Makes it possible to switch video streams during the session. Adds desktop sharing feature for chrome.

app.js

         var sess = connection.jingle.sessions[sid];
         if (data.stream.id === 'mixedmslabel') return;
         videoTracks = data.stream.getVideoTracks();
+        console.log("waiting..", videoTracks, selector[0]);
         if (videoTracks.length === 0 || selector[0].currentTime > 0) {
             RTC.attachMediaStream(selector, data.stream); // FIXME: why do i have to do this for FF?
             $(document).trigger('callactive.jingle', [selector, sid]);
     });
     console.log('new ssrcs', newssrcs);
 
+    // Have to clear presence map to get rid of removed streams
+    connection.emuc.clearPresenceMedia();
     var i = 0;
     Object.keys(newssrcs).forEach(function (mtype) {
         i++;
 });
 
 $(document).bind('presence.muc', function (event, jid, info, pres) {
+
+    // Remove old ssrcs coming from the jid
+    Object.keys(ssrc2jid).forEach(function(ssrc){
+       if(ssrc2jid[ssrc] == jid){
+           delete ssrc2jid[ssrc];
+       }
+    });
+
     $(pres).find('>media[xmlns="http://estos.de/ns/mjs"]>source').each(function (idx, ssrc) {
         //console.log(jid, 'assoc ssrc', ssrc.getAttribute('type'), ssrc.getAttribute('ssrc'));
         ssrc2jid[ssrc.getAttribute('ssrc')] = jid;
 //        TODO: Enable settings functionality. Need to uncomment the settings button in index.html.
 //        $('#settingsButton').css({visibility:"visible"});
     }
+    if(isDesktopSharingEnabled()) {
+        $('#desktopsharing').css({display:"inline"});
+    }
 }
 
 /*

config.js

 //  useStunTurn: true, // use XEP-0215 to fetch STUN and TURN server
 //  useIPv6: true, // ipv6 support. use at your own risk
     useNicks: false,
-    bosh: '//lambada.jitsi.net/http-bind' // FIXME: use xep-0156 for that
+    bosh: '//lambada.jitsi.net/http-bind', // FIXME: use xep-0156 for that
+    chromeDesktopSharing: false // Desktop sharing is disabled by default
 };

desktopsharing.js

+/**
+ * Indicates that desktop stream is currently in use(for toggle purpose).
+ * @type {boolean}
+ */
+var isUsingScreenStream = false;
+/**
+ * Indicates that switch stream operation is in progress and prevent from triggering new events.
+ * @type {boolean}
+ */
+var switchInProgress = false;
+
+/**
+ * @returns {boolean} <tt>true</tt> if desktop sharing feature is available and enabled.
+ */
+function isDesktopSharingEnabled() {
+    // Desktop sharing must be enabled in config and works on chrome only.
+    // Flag 'chrome://flags/#enable-usermedia-screen-capture' must be enabled.
+    return config.chromeDesktopSharing && RTC.browser == 'chrome';
+}
+
+/*
+ * Toggles screen sharing.
+ */
+function toggleScreenSharing() {
+    if (!(connection && connection.connected
+        && !switchInProgress
+        && getConferenceHandler().peerconnection.signalingState == 'stable'
+        && getConferenceHandler().peerconnection.iceConnectionState == 'connected')) {
+        return;
+    }
+    switchInProgress = true;
+
+    // Only the focus is able to set a shared key.
+    if(!isUsingScreenStream)
+    {
+        // Enable screen stream
+        getUserMediaWithConstraints(
+            ['screen'],
+            function(stream){
+                isUsingScreenStream = true;
+                gotScreenStream(stream);
+            },
+            getSwitchStreamFailed
+        );
+    } else {
+        // Disable screen stream
+        getUserMediaWithConstraints(
+            ['video'],
+            function(stream) {
+                isUsingScreenStream = false;
+                gotScreenStream(stream);
+            },
+            getSwitchStreamFailed, config.resolution || '360'
+        );
+    }
+}
+
+function getSwitchStreamFailed(error) {
+    console.error("Failed to obtain the stream to switch to", error);
+    switchInProgress = false;
+}
+
+function gotScreenStream(stream) {
+    var oldStream = connection.jingle.localVideo;
+
+    change_local_video(stream);
+
+    // FIXME: will block switchInProgress on true value in case of exception
+    getConferenceHandler().switchStreams(stream, oldStream, onDesktopStreamEnabled);
+}
+
+function onDesktopStreamEnabled() {
+    // Wait a moment before enabling the button
+    window.setTimeout(function() {
+        switchInProgress = false;
+    }, 3000);
+}

index.html

     <script src="libs/strophe/strophe.jingle.bundle.js?v=8"></script>
     <script src="libs/strophe/strophe.jingle.js?v=1"></script>
     <script src="libs/strophe/strophe.jingle.sdp.js?v=1"></script>
+    <script src="libs/strophe/strophe.jingle.sdp.util.js?v=1"></script>
     <script src="libs/strophe/strophe.jingle.sessionbase.js?v=1"></script>
     <script src="libs/strophe/strophe.jingle.session.js?v=1"></script>
     <script src="libs/colibri/colibri.focus.js?v=8"></script><!-- colibri focus implementation -->
     <script src="estos_log.js?v=2"></script><!-- simple stanza logger -->
     <script src="app.js?v=23"></script><!-- application logic -->
     <script src="chat.js?v=3"></script><!-- chat logic -->
+    <script src="desktopsharing.js?v=1"></script><!-- desktop sharing logic -->
     <script src="util.js?v=2"></script><!-- utility functions -->
     <script src="etherpad.js?v=5"></script><!-- etherpad plugin -->
     <script src="smileys.js?v=1"></script><!-- smiley images -->
                 <a class="button" onclick='Etherpad.toggleEtherpad(0);'><i title="Open shared document" class="fa fa-file-text fa-lg"></i></a>
             </span>
             <div class="header_button_separator"></div>
+            <span id="desktopsharing" style="display: none">
+                <a class="button" onclick="toggleScreenSharing();"><i title="Share screen" class="fa fa-desktop fa-lg"></i></a>
+                <div class="header_button_separator"></div>
+            </span>
             <a class="button" onclick='toggleFullScreen();'><i title="Enter / Exit Full Screen" class="fa fa-arrows-alt fa-lg"></i></a>
         </span>
     </div>

libs/colibri/colibri.focus.js

 ColibriFocus.prototype = Object.create(SessionBase.prototype);
 function ColibriFocus(connection, bridgejid) {
 
-    SessionBase.call(this, connection);
+    SessionBase.call(this, connection, Math.random().toString(36).substr(2, 12));
 
     this.bridgejid = bridgejid;
     this.peers = [];
     // media types of the conference
     this.media = ['audio', 'video'];
 
