RTCPeerConnection的作用是在浏览器之间建立数据的“点对点”（peer to peer）通信.
使用WebRTC的编解码器和协议做了大量的工作，方便了开发者，使实时通信成为可能，甚至在不可靠的网络，
比如这些如果在voip体系下开发工作量将非常大，而用webRTC的js开发者则不用考虑这些，举几个例子：
- 丢包隐藏
- 回声抵消
- 带宽自适应
- 动态抖动缓冲
- 自动增益控制
- 噪声抑制与抑制
- 图像清洗
不同客户端之间的音频/视频传递，是不用通过服务器的。但是，两个客户端之间建立信令联系，需要通过服务器。这个和XMPP的Jingle会话很类似。
服务器主要转递两种数据。
- 通信内容的元数据：打开/关闭对话（session）的命令、媒体文件的元数据（编码格式、媒体类型和带宽）等。
- 网络通信的元数据：IP地址、NAT网络地址翻译和防火墙等。
WebRTC协议没有规定与服务器的信令通信方式，因此可以采用各种方式，比如WebSocket。通过服务器，两个客户端按照Session Description Protocol（SDP协议）交换双方的元数据。
本地和远端通讯的过程有些像电话，比如张三正在试着打电话给李四，详细机制：
- 张三创造了一个RTCPeerConnection 对象。
- 张三通过RTCPeerConnection createOffer()方法创造了一个offer（SDP会话描述） 。
- 张三通过他创建的offer调用setLocalDescription()，保存本地会话描述。
- 张三发送信令给李四。
- 李四接通带有李四offer的电话，调用setRemoteDescription() ，李四的RTCPeerConnection知道张三的设置（张三的本地描述到了李四这里，就成了李四的远程会话描述）。
- 李四调用createAnswer()，将李四的本地会话描述（local session description）成功回调。
- 李四调用setLocalDescription()设置他自己的本地局部描述。
- 李四发送应答信令answer给张三。
- 张三将李四的应答answer用setRemoteDescription()保存为远程会话描述（李四的remote session description）。
SDP详解：
https://datatracker.ietf.org/doc/draft-nandakumar-rtcweb-sdp/?include_text=1
bitbucket的一步一步实验，动手代码
https://bitbucket.org/webrtc/codelab
WebSocket简介（用于信令通信）
https://dzone.com/refcardz/html5-websocket
http://www.infoq.com/articles/Web-Sockets-Proxy-Servers
信令服务或开源webRTC框架
https://easyrtc.com/products/easyrtc-opensource
https://github.com/priologic/easyrtc
https://github.com/andyet/signalmaster
如果您一行代码都不想写，可以看看 vLine, OpenTok and Asterisk.
这里有一个单页应用程序。本地和远程的视频在一个网页，RTCPeerConnection objects 直接交换数据和消息。
https://webrtc.github.io/samples/src/content/peerconnection/pc1/
HTML代码：
<!DOCTYPE html> <html> <head> ...... </head> <body> <div id="container"> <h1><a href="//webrtc.github.io/samples/" title="WebRTC samples homepage">WebRTC samples</a> <span>Peer connection</span></h1> <video id="localVideo" autoplay muted></video> <video id="remoteVideo" autoplay></video> <div> <button id="startButton">Start</button> <button id="callButton">Call</button> <button id="hangupButton">Hang Up</button> </div> </div> <script src="../../../js/adapter.js"></script> <script src="../../../js/common.js"></script> <script src="js/main.js"></script> <script src="../../../js/lib/ga.js"></script> </body> </html>
这里是主要视图：
<video id="localVideo" autoplay muted></video>
<video id="remoteVideo" autoplay></video>
<div>
<button id="startButton">Start</button>
<button id="callButton">Call</button>
<button id="hangupButton">Hang Up</button>
</div>
适配器js代码：
/* * Copyright (c) 2015 The WebRTC project authors. All Rights Reserved. * * Use of this source code is governed by a BSD-style license * that can be found in the LICENSE file in the root of the source * tree. */ /* More information about these options at jshint.com/docs/options */ /* jshint browser: true, camelcase: true, curly: true, devel: true, eqeqeq: true, forin: false, globalstrict: true, node: true, quotmark: single, undef: true, unused: strict */ /* global mozRTCIceCandidate, mozRTCPeerConnection, Promise, mozRTCSessionDescription, webkitRTCPeerConnection, MediaStreamTrack */ /* exported trace,requestUserMedia */ 'use strict'; var getUserMedia = null; var attachMediaStream = null; var reattachMediaStream = null; var webrtcDetectedBrowser = null; var webrtcDetectedVersion = null; var webrtcMinimumVersion = null; var webrtcUtils = { log: function() { // suppress console.log output when being included as a module. if (typeof module !== 'undefined' || typeof require === 'function' && typeof define === 'function') { return; } console.log.apply(console, arguments); }, extractVersion: function(uastring, expr, pos) { var match = uastring.match(expr); return match && match.length >= pos && parseInt(match[pos]); } }; function trace(text) { // This function is used for logging. if (text[text.length - 1] === ' ') { text = text.substring(0, text.length - 1); } if (window.performance) { var now = (window.performance.now() / 1000).toFixed(3); webrtcUtils.log(now + ': ' + text); } else { webrtcUtils.log(text); } } if (typeof window === 'object') { if (window.HTMLMediaElement && !('srcObject' in window.HTMLMediaElement.prototype)) { // Shim the srcObject property, once, when HTMLMediaElement is found. Object.defineProperty(window.HTMLMediaElement.prototype, 'srcObject', { get: function() { // If prefixed srcObject property exists, return it. // Otherwise use the shimmed property, _srcObject return 'mozSrcObject' in this ? this.mozSrcObject : this._srcObject; }, set: function(stream) { if ('mozSrcObject' in this) { this.mozSrcObject = stream; } else { // Use _srcObject as a private property for this shim this._srcObject = stream; // TODO: revokeObjectUrl(this.src) when !stream to release resources? this.src = URL.createObjectURL(stream); } } }); } // Proxy existing globals getUserMedia = window.navigator && window.navigator.getUserMedia; } // Attach a media stream to an element. attachMediaStream = function(element, stream) { element.srcObject = stream; }; reattachMediaStream = function(to, from) { to.srcObject = from.srcObject; }; if (typeof window === 'undefined' || !window.navigator) { webrtcUtils.log('This does not appear to be a browser'); webrtcDetectedBrowser = 'not a browser'; } else if (navigator.mozGetUserMedia && window.mozRTCPeerConnection) { webrtcUtils.log('This appears to be Firefox'); webrtcDetectedBrowser = 'firefox'; // the detected firefox version. webrtcDetectedVersion = webrtcUtils.extractVersion(navigator.userAgent, /Firefox/([0-9]+)./, 1); // the minimum firefox version still supported by adapter. webrtcMinimumVersion = 31; // The RTCPeerConnection object. window.RTCPeerConnection = function(pcConfig, pcConstraints) { if (webrtcDetectedVersion < 38) { // .urls is not supported in FF < 38. // create RTCIceServers with a single url. if (pcConfig && pcConfig.iceServers) { var newIceServers = []; for (var i = 0; i < pcConfig.iceServers.length; i++) { var server = pcConfig.iceServers[i]; if (server.hasOwnProperty('urls')) { for (var j = 0; j < server.urls.length; j++) { var newServer = { url: server.urls[j] }; if (server.urls[j].indexOf('turn') === 0) { newServer.username = server.username; newServer.credential = server.credential; } newIceServers.push(newServer); } } else { newIceServers.push(pcConfig.iceServers[i]); } } pcConfig.iceServers = newIceServers; } } return new mozRTCPeerConnection(pcConfig, pcConstraints); // jscs:ignore requireCapitalizedConstructors }; // The RTCSessionDescription object. if (!window.RTCSessionDescription) { window.RTCSessionDescription = mozRTCSessionDescription; } // The RTCIceCandidate object. if (!window.RTCIceCandidate) { window.RTCIceCandidate = mozRTCIceCandidate; } // getUserMedia constraints shim. getUserMedia = function(constraints, onSuccess, onError) { var constraintsToFF37 = function(c) { if (typeof c !== 'object' || c.require) { return c; } var require = []; Object.keys(c).forEach(function(key) { if (key === 'require' || key === 'advanced' || key === 'mediaSource') { return; } var r = c[key] = (typeof c[key] === 'object') ? c[key] : {ideal: c[key]}; if (r.min !== undefined || r.max !== undefined || r.exact !== undefined) { require.push(key); } if (r.exact !== undefined) { if (typeof r.exact === 'number') { r.min = r.max = r.exact; } else { c[key] = r.exact; } delete r.exact; } if (r.ideal !