Add RTP port-based media stream lookup fallback (#1480)

Add GetMediaStreamByRTPPort method to enable media stream identification by RTP port when SSRC and payload type matching fails. This provides an additional fallback mechanism in OnReceiveRTPPacket to correctly route incoming RTP packets to their corresponding media streams.

Author: agukasm

src/net/RTP/RTPSession.cs

@@ -2592,6 +2592,11 @@ private void OnReceiveRTPPacket(int localPort, IPEndPoint remoteEndPoint, byte[]
                     mediaStream = GetMediaStreamFromPayloadType(hdr.PayloadType);
                 }
 
+                if (mediaStream == null)
+                {
+                    mediaStream = GetMediaStreamByRTPPort(localPort);
+                }
+
                 if (mediaStream == null)
                 {
                     logger.LogWarning("An RTP packet with SSRC {SyncSource} and payload ID {PayloadType} was received that could not be matched to an audio or video stream.", hdr.SyncSource, hdr.PayloadType);
@@ -2644,6 +2649,35 @@ private MediaStream GetMediaStreamFromPayloadType(int payloadId)
             return null;
         }
 
+        private MediaStream GetMediaStreamByRTPPort(int port)
+        {
+            foreach (var audioStream in AudioStreamList)
+            {
+                if (audioStream?.GetRTPChannel()?.RTPPort == port)
+                {
+                    return audioStream;
+                }
+            }
+
+            foreach (var videoStream in VideoStreamList)
+            {
+                if (videoStream?.GetRTPChannel()?.RTPPort == port)
+                {
+                    return videoStream;
+                }
+            }
+
+            foreach (var textStream in TextStreamList)
+            {
+                if (textStream?.GetRTPChannel()?.RTPPort == port)
+                {
+                    return textStream;
+                }
+            }
+
+            return null;
+        }
+
         private MediaStream GetMediaStream(uint ssrc)
         {
             foreach (var audioStream in AudioStreamList)