream;
  videoEle.width = 320;
  videoEle.height = 240;
  videoEle.autoplay = true;
  $('#localVideoWarp').append(videoEle);
}

function addRemoteVideo(stream, remoteHandle) {

  // 同一个远端用户会多次触发onremotestream，需要去重
  if ($(`#remoteHandle${remoteHandle.id}`)[0]) {
    return;
  }

  const videoEle = document.createElement('video');
  videoEle.srcObject = stream;
  videoEle.width = 320;
  videoEle.height = 240;
  videoEle.autoplay = true;
  videoEle.id = `remoteHandle${remoteHandle.id}`;
  $('#remoteVideoWarp').append(videoEle);
}