-    this.sid = Math.random().toString(36).substr(2, 12);
     this.connection.jingle.sessions[this.sid] = this;
     this.mychannel = [];
     this.channels = [];
 
 // tell everyone about a new participants a=ssrc lines (isadd is true)
 // or a leaving participants a=ssrc lines
-// FIXME: should not take an SDP, but rather the a=ssrc lines and probably a=mid
-ColibriFocus.prototype.sendSSRCUpdate = function (sdp, jid, isadd) {
+ColibriFocus.prototype.sendSSRCUpdate = function (sdpMediaSsrcs, fromJid, isadd) {
     var self = this;
     this.peers.forEach(function (peerjid) {
-        if (peerjid == jid) return;
-        console.log('tell', peerjid, 'about ' + (isadd ? 'new' : 'removed') + ' ssrcs from', jid);
+        if (peerjid == fromJid) return;
+        console.log('tell', peerjid, 'about ' + (isadd ? 'new' : 'removed') + ' ssrcs from', fromJid);
         if (!self.remotessrc[peerjid]) {
             // FIXME: this should only send to participants that are stable, i.e. who have sent a session-accept
             // possibly, this.remoteSSRC[session.peerjid] does not exist yet
             console.warn('do we really want to bother', peerjid, 'with updates yet?');
         }
-        var channel;
         var peersess = self.connection.jingle.jid2session[peerjid];
-        var modify = $iq({to: peerjid, type: 'set'})
-            .c('jingle', {
-                xmlns: 'urn:xmpp:jingle:1',
-                action: isadd ? 'addsource' : 'removesource',
-                initiator: peersess.initiator,
-                sid: peersess.sid
-            }
-        );
-        // FIXME: only announce video ssrcs since we mix audio and dont need
-        //      the audio ssrcs therefore
-        var modified = false;
-        for (channel = 0; channel < sdp.media.length; channel++) {
-            modified = true;
-            tmp = SDPUtil.find_lines(sdp.media[channel], 'a=ssrc:');
-            modify.c('content', {name: SDPUtil.parse_mid(SDPUtil.find_line(sdp.media[channel], 'a=mid:'))});
-            modify.c('source', { xmlns: 'urn:xmpp:jingle:apps:rtp:ssma:0' });
-            // FIXME: not completly sure this operates on blocks and / or handles different ssrcs correctly
-            tmp.forEach(function (line) {
-                var idx = line.indexOf(' ');
-                var linessrc = line.substr(0, idx).substr(7);
-                modify.attrs({ssrc: linessrc});
-
-                var kv = line.substr(idx + 1);
-                modify.c('parameter');
-                if (kv.indexOf(':') == -1) {
-                    modify.attrs({ name: kv });
-                } else {
-                    modify.attrs({ name: kv.split(':', 2)[0] });
-                    modify.attrs({ value: kv.split(':', 2)[1] });
-                }
-                modify.up();
-            });
-            modify.up(); // end of source
-            modify.up(); // end of content
+        if(!peersess){
+            console.warn('no session with peer: '+peerjid+' yet...');
+            return;
         }
-        if (modified) {
-            self.connection.sendIQ(modify,
-                function (res) {
-                    console.warn('got modify result');
-                },
-                function (err) {
-                    console.warn('got modify error', err);
-                }
-            );
+
+        self.sendSSRCUpdateIq(sdpMediaSsrcs, peersess.sid, peersess.initiator, peerjid, isadd);
+    });
+};
+
+/**
+ * Overrides SessionBase.addSource.
+ *
+ * @param elem proprietary 'add source' Jingle request(XML node).
+ * @param fromJid JID of the participant to whom new ssrcs belong.
+ */
+ColibriFocus.prototype.addSource = function (elem, fromJid) {
+
+    var self = this;
+    this.peerconnection.addSource(elem);
+
+    var peerSsrc = this.remotessrc[fromJid];
+    //console.log("On ADD", self.addssrc, peerSsrc);
+    this.peerconnection.addssrc.forEach(function(val, idx){
+        if(!peerSsrc[idx]){
+            // add ssrc
+            peerSsrc[idx] = val;
         } else {
-            console.log('modification not necessary');
+            if(peerSsrc[idx].indexOf(val) == -1){
+                peerSsrc[idx] = peerSsrc[idx]+val;
+            }
+        }
+    });
+
+    var oldRemoteSdp = new SDP(this.peerconnection.remoteDescription.sdp);
+    this.modifySources(function(){
+        // Notify other participants about added ssrc
+        var remoteSDP = new SDP(self.peerconnection.remoteDescription.sdp);
+        var newSSRCs = oldRemoteSdp.getNewMedia(remoteSDP);
+        self.sendSSRCUpdate(newSSRCs, fromJid, true);
+    });
+};
+
+/**
+ * Overrides SessionBase.removeSource.
+ *
+ * @param elem proprietary 'remove source' Jingle request(XML node).
+ * @param fromJid JID of the participant to whom removed ssrcs belong.
+ */
+ColibriFocus.prototype.removeSource = function (elem, fromJid) {
+
+    var self = this;
+    this.peerconnection.removeSource(elem);
+
+    var peerSsrc = this.remotessrc[fromJid];
+    //console.log("On REMOVE", self.removessrc, peerSsrc);
+    this.peerconnection.removessrc.forEach(function(val, idx){
+        if(peerSsrc[idx]){
+            // Remove ssrc
+            peerSsrc[idx] = peerSsrc[idx].replace(val, '');
         }
     });
+
+    var oldSDP = new SDP(self.peerconnection.remoteDescription.sdp);
+    this.modifySources(function(){
+        // Notify other participants about removed ssrc
+        var remoteSDP = new SDP(self.peerconnection.remoteDescription.sdp);
+        var removedSSRCs = remoteSDP.getNewMedia(oldSDP);
+        self.sendSSRCUpdate(removedSSRCs, fromJid, false);
+    });
 };
 
 ColibriFocus.prototype.setRemoteDescription = function (session, elem, desctype) {
     this.updateChannel(remoteSDP, participant);
 
     // ACT 2: tell anyone else about the new SSRCs
-    this.sendSSRCUpdate(remoteSDP, session.peerjid, true);
+    this.sendSSRCUpdate(remoteSDP.getMediaSsrcMap(), session.peerjid, true);
 
