Don't ask me why... I did not find any reference or similar issue anywhere. I just worked around it by specifying two different port ranges for audio and video here (respectively offsetting the audio port range by two from 50000 to 50002 works also):
I just tried using the library on an Android device, and I realized that the SocketException is not thrown even if the UDP port is already used:
https://github.com/ngraziano/SharpRTSP/blob/a42acb1d27ebebb3e08b6739acbc8e3f5942709d/RTSP/UdpSocket.cs#L47
Don't ask me why... I did not find any reference or similar issue anywhere. I just worked around it by specifying two different port ranges for audio and video here (respectively offsetting the audio port range by two from 50000 to 50002 works also):
https://github.com/ngraziano/SharpRTSP/blob/a42acb1d27ebebb3e08b6739acbc8e3f5942709d/RtspClientExample/RTSPClient.cs#L174