Synthesise codec when adding pending track for no simulcast case also. (#2339)

* Synthesise codec when adding pending track for no simulcast case also. Older clients not using simulcast codecs were failing e2e migration tests. Problem is that they did not have layer information and hence SSRC could not be set on migration. A codec was getting added later (when OnTrack was received). I missed adding layers in that code. Could have cloned layers there and added it. But, simplifying and adding at the start itself. Also, cleaning up code in `MediaTrackReceiver` for no codecs case as it should not happen any more. * clone per layer * fix priority determination
2026-08-03 13:19:56 +00:00 · 2023-12-22 17:09:49 +05:30
parent 28ae092ea8
commit 26c96ec283
3 changed files with 60 additions and 89 deletions
@@ -221,8 +221,17 @@ func (t *MediaTrack) AddReceiver(receiver *webrtc.RTPReceiver, track *webrtc.Tra
 				break
 			}
 		}
-		if len(ti.Codecs) == 0 {
-			priority = 0
+		if priority < 0 {
+			switch len(ti.Codecs) {
+			case 0:
+				// audio track
+				priority = 0
+			case 1:
+				// older clients or non simulcast-codec, mime type only set later
+				if ti.Codecs[0].MimeType == "" {
+					priority = 0
+				}
+			}
 		}
 		if priority < 0 {
 			t.params.Logger.Warnw("could not find codec for webrtc receiver", nil, "webrtcCodec", mime, "track", logger.Proto(ti))
@@ -182,11 +182,6 @@ func (t *MediaTrackReceiver) SetupReceiver(receiver sfu.TrackReceiver, priority
 		if priority == 0 {
 			t.trackInfo.MimeType = receiver.Codec().MimeType
 			t.trackInfo.Mid = mid
-
-			// for clients don't have simulcast codecs (old version or single codec), add the primary codec
-			if len(t.trackInfo.Codecs) == 0 && t.trackInfo.Type == livekit.TrackType_VIDEO {
-				t.trackInfo.Codecs = append(t.trackInfo.Codecs, &livekit.SimulcastCodecInfo{})
-			}
 		}

 		for i, ci := range t.trackInfo.Codecs {
@@ -547,7 +542,7 @@ func (t *MediaTrackReceiver) SetLayerSsrc(mime string, rid string, ssrc uint32)
 	}
 	quality := buffer.SpatialLayerToVideoQuality(layer, t.trackInfo)
 	// set video layer ssrc info
-	for _, ci := range t.trackInfo.Codecs {
+	for i, ci := range t.trackInfo.Codecs {
 		if !strings.EqualFold(ci.MimeType, mime) {
 			continue
 		}
@@ -567,26 +562,12 @@ func (t *MediaTrackReceiver) SetLayerSsrc(mime string, rid string, ssrc uint32)
 		if !ssrcFound && matchingLayer != nil {
 			matchingLayer.Ssrc = ssrc
 		}
-		break
-	}

-	// for client don't use simulcast codecs (old client version or single codec)
-	if len(t.trackInfo.Codecs) == 0 {
-		// if origin layer has ssrc, don't override it
-		var matchingLayer *livekit.VideoLayer
-		ssrcFound := false
-		for _, l := range t.trackInfo.Layers {
-			if l.Quality == quality {
-				matchingLayer = l
-				if l.Ssrc != 0 {
-					ssrcFound = true
-				}
-				break
-			}
-		}
-		if !ssrcFound && matchingLayer != nil {
-			matchingLayer.Ssrc = ssrc
+		// for client don't use simulcast codecs (old client version or single codec)
+		if i == 0 {
+			t.trackInfo.Layers = ci.Layers
 		}
+		break
 	}
 	t.lock.Unlock()

@@ -636,25 +617,11 @@ func (t *MediaTrackReceiver) UpdateTrackInfo(ti *livekit.TrackInfo) {
 			break
 		}

+		// for client don't use simulcast codecs (old client version or single codec)
 		if i == 0 {
 			clonedInfo.Layers = ci.Layers
 		}
 	}
-
-	// for client don't use simulcast codecs (old client version or single codec)
-	if len(clonedInfo.Codecs) == 0 {
-		for _, layer := range clonedInfo.Layers {
-			for _, originLayer := range t.trackInfo.Layers {
-				if layer.Quality == originLayer.Quality {
-					if originLayer.Ssrc != 0 {
-						layer.Ssrc = originLayer.Ssrc
-					}
-					break
-				}
-			}
-		}
-	}
-
 	t.trackInfo = clonedInfo
 	t.lock.Unlock()

@@ -679,27 +646,11 @@ func (t *MediaTrackReceiver) UpdateVideoLayers(layers []*livekit.VideoLayer) {
 			}
 		}