     // ACT 3: note the SSRCs
     this.remotessrc[session.peerjid] = [];
         sdp.media[j] += ssrcs[j];
         this.peerconnection.enqueueRemoveSsrc(j, ssrcs[j]);
     }
-    this.sendSSRCUpdate(sdp, session.peerjid, false);
+    this.sendSSRCUpdate(sdp.getMediaSsrcMap(), session.peerjid, false);
 
     delete this.remotessrc[session.peerjid];
     this.modifySources();

libs/colibri/colibri.session.js

     console.log('ColibriSession.accept');
 };
 
+ColibriSession.prototype.addSource = function (elem, fromJid) {
+    this.colibri.addSource(elem, fromJid);
+};
+
+ColibriSession.prototype.removeSource = function (elem, fromJid) {
+    this.colibri.removeSource(elem, fromJid);
+};
+
 ColibriSession.prototype.terminate = function (reason) {
     this.colibri.terminate(this, reason);
 };

libs/strophe/strophe.jingle.adapter.js

      */
     this.pendingop = null;
 
+    /**
+     * Flag indicates that peer connection stream have changed and modifySources should proceed.
+     * @type {boolean}
+     */
+    this.switchstreams = false;
+
     // override as desired
     this.trace = function(what, info) {
         //console.warn('WTRACE', what, info);
     console.log('addssrc', new Date().getTime());
     console.log('ice', this.iceConnectionState);
     var sdp = new SDP(this.remoteDescription.sdp);
+    var mySdp = new SDP(this.peerconnection.localDescription.sdp);
 
     var self = this;
     $(elem).each(function (idx, content) {
         tmp = $(content).find('>source[xmlns="urn:xmpp:jingle:apps:rtp:ssma:0"]');
         tmp.each(function () {
             var ssrc = $(this).attr('ssrc');
+            if(mySdp.containsSSRC(ssrc)){
+                /**
+                 * This happens when multiple participants change their streams at the same time and
+                 * ColibriFocus.modifySources have to wait for stable state. In the meantime multiple
+                 * addssrc are scheduled for update IQ. See
+                 */
+                console.warn("Got add stream request for my own ssrc: "+ssrc);
+                return;
+            }
             $(this).find('>parameter').each(function () {
                 lines += 'a=ssrc:' + ssrc + ' ' + $(this).attr('name');
                 if ($(this).attr('value') && $(this).attr('value').length)
     console.log('removessrc', new Date().getTime());
     console.log('ice', this.iceConnectionState);
     var sdp = new SDP(this.remoteDescription.sdp);
+    var mySdp = new SDP(this.peerconnection.localDescription.sdp);
 
     var self = this;
     $(elem).each(function (idx, content) {
         tmp = $(content).find('>source[xmlns="urn:xmpp:jingle:apps:rtp:ssma:0"]');
         tmp.each(function () {
             var ssrc = $(this).attr('ssrc');
+            // This should never happen, but can be useful for bug detection
+            if(mySdp.containsSSRC(ssrc)){
+                console.error("Got remove stream request for my own ssrc: "+ssrc);
+                return;
+            }
             $(this).find('>parameter').each(function () {
                 lines += 'a=ssrc:' + ssrc + ' ' + $(this).attr('name');
                 if ($(this).attr('value') && $(this).attr('value').length)
 TraceablePeerConnection.prototype.modifySources = function(successCallback) {
     var self = this;
     if (this.signalingState == 'closed') return;
-    if (!(this.addssrc.length || this.removessrc.length || this.pendingop !== null)){
+    if (!(this.addssrc.length || this.removessrc.length || this.pendingop !== null || this.switchstreams)){
+        // There is nothing to do since scheduled job might have been executed by another succeeding call
         if(successCallback){
             successCallback();
         }
         return;
     }
 
+    // Reset switch streams flag
+    this.switchstreams = false;
+
     var sdp = new SDP(this.remoteDescription.sdp);
 
     // add sources
     }
     if (um.indexOf('screen') >= 0) {
         constraints.video = {
-            "mandatory": {
-                "chromeMediaSource": "screen"
+            mandatory: {
+                chromeMediaSource: "screen",
+                maxWidth: window.screen.width,
+                maxHeight: window.screen.height,
+                maxFrameRate: 3
             }
         };
     }

libs/strophe/strophe.jingle.js

                 }
                 break;
             case 'addsource': // FIXME: proprietary
-                sess.addSource($(iq).find('>jingle>content'));
+                sess.addSource($(iq).find('>jingle>content'), fromJid);
                 break;
             case 'removesource': // FIXME: proprietary
-                sess.removeSource($(iq).find('>jingle>content'));
+                sess.removeSource($(iq).find('>jingle>content'), fromJid);
                 break;
             default:
                 console.warn('jingle action not implemented', action);

