What is theoretically lowest latency you can have for video chat?

Question

I think video chat sucks massively because of lag.It goes like this...A: How is it going?... 3 second lag?A: I am aski B: OH I'm doing ..both pause....A: go ahead3 more secondsB: oh im doing great.C: ok greatLandlines phone worked better

LinuxBender · Accepted Answer

Depends on codec used and the latency/bufferbloat [1] between the clients and the server. If you and your friend are each sub-30ms from the server and using Opus [2], you should not even notice the delay. This also assumes your chat client is not running on a highly loaded CPU core. If either of you has latency and/or bufferbloat, you will have bad lag. You can also reduce the lag by lowering the bitrate in the client. If you are running your own Murmur server and using the Mumble client, it will show you how much latency and loss each person is experiencing. [3]
[1] - http://www.dslreports.com/speedtest
[2] - https://opus-codec.org/
[3] - https://www.mumble.info/

souprock · Answer

Over what distance? Using what technology constraints?
Suppose we make it analog and parallel. Each pixel of the camera gets a separate connection to the matching pixel on the display, analog all the way.
For a megapixel, we could run a million fibers, but the Earth could be in the way. You can't run fiber through the Earth. The solution is neutrino beams.

richbhanover · Answer

@LinuxBender is on the right track. Bufferbloat can cause this kind of lag. (There may be other causes, but first thing to do is check for bufferbloat.) To do this use:
http://dslreports.com/speedtest
This measures the latency/lag while data is being transferred. When it's complete, click "Results + Share" and you'll see a report. Send us the link of that page so we can see your results.