== undefined) { c.advanced = c.advanced || []; var oc = {}; if (typeof r.ideal === 'number') { oc[key] = {min: r.ideal, max: r.ideal}; } else { oc[key] = r.ideal; } c.advanced.push(oc); delete r.ideal; if (!Object.keys(r).length) { delete c[key]; } } }); if (require.length) { c.require = require; } return c; }; if (webrtcDetectedVersion < 38) { webrtcUtils.log('spec: ' + JSON.stringify(constraints)); if (constraints.audio) { constraints.audio = constraintsToFF37(constraints.audio); } if (constraints.video) { constraints.video = constraintsToFF37(constraints.video); } webrtcUtils.log('ff37: ' + JSON.stringify(constraints)); } return navigator.mozGetUserMedia(constraints, onSuccess, onError); }; navigator.getUserMedia = getUserMedia; // Shim for mediaDevices on older versions. if (!navigator.mediaDevices) { navigator.mediaDevices = {getUserMedia: requestUserMedia, addEventListener: function() { }, removeEventListener: function() { } }; } navigator.mediaDevices.enumerateDevices = navigator.mediaDevices.enumerateDevices || function() { return new Promise(function(resolve) { var infos = [ {kind: 'audioinput', deviceId: 'default', label: '', groupId: ''}, {kind: 'videoinput', deviceId: 'default', label: '', groupId: ''} ]; resolve(infos); }); }; if (webrtcDetectedVersion < 41) { // Work around http://bugzil.la/1169665 var orgEnumerateDevices = navigator.mediaDevices.enumerateDevices.bind(navigator.mediaDevices); navigator.mediaDevices.enumerateDevices = function() { return orgEnumerateDevices().then(undefined, function(e) { if (e.name === 'NotFoundError') { return []; } throw e; }); }; } } else if (navigator.webkitGetUserMedia && window.webkitRTCPeerConnection) { webrtcUtils.log('This appears to be Chrome'); webrtcDetectedBrowser = 'chrome'; // the detected chrome version. webrtcDetectedVersion = webrtcUtils.extractVersion(navigator.userAgent, /Chrom(e|ium)/([0-9]+)./, 2); // the minimum chrome version still supported by adapter. webrtcMinimumVersion = 38; // The RTCPeerConnection object. window.RTCPeerConnection = function(pcConfig, pcConstraints) { // Translate iceTransportPolicy to iceTransports, // see https://code.google.com/p/webrtc/issues/detail?id=4869 if (pcConfig && pcConfig.iceTransportPolicy) { pcConfig.iceTransports = pcConfig.iceTransportPolicy; } var pc = new webkitRTCPeerConnection(pcConfig, pcConstraints); // jscs:ignore requireCapitalizedConstructors var origGetStats = pc.getStats.bind(pc); pc.getStats = function(selector, successCallback, errorCallback) { // jshint ignore: line var self = this; var args = arguments; // If selector is a function then we are in the old style stats so just // pass back the original getStats format to avoid breaking old users. if (arguments.length > 0 && typeof selector === 'function') { return origGetStats(selector, successCallback); } var fixChromeStats = function(response) { var standardReport = {}; var reports = response.result(); reports.forEach(function(report) { var standardStats = { id: report.id, timestamp: report.timestamp, type: report.type }; report.names().forEach(function(name) { standardStats[name] = report.stat(name); }); standardReport[standardStats.id] = standardStats; }); return standardReport; }; if (arguments.length >= 2) { var successCallbackWrapper = function(response) { args[1](fixChromeStats(response)); }; return origGetStats.apply(this, [successCallbackWrapper, arguments[0]]); } // promise-support return new Promise(function(resolve, reject) { if (args.length === 1 && selector === null) { origGetStats.apply(self, [ function(response) { resolve.apply(null, [fixChromeStats(response)]); }, reject]); } else { origGetStats.apply(self, [resolve, reject]); } }); }; return pc; }; // add promise support ['createOffer', 'createAnswer'].forEach(function(method) { var nativeMethod = webkitRTCPeerConnection.prototype[method]; webkitRTCPeerConnection.prototype[method] = function() { var self = this; if (arguments.length < 1 || (arguments.length === 1 && typeof(arguments[0]) === 'object')) { var opts = arguments.length === 1 ? arguments[0] : undefined; return new Promise(function(resolve, reject) { nativeMethod.apply(self, [resolve, reject, opts]); }); } else { return nativeMethod.apply(this, arguments); } }; }); ['setLocalDescription', 'setRemoteDescription', 'addIceCandidate'].forEach(function(method) { var nativeMethod = webkitRTCPeerConnection.prototype[method]; webkitRTCPeerConnection.prototype[method] = function() { var args = arguments; var self = this; return new Promise(function(resolve, reject) { nativeMethod.apply(self, [args[0], function() { resolve(); if (args.length >= 2) { args[1].apply(null, []); } }, function(err) { reject(err); if (args.length >= 3) { args[2].apply(null, [err]); } }] ); }); }; }); // getUserMedia constraints shim. var constraintsToChrome = function(c) { if (typeof c !== 'object' || c.mandatory || c.optional) { return c; } var cc = {}; Object.keys(c).forEach(function(key) { if (key === 'require' || key === 'advanced' || key === 'mediaSource') { return; } var r = (typeof c[key] === 'object') ? c[key] : {ideal: c[key]}; if (r.exact !== undefined && typeof r.exact === 'number') { r.min = r.max = r.exact; } var oldname = function(prefix, name) { if (prefix) { return prefix + name.charAt(0).toUpperCase() + name.slice(1); } return (name === 'deviceId') ? 'sourceId' : name; }; if (r.ideal !== undefined) { cc.optional = cc.optional || []; var oc = {}; if (typeof r.ideal === 'number') { oc[oldname('min', key)] = r.ideal; cc.optional.push(oc); oc = {}; oc[oldname('max', key)] = r.ideal; cc.optional.push(oc); } else { oc[oldname('', key)] = r.ideal; cc.optional.push(oc); } } if (r.exact !== undefined && typeof r.exact !== 'number') { cc.mandatory = cc.mandatory || {}; cc.mandatory[oldname('', key)] = r.exact; } else { ['min', 'max'].forEach(function(mix) { if (r[mix] !== undefined) { cc.mandatory = cc.mandatory || {}; cc.mandatory[oldname(mix, key)] = r[mix]; } }); } }); if (c.advanced) { cc.optional = (cc.optional || []).concat(c.advanced); } return cc; }; getUserMedia = function(constraints, onSuccess, onError) { if (constraints.audio) { constraints.audio = constraintsToChrome(constraints.audio); } if (constraints.video) { constraints.video = constraintsToChrome(constraints.video); } webrtcUtils.log('chrome: ' + JSON.stringify(constraints)); return navigator.webkitGetUserMedia(constraints, onSuccess, onError); }; navigator.getUserMedia = getUserMedia; if (!navigator.mediaDevices) { navigator.mediaDevices = {getUserMedia: requestUserMedia, enumerateDevices: function() { return new Promise(function(resolve) { var kinds = {audio: 'audioinput', video: 'videoinput'}; return MediaStreamTrack.getSources(function(devices) { resolve(devices.map(function(device) { return {label: device.label, kind: kinds[device.kind], deviceId: device.id, groupId: ''}; })); }); }); }}; } // A shim for getUserMedia method on the mediaDevices object. // TODO(KaptenJansson) remove once implemented in Chrome stable. if (!navigator.mediaDevices.getUserMedia) { navigator.mediaDevices.getUserMedia = function(constraints) { return requestUserMedia(constraints); }; } else { // Even though Chrome 45 has navigator.mediaDevices and a getUserMedia // function which returns a Promise, it does not accept spec-style // constraints. var origGetUserMedia = navigator.mediaDevices.getUserMedia. bind(navigator.mediaDevices); navigator.mediaDevices.getUserMedia = function(c) { webrtcUtils.log('spec: ' + JSON.stringify(c)); // whitespace for alignment c.audio = constraintsToChrome(c.audio); c.video = constraintsToChrome(c.video); webrtcUtils.log('chrome: ' + JSON.stringify(c)); return origGetUserMedia(c); }; } // Dummy devicechange event methods. // TODO(KaptenJansson) remove once implemented in Chrome stable. if (typeof navigator.mediaDevices.addEventListener === 'undefined') { navigator.mediaDevices.addEventListener = function() { webrtcUtils.log('Dummy mediaDevices.addEventListener called.'); }; } if (typeof navigator.mediaDevices.removeEventListener === 'undefined') { navigator.mediaDevices.removeEventListener = function() { webrtcUtils.log('Dummy mediaDevices.removeEventListener called.'); }; } // Attach a media stream to an element. attachMediaStream = function(element, stream) { if (webrtcDetectedVersion >= 43) { element.srcObject = stream; } else if (typeof element.src !