libs/strophe/strophe.jingle.sdp.js

     this.session = this.media.shift() + '\r\n';
     this.raw = this.session + this.media.join('');
 }
-
+/**
+ * Returns map of MediaChannel mapped per channel idx.
+ */
+SDP.prototype.getMediaSsrcMap = function() {
+    var self = this;
+    var media_ssrcs = {};
+    for (channelNum = 0; channelNum < self.media.length; channelNum++) {
+        modified = true;
+        tmp = SDPUtil.find_lines(self.media[channelNum], 'a=ssrc:');
+        var type = SDPUtil.parse_mid(SDPUtil.find_line(self.media[channelNum], 'a=mid:'));
+        var channel = new MediaChannel(channelNum, type);
+        media_ssrcs[channelNum] = channel;
+        tmp.forEach(function (line) {
+            var linessrc = line.substring(7).split(' ')[0];
+            // allocate new ChannelSsrc
+            if(!channel.ssrcs[linessrc]) {
+                channel.ssrcs[linessrc] = new ChannelSsrc(linessrc, type);
+            }
+            channel.ssrcs[linessrc].lines.push(line);
+        });
+    }
+    return media_ssrcs;
+}
+/**
+ * Returns <tt>true</tt> if this SDP contains given SSRC.
+ * @param ssrc the ssrc to check.
+ * @returns {boolean} <tt>true</tt> if this SDP contains given SSRC.
+ */
+SDP.prototype.containsSSRC = function(ssrc) {
+    var channels = this.getMediaSsrcMap();
+    var contains = false;
+    Object.keys(channels).forEach(function(chNumber){
+        var channel = channels[chNumber];
+        //console.log("Check", channel, ssrc);
+        if(Object.keys(channel.ssrcs).indexOf(ssrc) != -1){
+            contains = true;
+        }
+    });
+    return contains;
+}
+/**
+ * Returns map of MediaChannel that contains only media not contained in <tt>otherSdp</tt>. Mapped by channel idx.
+ * @param otherSdp the other SDP to check ssrc with.
+ */
+SDP.prototype.getNewMedia = function(otherSdp) {
+    var myMedia = this.getMediaSsrcMap();
+    var othersMedia = otherSdp.getMediaSsrcMap();
+    var newMedia = {};
+    Object.keys(othersMedia).forEach(function(channelNum) {
+        var myChannel = myMedia[channelNum];
+        var othersChannel = othersMedia[channelNum];
+        if(!myChannel && othersChannel) {
+            // Add whole channel
+            newMedia[channelNum] = othersChannel;
+            return;
+        }
+        // Look for new ssrcs accross the channel
+        Object.keys(othersChannel.ssrcs).forEach(function(ssrc) {
+            if(Object.keys(myChannel.ssrcs).indexOf(ssrc) === -1) {
+                // Allocate channel if we've found ssrc that doesn't exist in our channel
+                if(!newMedia[channelNum]){
+                    newMedia[channelNum] = new MediaChannel(othersChannel.chNumber, othersChannel.mediaType);
+                }
+                newMedia[channelNum].ssrcs[ssrc] = othersChannel.ssrcs[ssrc];
+            }
+        })
+    });
+    return newMedia;
+}
 // remove iSAC and CN from SDP
 SDP.prototype.mangle = function () {
     var i, j, mline, lines, rtpmap, newdesc;
         }
     }
     return media;
-};
-
-SDPUtil = {
-    iceparams: function (mediadesc, sessiondesc) {
-        var data = null;
-        if (SDPUtil.find_line(mediadesc, 'a=ice-ufrag:', sessiondesc) &&
-            SDPUtil.find_line(mediadesc, 'a=ice-pwd:', sessiondesc)) {
-            data = {
-                ufrag: SDPUtil.parse_iceufrag(SDPUtil.find_line(mediadesc, 'a=ice-ufrag:', sessiondesc)),
-                pwd: SDPUtil.parse_icepwd(SDPUtil.find_line(mediadesc, 'a=ice-pwd:', sessiondesc))
-            };
-        }
-        return data;
-    },
-    parse_iceufrag: function (line) {
-        return line.substring(12);
-    },
-    build_iceufrag: function (frag) {
-        return 'a=ice-ufrag:' + frag;
-    },
-    parse_icepwd: function (line) {
-        return line.substring(10);
-    },
-    build_icepwd: function (pwd) {
-        return 'a=ice-pwd:' + pwd;
-    },
-    parse_mid: function (line) {
-        return line.substring(6);
-    },
-    parse_mline: function (line) {
-        var parts = line.substring(2).split(' '),
-            data = {};
-        data.media = parts.shift();
-        data.port = parts.shift();
-        data.proto = parts.shift();
-        if (parts[parts.length - 1] === '') { // trailing whitespace
-            parts.pop();
-        }
-        data.fmt = parts;
-        return data;
-    },
-    build_mline: function (mline) {
-        return 'm=' + mline.media + ' ' + mline.port + ' ' + mline.proto + ' ' + mline.fmt.join(' ');
-    },
-    parse_rtpmap: function (line) {
-        var parts = line.substring(9).split(' '),
-            data = {};
-        data.id = parts.shift();
-        parts = parts[0].split('/');
-        data.name = parts.shift();
-        data.clockrate = parts.shift();
-        data.channels = parts.length ? parts.shift() : '1';
-        return data;
-    },
-    build_rtpmap: function (el) {
-        var line = 'a=rtpmap:' + el.getAttribute('id') + ' ' + el.getAttribute('name') + '/' + el.getAttribute('clockrate');
-        if (el.getAttribute('channels') && el.getAttribute('channels') != '1') {
-            line += '/' + el.getAttribute('channels');
-        }
-        return line;
-    },
-    parse_crypto: function (line) {
-        var parts = line.substring(9).split(' '),
-            data = {};
-        data.tag = parts.shift();
-        data['crypto-suite'] = parts.shift();
-        data['key-params'] = parts.shift();
-        if (parts.length) {
-            data['session-params'] = parts.join(' ');
-        }
-        return data;
-    },
-    parse_fingerprint: function (line) { // RFC 4572
-        var parts = line.substring(14).split(' '),
-            data = {};
-        data.hash = parts.shift();
-        data.fingerprint = parts.shift();
-        // TODO assert that fingerprint satisfies 2UHEX *(":" 2UHEX) ?
-        return data;
-    },
-    parse_fmtp: function (line) {
-        var parts = line.split(' '),
-            i, key, value,
-            data = [];
-        parts.shift();
-        parts = parts.join(' ').split(';');
-        for (i = 0; i < parts.length; i++) {
-            key = parts[i].split('=')[0];
-            while (key.length && key[0] == ' ') {
-                key = key.substring(1);
-            }
-            value = parts[i].split('=')[1];
-            if (key && value) {
-                data.push({name: key, value: value});
-            } else if (key) {
-                // rfc 4733 (DTMF) style stuff
-                data.push({name: '', value: key});
-            }
-        }
-        return data;
-    },
-    parse_icecandidate: function (line) {
-        var candidate = {},
-            elems = line.split(' ');
-        candidate.foundation = elems[0].substring(12);
-        candidate.component = elems[1];
-        candidate.protocol = elems[2].toLowerCase();
-        candidate.priority = elems[3];
-        candidate.ip = elems[4];
-        candidate.port = elems[5];
-        // elems[6] => "typ"
-        candidate.type = elems[7];
-        candidate.generation = 0; // default value, may be overwritten below
-        for (var i = 8; i < elems.length; i += 2) {
-            switch (elems[i]) {
-                case 'raddr':
-                    candidate['rel-addr'] = elems[i + 1];
-                    break;
-                case 'rport':
-                    candidate['rel-port'] = elems[i + 1];
-                    break;
-                case 'generation':
