Hacker News Reader

Comment by bawana | Hacker News Reader

Why didn't video cables go optical? Like toslink did w audio?

There are lots of options for optical cabling (e.g. cheap plastic fibers vs. glass fibers) and all have different tradeoffs, e.g. available bandwidth vs. cost. However from what I've seen basically all options are more expensive then equivalent electrical connections (we use both optical and electrical networks in cars).

A major advantage of optical is that there are no EMV problems and that you are electrically decoupled (e.g. no hum loops). This might be one of the reasons why toslink is optical. For displays ground loops are typically no problem compared to amplifiers/speakers.

Thunderbolt was supposed to go optical. You can read about it here, under "Copper vs. optical":

https://en.wikipedia.org/wiki/Thunderbolt_(interface)

USB3 was also supposed to have fiber components. Really hard to find references for this online since at CES 2008 they showed the connectors without any optical stuff, but I found this: http://www.theregister.co.uk/2007/09/19/idf_usb_3_announced/

Anyone know why they didn't end up going optical + copper for USB3?

No advantage. It's still all wires inside the computer and the monitor.

Yes, but inside the computer you have the luxury of static, pre-calculated track layouts that optimise for latency, noise and general integrity. A general purpose, variable length, high bandwidth cable and connectors is a much harder problem, thus the kind of issues we see here sending raw video signals of extremely high fidelity between card and monitor.

Latency and cost, probably.

What latency?

Electric to light to electric would add latency perhaps? Random guess

It wouldn't, not at the scale of inter-device cables.

Reply on news.ycombinator.com