== 'undefined') { element.src = URL.createObjectURL(stream); } else { webrtcUtils.log('Error attaching stream to element.'); } }; reattachMediaStream = function(to, from) { if (webrtcDetectedVersion >= 43) { to.srcObject = from.srcObject; } else { to.src = from.src; } }; } else if (navigator.mediaDevices && navigator.userAgent.match( /Edge/(d+).(d+)$/)) { webrtcUtils.log('This appears to be Edge'); webrtcDetectedBrowser = 'edge'; webrtcDetectedVersion = webrtcUtils.extractVersion(navigator.userAgent, /Edge/(d+).(d+)$/, 2); // the minimum version still supported by adapter. webrtcMinimumVersion = 12; if (RTCIceGatherer) { window.RTCIceCandidate = function(args) { return args; }; window.RTCSessionDescription = function(args) { return args; }; window.RTCPeerConnection = function(config) { var self = this; this.onicecandidate = null; this.onaddstream = null; this.onremovestream = null; this.onsignalingstatechange = null; this.oniceconnectionstatechange = null; this.onnegotiationneeded = null; this.ondatachannel = null; this.localStreams = []; this.remoteStreams = []; this.getLocalStreams = function() { return self.localStreams; }; this.getRemoteStreams = function() { return self.remoteStreams; }; this.localDescription = new RTCSessionDescription({ type: '', sdp: '' }); this.remoteDescription = new RTCSessionDescription({ type: '', sdp: '' }); this.signalingState = 'stable'; this.iceConnectionState = 'new'; this.iceOptions = { gatherPolicy: 'all', iceServers: [] }; if (config && config.iceTransportPolicy) { switch (config.iceTransportPolicy) { case 'all': case 'relay': this.iceOptions.gatherPolicy = config.iceTransportPolicy; break; case 'none': // FIXME: remove once implementation and spec have added this. throw new TypeError('iceTransportPolicy "none" not supported'); } } if (config && config.iceServers) { this.iceOptions.iceServers = config.iceServers; } // per-track iceGathers etc this.mLines = []; this._iceCandidates = []; this._peerConnectionId = 'PC_' + Math.floor(Math.random() * 65536); // FIXME: Should be generated according to spec (guid?) // and be the same for all PCs from the same JS this._cname = Math.random().toString(36).substr(2, 10); }; window.RTCPeerConnection.prototype.addStream = function(stream) { // clone just in case we're working in a local demo // FIXME: seems to be fixed this.localStreams.push(stream.clone()); // FIXME: maybe trigger negotiationneeded? }; window.RTCPeerConnection.prototype.removeStream = function(stream) { var idx = this.localStreams.indexOf(stream); if (idx > -1) { this.localStreams.splice(idx, 1); } // FIXME: maybe trigger negotiationneeded? }; // SDP helper from sdp-jingle-json with modifications. window.RTCPeerConnection.prototype._toCandidateJSON = function(line) { var parts; if (line.indexOf('a=candidate:') === 0) { parts = line.substring(12).split(' '); } else { // no a=candidate parts = line.substring(10).split(' '); } var candidate = { foundation: parts[0], component: parts[1], protocol: parts[2].toLowerCase(), priority: parseInt(parts[3], 10), ip: parts[4], port: parseInt(parts[5], 10), // skip parts[6] == 'typ' type: parts[7] //generation: '0' }; for (var i = 8; i < parts.length; i += 2) { if (parts[i] === 'raddr') { candidate.relatedAddress = parts[i + 1]; // was: relAddr } else if (parts[i] === 'rport') { candidate.relatedPort = parseInt(parts[i + 1], 10); // was: relPort } else if (parts[i] === 'generation') { candidate.generation = parts[i + 1]; } else if (parts[i] === 'tcptype') { candidate.tcpType = parts[i + 1]; } } return candidate; }; // SDP helper from sdp-jingle-json with modifications. window.RTCPeerConnection.prototype._toCandidateSDP = function(candidate) { var sdp = []; sdp.push(candidate.foundation); sdp.push(candidate.component); sdp.push(candidate.protocol.toUpperCase()); sdp.push(candidate.priority); sdp.push(candidate.ip); sdp.push(candidate.port); var type = candidate.type; sdp.push('typ'); sdp.push(type); if (type === 'srflx' || type === 'prflx' || type === 'relay') { if (candidate.relatedAddress && candidate.relatedPort) { sdp.push('raddr'); sdp.push(candidate.relatedAddress); // was: relAddr sdp.push('rport'); sdp.push(candidate.relatedPort); // was: relPort } } if (candidate.tcpType && candidate.protocol.toUpperCase() === 'TCP') { sdp.push('tcptype'); sdp.push(candidate.tcpType); } return 'a=candidate:' + sdp.join(' '); }; // SDP helper from sdp-jingle-json with modifications. window.RTCPeerConnection.prototype._parseRtpMap = function(line) { var parts = line.substr(9).split(' '); var parsed = { payloadType: parseInt(parts.shift(), 10) // was: id }; parts = parts[0].split('/'); parsed.name = parts[0]; parsed.clockRate = parseInt(parts[1], 10); // was: clockrate parsed.numChannels = parts.length === 3 ? parseInt(parts[2], 10) : 1; // was: channels return parsed; }; // Parses SDP to determine capabilities. window.RTCPeerConnection.prototype._getRemoteCapabilities = function(section) { var remoteCapabilities = { codecs: [], headerExtensions: [], fecMechanisms: [] }; var i; var lines = section.split(' '); var mline = lines[0].substr(2).split(' '); var rtpmapFilter = function(line) { return line.indexOf('a=rtpmap:' + mline[i]) === 0; }; var fmtpFilter = function(line) { return line.indexOf('a=fmtp:' + mline[i]) === 0; }; var parseFmtp = function(line) { var parsed = {}; var kv; var parts = line.substr(('a=fmtp:' + mline[i]).length + 1).split(';'); for (var j = 0; j < parts.length; j++) { kv = parts[j].split('='); parsed[kv[0].trim()] = kv[1]; } console.log('fmtp', mline[i], parsed); return parsed; }; var rtcpFbFilter = function(line) { return line.indexOf('a=rtcp-fb:' + mline[i]) === 0; }; var parseRtcpFb = function(line) { var parts = line.substr(('a=rtcp-fb:' + mline[i]).length + 1) .split(' '); return { type: parts.shift(), parameter: parts.join(' ') }; }; for (i = 3; i < mline.length; i++) { // find all codecs from mline[3..] var line = lines.filter(rtpmapFilter)[0]; if (line) { var codec = this._parseRtpMap(line); var fmtp = lines.filter(fmtpFilter); codec.parameters = fmtp.length ? parseFmtp(fmtp[0]) : {}; codec.rtcpFeedback = lines.filter(rtcpFbFilter).map(parseRtcpFb); remoteCapabilities.codecs.push(codec); } } return remoteCapabilities; }; // Serializes capabilities to SDP. window.RTCPeerConnection.prototype._capabilitiesToSDP = function(caps) { var sdp = ''; caps.codecs.forEach(function(codec) { var pt = codec.payloadType; if (codec.preferredPayloadType !== undefined) { pt = codec.preferredPayloadType; } sdp += 'a=rtpmap:' + pt + ' ' + codec.name + '/' + codec.clockRate + (codec.numChannels !