-                    candidate.generation = elems[i + 1];
-                    break;
-                default: // TODO
-                    console.log('parse_icecandidate not translating "' + elems[i] + '" = "' + elems[i + 1] + '"');
-            }
-        }
-        candidate.network = '1';
-        candidate.id = Math.random().toString(36).substr(2, 10); // not applicable to SDP -- FIXME: should be unique, not just random
-        return candidate;
-    },
-    build_icecandidate: function (cand) {
-        var line = ['a=candidate:' + cand.foundation, cand.component, cand.protocol, cand.priority, cand.ip, cand.port, 'typ', cand.type].join(' ');
-        line += ' ';
-        switch (cand.type) {
-            case 'srflx':
-            case 'prflx':
-            case 'relay':
-                if (cand.hasOwnAttribute('rel-addr') && cand.hasOwnAttribute('rel-port')) {
-                    line += 'raddr';
-                    line += ' ';
-                    line += cand['rel-addr'];
-                    line += ' ';
-                    line += 'rport';
-                    line += ' ';
-                    line += cand['rel-port'];
-                    line += ' ';
-                }
-                break;
-        }
-        line += 'generation';
-        line += ' ';
-        line += cand.hasOwnAttribute('generation') ? cand.generation : '0';
-        return line;
-    },
-    parse_ssrc: function (desc) {
-        // proprietary mapping of a=ssrc lines
-        // TODO: see "Jingle RTP Source Description" by Juberti and P. Thatcher on google docs
-        // and parse according to that
-        var lines = desc.split('\r\n'),
-            data = {};
-        for (var i = 0; i < lines.length; i++) {
-            if (lines[i].substring(0, 7) == 'a=ssrc:') {
-                var idx = lines[i].indexOf(' ');
-                data[lines[i].substr(idx + 1).split(':', 2)[0]] = lines[i].substr(idx + 1).split(':', 2)[1];
-            }
-        }
-        return data;
-    },
-    parse_rtcpfb: function (line) {
-        var parts = line.substr(10).split(' ');
-        var data = {};
-        data.pt = parts.shift();
-        data.type = parts.shift();
-        data.params = parts;
-        return data;
-    },
-    parse_extmap: function (line) {
-        var parts = line.substr(9).split(' ');
-        var data = {};
-        data.value = parts.shift();
-        if (data.value.indexOf('/') != -1) {
-            data.direction = data.value.substr(data.value.indexOf('/') + 1);
-            data.value = data.value.substr(0, data.value.indexOf('/'));
-        } else {
-            data.direction = 'both';
-        }
-        data.uri = parts.shift();
-        data.params = parts;
-        return data;
-    },
-    find_line: function (haystack, needle, sessionpart) {
-        var lines = haystack.split('\r\n');
-        for (var i = 0; i < lines.length; i++) {
-            if (lines[i].substring(0, needle.length) == needle) {
-                return lines[i];
-            }
-        }
-        if (!sessionpart) {
-            return false;
-        }
-        // search session part
-        lines = sessionpart.split('\r\n');
-        for (var j = 0; j < lines.length; j++) {
-            if (lines[j].substring(0, needle.length) == needle) {
-                return lines[j];
-            }
-        }
-        return false;
-    },
-    find_lines: function (haystack, needle, sessionpart) {
-        var lines = haystack.split('\r\n'),
-            needles = [];
-        for (var i = 0; i < lines.length; i++) {
-            if (lines[i].substring(0, needle.length) == needle)
-                needles.push(lines[i]);
-        }
-        if (needles.length || !sessionpart) {
-            return needles;
-        }
-        // search session part
-        lines = sessionpart.split('\r\n');
-        for (var j = 0; j < lines.length; j++) {
-            if (lines[j].substring(0, needle.length) == needle) {
-                needles.push(lines[j]);
-            }
-        }
-        return needles;
-    },
-    candidateToJingle: function (line) {
-        // a=candidate:2979166662 1 udp 2113937151 192.168.2.100 57698 typ host generation 0
-        //      <candidate component=... foundation=... generation=... id=... ip=... network=... port=... priority=... protocol=... type=.../>
-        if (line.substring(0, 12) != 'a=candidate:') {
-            console.log('parseCandidate called with a line that is not a candidate line');
-            console.log(line);
-            return null;
-        }
-        if (line.substring(line.length - 2) == '\r\n') // chomp it
-            line = line.substring(0, line.length - 2);
-        var candidate = {},
-            elems = line.split(' '),
-            i;
-        if (elems[6] != 'typ') {
-            console.log('did not find typ in the right place');
-            console.log(line);
-            return null;
-        }
-        candidate.foundation = elems[0].substring(12);
-        candidate.component = elems[1];
-        candidate.protocol = elems[2].toLowerCase();
-        candidate.priority = elems[3];
-        candidate.ip = elems[4];
-        candidate.port = elems[5];
-        // elems[6] => "typ"
-        candidate.type = elems[7];
-        for (i = 8; i < elems.length; i += 2) {
-            switch (elems[i]) {
-                case 'raddr':
-                    candidate['rel-addr'] = elems[i + 1];
-                    break;
-                case 'rport':
-                    candidate['rel-port'] = elems[i + 1];
-                    break;
-                case 'generation':
-                    candidate.generation = elems[i + 1];
-                    break;
-                default: // TODO
-                    console.log('not translating "' + elems[i] + '" = "' + elems[i + 1] + '"');
-            }
-        }
-        candidate.network = '1';
-        candidate.id = Math.random().toString(36).substr(2, 10); // not applicable to SDP -- FIXME: should be unique, not just random
-        return candidate;
-    },
-    candidateFromJingle: function (cand) {
-        var line = 'a=candidate:';
-        line += cand.getAttribute('foundation');
-        line += ' ';
-        line += cand.getAttribute('component');
-        line += ' ';
-        line += cand.getAttribute('protocol'); //.toUpperCase(); // chrome M23 doesn't like this
-        line += ' ';
-        line += cand.getAttribute('priority');
-        line += ' ';
-        line += cand.getAttribute('ip');
-        line += ' ';
-        line += cand.getAttribute('port');
-        line += ' ';
-        line += 'typ';
-        line += ' ' + cand.getAttribute('type');
-        line += ' ';
-        switch (cand.getAttribute('type')) {
-            case 'srflx':
-            case 'prflx':
-            case 'relay':
-                if (cand.getAttribute('rel-addr') && cand.getAttribute('rel-port')) {
-                    line += 'raddr';
-                    line += ' ';
-                    line += cand.getAttribute('rel-addr');
-                    line += ' ';
-                    line += 'rport';
-                    line += ' ';
-                    line += cand.getAttribute('rel-port');
-                    line += ' ';
-                }
-                break;
-        }
-        line += 'generation';
-        line += ' ';
-        line += cand.getAttribute('generation') || '0';
-        return line + '\r\n';
-    }
-};
+};

