Building a Video Wall out of Old Laptops?

alphakappa asks: "I am interested in building a video wall as a personal project using recycled old laptops so that I can make use of the display controllers that are already present. Is there free or cheap software that can extend the display on Windows and still be capable of showing different videos on different zones (like, say run a video in one zone while showing a powerpoint presentation in another one) What tools would you use?"

Projector

[Dan East]

Buy a projector for $1000 and be done with it. The display controller is part of the motherboard, so you would need the entire laptop, not just the display. Thus the power consumption would quickly increase since you're powering entire laptops. Also, the lead length between the panel and the onboard controller must be very short - just a couple inches. So the bulk of the laptop will have to be mounted right with the panel. The displays will look significantly different - particularly with respect to white (some will have a yellow tint, others a blue tint), If you sit down and add up the bandwidth - full motion video at say 1024x768, times however many laptops you're driving, equals a crapload of bandwidth. We're talking gigabit requirements. If these are old salvaged laptops then you'll be lucky if they even have 100Base-T.

As I said, buy a projector for $600, plug it in and enjoy.

Dan East

Practicality

[cephalien]

This really doesn't seem feasible, unless you have some serious hardware engineering prowess. What it seems like you want to do is span the laptop video on multiple monitors? If you want to do this with 'external' displays, then the problem is spanning across those individual laptops. With network access, you might be able to fudge something with VNC (although, don't expect great speed on that). Otherwise, I'd say probably not. From what I know, most of those art displays using regular PCs/monitors used specialized software or particular effects not available in a standard configuration to do what they do.

An alternative

[Z00L00K]

is to run Linux on all laptops and execute them all as X servers without any window managers.

Then you have a server that throws X applications onto the laptop displays where you will get just about any look&feel you like.

OK, it's crude and may require some work. The laptops may never be a really good solution anyway. Also consider the cost of additional hardware involved and you may be better off with a good projector or "standard" flat-screen LCD:s connected to a single computer with multiple graphic cards where you stretch the desktop to cover multiple monitors.

It's possible to run multiple monitors under both Linux and Windows without any problems.

Re:Windows?

[cephalien]

Assuming that we're talking about a heterogeneous combination of laptops, some of which are unlikely to be anywhere near current, I think Windows (as far as driver support, at least) would be the sensible solution. Since they all likely come with a license for one or the other version, there shouldn't be much of an issue with legality anyway.

Linux would be more flexible, yes, but not when you're trying to get old displays working as fast as possible, along with builtin networking or even wireless, without having to go through a tedious setup for each different machine.

The Projector bulbs

[dj245]

The major cost of projectors is in the bulbs. A $600 projector that takes $300 bulbs that only last maybe 2000 hours is no fun. When you have the $300 bulb on your mind you get really stingy about turning the TV off all the time. To get around this, there are about two solutions.

1. Build you own projector, and spec a better cheaper bulb that lasts longer
2. Buy something like the LumenLab Evo [lumenlab.com] which takes $30 bulbs that are supposed to last 6000 hours.

I went with option 2 because I'm a lazy bastard. While there are better projectors with higher resolution, for now (I graduate in 3 weeks) it was worth every penny and then some.

XDMX

[MicklePickle]

I've tried XDMX on exactly this setup. I had a number of old laptops, (nine to be exact), that I converted to
one large X display. Worked really well. The screen was huge - 3x3 17" laptop screens adds up to a big display. The downside? You have to have a dedicated switch to handle the traffic, (because there is a LOT of traffic - even when moving the mouse the switch goes bonkers). Also, it's slow. Much slower than an individual display, but good for displaying static images.
Once I had it setup I didn't use it much, and in the end just used each laptop as an network mp3 player in each room of the house. Much better use for them.