diff --git a/pkg/rtc/mediatrack.go b/pkg/rtc/mediatrack.go
index 73796cb73..7a3ca64fc 100644
--- a/pkg/rtc/mediatrack.go
+++ b/pkg/rtc/mediatrack.go
@@ -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))
diff --git a/pkg/rtc/mediatrackreceiver.go b/pkg/rtc/mediatrackreceiver.go
index 3942264ef..b4128f690 100644
--- a/pkg/rtc/mediatrackreceiver.go
+++ b/pkg/rtc/mediatrackreceiver.go
@@ -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()
diff --git a/pkg/rtc/participant.go b/pkg/rtc/participant.go
index b9c4d4942..154d7c794 100644
--- a/pkg/rtc/participant.go
+++ b/pkg/rtc/participant.go
@@ -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)
 			}
 		}
 	}