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Comment by mulmen | Hacker News Reader

Why can’t you just run a longer cable into a temperature/noise controlled room nearby?

Good question!

So there are a couple of options, depending on the hardware. If it kicked out HD-SDI you could just patch the display into the coax in the building and have done with it.

But that only worked if you were in the same building and your machine kicked out HD-SDI

Most machines either shat out dual-link DVI or worse, some custom shit. Getting a cable that can reliably transport dual-link DVI >10 meters was difficult and expensive. Worse still, it had a habit of dropping back to single link, or some other failure mode that was everso annoying to debug. More over, 10 meters often isn't far enough. Especially if the room had a projector (so might be >5m long throw.)

Now, thats the simple case. The hard case is multi-building. Say, you have an operator working in london, and the director in new york, you want to give them the highest quality picture possible. The only way to do that at the time was with one of these cards, or some nasty SDI-hardware h264 transcoder (hugely expensive at the time)

I really wish I could remember what they were called. They appear to have fallen out of favour.

Now, you'd just use cynesync, as you're laptop can encode video in real time now (https://www.backlight.co/product/cinesync) Also, rumour has it that the wolverene movie was leaked because a producer got coked up and left an unencypted laptop on a plane, rather than using cynesync to show an edit to someone important. Alas I can't verify that.

I'd love to hear more stories about coked-up producers in the film industry from 15+ years ago. Having done technical codec work adjacent to some of it in the past, it's a wild business to be in.

> Say, you have an operator working in london, and the director in new york, you want to give them the highest quality picture possible.

This is exactly the insight I was hoping for. Thank you.

Were they Teradici cards?

YES

thats the one! many thanks

Based on the comment of 15k spinning drives this must have been quite some time ago, but there's very definite reach length limits on DVI and displayport cables. Let's say this was in 2007 and the maximum state of the art was a dual link DVI 2560x1600 display, you can't extend that in any practical way beyond about 15 feet. Extending USB keyboard and mouse by comparison is trivial. Unless all of the desks and workstations were set up directly on one side of an acoustic barrier wall, a hard problem to solve.

> you can't extend that in any practical way beyond about 15 feet

For passive cables, that makes sense. But with repeaters, wouldn't you be able to go further? Maybe cable repeaters like that are newer than I imagine.

I bought an expensive 10m (30ft) active HDMI cable for connecting my PC to my TV. It said it was UltraHD rated, but could never get it to work reliably beyond 1080p.

You need fiber for that -- I have a pair of them (100' to my desk, 30' to my TV), and they've been rock-solid for 4 years.

So the issue was more that dual-link DVI was very rare, and getting hardware to encode/transmute it reliably and at high bit-depth was almost impossible.

By about 2014 hardware encoders were good enough to send decent quality video over gigabit.

Somehow those didn't show up on my searches, though it was a few years ago.

Thanks though, will keep it in mind. These days Steam Link is decent enough for what I wanted, but ya never know.

> I bought an expensive 10m (30ft) active HDMI cable

I think what I was referring to are repeaters you put between cables, that amplifies the signal. You connect that device between two HDMI cables (say 5m) + connect it to power for it to actually extend the distance the signal can travel.

I'm not sure what an active HDMI cable would be, maybe circuitry inside the cable that draws power from the HDMI port?

I think "active" HDMI is similar to the expensive USB3 cables, which are basically fibre optic cables in disguise

https://www.chargerlab.com/the-way-to-metaverse%EF%BC%9Ftear...

> maybe circuitry inside the cable that draws power from the HDMI port

Pretty much:

https://www.cablematters.com/Blog/HDMI/how-do-active-hdmi-ca...

Perhaps they're better now but, yeah, for me it didn't work out as intended.

Sounds like hocus pocus to me (like gold plated connectors), maybe you get like half a meter of extended distance or something with those? If I had to I'd go the repeater way (or as others mentioned: fiber, but sounds expensive and not maintenance free)

I've not had any issues getting full bandwidth (4k60hz) from my active HDMI cable.

Also I believe there are displayport cables that do the data transfer over optical fiber for long runs as well.

You can, and people do.

There are a slew of HDMI extension systems, some that even use ethernet with hardware encoding/decoding. Grandparent commenter hasn't worked in the industry in at least a decade if they're talking about DVI.

These days, if you're just wiring to a single workstation in a nearby next room, 50 meter active optical Thunderbolt 3/4 cables can carry 5K+ DisplayPort video passthrough and data from your USB peripherals.

(It's "passthrough" and not "uncompressed" because DisplayPort may use DSC depending on the resolution and frame rate.)

US$500 for an optical cable can be a lot cheaper than paying for HDMI extender sender and receiver boxes.

In a modern video editing system it's still a non trivial challenge, because you can't just go using any COTS HDMI extension system, which might be good for 2160p30 at 420 color space, or maybe 2160p60 at 420 color space, but may NOT be capable of 2160p60 at 422 or 444 color space. Or may not function for DCI resolution at 4096x2160. Or anything 8K.

There's plenty of HDMI2.0 compliant "video over ethernet cable or fiber things" which are the ordinary COTS products that may not be sufficient for serious video editing needs.

People on video editing workstations these days are using higher end monitors that can be trusted to work in 10bit color and to match a certain color space grading.

On the other hand it's a lot easier these days to have a relatively quiet video editing workstation that has 8 to 16TB of local, pci-express bus attached NVME storage for work space, and that same workstation can have a not-very-expensive 100GbE NIC in it attached to some large/noisy storage elsewhere.

> some that even use ethernet with hardware encoding/decoding

We had those, the problem is that they loose bitdepth. They were also fucking unreliable. We had a lot HDMI extenders and they worked for 1920x1080, and sometimes 2k if you were lucky.

we used them for the "prosumer" LCD projectors we had the in the review rooms. They didn't work so well for the massive christie projectors. (I seem to recall they abused 3g-SDI to get resolution)

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