I do this a lot and have tried many things, so the other day when a friend asked for advice I cam up with this. Then I just noticed the same question on the Isadora list today, and I do get asked this fairly often, so I though I would try and share my opinions here.

This is part one where I just cover the options.
Part 2 will cover some less successful options.
and Parts 3-7 will go over specific setups and provide a complete "Cookbook" with photos, screen shots, diagrams and even example files where applicable.

First off lets outline the dilemma. You are doing a show, installation, or presentation with multiple displays. With cheap projectors and screens this is getting very common. Two obvious solutions are to use a Video player or PC per screen, or to get a bunch of dual head video cards and pack them into one big tower computer. But there are a few issues with that. One it’s expensive, two it takes a lot of space, and three how do you synchronize all your content.

Some of those might not be a problem, space is an issue for touring, and some installations, but others have plenty of space. And though it’s hard to believe some shows have plenty of money too. And there are off the shelf solutions for synced video like Dataton Watchout, but they tent to hit the pocket book pretty hard too.
But for the rest of us lets say we want to do as much as we can with the laptop we have in order to solve all three problems at once. So what we want is to run multiple screens or projectors from one Laptop.

Now a quick overview of the possible solutions that we will cover.

• My favorite solution now is the Matrox Dual Head 2 go. (well I bought the triple head but same thing)
  • $170 for the dual head 2 go and $300 for the triple head 2 go.
  • This works kind of funky with Isadora or any other display system because the computer sees one monitor that is double wide and then split across 2 physical devices. So in Isadora for the dual head I put 2 Isadora projectors set to the same Isadora stage, both set to 50% width, and one with a 50% left setting.
  • But it’s fast pretty easy, pretty cheap, and works with a laptop.
• Here is another options common in the VJ world that I have tried our but never used: use two scan converters with zoom function.
  • You just have 1 desktop, with two small video windows say 2 Isadora stages set to 320×240. Then you send that out to both scan converters. (loop out of one into the other)
  • now you see your whole desktop on both projectors
  • so now you use the zoom feature to zoom in on each 320×240 video area, and that is all that is seen on the projectors.
  • this is pretty low res, but works from a laptop, and even on slower computers and laptops that don’t support dual head at all because the video is small. Oh and you end up sending analog video to the projectors on a coaxial cable which is cheap too. It works well and you can see why mobile VJ’s have been doing this for years; it works on a laptop and the Matrox thing is pretty new. However I never dug the low res.
  • The price is similar with the scan converters costing about $150 each.
• Not strictly from ‘a’ laptop, more from a bunch of laptops. I’ve also done the multiple Isadora computers synced, I do this a lot actually and it’s great. However It’s much more expensive, and you have to build a lot of control logic in Isadora, so I would only recommend this if you need to run more screens than you can put out of one computer. I tend to find the limit is 3 screens for a fast computer.
  • But if you are doing lots of video effects or high res video then maybe you can only do one or two. For an opera where they were playing back HD video at full res Isadora on a PC could only do one stream per computer and had plenty of money to rent 4 laptop computers.
  • You don’t need a second license of for Isadora, you can run Isadora in Demo mode on the second computer. You can’t save any edits, so you have to edit on the registered computer and copy the file over to the second computer. It’s a pain to keep updating as you might guess, I finally wrote a PERL script to do it automatically for the last show.
• This one also breaks the cheap and use what you have options, but there are a few laptops out there with dual output video cards. Dell and Alienware for example have some high end systems with this option. (there are others as well) I have the Dell XPS which has a ATI Radeon Mobility 9700 with DVI and VGA outputs. (can be 2 VGA outputs with a DVI-VGA adaptor) The problem for me is that while I can run 2 projectors, I then no longer have a control screen and I have to run blind since the ATI card can only drive 2 outputs at once, and the Laptop screen counts as one of those outputs.
• Last option, and not at all recomended is an add on vga output for laptops. I have tried the USB2SVGA and the VTbook PCMCIA card, and will go over those options in a later post, but the short answer is that they are not sutable for video work. They might be fine if you are doing a slide show or PPT presentation, but that’s about it.

But I really like the Matrox solution the best, and even with multiple slave computers I try and do the first 3 screens with a fast Mac or PC and the Matrox, and then slave the rest.