javascript - 无法设置远程应答 sdp：在错误状态下调用：STATE_INPROGRESS

Question

我在 WebRTC 和 WebSockets 上进行多用户视频聊天。当 2 个用户连接时一切正常，但当第 3 个用户连接第一个视频时消失，第一个和第三个用户之间的新视频建立。

错误：

“在错误状态下调用：STATE_INPROGRESS”

和

“错误处理 ICE 候选”

请指教我做错了什么。提前致谢！

这是我的代码：

var peerConnections = {};
var mainStream;
var currentId;

navigator.getUserMedia(
  { audio: true, video: true },
  gotStream,
  function(error) { console.log(error) }
);

function getPeerConnection(id) {
  // return connection if available
  if (peerConnections[id]) {
    return peerConnections[id];
  }

  // create new connection else
  var pc = new RTCPeerConnection(null);
  peerConnections[id] = pc;

  pc.addStream(mainStream);
  pc.onicecandidate = function (event) {
    console.log('on ice candidate', event);
    if (event.candidate) {
      sendMessage({
        type: 'candidate',
        label: event.candidate.sdpMLineIndex,
        id: event.candidate.sdpMid,
        candidate: event.candidate.candidate,
        by: currentId,
        to: id
      });
    }
  };


  pc.onaddstream = function(evt) {
      var elements = document.querySelectorAll('.remoteVideo2');
      // when stream arrives loop through containers and add video
      for(var i =0; i < elements.length; i++) {
        console.log('element[i].src', elements[i].src);
        if(!elements[i].src){
          elements[i].src = URL.createObjectURL(evt.stream);
          break;
        }
      }
  };
  return pc;
}

// add local video
function gotStream(stream) {
    mainStream = stream;
    document.getElementById("localVideo").src = URL.createObjectURL(stream);
}

function createOffer(userId) {
  var pc = getPeerConnection(userId);
  pc.createOffer(
    function(description){
      pc.setLocalDescription(description);
      socket.emit('message', description);
    },
    function(error) { console.log(error) },
  );
}

function createAnswer(userId) {
  var pc = getPeerConnection(userId);
  pc.createAnswer(
    function(description){
      pc.setLocalDescription(description);
      socket.emit('message', description);
    },
    function(error) { console.log(error) },
    { 'mandatory': { 'OfferToReceiveAudio': true, 'OfferToReceiveVideo': true } }
  );
}

////////////////////////////////////////////////
// Socket.io

var socket = io.connect('https://my.webrtc.server:8888');

    window.room = prompt("Enter room name:");

    if (room !== "") {
      socket.emit('create or join', room);
    }

function sendMessage(message) {
  socket.emit('message', message);
}

socket.on('message', function (data) {
  handleMessage(data);
});

// handling all type of messages
function handleMessage(message) {
  var pc = getPeerConnection(message.id);
  if (message.type === 'offer') {
    pc.setRemoteDescription(new SessionDescription(message), function() {
      createAnswer(message.id);
    });
  }
  else if (message.type === 'answer') {
    pc.setRemoteDescription(new SessionDescription(message), function() {
    });
  }
  else if (message.type === 'candidate') {
    var candidate = new IceCandidate({sdpMLineIndex: message.label, candidate: message.candidate});
    pc.addIceCandidate(candidate, function(){console.log('candidate is ok')}, function(e){console.log('error candidate', e)});
  }
}

// creating new offer on new peer connected to the room
socket.on('peer.connected', function (data) {
  createOffer(data.id);
});

这是服务器端：

var socketIO = require('socket.io'),

module.exports = function (server, config) {
    var io = socketIO.listen(server);
    var rooms = {};

    io.sockets.on('connection', function (client) {
        client.resources = {
            screen: false,
            video: true,
            audio: false
        };

        // pass a message to another id
        client.on('message', function (details) {
                details.id = client.id;
                client.broadcast.emit('message', details);
            if (!details) return;
        });

         // Create or join here
        client.on('create or join', function(room) {
        if(room){
                if(!rooms[room]){
                        rooms[room] = [client];
                } else {
                        rooms[room].push(client);
                }
        }

        rooms[room].forEach(function(sock){
                sock.emit('peer.connected', {id: client.id});
        });
  });

};