another newbie with video display needs, but very flexible re solutions

Stuart R

Hello all,

I'm another guy who has been tossed into the deep end in terms of providing video display solutions for our school theatre. I've spent a couple of sessions reading through relevant posts in this forum, and checked out many of the leads and products recommended, but am still far from confident on how to proceed. One of the things I've gleaned from past threads I've read is that there are lots of solutions to lots of scenarios and that if I'm not too picky, most things are achievable.

So we now have an ultra-short throw projector set up backstage for rear projection onto a center screen (roughly 12' h x 20' w ), to be used (mainly) as a backdrop for scenes in our theatre productions. Some of the backgrounds are basically slides, while others are animated, and lacking any dedicated video mapping software, for our first go at this we simply put the slides and the videos into a Powerpoint file and ran them on a MacBook Pro, with a USB-C to HDMI adaptor plus a 50' HDMI cable from there to the screen. It worked fine.

The new additions are two front throw projectors, mounted on lighting pipes over the audience, with matching screens on each side of the proscenium. The presence of *three* screens is setting imaginations ablaze, and the creatives now want to be able to send 1, 2, or 3 outputs to 1, 2, or 3 screens. Here is a visual:


Note the last item - a desire to be able to pretend we're having a rock concert and use a camera to capture an onstage speaker and project them in close up on the side screens. [In fact, the director wants to know if the camera can be WIRELESS so he can have the operator super mobile and make everyone seasick (that last was my editorial addition).]

Finally, with three screens to manage, we figure we need to see them from the front in order to operate them intelligently which means running all three from the booth, which is about 75 feet from the FOH projectors and 110' from the rear projector.

So, starting at the booth, can we run three images on one MacBook Pro and send them out as three signals somehow? What software would we use? Would we need to beef up the graphics card or anything like that? Then, once outside the laptop, I assume we'd need to use an HDMI extender setup (one big transmitter and three little receivers?) to send the signals over Cat (5? 6?) to the three projectors? My next question is whether we'd need something like the BlackMagic Smart Videohub CleanSwitch 12 x 12 6G-SDI, though I've seen some people complaining about a) the issues with transitions (momentary fade to black between images?, and b) the fan noise.

Anyway, you can see that I've read just enough to confuse myself. Any guidance you could offer would be greatly appreciated.

Thanks -

Jay Ashworth

Well-Known Member
To get 3 images out of a Mac, you'll need to be on a ('trashcan') Mac Pro, or using a Triple-Head-To-Go adapter. I know used instances of both exist, but I don't know about current-new.

You can probably do most to all of what you want with QLab 4.x+ and a video license...


Well-Known Member
to 2nd Jay, and add on. At least aa ("trashcan" Mac Pro. The important detail is 4 discrete video outputs. 3 for your Audience (projectors) and one for your run/workstation view.
The new MacBook pro M1, and even the Macbook Pro 2019 I believe all support 4 displays.

I'm not familiar with the Triple-Head-To-Go adapter/VIdeo hardware, but I do know it works some magic video voodoo to use "fewer actual" outputs from the computer and virtualizes outputs. I believe it's basically a hardware version of what you can setup in Qlab. Where you might have a single projector to cover 3 smaller screens, use the surface utility in qlab to discretely separate out pieces of the overall projection and limit them to the screens.

There are two components to the setup you are looking at:
(1) Hardware
It seems like you have a good handle on this. 75' runs is about the limit for standard copper "active" HDMI cable. (Active cables has a direction, (Source-> display) and won't work if connected backwards.)
They make Optical HDMI cables which are delicate but cover the distances you are looking for and I think create a simpler system then powered cat5e/fiber transceivers-receivers at the end.
If your projectors have SDI-HD that is the best options in my opinion, but it means an added or shifted cost down the line, since most standard video ouputs from a computer are not SDI you'd requires some Blackmagic/Aja/Decimator/etc USB to SDI boxes. But the SDI cable is compartablye cheap and rugged when compared to HDMI

(2) Software
Qlab 4.x or 5
Following the Qlab use forums and FAQ would be helpful here but useing 3 descrete hardware video sends makes mucking around in the "surfaces" editor in Qlab simplier
All of your video outputs will popluate here and your camera capture hardware

Under the lowest common ideal situation

I'd recommend a M1 macbook pro
(3) HDMI to SDI 3G
(1) HDMI or SDI to USB-C capture for camera. (Blackmagic makes one to, but couldn't track it down at the moment)
(3) USB-C to HDMI dongles

You may need a USB-C dock of a fancier variety to split your your USBC (PCIe data lanes) as the M1 Macbook pro only has 3 USBC and 1 HDMI output, and the older 2016 formfactors have 4 USB-C but one is needed for power/charging

In general I think it's worth utilize SDI connections instead of HDMI. If your video projectors don't have SDI, then you can disregard the HDMI to 3G encoders
A Mac Trashcan Pro, will require THunderbolt to HDMI adapters.
The new Mac Pro Towers, and iMac Pro's are all USBC I believe, but double check.

4 unique video outputs requires more than a 500 computer from Walmart (again 'Triple-Head-to-GO' helps solve low video output options)

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