Let’s say you want to send an HDMI signal (or VGA, if that helps) from a podium on a stage to a control booth about 70 meters away as the crow flies, meaning you’d probably need about a hundred meters of cabling to run it down the walls and around the corners and such (but with a mostly clear line of sight, if that matters). The signal is coming from a standard commercial-grade laptop at the source. If it matters, it contains a PowerPoint with much embedded audio and video.
Are there readily available commercial solutions? Wireless HDMI can’t go this far, right, or at least not stably? HDMI over ethernet seems to have a range topping out around a hundred meters, and that’s under best-case circumstances? HDMI over fibre or SDI would seem to have a better chance? Does VGA have a better chance than HDMI, assuming there is a sound pickup on stage?
For what it’s worth, the signal is coming right back to the stage, to a 32 by 8 meter LED screen, using installed cabling. But there are no hookups on stage.
I’m not sure if this fits HDMI (because I don’t know of such things) but I used to send signals from probes to computers and ethernet/USB connections using fiber optics.
We did 200 meters, I think.
heres a potentially relent link to fiber optic modems. (again, I apologize for my ignorance)
startech.com would be my first choice for manufacturer.
There are also HDMI over IP devices, so you could use a normal Ethernet switch halfway along to extend the run. I’m not sure which is most cost effective.
Another idea:
Second laptop in the control booth, then either use something like VLC to stream the desktop to the second laptop over a network connection (cable or wifi).
OR put the powerpoint on the second laptop and remote control it from the first laptop.
You can get all sorts of media adapters to allow you to put HDMI on coaxial cable, twisted pair (Cat 5e or 6), fiber, and so forth. I think that Kramer makes a set of transceivers for twisted pair that are reasonably priced and work well. To be honest, you can often go well beyond 100 meters with a set-up like this, especially if it’s in a “friendly” environment.
Conversion to IP is an option, but I would personally avoid that unless you need to put the signal on a network for distribution to multiple points. Converters and hardwired cable is basic and pretty fool-proof.
One other way to do it would be to place one computer near the projector and cast the display to it from another computer using Windows screen casting, or remotely control it using something TeamViewer or any other kind of remote control solution, over standard network connections.
I can’t believe there’s any auditorium without any cable connections from the stage to the control booth! How’s the podium microphone work?
They may not have HDMI cables (HDMI probably didn’t exist when the stage was built), but they must have other connections. Look for a spare one that can be used, and then get adapters like people have mentioned (HDMI over coax, over CAT5, etc.) to use that builtin cable.
For example, there is likely another unused microphone audio outlet near the stage – those connect back to the control booth usually with shielded twisted pair cable and XLR3 (RS297) connectors. Thay is pretty similar to CAT5 cable, and should be able to carry a HDMI signal.
If it’s a one-off, the absolute easiest would be Mangetout’s suggestion. Computer at the control booth sends the video signal, second computer on stage controls the first using some remove viewing software over wifi.
If you’re looking for a permanent solution, fiber HDMI cables or a set of HDBaseT extenders (needs single Cat6). HDBaseT comes in a couple varieties with varying ranges, so make sure you get the 100m ones and not the 70m.
VGA will also make that distance no problem, but you’ll be losing some contrast and saturation. There are line amps to mitigate this, but analog fails gracefully as the signal attenuates, unlike digital. This would suck as a long-term solution, however, as VGA is obsolete at this point.
Many thanks to you all for your helpful suggestions. It is indeed a one-off solution (though it’s not an uncommon problem that our organization faces, as we hold different events around the world). This theater is in Phnom Penh, Cambodia, and was actually built in 2012. The screen is pretty amazing, at 32 by 8 meters, but the stage has mic hookups and that’s it. Evidently at some of these theaters it’s pretty rare for them that someone wants to control from the podium.
But again, it’s not an uncommon situation, so we probably need to purchase the right kind of equipment and carry it with us. We have wireless HDMI adapters, but we find them to be too unreliable. (They seem to overheat, if nothing else.)
We’re actually in Jakarta today and using a similar setup, except that here they have a converter that connects with a 10-meter cable to a port on the stage and then goes back to the control room. We had a hard time getting the HDMI feed to the control room, for whatever reason, but VGA worked. For our production, the quality is just fine. So, maybe that’s the option we should look at next week in Cambodia? I’m actually thinking about borrowing the converter and receiver here in Jakarta and picking up cabling of some sort to take with it to Cambodia, given that the truly proper equipment may be hard to find there.
