【发布时间】：2013-06-27 19:45:33
【问题描述】：
编辑：我写了一个详细的教程来解释如何构建一个简单的视频聊天应用程序，包括一个信令服务器：
Tutorial: Create your own Videochat-Application with HTML and JavaScript
如果您觉得它有帮助且易于理解，请告诉我。谢谢！
我正在尝试通过 WebRTC 和 Websocket (nodejs-server) 让 Streams 工作。据我所知，通过 SDP 的握手工作并建立了对等连接。 问题是 - 远程视频没有播放。 src-Attribute 获取 Blob 并设置了自动播放，但它不会播放。 也许我对 ICE 候选人做错了什么（它们用于媒体流，对吗？）。 有什么方法可以检查 PeerConnection 是否设置正确？
编辑：也许我应该解释一下代码是如何工作的
在加载网站时，会建立与 websocket-server 的连接，使用 googles STUN-server 创建 PeerConnection，并收集视频和音频流并将其添加到 PeerConnection
当一个用户单击“创建报价”按钮时，一条包含其会话描述 (SDP) 的消息被发送到服务器（客户端函数 sendOffer()），服务器将其广播给另一个用户
其他用户收到消息并保存他收到的 SDP
如果用户点击“accept offer”，SDP 被添加到 RemoteDescription (func createAnswer())，然后发送一个应答消息（包含应答用户的 SDP）给提供用户
在提供用户端执行 func offerAccepted()，它将其他用户的 SDP 添加到他的 RemoteDesription。
我不确定在什么时候调用了 icecandidate-handlers，但我认为它们应该可以工作，因为我在两边都得到了两个日志。
这是我的代码（这只是为了测试，所以即使有一个叫做广播的功能，也意味着一次只能有2个用户在同一个网站上）：
index.html 的标记：
<!DOCTYPE html>
<html>
<head>
<meta charset="utf-8">
<style>
#acceptOffer {
display: none;
}
</style>
</head>
<body>
<h2>Chat</h2>
<div>
<textarea class="output" name="" id="" cols="30" rows="10"></textarea>
</div>
<button id="createOffer">create Offer</button>
<button id="acceptOffer">accept Offer</button>
<h2>My Stream</h2>
<video id="myStream" autoplay src=""></video>
<h2>Remote Stream</h2>
<video id="remoteStream" autoplay src=""></video>
<script src="http://ajax.googleapis.com/ajax/libs/jquery/1.9.1/jquery.min.js"></script>
<script src="websocketClient.js"></script>
</body>
</html>
这是服务器代码：
"use strict";
var webSocketsServerPort = 61122;
var webSocketServer = require('websocket').server,
http = require('http'),
clients = [];
var server = http.createServer(function(request, response) {
// Not important for us. We're writing WebSocket server, not HTTP server
});
server.listen(webSocketsServerPort, function() {
console.log((new Date()) + " Server is listening on port " + webSocketsServerPort);
});
var wsServer = new webSocketServer({
httpServer: server
});
wsServer.on('request', function(request) {
console.log((new Date()) + ' Connection from origin ' + request.origin + '.');
var connection = request.accept(null, request.origin),
index = clients.push(connection) - 1,
userName=false;
console.log((new Date()) + ' Connection accepted from '+connection.remoteAddress);
// user sent some message
connection.on('message', function(message) {
var json = JSON.parse(message.utf8Data);
console.log(json.type);
switch (json.type) {
case 'broadcast':
broadcast(json);
break;
case 'emit':
emit({type:'offer', data:json.data.data});
break;
case 'client':
respondToClient(json, clients[index]);
break;
default:
respondToClient({type:'error', data:'Sorry, i dont understand that.'}, clients[index]);
break;
}
});
connection.on('close', function(connection) {
clients.splice(index,1);
console.log((new Date()) + " Peer " + connection.remoteAddress + " disconnected.");
broadcast({type:'text', data: userName+' has left the channel.'});
});
var respondToClient = function(data, client){
client.sendUTF(JSON.stringify( data ));
};
var broadcast = function(data){
for(var i = 0; i < clients.length; i++ ) {
if(i != index ) {
clients[i].sendUTF(JSON.stringify( data ));
}
}
};
var emit = function(){
// TBD
};
});
这里是客户端代码：
$(function () {
"use strict";
/**
* Websocket Stuff
**/
window.WebSocket = window.WebSocket || window.MozWebSocket;
// open connection
var connection = new WebSocket('ws://url-to-node-server:61122'),
myName = false,
mySDP = false,
otherSDP = false;
connection.onopen = function () {
console.log("connection to WebSocketServer successfull");
};
connection.onerror = function (error) {
console.log("WebSocket connection error");
};
connection.onmessage = function (message) {
try {
var json = JSON.parse(message.data),
output = document.getElementsByClassName('output')[0];
