[Live-devel] RTP-over-TCP streaming (Noam Camiel)

[Noam Camiel]

Thanks for the replies sent on the subject of RTP-over-TCP

I've looked into this issue and have managed to get good results.  

The original problem I had was using testOnDemandRTSPServer example to play a stream of of
 mpeg4 encodered frames (elementary stream) via TCP (RTP over TCP). The
 video is played for short duration (a minute to 20 minutes) and then stops.  

I sniffed the packets used in the above configuration and compared them to a working TCP streaming server source.  One of the differences found was a specification of a session timeout included in the working streaming server RTSP responses.

Example:
Session: 457942862;timeout=80

This timeout appears in the RTSP server response to both SETUP and PLAY RTSP commands.

As a result of adding the session timeout, the client periodically sends keep-alive messages which VLC refers to as "live 555 debug: reset the timeout timer".
This keep-alive client message requires the server to reply to that message, something which was not currently implemented in live.  I've added a simple implementation to answer the keep-alive message (two different ones, for VLC and Real-Player).

As a result of doing the above I now have what appears to be a working RTP-over-TCP streaming solution for mpeg4 encodered frames.

I'd appreciate any input on the meaning of the session timeout field, its recommended value (80?).  

Regarding a different matter, I am curious if adding the session timeout will help solve video frame timing glitches (?) that cause clients (such as VLC) to treat video packets as old packets after a long time that video plays. 
In such cases all packets are referred to as "late picture skipped(65137)"  and the following message is displayed: "more than 5 seconds of late video -> dropping frame (computer too slow ?)" In such a situation all packets are assumed as old and no video is displayed.

I will keep testing to see if such a situation appears with the session-timeout addition.

Noam Camiel




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