== 1 ? '/' + codec.numChannels : '') + ' '; if (codec.parameters && codec.parameters.length) { sdp += 'a=ftmp:' + pt + ' '; Object.keys(codec.parameters).forEach(function(param) { sdp += param + '=' + codec.parameters[param]; }); sdp += ' '; } if (codec.rtcpFeedback) { // FIXME: special handling for trr-int? codec.rtcpFeedback.forEach(function(fb) { sdp += 'a=rtcp-fb:' + pt + ' ' + fb.type + ' ' + fb.parameter + ' '; }); } }); return sdp; }; // Calculates the intersection of local and remote capabilities. window.RTCPeerConnection.prototype._getCommonCapabilities = function(localCapabilities, remoteCapabilities) { var commonCapabilities = { codecs: [], headerExtensions: [], fecMechanisms: [] }; localCapabilities.codecs.forEach(function(lCodec) { for (var i = 0; i < remoteCapabilities.codecs.length; i++) { var rCodec = remoteCapabilities.codecs[i]; if (lCodec.name === rCodec.name && lCodec.clockRate === rCodec.clockRate && lCodec.numChannels === rCodec.numChannels) { // push rCodec so we reply with offerer payload type commonCapabilities.codecs.push(rCodec); // FIXME: also need to calculate intersection between // .rtcpFeedback and .parameters break; } } }); localCapabilities.headerExtensions.forEach(function(lHeaderExtension) { for (var i = 0; i < remoteCapabilities.headerExtensions.length; i++) { var rHeaderExtension = remoteCapabilities.headerExtensions[i]; if (lHeaderExtension.uri === rHeaderExtension.uri) { commonCapabilities.headerExtensions.push(rHeaderExtension); break; } } }); // FIXME: fecMechanisms return commonCapabilities; }; // Parses DTLS parameters from SDP section or sessionpart. window.RTCPeerConnection.prototype._getDtlsParameters = function(section, session) { var lines = section.split(' '); lines = lines.concat(session.split(' ')); // Search in session part, too. var fpLine = lines.filter(function(line) { return line.indexOf('a=fingerprint:') === 0; }); fpLine = fpLine[0].substr(14); var dtlsParameters = { role: 'auto', fingerprints: [{ algorithm: fpLine.split(' ')[0], value: fpLine.split(' ')[1] }] }; return dtlsParameters; }; // Serializes DTLS parameters to SDP. window.RTCPeerConnection.prototype._dtlsParametersToSDP = function(params, setupType) { var sdp = 'a=setup:' + setupType + ' '; params.fingerprints.forEach(function(fp) { sdp += 'a=fingerprint:' + fp.algorithm + ' ' + fp.value + ' '; }); return sdp; }; // Parses ICE information from SDP section or sessionpart. window.RTCPeerConnection.prototype._getIceParameters = function(section, session) { var lines = section.split(' '); lines = lines.concat(session.split(' ')); // Search in session part, too. var iceParameters = { usernameFragment: lines.filter(function(line) { return line.indexOf('a=ice-ufrag:') === 0; })[0].substr(12), password: lines.filter(function(line) { return line.indexOf('a=ice-pwd:') === 0; })[0].substr(10), }; return iceParameters; }; // Serializes ICE parameters to SDP. window.RTCPeerConnection.prototype._iceParametersToSDP = function(params) { return 'a=ice-ufrag:' + params.usernameFragment + ' ' + 'a=ice-pwd:' + params.password + ' '; }; window.RTCPeerConnection.prototype._getEncodingParameters = function(ssrc) { return { ssrc: ssrc, codecPayloadType: 0, fec: 0, rtx: 0, priority: 1.0, maxBitrate: 2000000.0, minQuality: 0, framerateBias: 0.5, resolutionScale: 1.0, framerateScale: 1.0, active: true, dependencyEncodingId: undefined, encodingId: undefined }; }; // Create ICE gatherer, ICE transport and DTLS transport. window.RTCPeerConnection.prototype._createIceAndDtlsTransports = function(mid, sdpMLineIndex) { var self = this; var iceGatherer = new RTCIceGatherer(self.iceOptions); var iceTransport = new RTCIceTransport(iceGatherer); iceGatherer.onlocalcandidate = function(evt) { var event = {}; event.candidate = {sdpMid: mid, sdpMLineIndex: sdpMLineIndex}; var cand = evt.candidate; var isEndOfCandidates = !(cand && Object.keys(cand).length > 0); if (isEndOfCandidates) { event.candidate.candidate = 'candidate:1 1 udp 1 0.0.0.0 9 typ endOfCandidates'; } else { // RTCIceCandidate doesn't have a component, needs to be added cand.component = iceTransport.component === 'RTCP' ? 2 : 1; event.candidate.candidate = self._toCandidateSDP(cand); } if (self.onicecandidate !== null) { if (self.localDescription && self.localDescription.type === '') { self._iceCandidates.push(event); } else { self.onicecandidate(event); } } }; iceTransport.onicestatechange = function() { /* console.log(self._peerConnectionId, 'ICE state change', iceTransport.state); */ self._updateIceConnectionState(iceTransport.state); }; var dtlsTransport = new RTCDtlsTransport(iceTransport); dtlsTransport.ondtlsstatechange = function() { /* console.log(self._peerConnectionId, sdpMLineIndex, 'dtls state change', dtlsTransport.state); */ }; dtlsTransport.onerror = function(error) { console.error('dtls error', error); }; return { iceGatherer: iceGatherer, iceTransport: iceTransport, dtlsTransport: dtlsTransport }; }; window.RTCPeerConnection.prototype.setLocalDescription = function(description) { var self = this; if (description.type === 'offer') { if (!description.ortc) { // FIXME: throw? } else { this.mLines = description.ortc; } } else if (description.type === 'answer') { var sections = self.remoteDescription.sdp.split(' m='); var sessionpart = sections.shift(); sections.forEach(function(section, sdpMLineIndex) { section = 'm=' + section; var iceGatherer = self.mLines[sdpMLineIndex].iceGatherer; var iceTransport = self.mLines[sdpMLineIndex].iceTransport; var dtlsTransport = self.mLines[sdpMLineIndex].dtlsTransport; var rtpSender = self.mLines[sdpMLineIndex].rtpSender; var localCapabilities = self.mLines[sdpMLineIndex].localCapabilities; var remoteCapabilities = self.mLines[sdpMLineIndex].remoteCapabilities; var sendSSRC = self.mLines[sdpMLineIndex].sendSSRC; var recvSSRC = self.mLines[sdpMLineIndex].recvSSRC; var remoteIceParameters = self._getIceParameters(section, sessionpart); iceTransport.start(iceGatherer, remoteIceParameters, 'controlled'); var remoteDtlsParameters = self._getDtlsParameters(section, sessionpart); dtlsTransport.start(remoteDtlsParameters); if (rtpSender) { // calculate intersection of capabilities var params = self._getCommonCapabilities(localCapabilities, remoteCapabilities); params.muxId = sendSSRC; params.encodings = [self._getEncodingParameters(sendSSRC)]; params.rtcp = { cname: self._cname, reducedSize: false, ssrc: recvSSRC, mux: true }; rtpSender.send(params); } }); } this.localDescription = description; switch (description.type) { case 'offer': this._updateSignalingState('have-local-offer'); break; case 'answer': this._updateSignalingState('stable'); break; } // FIXME: need to _reliably_ execute after args[1] or promise window.setTimeout(function() { // FIXME: need to apply ice candidates in a way which is async but in-order self._iceCandidates.forEach(function(event) { if (self.onicecandidate !== null) { self.onicecandidate(event); } }); self._iceCandidates = []; }, 50); if (arguments.length > 1 && typeof arguments[1] === 'function') { window.setTimeout(arguments[1], 0); } return new Promise(function(resolve) { resolve(); }); }; window.RTCPeerConnection.prototype.setRemoteDescription = function(description) { // FIXME: for type=offer this creates state. which should not // happen before SLD with type=answer but... we need the stream // here for onaddstream. var self = this; var sections = description.sdp.split(' m='); var sessionpart = sections.shift(); var stream = new MediaStream(); sections.forEach(function(section, sdpMLineIndex) { section = 'm=' + section; var lines = section.split(' '); var mline = lines[0].substr(2).split(' '); var kind = mline[0]; var line; var iceGatherer; var iceTransport; var dtlsTransport; var rtpSender; var rtpReceiver; var sendSSRC; var recvSSRC; var mid = lines.filter(function(line) { return line.indexOf('a=mid:') === 0; })[0].substr(6); var cname; var remoteCapabilities; var params; if (description.type === 'offer') { var transports = self._createIceAndDtlsTransports(mid, sdpMLineIndex); var localCapabilities = RTCRtpReceiver.getCapabilities(kind); // determine remote caps from SDP remoteCapabilities = self._getRemoteCapabilities(section); line = lines.filter(function(line) { return line.indexOf('a=ssrc:') === 0 && line.split(' ')[1].indexOf('cname:') === 0; }); sendSSRC = (2 * sdpMLineIndex + 2) * 1001; if (line) { // FIXME: alot of assumptions here recvSSRC = line[0].split(' ')[0].split(':')[1]; cname = line[0].split(' ')[1].split(':')[1]; } rtpReceiver = new RTCRtpReceiver(transports.dtlsTransport, kind); // calculate intersection so no unknown caps get passed into the RTPReciver params = self._getCommonCapabilities(localCapabilities, remoteCapabilities); params.muxId = recvSSRC; params.encodings = [self._getEncodingParameters(recvSSRC)]; params.rtcp = { cname: cname, reducedSize: false, ssrc: sendSSRC, mux: true }; rtpReceiver.receive(params); // FIXME: not correct when there are multiple streams but that is // not currently supported. stream.addTrack(rtpReceiver.track); // FIXME: honor a=sendrecv if (self.localStreams.length > 0 && self.localStreams[0].getTracks().length >= sdpMLineIndex) { // FIXME: actually more complicated, needs to match types etc var localtrack = self.localStreams[0].getTracks()[sdpMLineIndex]; rtpSender = new RTCRtpSender(localtrack, transports.dtlsTransport); } self.mLines[sdpMLineIndex] = { iceGatherer: transports.iceGatherer, iceTransport: transports.iceTransport, dtlsTransport: transports.dtlsTransport, localCapabilities: localCapabilities, remoteCapabilities: remoteCapabilities, rtpSender: rtpSender, rtpReceiver: rtpReceiver, kind: kind, mid: mid, sendSSRC: sendSSRC, recvSSRC: recvSSRC }; } else { iceGatherer = self.mLines[sdpMLineIndex].iceGatherer; iceTransport = self.mLines[sdpMLineIndex].iceTransport; dtlsTransport = self.mLines[sdpMLineIndex].dtlsTransport; rtpSender = self.mLines[sdpMLineIndex].rtpSender; rtpReceiver = self.mLines[sdpMLineIndex].rtpReceiver; sendSSRC = self.mLines[sdpMLineIndex].sendSSRC; recvSSRC = self.mLines[sdpMLineIndex].recvSSRC; } var remoteIceParameters = self._getIceParameters(section, sessionpart); var remoteDtlsParameters = self._getDtlsParameters(section, sessionpart); // for answers we start ice and dtls here, otherwise this is done in SLD if (description.type === 'answer') { iceTransport.start(iceGatherer, remoteIceParameters, 'controlling'); dtlsTransport.start(remoteDtlsParameters); // determine remote caps from SDP remoteCapabilities = self._getRemoteCapabilities(section); // FIXME: store remote caps? if (rtpSender) { params = remoteCapabilities; params.muxId = sendSSRC; params.encodings = [self._getEncodingParameters(sendSSRC)]; params.rtcp = { cname: self._cname, reducedSize: false, ssrc: recvSSRC, mux: true }; rtpSender.send(params); } // FIXME: only if a=sendrecv var bidi = lines.filter(function(line) { return line.indexOf('a=ssrc:') === 0; }).length > 0; if (rtpReceiver && bidi) { line = lines.filter(function(line) { return line.indexOf('a=ssrc:') === 0 && line.split(' ')[1].indexOf('cname:') === 0; }); if (line) { // FIXME: alot of assumptions here recvSSRC = line[0].split(' ')[0].split(':')[1]; cname = line[0].split(' ')[1].split(':')[1]; } params = remoteCapabilities; params.muxId = recvSSRC; params.encodings = [self._getEncodingParameters(recvSSRC)]; params.rtcp = { cname: cname, reducedSize: false, ssrc: sendSSRC, mux: true }; rtpReceiver.receive(params, kind); stream.addTrack(rtpReceiver.track); self.mLines[sdpMLineIndex].recvSSRC = recvSSRC; } } }); this.remoteDescription = description; switch (description.type) { case 'offer': this._updateSignalingState('have-remote-offer'); break; case 'answer': this._updateSignalingState('stable'); break; } window.setTimeout(function() { if (self.onaddstream !== null && stream.getTracks().length) { self.remoteStreams.push(stream); window.setTimeout(function() { self.onaddstream({stream: stream}); }, 0); } }, 0); if (arguments.length > 1 && typeof arguments[1] === 'function') { window.setTimeout(arguments[1], 0); } return new Promise(function(resolve) { resolve(); }); }; window.RTCPeerConnection.prototype.close = function() { this.mLines.forEach(function(mLine) { /* not yet if (mLine.iceGatherer) { mLine.iceGatherer.close(); } */ if (mLine.iceTransport) { mLine.iceTransport.stop(); } if (mLine.dtlsTransport) { mLine.dtlsTransport.stop(); } if (mLine.rtpSender) { mLine.rtpSender.stop(); } if (mLine.rtpReceiver) { mLine.rtpReceiver.stop(); } }); // FIXME: clean up tracks, local streams, remote streams, etc this._updateSignalingState('closed'); this._updateIceConnectionState('closed'); }; // Update the signaling state. window.RTCPeerConnection.prototype._updateSignalingState = function(newState) { this.signalingState = newState; if (this.onsignalingstatechange !== null) { this.onsignalingstatechange(); } }; // Update the ICE connection state. // FIXME: should be called 'updateConnectionState', also be called for // DTLS changes and implement // https://lists.w3.org/Archives/Public/public-webrtc/2015Sep/0033.html window.RTCPeerConnection.prototype._updateIceConnectionState = function(newState) { var self = this; if (this.iceConnectionState !== newState) { var agreement = self.mLines.every(function(mLine) { return mLine.iceTransport.state === newState; }); if (agreement) { self.iceConnectionState = newState; if (this.oniceconnectionstatechange !== null) { this.oniceconnectionstatechange(); } } } }; window.RTCPeerConnection.prototype.createOffer = function() { var self = this; var offerOptions; if (arguments.length === 1 && typeof arguments[0] !== 'function') { offerOptions = arguments[0]; } else if (arguments.length === 3) { offerOptions = arguments[2]; } var tracks = []; var numAudioTracks = 0; var numVideoTracks = 0; // Default to sendrecv. if (this.localStreams.length) { numAudioTracks = this.localStreams[0].getAudioTracks().length; numVideoTracks = this.localStreams[0].getAudioTracks().length; } // Determine number of audio and video tracks we need to send/recv. if (offerOptions) { // Deal with Chrome legacy constraints... if (offerOptions.mandatory) { if (offerOptions.mandatory.OfferToReceiveAudio) { numAudioTracks = 1; } else if (offerOptions.mandatory.OfferToReceiveAudio === false) { numAudioTracks = 0; } if (offerOptions.mandatory.OfferToReceiveVideo) { numVideoTracks = 1; } else if (offerOptions.mandatory.OfferToReceiveVideo === false) { numVideoTracks = 0; } } else { if (offerOptions.offerToReceiveAudio !== undefined) { numAudioTracks = offerOptions.offerToReceiveAudio; } if (offerOptions.offerToReceiveVideo !== undefined) { numVideoTracks = offerOptions.offerToReceiveVideo; } } } if (this.localStreams.length) { // Push local streams. this.localStreams[0].getTracks().forEach(function(track) { tracks.push({ kind: track.kind, track: track, wantReceive: track.kind === 'audio' ? numAudioTracks > 0 : numVideoTracks > 0 }); if (track.kind === 'audio') { numAudioTracks--; } else if (track.kind === 'video') { numVideoTracks--; } }); } // Create M-lines for recvonly streams. while (numAudioTracks > 0 || numVideoTracks > 0) { if (numAudioTracks > 0) { tracks.push({ kind: 'audio', wantReceive: true }); numAudioTracks--; } if (numVideoTracks > 0) { tracks.push({ kind: 'video', wantReceive: true }); numVideoTracks--; } } var sdp = 'v=0 ' + 'o=thisisadapterortc 8169639915646943137 2 IN IP4 127.0.0.1 ' + 's=- ' + 't=0 0 '; var mLines = []; tracks.forEach(function(mline, sdpMLineIndex) { // For each track, create an ice gatherer, ice transport, dtls transport, // potentially rtpsender and rtpreceiver. var track = mline.track; var kind = mline.kind; var mid = Math.random().toString(36).substr(2, 10); var transports = self._createIceAndDtlsTransports(mid, sdpMLineIndex); var localCapabilities = RTCRtpSender.getCapabilities(kind); var rtpSender; // generate an ssrc now, to be used later in rtpSender.send var sendSSRC = (2 * sdpMLineIndex + 1) * 1001; //Math.floor(Math.random()*4294967295); var recvSSRC; // don't know yet if (track) { rtpSender = new RTCRtpSender(track, transports.dtlsTransport); } var rtpReceiver; if (mline.wantReceive) { rtpReceiver = new RTCRtpReceiver(transports.dtlsTransport, kind); } mLines[sdpMLineIndex] = { iceGatherer: transports.iceGatherer, iceTransport: transports.iceTransport, dtlsTransport: transports.dtlsTransport, localCapabilities: localCapabilities, remoteCapabilities: null, rtpSender: rtpSender, rtpReceiver: rtpReceiver, kind: kind, mid: mid, sendSSRC: sendSSRC, recvSSRC: recvSSRC }; // Map things to SDP. // Build the mline. sdp += 'm=' + kind + ' 9 UDP/TLS/RTP/SAVPF '; sdp += localCapabilities.codecs.map(function(codec) { return codec.preferredPayloadType; }).join(' ') + ' '; sdp += 'c=IN IP4 0.0.0.0 '; sdp += 'a=rtcp:9 IN IP4 0.0.0.0 '; // Map ICE parameters (ufrag, pwd) to SDP. sdp += self._iceParametersToSDP( transports.iceGatherer.getLocalParameters()); // Map DTLS parameters to SDP. sdp += self._dtlsParametersToSDP( transports.dtlsTransport.getLocalParameters(), 'actpass'); sdp += 'a=mid:' + mid + ' '; if (rtpSender && rtpReceiver) { sdp += 'a=sendrecv '; } else if (rtpSender) { sdp += 'a=sendonly '; } else if (rtpReceiver) { sdp += 'a=recvonly '; } else { sdp += 'a=inactive '; } sdp += 'a=rtcp-mux '; // Add a=rtpmap lines for each codec. Also fmtp and rtcp-fb. sdp += self._capabilitiesToSDP(localCapabilities); if (track) { sdp += 'a=msid:' + self.localStreams[0].id + ' ' + track.id + ' '; sdp += 'a=ssrc:' + sendSSRC + ' ' + 'msid:' + self.localStreams[0].id + ' ' + track.id + ' '; } sdp += 'a=ssrc:' + sendSSRC + ' cname:' + self._cname + ' '; }); var desc = new RTCSessionDescription({ type: 'offer', sdp: sdp, ortc: mLines }); if (arguments.length && typeof arguments[0] === 'function') { window.setTimeout(arguments[0], 0, desc); } return new Promise(function(resolve) { resolve(desc); }); }; window.RTCPeerConnection.prototype.createAnswer = function() { var self = this; var answerOptions; if (arguments.length === 1 && typeof arguments[0] !== 'function') { answerOptions = arguments[0]; } else if (arguments.length === 3) { answerOptions = arguments[2]; } var sdp = 'v=0 ' + 'o=thisisadapterortc 8169639915646943137 2 IN IP4 127.0.0.1 ' + 's=- ' + 't=0 0 '; this.mLines.forEach(function(mLine/*, sdpMLineIndex*/) { var iceGatherer = mLine.iceGatherer; //var iceTransport = mLine.iceTransport; var dtlsTransport = mLine.dtlsTransport; var localCapabilities = mLine.localCapabilities; var remoteCapabilities = mLine.remoteCapabilities; var rtpSender = mLine.rtpSender; var rtpReceiver = mLine.rtpReceiver; var kind = mLine.kind; var sendSSRC = mLine.sendSSRC; //var recvSSRC = mLine.recvSSRC; // Calculate intersection of capabilities. var commonCapabilities = self._getCommonCapabilities(localCapabilities, remoteCapabilities); // Map things to SDP. // Build the mline. sdp += 'm=' + kind + ' 9 UDP/TLS/RTP/SAVPF '; sdp += commonCapabilities.codecs.map(function(codec) { return codec.payloadType; }).join(' ') + ' '; sdp += 'c=IN IP4 0.0.0.0 '; sdp += 'a=rtcp:9 IN IP4 0.0.0.0 '; // Map ICE parameters (ufrag, pwd) to SDP. sdp += self._iceParametersToSDP(iceGatherer.getLocalParameters()); // Map DTLS parameters to SDP. sdp += self._dtlsParametersToSDP(dtlsTransport.getLocalParameters(), 'active'); sdp += 'a=mid:' + mLine.mid + ' '; if (rtpSender && rtpReceiver) { sdp += 'a=sendrecv '; } else if (rtpReceiver) { sdp += 'a=sendonly '; } else if (rtpSender) { sdp += 'a=sendonly '; } else { sdp += 'a=inactive '; } sdp += 'a=rtcp-mux '; // Add a=rtpmap lines for each codec. Also fmtp and rtcp-fb. sdp += self._capabilitiesToSDP(commonCapabilities); if (rtpSender) { // add a=ssrc lines from RTPSender sdp += 'a=msid:' + self.localStreams[0].id + ' ' + rtpSender.track.id + ' '; sdp += 'a=ssrc:' + sendSSRC + ' ' + 'msid:' + self.localStreams[0].id + ' ' + rtpSender.track.id + ' '; } sdp += 'a=ssrc:' + sendSSRC + ' cname:' + self._cname + ' '; }); var desc = new RTCSessionDescription({ type: 'answer', sdp: sdp // ortc: tracks -- state is created in SRD already }); if (arguments.length && typeof arguments[0] === 'function') { window.setTimeout(arguments[0], 0, desc); } return new Promise(function(resolve) { resolve(desc); }); }; window.RTCPeerConnection.prototype.addIceCandidate = function(candidate) { // TODO: lookup by mid var mLine = this.mLines[candidate.sdpMLineIndex]; if (mLine) { var cand = Object.keys(candidate.candidate).length > 0 ? this._toCandidateJSON(candidate.candidate) : {}; // dirty hack to make simplewebrtc work. // FIXME: need another dirty hack to avoid adding candidates after this if (cand.type === 'endOfCandidates') { cand = {}; } // dirty hack to make chrome work. if (cand.protocol === 'tcp' && cand.port === 0) { cand = {}; } mLine.iceTransport.addRemoteCandidate(cand); } if (arguments.length > 1 && typeof arguments[1] === 'function') { window.setTimeout(arguments[1], 0); } return new Promise(function(resolve) { resolve(); }); }; window.RTCPeerConnection.prototype.getStats = function() { var promises = []; this.mLines.forEach(function(mLine) { ['rtpSender', 'rtpReceiver', 'iceGatherer', 'iceTransport', 'dtlsTransport'].forEach(function(thing) { if (mLine[thing]) { promises.push(mLine[thing].getStats()); } }); }); var cb = arguments.length > 1 && typeof arguments[1] === 'function' && arguments[1]; return new Promise(function(resolve) { var results = {}; Promise.all(promises).then(function(res) { res.forEach(function(result) { Object.keys(result).forEach(function(id) { results[id] = result[id]; }); }); if (cb) { window.setTimeout(cb, 0, results); } resolve(results); }); }); }; } } else { webrtcUtils.log('Browser does not appear to be WebRTC-capable'); } // Returns the result of getUserMedia as a Promise. function requestUserMedia(constraints) { return new Promise(function(resolve, reject) { getUserMedia(constraints, resolve, reject); }); } var webrtcTesting = {}; try { Object.defineProperty(webrtcTesting, 'version', { set: function(version) { webrtcDetectedVersion = version; } }); } catch (e) {} if (typeof module !== 'undefined') { var RTCPeerConnection; if (typeof window !== 'undefined') { RTCPeerConnection = window.RTCPeerConnection; } module.exports = { RTCPeerConnection: RTCPeerConnection, getUserMedia: getUserMedia, attachMediaStream: attachMediaStream, reattachMediaStream: reattachMediaStream, webrtcDetectedBrowser: webrtcDetectedBrowser, webrtcDetectedVersion: webrtcDetectedVersion, webrtcMinimumVersion: webrtcMinimumVersion, webrtcTesting: webrtcTesting, webrtcUtils: webrtcUtils //requestUserMedia: not exposed on purpose. //trace: not exposed on purpose. }; } else if ((typeof require === 'function') && (typeof define === 'function')) { // Expose objects and functions when RequireJS is doing the loading. define([], function() { return { RTCPeerConnection: window.RTCPeerConnection, getUserMedia: getUserMedia, attachMediaStream: attachMediaStream, reattachMediaStream: reattachMediaStream, webrtcDetectedBrowser: webrtcDetectedBrowser, webrtcDetectedVersion: webrtcDetectedVersion, webrtcMinimumVersion: webrtcMinimumVersion, webrtcTesting: webrtcTesting, webrtcUtils: webrtcUtils //requestUserMedia: not exposed on purpose. //trace: not exposed on purpose. }; }); }
交互js代码
