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creative opportunities for giant LED outdoor screens

Aug 05 2007 | 9:52 pm

Hello all

I work upon a not-for-profit project initiated by the BBC/British Broadcasting Corporation, which involves the installation of giant outdoor LED screens in major UK towns and cities.

The purpose of these is for the showcasing of creative talent; specifically within each region but also across the UK and indeed the world. Be it film, video, animation, programming, interactive media arts and also live activities.

I myself manage the giant screen in the city of Liverpool, but also look after interactive and artistic content across the entire network (to date including Manchester, Birmingham, Hull, Bradford, Rotherham, Derby, Leeds, Liverpool and forthcoming in Swindon).

We are particularly keen to encourage motion-sensitive response and public interactivity utilizing on-screen surveillance-style cameras that point into the public space below. Here in Liverpool we have been the development site for this type of installation; see below:

We are always looking for more applications, be they ?ambient? (capable of running as part of general operations, dipping in and out throughout the day or night), ?active? (requiring street-level management, from fencing to stewards and/or additional infrastructure for a realisable time period or one-off events), overnight ?muteloops? (screens operate 24/7, with audio, but go silent from midnight until 6am? this is a time when we can experiment with self-generating weirdness to entertain clubbers and night owls!), or any other form you can think of.

I?ll be honest, we operate with very little budget and payment is not always possible, but SOMETIMES it is, especially when our respective city governors get all excited about a project and throw some cash our way. In my own patch of Liverpool, I am particularly looking for motion-sensitive works to showcase during 2008 when the city celebrates European Capital of Culture? and I?m determined to locate some funds to help make this happen.

At worst? Suitable projects feature upon an exciting, emerging platform that is still so experimental that no one, not anywhere in the world, really and truly knows what works and what doesn?t. How do I know? Because I?m also producing the arts and events programme for the largest international conference on the topic:

I?m sure you want to know about size, right? Typically 26 square metres, LED, around 10 metres high.

Each site has a high-spec PC and mini-Mac, each with a feed of the on-screen camera (which can pan, tilt and zoom in or out for the desired angle), which we use for applications of this type. A work might typically be scheduled to appear 5x per day for half an hour each time.

What say you? Anyone? Interactive artworks? Responsive applications using a live video camera feed? The kudos, or the cash? You lot are the brains, while I provide the flesh-sacrifice required in running this inspiring yet occasionally infuriating behemoths.

Hello? (sniff)

– Bren

Aug 07 2007 | 12:38 am

Hi Bren,

I’m interested.
For other people who might also be, it would be useful to know what the pixel map of the screen is. In other words, how many pixels horizontally and vertically? This will help people work out what kind of images will work.

Being a bit geeky about these things, a full tech spec would also be useful. In other words,

What connects the computers to the screen?
What kind of camera do you have?

Bear in mind that people will probably need to at least travel to the site and stay for a coupla days to make anything interactive function right. At a minimum I’m sure contributors would like to know they have travel and accomodation paid for…..

Definitely intersted in the urban screen conference but couldn’t get the link to work….


Aug 07 2007 | 10:56 pm

Apologies all, my head is filled with screens-related nonsense, that link should read for the forthcoming conference on content for outdoor media.

Marcus, I know how ravenous you content creators can be for tech specs, oh, don’t I know!

I have some everyman documents available (and I will be in touch with you directly), but generally speaking, if you will allow me to adopt my official-yet-calming tone…

Generally, the screens possess fewer lines of resolution than a domestic digital television. It should be borne in mind that work including highly defined, hairline detail may not appear to its best effect. This also affects work that is very dark, as the screen is often in direct sunlight, while video pieces containing lots of delicate, shaded elements and little contrast do not appear to their best advantage. Scaling technology is in place to enhance perception, and a typical full-screen background image would normally be delivered at 1024 x 768, should you wish to use this as a guide.

If none of this means anything to you, don?t worry. Just submit material to the best of your ability, and we will take care of the rest.

This completes my assembly for today.

Aug 09 2007 | 5:04 pm

The reason I ask is that if you

Aug 09 2007 | 6:26 pm

Aug 10 2007 | 7:53 am

only true of the newer element labs-style screens.

The older jumbotron -style screens often work from broadcast video inputs. Mostly designed to work with broadcast equipment.
component and sdi feeds mostly.

but the question is how you get from the Mac or PC to this…. and what kinda devices are being used…. and how they shift the gamma…. and how they do the scaling…. and whether they add artefacts or deal with fields…. and a whole number of other issues.

Thus the need to get an idea of what kit is on the ground.
Just like any other interactive art installation…..


Aug 20 2007 | 10:03 am

Hi Marcus, Joshua

Sorry for the delay in reply, it’s a bit manic in the summer silly season of live screen-related events right now and this has been my first opportunity…

Your responses have sent me a bit shivery – it’s like you’ve looked into my soul or something. Just a few years ago I would have had no idea what you were talking about, but now I get goosebumps when someone talks resolution and scaling and pixels.

Perhaps you could set up an premium rate chatline for repressed screen operators; maybe make a short TV ad in which you loll on a mattress of circuit boards in a disco wig wreathed in soldering mist.

