[Live-devel] Unable to play RTP over TCP when RTT is large

[Ross Finlayson]

This has nothing to do with our software; it’s an inevitable property of TCP connections.

You realize, I hope, that the bitrate of a TCP connection is inversely proportional to the connection’s RTT (round-trip-time); e.g., see
	https://www.switch.ch/network/tools/tcp_throughput/

It’s also important to understand that - with our software - you are streaming datagrams, which means that - even if you’re encapsulating them within a TCP connection - you have to be prepared for the possibility of some of these datagrams being lost.  It’s important to understand the difference between transmitting a stream - which occurs at a fixed data rate, regardless of what kind of network you happen to have underneath you - and downloading a file (i.e, the World-Wide Web), which occurs over TCP connections whose speed automatically matches the speed of the underlying network.  We’re doing the former; not the latter.

Streaming over TCP is generally a bad idea; it’s something that you should do only as a last resort, if you have a firewall - between your back-end server and proxy server - that blocks UDP packets.


Ross Finlayson
Live Networks, Inc.
http://www.live555.com/