switch(json.callback) {
case 'offer':
otherSDP = json.data;
document.getElementById('acceptOffer').style.display = 'block';
break;
case 'setIceCandidate':
console.log('ICE CANDITATE ADDED');
peerConnection.addIceCandidate(json.data);
break;
case 'text':
var text = output.value;
output.value = json.data+'\n'+output.value;
break;
case 'answer':
otherSDP = json.data;
offerAccepted();
break;
}
} catch (e) {
console.log('This doesn\'t look like a valid JSON or something else went wrong.');
return;
}
};
/**
* P2P Stuff
**/
navigator.getMedia = ( navigator.getUserMedia ||
navigator.webkitGetUserMedia ||
navigator.mozGetUserMedia ||
navigator.msGetUserMedia);
// create Connection
var peerConnection = new webkitRTCPeerConnection(
{ "iceServers": [{ "url": "stun:stun.l.google.com:19302" }] }
);
var remoteVideo = document.getElementById('remoteStream'),
myVideo = document.getElementById('myStream'),
// get local video-Stream and add to Peerconnection
stream = navigator.webkitGetUserMedia({ audio: false, video: true }, function (stream) {
myVideo.src = webkitURL.createObjectURL(stream);
console.log(stream);
peerConnection.addStream(stream);
});
// executes if other side adds stream
peerConnection.onaddstream = function(e){
console.log("stream added");
if (!e)
{
return;
}
remoteVideo.setAttribute("src",URL.createObjectURL(e.stream));
console.log(e.stream);
};
// executes if my icecandidate is received, then send it to other side
peerConnection.onicecandidate = function(candidate){
console.log('ICE CANDITATE RECEIVED');
var json = JSON.stringify( { type: 'broadcast', callback:'setIceCandidate', data:candidate});
connection.send(json);
};
// send offer via Websocket
var sendOffer = function(){
peerConnection.createOffer(function (sessionDescription) {
peerConnection.setLocalDescription(sessionDescription);
// POST-Offer-SDP-For-Other-Peer(sessionDescription.sdp, sessionDescription.type);
var json = JSON.stringify( { type: 'broadcast', callback:'offer',data:{sdp:sessionDescription.sdp,type:'offer'}});
connection.send(json);
}, null, { 'mandatory': { 'OfferToReceiveAudio': true, 'OfferToReceiveVideo': true } });
};
// executes if offer is received and has been accepted
var createAnswer = function(){
peerConnection.setRemoteDescription(new RTCSessionDescription(otherSDP));
peerConnection.createAnswer(function (sessionDescription) {
peerConnection.setLocalDescription(sessionDescription);
// POST-answer-SDP-back-to-Offerer(sessionDescription.sdp, sessionDescription.type);
var json = JSON.stringify( { type: 'broadcast', callback:'answer',data:{sdp:sessionDescription.sdp,type:'answer'}});
connection.send(json);
}, null, { 'mandatory': { 'OfferToReceiveAudio': true, 'OfferToReceiveVideo': true } });
};
// executes if other side accepted my offer
var offerAccepted = function(){
peerConnection.setRemoteDescription(new RTCSessionDescription(otherSDP));
console.log('it should work now');
};
$('#acceptOffer').on('click',function(){
createAnswer();
});
$('#createOffer').on('click',function(){
sendOffer();
});
});
我还读到必须在发送任何报价之前收集本地媒体流。这是否意味着我必须在创建 PeerConnection 时添加它？ IE。像这样：
// create Connection
var peerConnection = new webkitRTCPeerConnection(
{
"iceServers": [{ "url": "stun:stun.l.google.com:19302" }],
"mediaStream": stream // attach media stream here?
}
);
在此先感谢，感谢您的帮助！
EDIT2： 我现在更进一步了。由于“指定了无效或非法的字符串。”，添加远程冰候选（客户端代码中的 switch-case setIceCandidate）似乎不起作用。 json.data.candidate-object 看起来像这样：
candidate: "a=candidate:1663431597 2 udp 1845501695 141.84.69.86 57538 typ srflx raddr 10.150.16.92 rport 57538 generation 0
↵"
sdpMLineIndex: 1
sdpMid: "video"
我尝试创建一个这样的新候选人
var remoteCandidate = new RTCIceCandidate(json.data.candidate);
peerConnection.addIceCandidate(remoteCandidate);
但我仍然遇到语法错误
【问题讨论】：
标签： stream websocket p2p webrtc stun