15+ Projectors connected to a macbook pro and qlab

[Robert B]

Hello!

My school is putting on a showing of Les Miserables. We want it to be as immersive as possible and due to limited space in the theatre, we are heavily relying on projections. Now here comes the part I'm having trouble with: We are going to be using upwards of 15 projectors and really really want to use Qlab to control them.  We are an all apple school, with the exception of an Alienware editing pc with a Quadro RTX 4000. We are looking to find hardware that will split thunderbolt into 15 or so HDMI outputs in order to control each projector individually. Any thoughts on how best to accomplish this?

Thanks

[jtb0...@gmail.com]

Silly question but why not network a number of Mac ps all running qlab instead of one computer trying to run 15+ projectors?

 

I’d think that you would have significant processor issues trying to drive that many video feeds at once

On Sep 14, 2021, at 6:24 PM, Robert B <r22b...@saes.org> wrote:

Hello!

My school is putting on a showing of Les Miserables. We want it to be as immersive as possible and due to limited space in the theatre, we are heavily relying on projections. Now here comes the part I'm having trouble with: We are going to be using upwards of 15 projectors and really really want to use Qlab to control them.  We are an all apple school, with the exception of an Alienware editing pc with a Quadro RTX 4000. We are looking to find hardware that will split thunderbolt into 15 or so HDMI outputs in order to control each projector individually. Any thoughts on how best to accomplish this?

Thanks

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[Taylor Glad]

Your Mac hardware will likely be a limitation processing all that, like jtb0... said.

I'd also recommend multiple computers triggered by a main computer with OSC.

I have a setup I can share of scripts and OSC cues I made to make things easier with the multiple computers. (Scripts to rewrite OSC cues which target settings on other computers, and some that send OSC replies back. Can get a little tangled, but easier than changing the fade time on 7 different Macs.)

(Plus with everything on a network, file transfers over network are a lot easier than shuttling drives around)

[jimsta...@zoho.com]

Something like this, actually a pair of them?

https://www.bhphotovideo.com/c/product/1161306-REG/kanexpro_hdsp184k_hdmi_8_port_distribution_amplifier.html

How long are your cable runs? You may want to convert the one output of the QLab computer to SDI, run long SDI cables and distribution. Do the projectors have SDI input?

A few options on the B&H website, including ones with SDI and HDMI outputs.

You can buy long HDMI cables, but it'd be hard to find more difficult cables to manage.

Jim

[Taylor Glad]

The distribution amplifier works if each projector is receiving the same image. But since Robert is seeking individual control, that won't provide that for him.

[Robert B]

Thanks, I see what Y'all are saying. Looks like networking computers together is the way to go... We don't have many resources so 15 macs are out of the question... BUT would something like a raspberry pi work? Rpis are cheap enough that we can get as many as we need... Playing off of that, is there a way to output a network stream protocol from qlab and stream it to something like vlc on a Rpi and use the HDMI out on a Rpi? Or what about Syphon to Rpi or Syphon to NDI? It's easy enough to run cat 6 to anywhere in the theatre, so there is no barrier there. 

Thanks a lot!

[Adam Burgess]

Non-tech answer: 

If you hint at a sewer scene, or a street scene; and, the actors, lights, and band are doing ok - the audience WILL be immersed. 

Technical questions:

how hard is a school lighting guy’s job going to be not overpowering 15(!) projectors? 

If the whole school has many Apples, I’m sure that 5-7 moderately capable machines could do it without much extra hardware. To do scenery from a distance, the resolution doesn’t have to be massive. 

If you’re asking about how, is it not too big a job from the start?

[Sam Kusnetz]

Hi Robert

I recently was hired to program a sixteen-output QLab rig in a very large room. The sixteen projectors were aligned to the architecture so that none of the projectors needed to blend, but they created a single cohesive image, so timing had to be airtight.

We solved it by using two Mac Pros with two Vega II video cards each. Each card drove four projectors. One Mac was designated as the primary and it sends OSC show control messages to the second Mac. The longest cue is about 17 minutes and we see no visibly apparent drift.

Needless to say, this was not a low-budget situation… each projector cost about $3500 and each Mac cost about $30,000.

Even with all that horsepower, we have had problems of one kind or another. Video systems on this scale take a lot of work and a lot of time to prepare, program, and maintain.

A single Mac driving sixteen individual video outputs will be computationally expensive no matter how you do it, physical connections, Syphon, anything. Decoding and rendering pixels is hard!

If you want to keep costs down and have a lot of low- to middle-end hardware lying around, your best bet is to devise a test for two or three Macs or Pis driving a single projector each with the video content stored locally on that computer, and another Mac acting as the conductor for the system. If you can develop a workflow that’s acceptable to your situation, you’ll be able to drive all your screens without needing a single monster machine to do tons of heavy lifting.

Good luck! Keep us posted.

Sam

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[aroom]

Hello,

You could use raspberry media players controlled by OSC to output videos. I’ve been doing that in the past, but you’ll be limited to the soft been used on those raspberry regarding video effect, like fade in or fade out. You’ll be using QLab just to send an OSC message to the network to play specific media on specific raspberry player.

You can have a look at those softwares:

https://github.com/KenT2/pipresents-beep

https://github.com/rasmuskreiner/OSCVideo

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[micpool]

On Wednesday, September 15, 2021 at 1:33:11 PM UTC+1 Robert B wrote:

Thanks, I see what Y'all are saying. Looks like networking computers together is the way to go...

I don't think that is what EVERYONE is saying!

In an attempt to  get this back to a reasonable level of complexity that might be handled at a school level ( or indeed  by many professional theatres),  I have to say that I have done some large scale productions in International opera houses and in the West End, and I have rarely used more than 5 projectors. 

The complications of wrangling 15 projectors worth of content across multiple macs and QLab workspace,s even with a full time video team ,  should not be underestimated. Unless you have come up with a stunning visual concept that requires that number of projectors, and would make not sleeping between now, and the production closing worthwhile,  I would examine why you think you need 15 projectors and what the alternatives are.

For most theatre  uses, projectors of between 10000 and 20000 ANSI lumens are appropriate, and you might cover areas of between 4x3 metres to backcloths the full width and height of your stage using 1 or 2 of these. For high contrast black and white content 8000 lumens may be sufficient on smaller surfaces.

More complex or larger  sets could probably be covered adequately by 4 such projectors at 1920x1080 resolution per projector.

Using these four projectors you could  give the illusion of many individual projected areas, through the technique of projection mapping. Any projector can cover multiple scenic elements and content can be directed to all the scenic elements falling  in a single projectors beam, individually.

If you can post what projectors and most importantly lenses you have available  for this project, and a rough sketch of what the set might look like, someone may be able to suggest  a manageable projector set up using 1 or 2 computers that will produce impactful results.

Good Luck!

Mic