fix(multi-stream): Fix local SSRC cache to include multiple video streams. (#2006)

* fix(multi-stream): Fix local SSRC cache to include multiple video streams.
If multiple local video streams are found in the SDP, cache all of them instead of the first video SSRC. This fixes an issue where the resolution/fps stats for the screenshare track are not available.

* squash: new track inherits the source name of old track if it exists.

JitsiConference.js

         }
 
         if (FeatureFlags.isMultiStreamSupportEnabled() && mediaType === MediaType.VIDEO) {
+            const sourceName = getSourceNameForJitsiTrack(
+                this.myUserId(),
+                mediaType,
+                this.getLocalTracks(mediaType)?.length);
+
+            track.setSourceName(sourceName);
             const addTrackPromises = [];
 
             this.p2pJingleSession && addTrackPromises.push(this.p2pJingleSession.addTracks([ track ]));
  */
 JitsiConference.prototype.replaceTrack = function(oldTrack, newTrack) {
     const oldVideoType = oldTrack?.getVideoType();
+    const mediaType = oldTrack?.getType() || newTrack?.getType();
     const newVideoType = newTrack?.getVideoType();
 
     if (FeatureFlags.isMultiStreamSupportEnabled() && oldTrack && newTrack && oldVideoType !== newVideoType) {
         throw new Error(`Replacing a track of videoType=${oldVideoType} with a track of videoType=${newVideoType} is`
             + ' not supported in this mode.');
     }
+
+    if (FeatureFlags.isSourceNameSignalingEnabled() && newTrack) {
+        if (oldTrack) {
+            newTrack.setSourceName(oldTrack.getSourceName());
+        } else {
+            const sourceName = getSourceNameForJitsiTrack(
+                this.myUserId(),
+                mediaType,
+                this.getLocalTracks(mediaType)?.length);
+
+            newTrack.setSourceName(sourceName);
+        }
+    }
     const oldTrackBelongsToConference = this === oldTrack?.conference;
 
     if (oldTrackBelongsToConference && oldTrack.disposed) {

modules/RTC/TraceablePeerConnection.js

  */
 TraceablePeerConnection.prototype._extractSSRCMap = function(desc) {
     /**
-     * Track SSRC infos mapped by stream ID (msid) or mediaType (unfied-plan)
+     * Track SSRC infos mapped by stream ID (msid) or mediaType (unified-plan)
      * @type {Map<string,TrackSSRCInfo>}
      */
     const ssrcMap = new Map();
     // For unified plan clients, only the first audio and video mlines will have ssrcs for the local sources.
     // The rest of the m-lines are for the recv-only sources, one for each remote source.
     if (this._usesUnifiedPlan) {
-        media = [];
-        [ MediaType.AUDIO, MediaType.VIDEO ].forEach(mediaType => {
-            const mLine = session.media.find(m => m.type === mediaType);
+        if (FeatureFlags.isMultiStreamSupportEnabled()) {
+            media = media.filter(mline => mline.direction === MediaDirection.SENDONLY
+                || mline.direction === MediaDirection.SENDRECV);
+            logger.warn(`local m-lines is ${media.length}`);
+        } else {
+            media = [];
+            [ MediaType.AUDIO, MediaType.VIDEO ].forEach(mediaType => {
+                const mLine = session.media.find(m => m.type === mediaType);
 
-            mLine && media.push(mLine);
-        });
+                mLine && media.push(mLine);
+            });
+        }
     }
 
+    let index = 0;
+
     for (const mLine of media) {
         if (!Array.isArray(mLine.ssrcs)) {
             continue; // eslint-disable-line no-continue
 
         if (Array.isArray(mLine.ssrcGroups)) {
             for (const group of mLine.ssrcGroups) {
-                if (typeof group.semantics !== 'undefined'
-                    && typeof group.ssrcs !== 'undefined') {
+                if (typeof group.semantics !== 'undefined' && typeof group.ssrcs !== 'undefined') {
                     // Parse SSRCs and store as numbers
                     const groupSSRCs = group.ssrcs.split(' ').map(ssrcStr => parseInt(ssrcStr, 10));
                     const primarySSRC = groupSSRCs[0];
             // the standard and the unified plan SDPs do not have a proper msid attribute for the sources.
             // Also the ssrcs for sources do not change for Unified plan clients since RTCRtpSender#replaceTrack is
             // used for switching the tracks so it is safe to use the mediaType as the key for the TrackSSRCInfo map.
-            const key = this._usesUnifiedPlan ? mLine.type : ssrc.value;
+            const key = this._usesUnifiedPlan
+                ? FeatureFlags.isMultiStreamSupportEnabled() ? `${mLine.type}-${index}` : mLine.type
+                : ssrc.value;
             const ssrcNumber = ssrc.id;
             let ssrcInfo = ssrcMap.get(key);
 
                 }
             }
         }
+
+        // Currently multi-stream is supported for video only.
+        mLine.type === MediaType.VIDEO && index++;
     }
 
     return ssrcMap;
  */
 TraceablePeerConnection.prototype._processLocalSSRCsMap = function(ssrcMap) {
     for (const track of this.localTracks.values()) {
-        const sourceIdentifier = this._usesUnifiedPlan ? track.getType() : track.storedMSID;
+        let sourceIndex, sourceName;
+
+        if (FeatureFlags.isMultiStreamSupportEnabled()) {
+            sourceName = track.getSourceName();
+            sourceIndex = sourceName?.indexOf('-') + 2;
+        }
+
+        const sourceIdentifier = this._usesUnifiedPlan
+            ? FeatureFlags.isMultiStreamSupportEnabled() && sourceIndex
+                ? `${track.getType()}-${sourceName.substr(sourceIndex, 1)}` : track.getType()
+            : track.storedMSID;
 
         if (ssrcMap.has(sourceIdentifier)) {
             const newSSRC = ssrcMap.get(sourceIdentifier);

modules/statistics/RTPStatsCollector.js

                 return;
             }
 
-            const ssrc = this.peerconnection.getLocalSSRC(localVideoTracks[0]);
+            const ssrc = this.peerconnection.getSsrcByTrackId(now.trackIdentifier);
 
             if (!ssrc) {
                 return;