I can only talk on behalf of the present BBC network, not all of which are uniform, and specifically as to my own screen in Liverpool. Bear in mind that I am a fan of the try-it-and-see approach, but I can understand how you would wish to avoid senseless rendering and development if the subtleties are not apparent.

From Mac or PC it is literally video and audio out to BNC composite video and XLR audio as part of an overdall matrix, the on-screen switching between which can be automated to receive and/or distribute between sources.

Maybe I’m not using the terminology in the correct sense, but we have always found a way to make it work so far.

I’m sure you can also understand the sensitivities involved in posting exact specifications over the internet, but I’m here to help however I can.

Cheers for your interest!! Have you ever fancied being a screen manager?!

Aug 20 2007 | 10:38 am

Quote: wrote on Mon, 20 August 2007 11:03
> I can only talk on behalf of the present BBC network, not all of which are uniform, and specifically as to my own screen in Liverpool. Bear in mind that I am a fan of the try-it-and-see approach, but I can understand how you would wish to avoid senseless rendering and development if the subtleties are not apparent.

Dont mean to be rude, but a tech spec is essential in this line of work. and i cant see that any information you would disclose here about the screen and speakers would have an effect on security at the event…

the try-it-and-see approach may be possible if you are working for a funded institution, but not as an individual doing unpaid work.



Aug 20 2007 | 11:19 am

That’s fair comment Joshua, thanks. I certainly don’t want to abuse any advice or assistance anyone is willing to offer. Let me know if you feel this post is unsuited to the forum.

Aug 20 2007 | 11:21 am

Wrong J, sorry.

Aug 20 2007 | 12:17 pm

Quote: wrote on Mon, 20 August 2007 12:19
> That’s fair comment Joshua, thanks. I certainly don’t want to abuse any advice or assistance anyone is willing to offer. Let me know if you feel this post is unsuited to the forum.

its not that its unsuited to the forum, its just that you have to be specific about the technical aspects of a project. otherwise you may end up with an even more stressful event!

as lyallmarcus points out, works done in jitter are (generally speaking) bespoke systems and require to be programmed to fit within such parameters. the nature of programming is (very) time-consuming and one may not be able to adapt jitter patches there and then.

also it sounds like anyone presenting work there would have to use the mac-mini, and this particular machine has limited graphics hardware for jitter use. i havent done any tests with that particular machine, but i would imagine that processing a 1024×768 video in real-time would put it under quite some strain…

this doesnt necessarily mean its unworkable, especially since (as you point out) this is an outdoor screen and is not designed for detailed, delicate or shaded visual work.

to make things clearer:

i would provide the following info:

screen make / brand / model
screen connection BNC
screen resolution: maximum of 1024×768
number of colours: thousands / millions?
screen luminosity / brightness
a picture of the screen in situ?

what is the mixing matrix you are referring to?

stereo XLR
can you use sound from the space?

can you provide a plan of the space, in case the works use sensors for interactive elements…

j (justin)

Aug 22 2007 | 11:43 am


Very happy to do some homework here to make this work.

If we know the model of screen (screens if applied nationwide), and their physical size, we can work out roughly how many physical pixels are one each screen, in other words, how many actual LED clusters we are sending info to.

This will give us an idea of how much detail we’re really talking about. Bear in mind that screens vary in dot pitch (distance between pixels) from about 4mm to 25mm.

The composite video feed doesn’t help matters. It’s probably the worst video signal available, but quite common in older screens.

This means that you render everything a little bigger than normal, to cope with the picture degradation (as I discovered on another job recently). Maybe 150%…

The other issue is how the Mac Mini outputs composite video. If it’s a little USB/firewire device, we’re in trouble. Is there some kinda built-in video output in the Mac Mini? Hopefully not….Maybe a Mac Mini is a little underpowered for what you’re doing here…..or is it just me?

It needs to be converted using a professional scan converter, like a Barco ImagePro or Matrox MXO, otherwise the video output is going to be really crap…. ImagePro is good, because it can cleanly scale the image up to the right size.

Sorry. Going on here a bit.
As a punter, this is what I want to know:

1) Make of screen. Including Dot Pitch. 5mm? 8mm? 20mm?
2) Exact size of screen. Preferably, number of actual panels.
3) How does the Mac Mini DVI feed get turned into composite?
4) Is it possible to use an SDI signal instead? (it being 2007 and the BBC and all that)
5) Sound spec as post below.
6) Plan of space as post below.

Once you’ve got that, we can put a brief together, like:

1) "Please make a Jitter patch that outputs a 640×480 image (but needs to run cleanly on a Mac Mini)."

2) "You’ve got a Unibrain USB camera as an input."

That sort of thing.

Most of the dudes on this forum have a lot of experience with hands-on installations. This means we havbe all been through the pain of slaving at a keyboard in our studio for weeks to make something that looks great, only to show it on a screen, or in a space that makes it look absolutely shite. It happens A LOT. Particularly when big clients with budgets are absent. However, I realise it seems like the Spanish Inquisition at times.

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