Deal with reordered keyframes.

rtpconn/rtpreader.go

@@ -59,7 +59,7 @@ func readLoop(conn *rtpUpConnection, track *rtpUpTrack) {
 
 		first, index := track.cache.Store(
 			packet.SequenceNumber, packet.Timestamp,
-			kf, buf[:bytes],
+			kf, packet.Marker, buf[:bytes],
 		)
 
 		_, rate := track.rate.Estimate()

rtpconn/rtpwriter.go

@@ -209,7 +209,7 @@ func (writer *rtpWriter) add(track conn.DownTrack, add bool, max int) error {
 }
 
 func sendKeyframe(track conn.DownTrack, cache *packetcache.Cache) {
-	_, kf := cache.Keyframe()
+	_, _, kf := cache.Keyframe()
 	if len(kf) == 0 {
 		return
 	}