+		// for client don't use simulcast codecs (old client version or single codec)
 		if i == 0 {
 			t.trackInfo.Layers = ci.Layers
 		}
 	}
-
-	// for client don't use simulcast codecs (old client version or single codec)
-	if len(t.trackInfo.Codecs) == 0 {
-		originLayers := t.trackInfo.Layers
-		t.trackInfo.Layers = []*livekit.VideoLayer{}
-		for layerIdx, layer := range layers {
-			t.trackInfo.Layers = append(t.trackInfo.Layers, proto.Clone(layer).(*livekit.VideoLayer))
-			for _, l := range originLayers {
-				if l.Quality == t.trackInfo.Layers[layerIdx].Quality {
-					if l.Ssrc != 0 {
-						t.trackInfo.Layers[layerIdx].Ssrc = l.Ssrc
-					}
-					break
-				}
-			}
-		}
-	}
 	t.lock.Unlock()

 	t.updateTrackInfoOfReceivers()
@@ -1645,41 +1645,52 @@ func (p *ParticipantImpl) addPendingTrackLocked(req *livekit.AddTrackRequest) *l
 		ti.Stream = StreamFromTrackSource(ti.Source)
 	}
 	p.setStableTrackID(req.Cid, ti)
-	seenCodecs := make(map[string]struct{})
-	for _, codec := range req.SimulcastCodecs {
-		mime := codec.Codec
+
+	if len(req.SimulcastCodecs) == 0 {
 		if req.Type == livekit.TrackType_VIDEO {
-			if !strings.HasPrefix(mime, "video/") {
-				mime = "video/" + mime
+			// clients not supporting simulcast codecs, synthesise a codec
+			ti.Codecs = append(ti.Codecs, &livekit.SimulcastCodecInfo{
+				Cid:    req.Cid,
+				Layers: req.Layers,
+			})
+		}
+	} else {
+		seenCodecs := make(map[string]struct{})
+		for _, codec := range req.SimulcastCodecs {
+			mime := codec.Codec
+			if req.Type == livekit.TrackType_VIDEO {
+				if !strings.HasPrefix(mime, "video/") {
+					mime = "video/" + mime
+				}
+				if !IsCodecEnabled(p.enabledPublishCodecs, webrtc.RTPCodecCapability{MimeType: mime}) {
+					altCodec := selectAlternativeVideoCodec(p.enabledPublishCodecs)
+					p.pubLogger.Infow("falling back to alternative codec",
+						"codec", mime,
+						"altCodec", altCodec,
+						"trackID", ti.Sid,
+					)
+					// select an alternative MIME type that's generally supported
+					mime = altCodec
+				}
+			} else if req.Type == livekit.TrackType_AUDIO && !strings.HasPrefix(mime, "audio/") {
+				mime = "audio/" + mime
 			}
-			if !IsCodecEnabled(p.enabledPublishCodecs, webrtc.RTPCodecCapability{MimeType: mime}) {
-				altCodec := selectAlternativeVideoCodec(p.enabledPublishCodecs)
-				p.pubLogger.Infow("falling back to alternative codec",
-					"codec", mime,
-					"altCodec", altCodec,
-					"trackID", ti.Sid,
-				)
-				// select an alternative MIME type that's generally supported
-				mime = altCodec
+
+			if _, ok := seenCodecs[mime]; ok || mime == "" {
+				continue
 			}
-		} else if req.Type == livekit.TrackType_AUDIO && !strings.HasPrefix(mime, "audio/") {
-			mime = "audio/" + mime
-		}
+			seenCodecs[mime] = struct{}{}

-		if _, ok := seenCodecs[mime]; ok || mime == "" {
-			continue
+			clonedLayers := make([]*livekit.VideoLayer, 0, len(req.Layers))
+			for _, l := range req.Layers {
+				clonedLayers = append(clonedLayers, proto.Clone(l).(*livekit.VideoLayer))
+			}
+			ti.Codecs = append(ti.Codecs, &livekit.SimulcastCodecInfo{
+				MimeType: mime,
+				Cid:      codec.Cid,
+				Layers:   clonedLayers,
+			})
 		}
-		seenCodecs[mime] = struct{}{}
-
-		clonedLayers := make([]*livekit.VideoLayer, 0, len(req.Layers))
-		for _, l := range req.Layers {
-			clonedLayers = append(clonedLayers, proto.Clone(l).(*livekit.VideoLayer))
-		}
-		ti.Codecs = append(ti.Codecs, &livekit.SimulcastCodecInfo{
-			MimeType: mime,
-			Cid:      codec.Cid,
-			Layers:   clonedLayers,
-		})
 	}

 	p.params.Telemetry.TrackPublishRequested(context.Background(), p.ID(), p.Identity(), ti)
@@ -1901,7 +1912,7 @@ func (p *ParticipantImpl) addMigrateMutedTrack(cid string, ti *livekit.TrackInfo
 	for _, codec := range ti.Codecs {
 		for ssrc, info := range p.params.SimTracks {
 			if info.Mid == codec.Mid {
-				mt.MediaTrackReceiver.SetLayerSsrc(codec.MimeType, info.Rid, ssrc)
+				mt.SetLayerSsrc(codec.MimeType, info.Rid, ssrc)
 			}
 		}
 	}