Send publisher max layer change info to telemetry (#748)

Signed-off-by: shishir gowda <shishir@livekit.io>

pkg/rtc/mediatrack.go

@@ -188,6 +188,8 @@ func (t *MediaTrack) AddReceiver(receiver *webrtc.RTPReceiver, track *webrtc.Tra
 			)
 		}
 
+		newWR.OnMaxLayerChange(t.OnMaxLayerChange)
+
 		t.buffer = buff
 
 		t.MediaTrackReceiver.SetupReceiver(newWR, priority, mid)
@@ -234,3 +236,17 @@ func (t *MediaTrack) SetRTT(rtt uint32) {
 func (t *MediaTrack) HasPendingCodec() bool {
 	return len(t.params.TrackInfo.Codecs) > len(t.Receivers())
 }
+
+func (t *MediaTrack) OnMaxLayerChange(maxLayer int32) {
+	ti := &livekit.TrackInfo{
+		Sid:  t.trackInfo.Sid,
+		Type: t.trackInfo.Type,
+	}
+
+	if layer, ok := t.MediaTrackReceiver.layerDimensions[livekit.VideoQuality(maxLayer)]; ok {
+		ti.Layers = []*livekit.VideoLayer{{Quality: livekit.VideoQuality(maxLayer), Width: layer.Width, Height: layer.Height}}
+	} else if maxLayer == -1 {
+		ti.Layers = []*livekit.VideoLayer{{Quality: livekit.VideoQuality_OFF}}
+	}
+	t.params.Telemetry.TrackPublishedUpdate(context.Background(), t.PublisherID(), ti)
+}

pkg/sfu/receiver.go

@@ -97,6 +97,9 @@ type WebRTCReceiver struct {
 
 	// update stats
 	onStatsUpdate func(w *WebRTCReceiver, stat *livekit.AnalyticsStat)
+
+	// update layer info
+	onMaxLayerChange func(maxLayer int32)
 }
 
 func RidToLayer(rid string) int32 {
@@ -182,6 +185,7 @@ func NewWebRTCReceiver(
 		isSVC:                IsSvcCodec(track.Codec().MimeType),
 	}
 
+	w.streamTrackerManager.OnMaxLayerChanged(w.onMaxLayerChange)
 	w.streamTrackerManager.OnAvailableLayersChanged(w.downTrackLayerChange)
 	w.streamTrackerManager.OnBitrateAvailabilityChanged(w.downTrackBitrateAvailabilityChange)
 
@@ -259,6 +263,10 @@ func (w *WebRTCReceiver) OnStatsUpdate(fn func(w *WebRTCReceiver, stat *livekit.
 	w.onStatsUpdate = fn
 }
 
+func (w *WebRTCReceiver) OnMaxLayerChange(fn func(maxLayer int32)) {
+	w.streamTrackerManager.OnMaxLayerChanged(fn)
+}
+
 func (w *WebRTCReceiver) GetConnectionScore() float32 {
 	return w.connectionStats.GetScore()
 }

pkg/sfu/streamtrackermanager.go

@@ -73,6 +73,7 @@ type StreamTrackerManager struct {
 
 	onAvailableLayersChanged     func(availableLayers []int32)
 	onBitrateAvailabilityChanged func()
+	onMaxLayerChanged            func(maxLayer int32)
 }
 
 func NewStreamTrackerManager(logger logger.Logger, source livekit.TrackSource) *StreamTrackerManager {
@@ -91,6 +92,10 @@ func (s *StreamTrackerManager) OnBitrateAvailabilityChanged(f func()) {
 	s.onBitrateAvailabilityChanged = f
 }
 
+func (s *StreamTrackerManager) OnMaxLayerChanged(f func(maxLayer int32)) {
+	s.onMaxLayerChanged = f
+}
+
 func (s *StreamTrackerManager) AddTracker(layer int32) *StreamTracker {
 	var params StreamTrackerParams
 	if s.source == livekit.TrackSource_SCREEN_SHARE {
@@ -318,10 +323,20 @@ func (s *StreamTrackerManager) addAvailableLayer(layer int32) {
 	if s.onAvailableLayersChanged != nil {
 		s.onAvailableLayersChanged(layers)
 	}
+
+	// check if new layer was the max layer
+	if layers[len(layers)-1] == layer && s.onMaxLayerChanged != nil {
+		s.onMaxLayerChanged(layer)
+	}
 }
 
 func (s *StreamTrackerManager) removeAvailableLayer(layer int32) {
 	s.lock.Lock()
+	prevMaxLayer := InvalidLayerSpatial
+	if len(s.availableLayers) > 0 {
+		prevMaxLayer = s.availableLayers[len(s.availableLayers)-1]
+	}
+
 	newLayers := make([]int32, 0, DefaultMaxLayerSpatial+1)
 	for _, l := range s.availableLayers {
 		if l != layer {
@@ -330,6 +345,11 @@ func (s *StreamTrackerManager) removeAvailableLayer(layer int32) {
 	}
 	sort.Slice(newLayers, func(i, j int) bool { return newLayers[i] < newLayers[j] })
 	s.availableLayers = newLayers
+
+	curMaxLayer := InvalidLayerSpatial
+	if len(s.availableLayers) > 0 {
+		curMaxLayer = s.availableLayers[len(s.availableLayers)-1]
+	}
 	s.lock.Unlock()
 
 	s.logger.Debugw("available layers changed - layer gone", "removed", layer, "layers", newLayers)
@@ -338,4 +358,9 @@ func (s *StreamTrackerManager) removeAvailableLayer(layer int32) {
 	if s.onAvailableLayersChanged != nil {
 		s.onAvailableLayersChanged(newLayers)
 	}
+
+	// if maxLayer was removed, send the new maxLayer
+	if curMaxLayer != prevMaxLayer && s.onMaxLayerChanged != nil {
+		s.onMaxLayerChanged(curMaxLayer)
+	}
 }