libs/strophe/strophe.jingle.sdp.util.js

+/**
+ * Contains utility classes used in SDP class.
+ *
+ */
+
+/**
+ * Class holds a=ssrc lines and media type a=mid
+ * @param ssrc synchronization source identifier number(a=ssrc lines from SDP)
+ * @param type media type eg. "audio" or "video"(a=mid frm SDP)
+ * @constructor
+ */
+function ChannelSsrc(ssrc, type) {
+    this.ssrc = ssrc;
+    this.type = type;
+    this.lines = [];
+}
+
+/**
+ * Helper class represents media channel. Is a container for ChannelSsrc, holds channel idx and media type.
+ * @param channelNumber channel idx in SDP media array.
+ * @param mediaType media type(a=mid)
+ * @constructor
+ */
+function MediaChannel(channelNumber, mediaType) {
+    /**
+     * SDP channel number
+     * @type {*}
+     */
+    this.chNumber = channelNumber;
+    /**
+     * Channel media type(a=mid)
+     * @type {*}
+     */
+    this.mediaType = mediaType;
+    /**
+     * The maps of ssrc numbers to ChannelSsrc objects.
+     */
+    this.ssrcs = {};
+}
+
+SDPUtil = {
+    iceparams: function (mediadesc, sessiondesc) {
+        var data = null;
+        if (SDPUtil.find_line(mediadesc, 'a=ice-ufrag:', sessiondesc) &&
+            SDPUtil.find_line(mediadesc, 'a=ice-pwd:', sessiondesc)) {
+            data = {
+                ufrag: SDPUtil.parse_iceufrag(SDPUtil.find_line(mediadesc, 'a=ice-ufrag:', sessiondesc)),
+                pwd: SDPUtil.parse_icepwd(SDPUtil.find_line(mediadesc, 'a=ice-pwd:', sessiondesc))
+            };
+        }
+        return data;
+    },
+    parse_iceufrag: function (line) {
+        return line.substring(12);
+    },
+    build_iceufrag: function (frag) {
+        return 'a=ice-ufrag:' + frag;
+    },
+    parse_icepwd: function (line) {
+        return line.substring(10);
+    },
+    build_icepwd: function (pwd) {
+        return 'a=ice-pwd:' + pwd;
+    },
+    parse_mid: function (line) {
+        return line.substring(6);
+    },
+    parse_mline: function (line) {
+        var parts = line.substring(2).split(' '),
+            data = {};
+        data.media = parts.shift();
+        data.port = parts.shift();
+        data.proto = parts.shift();
+        if (parts[parts.length - 1] === '') { // trailing whitespace
+            parts.pop();
+        }
+        data.fmt = parts;
+        return data;
+    },
+    build_mline: function (mline) {
+        return 'm=' + mline.media + ' ' + mline.port + ' ' + mline.proto + ' ' + mline.fmt.join(' ');
+    },
+    parse_rtpmap: function (line) {
+        var parts = line.substring(9).split(' '),
+            data = {};
+        data.id = parts.shift();
+        parts = parts[0].split('/');
+        data.name = parts.shift();
+        data.clockrate = parts.shift();
+        data.channels = parts.length ? parts.shift() : '1';
+        return data;
+    },
+    build_rtpmap: function (el) {
+        var line = 'a=rtpmap:' + el.getAttribute('id') + ' ' + el.getAttribute('name') + '/' + el.getAttribute('clockrate');
+        if (el.getAttribute('channels') && el.getAttribute('channels') != '1') {
+            line += '/' + el.getAttribute('channels');
+        }
+        return line;
+    },
+    parse_crypto: function (line) {
+        var parts = line.substring(9).split(' '),
+            data = {};
+        data.tag = parts.shift();
+        data['crypto-suite'] = parts.shift();
+        data['key-params'] = parts.shift();
+        if (parts.length) {
+            data['session-params'] = parts.join(' ');
+        }
+        return data;
+    },
+    parse_fingerprint: function (line) { // RFC 4572
+        var parts = line.substring(14).split(' '),
+            data = {};
+        data.hash = parts.shift();
+        data.fingerprint = parts.shift();
+        // TODO assert that fingerprint satisfies 2UHEX *(":" 2UHEX) ?
+        return data;
+    },
+    parse_fmtp: function (line) {
+        var parts = line.split(' '),
+            i, key, value,
+            data = [];
+        parts.shift();
+        parts = parts.join(' ').split(';');
+        for (i = 0; i < parts.length; i++) {
+            key = parts[i].split('=')[0];
+            while (key.length && key[0] == ' ') {
+                key = key.substring(1);
+            }
+            value = parts[i].split('=')[1];
+            if (key && value) {
+                data.push({name: key, value: value});
+            } else if (key) {
+                // rfc 4733 (DTMF) style stuff
+                data.push({name: '', value: key});
+            }
+        }
+        return data;
+    },
+    parse_icecandidate: function (line) {
+        var candidate = {},
+            elems = line.split(' ');
+        candidate.foundation = elems[0].substring(12);
+        candidate.component = elems[1];
+        candidate.protocol = elems[2].toLowerCase();
+        candidate.priority = elems[3];
+        candidate.ip = elems[4];
+        candidate.port = elems[5];
+        // elems[6] => "typ"
+        candidate.type = elems[7];
+        candidate.generation = 0; // default value, may be overwritten below
+        for (var i = 8; i < elems.length; i += 2) {
+            switch (elems[i]) {
+                case 'raddr':
+                    candidate['rel-addr'] = elems[i + 1];
+                    break;
+                case 'rport':
+                    candidate['rel-port'] = elems[i + 1];
+                    break;
+                case 'generation':
+                    candidate.generation = elems[i + 1];
+                    break;
+                default: // TODO
+                    console.log('parse_icecandidate not translating "' + elems[i] + '" = "' + elems[i + 1] + '"');
+            }
+        }
+        candidate.network = '1';
+        candidate.id = Math.random().toString(36).substr(2, 10); // not applicable to SDP -- FIXME: should be unique, not just random
+        return candidate;
+    },
+    build_icecandidate: function (cand) {
+        var line = ['a=candidate:' + cand.foundation, cand.component, cand.protocol, cand.priority, cand.ip, cand.port, 'typ', cand.type].join(' ');
+        line += ' ';
+        switch (cand.type) {
+            case 'srflx':
+            case 'prflx':
+            case 'relay':
+                if (cand.hasOwnAttribute('rel-addr') && cand.hasOwnAttribute('rel-port')) {
+                    line += 'raddr';
+                    line += ' ';
+                    line += cand['rel-addr'];
+                    line += ' ';
+                    line += 'rport';
+                    line += ' ';
+                    line += cand['rel-port'];
+                    line += ' ';
+                }
+                break;
+        }
+        line += 'generation';
+        line += ' ';
+        line += cand.hasOwnAttribute('generation') ? cand.generation : '0';
+        return line;
+    },
+    parse_ssrc: function (desc) {
+        // proprietary mapping of a=ssrc lines
+        // TODO: see "Jingle RTP Source Description" by Juberti and P. Thatcher on google docs
+        // and parse according to that
+        var lines = desc.split('\r\n'),
+            data = {};
+        for (var i = 0; i < lines.length; i++) {
+            if (lines[i].substring(0, 7) == 'a=ssrc:') {
+                var idx = lines[i].indexOf(' ');
+                data[lines[i].substr(idx + 1).split(':', 2)[0]] = lines[i].substr(idx + 1).split(':', 2)[1];
+            }
+        }
+        return data;
+    },
+    parse_rtcpfb: function (line) {
+        var parts = line.substr(10).split(' ');
+        var data = {};
+        data.pt = parts.shift();
+        data.type = parts.shift();
+        data.params = parts;
+        return data;
+    },
+    parse_extmap: function (line) {
+        var parts = line.substr(9).split(' ');
+        var data = {};
+        data.value = parts.shift();
+        if (data.value.indexOf('/') != -1) {
+            data.direction = data.value.substr(data.value.indexOf('/') + 1);
+            data.value = data.value.substr(0, data.value.indexOf('/'));
+        } else {
+            data.direction = 'both';
+        }
+        data.uri = parts.shift();
+        data.params = parts;
+        return data;
+    },
+    find_line: function (haystack, needle, sessionpart) {
+        var lines = haystack.split('\r\n');
+        for (var i = 0; i < lines.length; i++) {
+            if (lines[i].substring(0, needle.length) == needle) {
+                return lines[i];
+            }
+        }
+        if (!sessionpart) {
+            return false;
+        }
+        // search session part
+        lines = sessionpart.split('\r\n');
+        for (var j = 0; j < lines.length; j++) {
+            if (lines[j].substring(0, needle.length) == needle) {
+                return lines[j];
+            }
+        }
+        return false;
+    },
+    find_lines: function (haystack, needle, sessionpart) {
+        var lines = haystack.split('\r\n'),
+            needles = [];
+        for (var i = 0; i < lines.length; i++) {
+            if (lines[i].substring(0, needle.length) == needle)
+                needles.push(lines[i]);
+        }
+        if (needles.length || !sessionpart) {
+            return needles;
+        }
+        // search session part
+        lines = sessionpart.split('\r\n');
+        for (var j = 0; j < lines.length; j++) {
+            if (lines[j].substring(0, needle.length) == needle) {
+                needles.push(lines[j]);
+            }
+        }
+        return needles;
+    },
+    candidateToJingle: function (line) {
+        // a=candidate:2979166662 1 udp 2113937151 192.168.2.100 57698 typ host generation 0
+        //      <candidate component=... foundation=... generation=... id=... ip=... network=... port=... priority=... protocol=... type=.../>
+        if (line.substring(0, 12) != 'a=candidate:') {
+            console.log('parseCandidate called with a line that is not a candidate line');
+            console.log(line);
+            return null;
+        }
+        if (line.substring(line.length - 2) == '\r\n') // chomp it
+            line = line.substring(0, line.length - 2);
+        var candidate = {},
+            elems = line.split(' '),
+            i;
+        if (elems[6] != 'typ') {
+            console.log('did not find typ in the right place');
+            console.log(line);
+            return null;
+        }
+        candidate.foundation = elems[0].substring(12);
+        candidate.component = elems[1];
+        candidate.protocol = elems[2].toLowerCase();
+        candidate.priority = elems[3];
+        candidate.ip = elems[4];
+        candidate.port = elems[5];
+        // elems[6] => "typ"
+        candidate.type = elems[7];
+        for (i = 8; i < elems.length; i += 2) {
+            switch (elems[i]) {
+                case 'raddr':
+                    candidate['rel-addr'] = elems[i + 1];
+                    break;
+                case 'rport':
+                    candidate['rel-port'] = elems[i + 1];
+                    break;
+                case 'generation':
+                    candidate.generation = elems[i + 1];
+                    break;
+                default: // TODO
+                    console.log('not translating "' + elems[i] + '" = "' + elems[i + 1] + '"');
+            }
+        }
+        candidate.network = '1';
+        candidate.id = Math.random().toString(36).substr(2, 10); // not applicable to SDP -- FIXME: should be unique, not just random
+        return candidate;
+    },
+    candidateFromJingle: function (cand) {
+        var line = 'a=candidate:';
+        line += cand.getAttribute('foundation');
+        line += ' ';
+        line += cand.getAttribute('component');
+        line += ' ';
+        line += cand.getAttribute('protocol'); //.toUpperCase(); // chrome M23 doesn't like this
+        line += ' ';
+        line += cand.getAttribute('priority');
+        line += ' ';
+        line += cand.getAttribute('ip');
+        line += ' ';
+        line += cand.getAttribute('port');
+        line += ' ';
+        line += 'typ';
+        line += ' ' + cand.getAttribute('type');
+        line += ' ';
+        switch (cand.getAttribute('type')) {
+            case 'srflx':
+            case 'prflx':
+            case 'relay':
+                if (cand.getAttribute('rel-addr') && cand.getAttribute('rel-port')) {
+                    line += 'raddr';
+                    line += ' ';
+                    line += cand.getAttribute('rel-addr');
+                    line += ' ';
+                    line += 'rport';
+                    line += ' ';
+                    line += cand.getAttribute('rel-port');
+                    line += ' ';
+                }
+                break;
+        }
+        line += 'generation';
+        line += ' ';
+        line += cand.getAttribute('generation') || '0';
+        return line + '\r\n';
+    }
+};
+