A problem with any extender is the bandwidth the media used to extend over has. HDMI can now support up to 8k resolution, but needs eye watering bandwidth to do so. If you are only pushing 1080p or even 720p you you get away with much less, and you will tend to find solutions are more tolerant. Fibre optics in principle can deliver serious bandwidth, but fibres are not something you can purchase in your local friendly computer store, and they can be fragile - not really suited to applications where they get laid out and rolled up time and time again. Cat5/6 cable is both much more easily found, and more robust.
You can get professional HDMI over fibre solutions that are good to 20km if you use single mode fibre. But I have dealt with enough broken fibre optic cables in my time to never want to trust ones that are not installed permanently and never moved. Patch cables were a never ending source of pain. Just a simple accidental bit of physical abuse and they fail.
Perhaps the most useful extender over Cat5/6 is the HDFury Maestro that provide a Swiss Army Knife solution - scales video resolution, supports up to 4k, reticulates video, network, audio, IR control. But not cheap at $1k for both ends. If you ever need 4k video you must use Cat6a. But lesser video resolution should go over garden variety Cat5.
The idea that the video source does not belong on stage but only the presentation gets controlled from stage is very sound. A huge number of solutions are possible once this is adopted. It also means you can have someone next to the computer when it suddenly decides to misbehave, and the presenter can carry on talking to the audience instead of playing IT support. It might be possible to have a tablet computer act as a slaved screen showing the presentation control, run over WiFi via a remote desktop protocol is could be resistant to lots of problems, especially if it is simply a passive device, and its failure does not affect the ability of the presenter to control things.
A permanent solution, but also portable. Okay. Scrap the fiber optic HDMI cable suggestion, then. They’re not horribly fragile, but unless you can find one specifically made for touring I wouldn’t trust them in that context. That leaves you with two options. 1) The remote control option. It will always be easier to get a control signal across a venue than a high-bandwidth video signal. 2) HDBaseT. The set Francis linked look nice, but there are many manufacturers (HDBaseT is a standard, not a manufacturer) and you can get Tx/Rx pairs ranging from the simplest HDMI extenders up to fancy switcher/scalers.
Sorry Steven_G, missed your comment. I’m just peeved I didn’t get in first because I actually did a training seminar at work just two weeks ago on long range HDMI technologies, and all the good suggestions were taken. :mad: Except HDBaseT, which is probably the best solution for the OP if they don’t want to mess around with some sort of remote desktop option.
Since we’re all nerds here, no one proposed the simplest solution: put the laptop in the booth, and the person making the presentation at the podium just asks the technician in the booth to advance the slides, videos, etc. This is how a lot of presentations used to work in the pre-digital era, when slides were pieces of film in cardboard mounts in a carousel tray.
Of course, if there’s a lot of interactive stuff the presenter has to control directly, this may not be simple or even possible, but the OP didn’t specify that that was the case.
In a later post, the OP tells us that the screen is 32 meters by 8 meters. So it’s not just a simple HDTV. It’s probably a projection screen so there’s nothing to plug into.
HELP! I’m back with updates, and a great hope that one of you gurus can solve this problem for us. So, we succeeded in converting to SDI at the podium and sending the signal on a 100-meter SDI cable to the control booth. I should add that when we tested from a laptop in the booth itself, outputting directly to the controller, it gives us exactly what we want, which is a 16:9 display in the center of the 32 by 8 meter screen (lots of unused space on either side of center, which is fine with us). But when we project through the laptop and convert, the display is getting forced to the entire width of the screen. This doesn’t work for several reasons, one large one being that the image begins to repeat on the right side of the screen. In other words the last three panels on the right (these are 75 cm panels) repeat the first three panels on the left.
The best theory the guys here can come up with is that the converter can only handle 720p and that’s what it causing the problem. What do you guys think? Any ideas for a solution? Would it be something done in the LED control unit itself? Or on the display laptop? (By the way, we are simply displaying a PowerPoint.)
To answer those who asked, we do recognize that the laptop in the booth gets around this all, but the nature of the presentation, which has very many moving parts that are determined on the fly, makes it a very difficult solution.
Quick update. When we take the display laptop down to 1400 by 1050, we at least get something close to workable. It’s letterboxed and still stretched wider than our 16:9 aspect ratio, but we can live with it if need be. And I guess it gives a hint at our problem?
I wonder whether the SDI sender is not fully managing the EDID to VPID conversion. The laptop should be outputting the format it sees defined over the HDMI connection. It sees what the SDI box tells it over HDMI - via EDID. The SDI box should be telling it something sensible, preferably what it gets told by the end point in the control booth - which transits the connection via VPID. But if the laptop is told something silly it may be trying to re-sample to something idiotic, and may be doing it badly. Fiddling the laptop format may be a way to find a set of sort of compatible resampling parameters in the face of bad format info.
Just guessing I’m afraid.
There should be some guidance on how the SDI box is managing this.