/* * Copyright (c) 2015 The WebRTC project authors. All Rights Reserved. * * Use of this source code is governed by a BSD-style license * that can be found in the LICENSE file in the root of the source * tree. */ 'use strict'; var startButton = document.getElementById('startButton'); var callButton = document.getElementById('callButton'); var hangupButton = document.getElementById('hangupButton'); callButton.disabled = true; hangupButton.disabled = true; startButton.onclick = start; callButton.onclick = call; hangupButton.onclick = hangup; var startTime; var localVideo = document.getElementById('localVideo'); var remoteVideo = document.getElementById('remoteVideo'); localVideo.addEventListener('loadedmetadata', function() { trace('Local video videoWidth: ' + this.videoWidth + 'px, videoHeight: ' + this.videoHeight + 'px'); }); remoteVideo.addEventListener('loadedmetadata', function() { trace('Remote video videoWidth: ' + this.videoWidth + 'px, videoHeight: ' + this.videoHeight + 'px'); }); remoteVideo.onresize = function() { trace('Remote video size changed to ' + remoteVideo.videoWidth + 'x' + remoteVideo.videoHeight); // We'll use the first onsize callback as an indication that video has started // playing out. if (startTime) { var elapsedTime = window.performance.now() - startTime; trace('Setup time: ' + elapsedTime.toFixed(3) + 'ms'); startTime = null; } }; var localStream; var pc1; var pc2; var offerOptions = { offerToReceiveAudio: 1, offerToReceiveVideo: 1 }; function getName(pc) { return (pc === pc1) ? 'pc1' : 'pc2'; } function getOtherPc(pc) { return (pc === pc1) ? pc2 : pc1; } function gotStream(stream) { trace('Received local stream'); localVideo.srcObject = stream; localStream = stream; callButton.disabled = false; } function start() { trace('Requesting local stream'); startButton.disabled = true; navigator.mediaDevices.getUserMedia({ audio: true, video: true }) .then(gotStream) .catch(function(e) { alert('getUserMedia() error: ' + e.name); }); } function call() { callButton.disabled = true; hangupButton.disabled = false; trace('Starting call'); startTime = window.performance.now(); var videoTracks = localStream.getVideoTracks(); var audioTracks = localStream.getAudioTracks(); if (videoTracks.length > 0) { trace('Using video device: ' + videoTracks[0].label); } if (audioTracks.length > 0) { trace('Using audio device: ' + audioTracks[0].label); } var servers = null; pc1 = new RTCPeerConnection(servers); trace('Created local peer connection object pc1'); pc1.onicecandidate = function(e) { onIceCandidate(pc1, e); }; pc2 = new RTCPeerConnection(servers); trace('Created remote peer connection object pc2'); pc2.onicecandidate = function(e) { onIceCandidate(pc2, e); }; pc1.oniceconnectionstatechange = function(e) { onIceStateChange(pc1, e); }; pc2.oniceconnectionstatechange = function(e) { onIceStateChange(pc2, e); }; pc2.onaddstream = gotRemoteStream; pc1.addStream(localStream); trace('Added local stream to pc1'); trace('pc1 createOffer start'); pc1.createOffer(onCreateOfferSuccess, onCreateSessionDescriptionError, offerOptions); } function onCreateSessionDescriptionError(error) { trace('Failed to create session description: ' + error.toString()); } function onCreateOfferSuccess(desc) { trace('Offer from pc1 ' + desc.sdp); trace('pc1 setLocalDescription start'); pc1.setLocalDescription(desc, function() { onSetLocalSuccess(pc1); }, onSetSessionDescriptionError); trace('pc2 setRemoteDescription start'); pc2.setRemoteDescription(desc, function() { onSetRemoteSuccess(pc2); }, onSetSessionDescriptionError); trace('pc2 createAnswer start'); // Since the 'remote' side has no media stream we need // to pass in the right constraints in order for it to // accept the incoming offer of audio and video. pc2.createAnswer(onCreateAnswerSuccess, onCreateSessionDescriptionError); } function onSetLocalSuccess(pc) { trace(getName(pc) + ' setLocalDescription complete'); } function onSetRemoteSuccess(pc) { trace(getName(pc) + ' setRemoteDescription complete'); } function onSetSessionDescriptionError(error) { trace('Failed to set session description: ' + error.toString()); } function gotRemoteStream(e) { remoteVideo.srcObject = e.stream; trace('pc2 received remote stream'); } function onCreateAnswerSuccess(desc) { trace('Answer from pc2: ' + desc.sdp); trace('pc2 setLocalDescription start'); pc2.setLocalDescription(desc, function() { onSetLocalSuccess(pc2); }, onSetSessionDescriptionError); trace('pc1 setRemoteDescription start'); pc1.setRemoteDescription(desc, function() { onSetRemoteSuccess(pc1); }, onSetSessionDescriptionError); } function onIceCandidate(pc, event) { if (event.candidate) { getOtherPc(pc).addIceCandidate(new RTCIceCandidate(event.candidate), function() { onAddIceCandidateSuccess(pc); }, function(err) { onAddIceCandidateError(pc, err); } ); trace(getName(pc) + ' ICE candidate: ' + event.candidate.candidate); } } function onAddIceCandidateSuccess(pc) { trace(getName(pc) + ' addIceCandidate success'); } function onAddIceCandidateError(pc, error) { trace(getName(pc) + ' failed to add ICE Candidate: ' + error.toString()); } function onIceStateChange(pc, event) { if (pc) { trace(getName(pc) + ' ICE state: ' + pc.iceConnectionState); console.log('ICE state change event: ', event); } } function hangup() { trace('Ending call'); pc1.close(); pc2.close(); pc1 = null; pc2 = null; hangupButton.disabled = true; callButton.disabled = false; }
本地，呼叫者
// servers是配置文件(TURN and STUN配置) pc1 = new webkitRTCPeerConnection(servers); // ... pc1.addStream(localStream);
远端，被叫着
创建一个offer ，将其设定为PC1的局部描述（local description），PC2远程描述（remote description）。
这样可以不使用信令通讯，因为主叫和被叫都在同一网页上。
pc1.createOffer(gotDescription1); //... function gotDescription1(desc){ pc1.setLocalDescription(desc); trace("Offer from pc1 " + desc.sdp); pc2.setRemoteDescription(desc); pc2.createAnswer(gotDescription2); }
创建pc2，当pc1产生视频流，则显示在remoteVideo视频控件（video element）：
pc2 = new webkitRTCPeerConnection(servers); pc2.onaddstream = gotRemoteStream; //... function gotRemoteStream(e){ remoteVideo.src = URL.createObjectURL(e.stream);
trace('pc2 received remote stream'); }
运行结果：
Navigated to https://webrtc.github.io/samples/src/content/peerconnection/pc1/ adapter.js:32 This appears to be Chrome common.js:8 12.639: Requesting local stream adapter.js:32 chrome: {"audio":true,"video":true} common.js:8 12.653: Received local stream common.js:8 14.038: Local video videoWidth: 640px, videoHeight: 480px common.js:8 15.183: Starting call common.js:8 15.183: Using video device: Integrated Camera (04f2:b39a) common.js:8 15.183: Using audio device: 默认 common.js:8 15.185: Created local peer connection object pc1 common.js:8 15.186: Created remote peer connection object pc2 common.js:8 15.186: Added local stream to pc1 common.js:8 15.187: pc1 createOffer start common.js:8 15.190: Offer from pc1 v=0 o=- 5740173043645401541 2 IN IP4 127.0.0.1 s=- t=0 0 a=group:BUNDLE audio video a=msid-semantic: WMS ZWvBmXl2Dax58ugXR3BYDITTKIIV1TYPqViT m=audio 9 UDP/TLS/RTP/SAVPF 111 103 104 9 0 8 106 105 13 126 c=IN IP4 0.0.0.0 a=rtcp:9 IN IP4 0.0.0.0 a=ice-ufrag:MOApAbo/PL8Jl3m9 a=ice-pwd:dxcuXVAFcyVqbgwi0QdQNh0S a=fingerprint:sha-256 5F:CB:FF:EF:73:09:BC:0A:6F:18:0C:DB:11:A5:AE:AF:37:49:37:71:D0:FE:BA:39:EC:53:6B:10:8C:8A:95:9E a=setup:actpass a=mid:audio a=extmap:1 urn:ietf:params:rtp-hdrext:ssrc-audio-level a=extmap:3 http://www.webrtc.org/experiments/rtp-hdrext/abs-send-time a=sendrecv a=rtcp-mux a=rtpmap:111 opus/48000/2 a=fmtp:111 minptime=10; useinbandfec=1 a=rtpmap:103 ISAC/16000 a=rtpmap:104 ISAC/32000 a=rtpmap:9 G722/8000 a=rtpmap:0 PCMU/8000 a=rtpmap:8 PCMA/8000 a=rtpmap:106 CN/32000 a=rtpmap:105 CN/16000 a=rtpmap:13 CN/8000 a=rtpmap:126 telephone-event/8000 a=maxptime:60 a=ssrc:32244674 cname:anS0gTF+aWAKlwYj a=ssrc:32244674 msid:ZWvBmXl2Dax58ugXR3BYDITTKIIV1TYPqViT 8ae8dd85-bd5c-49ff-a9bd-f4b88f2663c7 a=ssrc:32244674 mslabel:ZWvBmXl2Dax58ugXR3BYDITTKIIV1TYPqViT a=ssrc:32244674 label:8ae8dd85-bd5c-49ff-a9bd-f4b88f2663c7 m=video 9 UDP/TLS/RTP/SAVPF 100 116 117 96 c=IN IP4 0.0.0.0 a=rtcp:9 IN IP4 0.0.0.0 a=ice-ufrag:MOApAbo/PL8Jl3m9 a=ice-pwd:dxcuXVAFcyVqbgwi0QdQNh0S a=fingerprint:sha-256 5F:CB:FF:EF:73:09:BC:0A:6F:18:0C:DB:11:A5:AE:AF:37:49:37:71:D0:FE:BA:39:EC:53:6B:10:8C:8A:95:9E a=setup:actpass