libs/strophe/strophe.jingle.session.js

 JingleSession.prototype = Object.create(SessionBase.prototype);
 function JingleSession(me, sid, connection) {
 
-    SessionBase.call(this, connection);
+    SessionBase.call(this, connection, sid);
 
     this.me = me;
-    this.sid = sid;
     this.initiator = null;
     this.responder = null;
     this.isInitiator = null;
     );
 };
 
+/**
+ * Implements SessionBase.sendSSRCUpdate.
+ */
+JingleSession.prototype.sendSSRCUpdate = function(sdpMediaSsrcs, fromJid, isadd) {
+
+    var self = this;
+    console.log('tell', self.peerjid, 'about ' + (isadd ? 'new' : 'removed') + ' ssrcs from' + self.me);
+
+    if (!(this.peerconnection.signalingState == 'stable' && this.peerconnection.iceConnectionState == 'connected')){
+        console.log("Too early to send updates");
+        return;
+    }
+
+    this.sendSSRCUpdateIq(sdpMediaSsrcs, self.sid, self.initiator, self.peerjid, isadd);
+};
+
 JingleSession.prototype.terminate = function (reason) {
     this.state = 'ended';
     this.reason = reason;

libs/strophe/strophe.jingle.sessionbase.js

 /**
  * Base class for ColibriFocus and JingleSession.
  * @param connection Strophe connection object
+ * @param sid my session identifier(resource)
  * @constructor
  */
-function SessionBase(connection){
+function SessionBase(connection, sid){
 
     this.connection = connection;
+    this.sid = sid;
     this.peerconnection
         = new TraceablePeerConnection(
             connection.jingle.ice_config,
 }
 
