fix subscription update on codec change (#757)

pkg/rtc/mediatracksubscriptions.go

@@ -224,9 +224,6 @@ func (t *MediaTrackSubscriptions) AddSubscriber(sub types.LocalParticipant, wr *
 	})
 
 	downTrack.OnMaxLayerChanged(func(dt *sfu.DownTrack, layer int32) {
-		if dt.Codec().MimeType == "" {
-			t.params.Logger.Errorw("codec mime type is empty", nil)
-		}
 		go t.notifySubscriberMaxQuality(subscriberID, dt.Codec(), QualityForSpatialLayer(layer))
 	})
 
@@ -438,10 +435,11 @@ func (t *MediaTrackSubscriptions) notifySubscriberMaxQuality(subscriberID liveki
 	} else {
 		maxQuality, ok := t.maxSubscriberQuality[subscriberID]
 		if ok {
-			if maxQuality.Quality == quality {
+			if maxQuality.Quality == quality && maxQuality.CodecMime == codec.MimeType {
 				t.maxQualityLock.Unlock()
 				return
 			}
+			maxQuality.CodecMime = codec.MimeType
 			maxQuality.Quality = quality
 		} else {
 			t.maxSubscriberQuality[subscriberID] = &types.SubscribedCodecQuality{

pkg/rtc/participant.go

@@ -209,7 +209,7 @@ func NewParticipant(params ParticipantParams) (*ParticipantImpl, error) {
 		Config:                  params.Config,
 		CongestionControlConfig: params.CongestionControlConfig,
 		Telemetry:               p.params.Telemetry,
-		EnabledCodecs:           p.params.EnabledCodecs,
+		EnabledCodecs:           enabledCodecs,
 		Logger:                  LoggerWithPCTarget(params.Logger, livekit.SignalTarget_SUBSCRIBER),
 	})
 	if err != nil {

pkg/sfu/downtrack.go

@@ -694,7 +694,8 @@ func (d *DownTrack) SetMaxSpatialLayer(spatialLayer int32) {
 		return
 	}
 
-	if d.onMaxLayerChanged != nil && d.kind == webrtc.RTPCodecTypeVideo && maxLayers.SpatialGreaterThanOrEqual(currentLayers) {
+	if d.onMaxLayerChanged != nil && d.kind == webrtc.RTPCodecTypeVideo &&
+		maxLayers.SpatialGreaterThanOrEqual(currentLayers) && d.bound.Load() {
 		//
 		// Notify when new max is
 		//   1. Equal to current -> already locked to the new max