a=mid:video a=extmap:2 urn:ietf:params:rtp-hdrext:toffset a=extmap:3 http://www.webrtc.org/experiments/rtp-hdrext/abs-send-time a=extmap:4 urn:3gpp:video-orientation a=sendrecv a=rtcp-mux a=rtpmap:100 VP8/90000 a=rtcp-fb:100 ccm fir a=rtcp-fb:100 nack a=rtcp-fb:100 nack pli a=rtcp-fb:100 goog-remb a=rtpmap:116 red/90000 a=rtpmap:117 ulpfec/90000 a=rtpmap:96 rtx/90000 a=fmtp:96 apt=100 a=ssrc-group:FID 1099776253 671187929 a=ssrc:1099776253 cname:anS0gTF+aWAKlwYj a=ssrc:1099776253 msid:ZWvBmXl2Dax58ugXR3BYDITTKIIV1TYPqViT eda73070-3562-4daf-ae0d-143694f294d5 a=ssrc:1099776253 mslabel:ZWvBmXl2Dax58ugXR3BYDITTKIIV1TYPqViT a=ssrc:1099776253 label:eda73070-3562-4daf-ae0d-143694f294d5 a=ssrc:671187929 cname:anS0gTF+aWAKlwYj a=ssrc:671187929 msid:ZWvBmXl2Dax58ugXR3BYDITTKIIV1TYPqViT eda73070-3562-4daf-ae0d-143694f294d5 a=ssrc:671187929 mslabel:ZWvBmXl2Dax58ugXR3BYDITTKIIV1TYPqViT a=ssrc:671187929 label:eda73070-3562-4daf-ae0d-143694f294d5 common.js:8 15.190: pc1 setLocalDescription start common.js:8 15.191: pc2 setRemoteDescription start common.js:8 15.192: pc2 createAnswer start common.js:8 15.202: pc1 setLocalDescription complete common.js:8 15.203: pc1 ICE candidate: candidate:2999745851 1 udp 2122260223 192.168.56.1 64106 typ host generation 0 common.js:8 15.204: pc1 ICE candidate: candidate:1425577752 1 udp 2122194687 172.17.22.106 64107 typ host generation 0 common.js:8 15.204: pc1 ICE candidate: candidate:2733511545 1 udp 2122129151 192.168.127.1 64108 typ host generation 0 common.js:8 15.204: pc1 ICE candidate: candidate:1030387485 1 udp 2122063615 192.168.204.1 64109 typ host generation 0 common.js:8 15.205: pc1 ICE candidate: candidate:3003979406 1 udp 2121998079 172.17.26.47 64110 typ host generation 0 common.js:8 15.206: pc2 setRemoteDescription complete common.js:8 15.206: Answer from pc2: v=0 o=- 3554329696104028001 2 IN IP4 127.0.0.1 s=- t=0 0 a=group:BUNDLE audio video a=msid-semantic: WMS m=audio 9 UDP/TLS/RTP/SAVPF 111 103 104 9 0 8 106 105 13 126 c=IN IP4 0.0.0.0 a=rtcp:9 IN IP4 0.0.0.0 a=ice-ufrag:raDEDz+tkFTWXMn8 a=ice-pwd:RQ8bf7mtOXHIDQ0/vF25IRMf a=fingerprint:sha-256 5F:CB:FF:EF:73:09:BC:0A:6F:18:0C:DB:11:A5:AE:AF:37:49:37:71:D0:FE:BA:39:EC:53:6B:10:8C:8A:95:9E a=setup:active a=mid:audio a=extmap:1 urn:ietf:params:rtp-hdrext:ssrc-audio-level a=extmap:3 http://www.webrtc.org/experiments/rtp-hdrext/abs-send-time a=recvonly a=rtcp-mux a=rtpmap:111 opus/48000/2 a=fmtp:111 minptime=10; useinbandfec=1 a=rtpmap:103 ISAC/16000 a=rtpmap:104 ISAC/32000 a=rtpmap:9 G722/8000 a=rtpmap:0 PCMU/8000 a=rtpmap:8 PCMA/8000 a=rtpmap:106 CN/32000 a=rtpmap:105 CN/16000 a=rtpmap:13 CN/8000 a=rtpmap:126 telephone-event/8000 a=maxptime:60 m=video 9 UDP/TLS/RTP/SAVPF 100 116 117 96 c=IN IP4 0.0.0.0 a=rtcp:9 IN IP4 0.0.0.0 a=ice-ufrag:raDEDz+tkFTWXMn8 a=ice-pwd:RQ8bf7mtOXHIDQ0/vF25IRMf a=fingerprint:sha-256 5F:CB:FF:EF:73:09:BC:0A:6F:18:0C:DB:11:A5:AE:AF:37:49:37:71:D0:FE:BA:39:EC:53:6B:10:8C:8A:95:9E a=setup:active a=mid:video a=extmap:2 urn:ietf:params:rtp-hdrext:toffset a=extmap:3 http://www.webrtc.org/experiments/rtp-hdrext/abs-send-time a=extmap:4 urn:3gpp:video-orientation a=recvonly a=rtcp-mux a=rtpmap:100 VP8/90000 a=rtcp-fb:100 ccm fir a=rtcp-fb:100 nack a=rtcp-fb:100 nack pli a=rtcp-fb:100 goog-remb a=rtpmap:116 red/90000 a=rtpmap:117 ulpfec/90000 a=rtpmap:96 rtx/90000 a=fmtp:96 apt=100 common.js:8 15.207: pc2 setLocalDescription start common.js:8 15.207: pc1 setRemoteDescription start common.js:8 15.208: pc2 received remote stream 2common.js:8 15.209: pc1 addIceCandidate success 3common.js:8 15.210: pc1 addIceCandidate success common.js:8 15.224: pc1 ICE candidate: candidate:2999745851 2 udp 2122260222 192.168.56.1 64111 typ host generation 0 common.js:8 15.224: pc1 ICE candidate: candidate:1425577752 2 udp 2122194686 172.17.22.106 64112 typ host generation 0 common.js:8 15.225: pc1 ICE candidate: candidate:2733511545 2 udp 2122129150 192.168.127.1 64113 typ host generation 0 common.js:8 15.225: pc1 ICE candidate: candidate:1030387485 2 udp 2122063614 192.168.204.1 64114 typ host generation 0 common.js:8 15.226: pc1 ICE candidate: candidate:3003979406 2 udp 2121998078 172.17.26.47 64115 typ host generation 0 common.js:8 15.226: pc1 ICE candidate: candidate:2999745851 1 udp 2122260223 192.168.56.1 64116 typ host generation 0 common.js:8 15.227: pc1 ICE candidate: candidate:1425577752 1 udp 2122194687 172.17.22.106 64117 typ host generation 0 common.js:8 15.227: pc1 ICE candidate: candidate:2733511545 1 udp 2122129151 192.168.127.1 64118 typ host generation 0 common.js:8 15.227: pc1 ICE candidate: candidate:1030387485 1 udp 2122063615 192.168.204.1 64119 typ host generation 0 common.js:8 15.228: pc1 ICE candidate: candidate:3003979406 1 udp 2121998079 172.17.26.47 64120 typ host generation 0 common.js:8 15.228: pc1 ICE candidate: candidate:2999745851 2 udp 2122260222 192.168.56.1 64121 typ host generation 0 common.js:8 15.228: pc1 ICE candidate: candidate:1425577752 2 udp 2122194686 172.17.22.106 64122 typ host generation 0 common.js:8 15.229: pc1 ICE candidate: candidate:2733511545 2 udp 2122129150 192.168.127.1 64123 typ host generation 0 common.js:8 15.229: pc1 ICE candidate: candidate:1030387485 2 udp 2122063614 192.168.204.1 64124 typ host generation 0 common.js:8 15.230: pc1 ICE candidate: candidate:3003979406 2 udp 2121998078 172.17.26.47 64125 typ host generation 0 common.js:8 15.231: pc1 addIceCandidate success common.js:8 15.231: pc2 setLocalDescription complete common.js:8 15.231: pc1 setRemoteDescription complete common.js:8 15.231: pc1 addIceCandidate success 8common.js:8 15.232: pc1 addIceCandidate success 5common.js:8 15.233: pc1 addIceCandidate success common.js:8 15.233: pc2 ICE state: checking main.js:197 ICE state change event: Event {isTrusted: true} common.js:8 15.243: pc2 ICE candidate: candidate:2999745851 1 udp 2122260223 192.168.56.1 64126 typ host generation 0 common.js:8 15.246: pc2 ICE candidate: candidate:1425577752 1 udp 2122194687 172.17.22.106 64127 typ host generation 0 common.js:8 15.247: pc2 ICE candidate: candidate:2733511545 1 udp 2122129151 192.168.127.1 64128 typ host generation 0 common.js:8 15.248: pc2 ICE candidate: candidate:1030387485 1 udp 2122063615 192.168.204.1 64129 typ host generation 0 common.js:8 15.249: pc2 ICE candidate: candidate:3003979406 1 udp 2121998079 172.17.26.47 64130 typ host generation 0 common.js:8 15.250: pc1 ICE state: checking main.js:197 ICE state change event: Event {isTrusted: true} 5common.js:8 15.251: pc2 addIceCandidate success common.js:8 16.271: pc1 ICE state: connected main.js:197 ICE state change event: Event {isTrusted: true} common.js:8 16.272: pc2 ICE state: connected main.js:197 ICE state change event: Event {isTrusted: true} common.js:8 16.326: Remote video size changed to 640x480 common.js:8 16.326: Setup time: 1142.795ms common.js:8 16.326: Remote video videoWidth: 640px, videoHeight: 480px common.js:8 16.326: Remote video size changed to 640x480 common.js:8 18.447: Ending call
但在真实世界，不可能不通过服务器传送信令，WebRTC 两端必须通过服务器交换信令。
- 用户相互发现对方和交换“真实世界”的信息，如姓名。
- WebRTC客户端应用程序交换网络信息。
- 视频格式和分辨率等交换数据。
- 客户端应用穿越NAT网关和防火墙。
所以，你的服务器端需要实现的功能：
- 用户发现和通信。
- 信令通信。
- NAT和防火墙的穿越。
- 在点对点通信失败后的中继服务（补救服务）。
STUN协议和它的扩展TURN使用ICE framework。
ICE先试图在节点直接连接，通过最低的延迟，通过UDP协议。在这个过程中：STUN服务器启用NAT后面找到它的公共地址和端口。
ICE顺序：
- 先UDP，
- 如果UDP失败 则TCP，
- 如果TCP失败 则HTTP，
- 最后HTTPS
具体实现：
- ICE 先使用 STUN 通过UDP直连
- 如果UDP、TCP、http等失败 则使用TURN 中继服务（Relay server）
STUN, TURN and signaling 介绍：
http://www.html5rocks.com/en/tutorials/webrtc/infrastructure/
许多现有的WebRTC应用只是Web浏览器之间的通信，但网关服务器可以使WebRTC应用在浏览器与设备如电话互动（PSTN和VoIP系统）。
2012五月，Doubango开源了sipml5 SIP客户端，sipml5是通过WebRTC和WebSocket，使视频和语音通话在浏览器和应用程序（iOS或Android）之间进行。
网址：