 
-SessionBase.prototype.modifySources = function() {
+SessionBase.prototype.modifySources = function (successCallback) {
     var self = this;
     this.peerconnection.modifySources(function(){
         $(document).trigger('setLocalDescription.jingle', [self.sid]);
+        if(successCallback) {
+            successCallback();
+        }
     });
 };
 
-SessionBase.prototype.addSource = function (elem) {
+SessionBase.prototype.addSource = function (elem, fromJid) {
 
     this.peerconnection.addSource(elem);
 
     this.modifySources();
 };
 
-SessionBase.prototype.removeSource = function (elem) {
+SessionBase.prototype.removeSource = function (elem, fromJid) {
 
     this.peerconnection.removeSource(elem);
 
     this.modifySources();
 };
+/**
+ * Switches video streams.
+ * @param new_stream new stream that will be used as video of this session.
+ * @param oldStream old video stream of this session.
+ * @param success_callback callback executed after successful stream switch.
+ */
+SessionBase.prototype.switchStreams = function (new_stream, oldStream, success_callback) {
+
+    var self = this;
+
+    // Remember SDP to figure out added/removed SSRCs
+    var oldSdp = new SDP(self.peerconnection.localDescription.sdp);
+
+    self.peerconnection.removeStream(oldStream);
+
+    self.connection.jingle.localVideo = new_stream;
+    self.peerconnection.addStream(self.connection.jingle.localVideo);
+
+    self.connection.jingle.localStreams = [];
+    self.connection.jingle.localStreams.push(self.connection.jingle.localAudio);
+    self.connection.jingle.localStreams.push(self.connection.jingle.localVideo);
+
+    self.peerconnection.switchstreams = true;
+    self.modifySources(function() {
+        console.log('modify sources done');
+
+        var newSdp = new SDP(self.peerconnection.localDescription.sdp);
+        console.log("SDPs", oldSdp, newSdp);
+        self.notifyMySSRCUpdate(oldSdp, newSdp);
+
+        success_callback();
+    });
+};
+
+/**
+ * Figures out added/removed ssrcs and send update IQs.
+ * @param old_sdp SDP object for old description.
+ * @param new_sdp SDP object for new description.
+ */
+SessionBase.prototype.notifyMySSRCUpdate = function (old_sdp, new_sdp) {
+
+    var old_media = old_sdp.getMediaSsrcMap();
+    var new_media = new_sdp.getMediaSsrcMap();
+    //console.log("old/new medias: ", old_media, new_media);
+
+    var toAdd = old_sdp.getNewMedia(new_sdp);
+    var toRemove = new_sdp.getNewMedia(old_sdp);
+    //console.log("to add", toAdd);
+    //console.log("to remove", toRemove);
+    if(Object.keys(toRemove).length > 0){
+        this.sendSSRCUpdate(toRemove, null, false);
+    }
+    if(Object.keys(toAdd).length > 0){
+        this.sendSSRCUpdate(toAdd, null, true);
+    }
+};
+
+/**
+ * Empty method that does nothing by default. It should send SSRC update IQs to session participants.
+ * @param sdpMediaSsrcs array of
+ * @param fromJid
+ * @param isAdd
+ */
+SessionBase.prototype.sendSSRCUpdate = function(sdpMediaSsrcs, fromJid, isAdd) {
+    //FIXME: put default implementation here(maybe from JingleSession?)
+}
+
+/**
+ * Sends SSRC update IQ.
+ * @param sdpMediaSsrcs SSRCs map obtained from SDP.getNewMedia. Cntains SSRCs to add/remove.
+ * @param sid session identifier that will be put into the IQ.
+ * @param initiator initiator identifier.
+ * @param toJid destination Jid
+ * @param isAdd indicates if this is remove or add operation.
+ */
+SessionBase.prototype.sendSSRCUpdateIq = function(sdpMediaSsrcs, sid, initiator, toJid, isAdd) {
+
+    var self = this;
+    var modify = $iq({to: toJid, type: 'set'})
+        .c('jingle', {
+            xmlns: 'urn:xmpp:jingle:1',
+            action: isAdd ? 'addsource' : 'removesource',
+            initiator: initiator,
+            sid: sid
+        }
+    );
+    // FIXME: only announce video ssrcs since we mix audio and dont need
+    //      the audio ssrcs therefore
+    var modified = false;
+    Object.keys(sdpMediaSsrcs).forEach(function(channelNum){
+        modified = true;
+        var channel = sdpMediaSsrcs[channelNum];
+        modify.c('content', {name: channel.mediaType});
+        // FIXME: not completly sure this operates on blocks and / or handles different ssrcs correctly
+        // generate sources from lines
+        Object.keys(channel.ssrcs).forEach(function(ssrcNum) {
+            var mediaSsrc = channel.ssrcs[ssrcNum];
+            modify.c('source', { xmlns: 'urn:xmpp:jingle:apps:rtp:ssma:0' });
+            modify.attrs({ssrc: mediaSsrc.ssrc});
+            // iterate over ssrc lines
+            mediaSsrc.lines.forEach(function (line) {
+                var idx = line.indexOf(' ');
+                var kv = line.substr(idx + 1);
+                modify.c('parameter');
+                if (kv.indexOf(':') == -1) {
+                    modify.attrs({ name: kv });
+                } else {
+                    modify.attrs({ name: kv.split(':', 2)[0] });
+                    modify.attrs({ value: kv.split(':', 2)[1] });
+                }
+                modify.up(); // end of parameter
+            });
+            modify.up(); // end of source
+        });
+        modify.up(); // end of content
+    });
+    if (modified) {
+        self.connection.sendIQ(modify,
+            function (res) {
+                console.info('got modify result', res);
+            },
+            function (err) {
+                console.error('got modify error', err);
+            }
+        );
+    } else {
+        console.log('modification not necessary');
+    }
+};
 
 // SDP-based mute by going recvonly/sendrecv
 // FIXME: should probably black out the screen as well

muc.js

         this.presMap['source' + sourceNumber + '_ssrc'] = ssrcs;
         this.presMap['source' + sourceNumber + '_direction'] = direction;
     },
+    clearPresenceMedia: function () {
+        var self = this;
+        Object.keys(this.presMap).forEach( function(key) {
+            if(key.indexOf('source') != -1) {
+                delete self.presMap[key];
+            }
+        });
+    },
     addPreziToPresence: function (url, currentSlide) {
         this.presMap['prezins'] = 'http://jitsi.org/jitmeet/prezi';
         this.presMap['preziurl'] = url;