Created TCP/SRT tunnel

[ethouris]

1. Created srt-tunnel application:
   • runs a tunnel between two media, either TCP or SRT
   • tunnels can be composed in chains
   • predicted use case: TCP <-> SRT <---> SRT <-> TCP to handle RTMP
2. Upgraded srt-test-relay application to test the SRT endpoint of two-way communication
3. Created tcp-echo-server.tcl and tcp-echo-client.tcl for testing the TCP endpoint of two-way communication

[maxsharabayko]

Adding a documentation to docs/tcp-tunnel.md (or somth else) would be helpful.

[alexpokotilo]

In case you are planning to use this setup to handle RTMP you need to setup SRT<-->SRT in lossless mode without jitter(all packages arrives in the same order they send) or this will not gonna work.
But how are you planning to do this ?

[ethouris]

In case you are planning to use this setup to handle RTMP you need to setup SRT<-->SRT in lossless mode without jitter(all packages arrives in the same order they send) or this will not gonna work.
But how are you planning to do this ?

The tunnel works in a "file transmission" mode. So you make TCP>SRT <---> SRT>TCP combination so that you take advantage of a better loss handling by SRT, but there are no live mode features in use.

For sending it using live SRT, some other application would have to be used - a combination of applications that serve as full-fledged RTMP client and server.