I have to write an app in C#. The aplication is a video streaming client-server using rtsp protocol. It is dificult to me to start implementing because i never done before such a big app. If someone could give me some hints or a guideline I will apreciate.
Don't do it yourself if you've never written a networking application before. It's no easy task to write a scalable and robust networking app and it's even harder to implement an existing protocol so that the implementation is fully compatible with the specification. You will fail or end up long over budget.
It will be far easier and cheaper to buy an existing component or integrate an existing server.
Google "streamcoders" for find a library which can handle RTSP.