Odd RTP behaviour

[azrael808]

I have been experimenting with the JMF API's, and have written a small program based on AVTransmit2.java that can be found on the Sun website. Originally, I had two PC's connected using a cat5 crossover cable; and I was using JMStudio on the client machine to receive the RTP transmission. I had no problems receiving the video stream until I connected the two machines to my LAN. Now JMStudio does not detect a stream when I try to pick up the transmission from the server machine. The two machines are able to ping each other across the network, and the server seems to be sending the RTP packets to the correct machine, but JMstudio is unable to detect the stream. I tried switching the two machines back to using the crossover cable, and the system works fine.

Does anyone have any idea why this would be? If posting my code would help, just ask; i'd be more than happy to! I don't see why the RTP stream won't work over a LAN, when it's using the same protocols as the point-to-point connection.

Any suggestions would be most appreciated. Thank you in advance.

Peter Green

 

[tregovic]

What ports are you using for your rtp traffic?
It is possible that the two machines that you have set up on your network are going through a router that is not passing those ports.


Tim

 

[azrael808]

Worked out what it was:

The code was calling InetAddress.getLocalHost(), which was only returning the correct address when the two PC's had static IP address, ie, when they were connected by a cross-over cable! Had to implement a java security policy file to allow the code to query a remote DNS server.

Pete