Fix receiveForRtx usage for simulcast

rtpreceiver.go

@@ -433,6 +433,19 @@ func (r *RTPReceiver) receiveForRtx(ssrc SSRC, rsid string, streamInfo *intercep
 	track.repairRtcpInterceptor = rtcpInterceptor
 	track.repairStreamChannel = make(chan rtxPacketWithAttributes)
 
+	// If this function is called to read simulcast layer, do not apply rtx logic
+	if ssrc == 0 {
+		go func() {
+			b := make([]byte, r.api.settingEngine.getReceiveMTU())
+			for {
+				if _, _, readErr := track.repairInterceptor.Read(b, nil); readErr != nil {
+					return
+				}
+			}
+		}()
+		return nil
+	}
+
 	go func() {
 		for {
 			b := r.rtxPool.Get().([]byte) // nolint:forcetypeassert