How to Send data over UDP socket as it is being written?

Question

I have connected two Linux Machines using netcat over WLAN using Server-Client design. And now i am able to send and receive messages between them. On the server i use UDP socket creation :

$ nc -u -l 3333

and on the client side i connect to the port using the port number and destination IP :

$ nc -u 192.168.178.160 3333

This leads to a bi-directional connection between server and client. One couldn't tell, but i guess it is quite Real-Time . now i want to develop the functionality and try and establish a real-time speech connection between the two sides. Recording via Microphones is also feasible through arecord commands which write the speech data to a .wav file . Transmission of the .wav file is possible, only after it has been fully recorded but this is of no use since what is desired, is a Real-Time communication. Of course the received speech signals have to be instantly played back on the other end. Has anyone any idea how to make it Real-Time ?

Answer 1

Fidelity means a large buffer count to preserve sound continuity despite network latency and latency variation, low sound delay approximating to real time means a small buffer count to reduce overall latency. You cannot have both.

IME, you need to keep ~250ms max. of sound buffered at both ends to maintain an illusion of 'real time' speech. This queue of buffers needs to be emptied at the fixed rate necessary to reproduce the speech and kept topped-up by the network protocol as necessary. If the network latency is too low to top up buffer pools of that size, the buffer pool has to be made larger, the queue longer and the perceived real-time performance will suffer.

The TCP/UDP issue is a red-herring on most network connections.

Just be thankful that you are not streaming video:)