warn for multiple dd ext (#3135)

* warn for multiple dd ext

* unused

pkg/sfu/buffer/buffer.go

@@ -134,7 +134,6 @@ type Buffer struct {
 	packetNotFoundCount   atomic.Uint32
 	packetTooOldCount     atomic.Uint32
 	extPacketTooMuchCount atomic.Uint32
-	invalidPacketCount    atomic.Uint32
 
 	primaryBufferForRTX *Buffer
 	rtxPktBuf           []byte
@@ -231,6 +230,10 @@ func (b *Buffer) Bind(params webrtc.RTPParameters, codec webrtc.RTPCodecCapabili
 		switch ext.URI {
 		case dd.ExtensionURI:
 			if IsSvcCodec(codec.MimeType) {
+				if b.ddExtID != 0 {
+					b.logger.Warnw("multiple dependency descriptor extensions found", nil, "id", ext.ID, "previous", b.ddExtID)
+					continue
+				}
 				b.ddExtID = uint8(ext.ID)
 				frc := NewFrameRateCalculatorDD(b.clockRate, b.logger)
 				for i := range b.frameRateCalculator {