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XSIra 2005-06-01 11:11
Hoping someone might have a suggestion on how to do this...
I'm planning my company's booth at a tradeshow, and we'll have three poweful video projectors, projecting onto a screen approximately 60ft x 15ft. The video source will come from one PC , and will be in HD format. We can get our hands on a matrox video card with three outputs.
I was wondering if anyone had an idea if this would be possible to do, and if so, if the image quality would be ok? I figured that if the video was windows media format, with a ratio of 1920px x 1024px, I could span the three 'monitors' (projectors/screens). Any thoughts?
Tx!
Ira
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Slaughterer 2005-06-01 17:09
I think a triplehead Matrox ought to do this, but I have no personal experience with Matrox triples. Is your video really 4:1 aspect ratio? You say your video will be at 1920x1024. Assuming the normal square pixels, that's just under 2:1. Are you going to stretch/squash or do you not really need that much screen?
Assuming you only want to show one picture with square pixels, you only need two monitors (projectors) at 1280x1024 and you'll have some blank space on either side.
Assuming 3 monitors at 1280x1024, you'll have 3840 pixels across. You could put exactly two of your videos side by side.
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XSIra 2005-06-01 22:29
Thanks for the reply. Sorry, I made a mistake on the pixel size, it's not 1024 high. I guess that's the real question. Assuming I can get a Matrox triple output card send 3 signals at 1280x1024 each, what would the video resolution need to be? I think that there's roughly a 2000 pixel wide maximum for HD (?), so would it make sense to have the video source at 1920x512, and play it fullscreen accross the 3?
Ira
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Slaughterer 2005-06-02 11:55
HD's 1080i mode (and the less-used 1080p mode) are 1920x1080 pixels. If you were using a HD video device for playback, that would be your limit. If you're shooting in HD, that's again your limit. But if you're doing this all in a PC, you're not tied to HD resolutions. You should be able to do whatever resolution you like, though I'd pay close attention to the projector and Matrox specs when choosing.
If you're limited to 1920x480 (true 4:1 aspect), then you only need TWO monitors. Run them both at 1024x768 for a total of 2048x768. Put your video in the center and you'll have 64 black pixels left and right, and 144 top and bottom. Zoom your projectors so this unused black area projects beyond the edges of the screen.
Even better, put the video at the bottom of the screen and let all the unused black go off the top. That way you don't get any "near-black" spill light on your stage or in your speaker's eyes.
If you decide on some other resolution, you still may benefit from using only two monitors anyway. Three 4:3 monitors WILL provide true 4:1 with no waste though. It's worth it only IF you can use the resolution.
In any case, one thing to worry about is the seam in the middle. If you have one video playing that spans two "monitors," there will be zero overlap in the center, requiring meticulous setup in order to appear seamless. If you could specially prepare the video beforehand, you might want a left-video and a right-video, that overlap and crossfade in the center. It may give a more seamless appearance when projected. I'll draw you a picture if this isn't clear.
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Slaughterer 2005-06-02 12:00
Assuming you can use the resolution, three monitors playing 1280x1024 is 3840x1024. It's an awful lot of pixels for one PC to play in realtime. You may not get there, performance-wise.
There are other possibilities for utilizing the three monitors:
3 x 800x600 = 2400x600
3 x 640x480 = 1920x480 (aha, 1080i width, how convenient)
I don't think you can set a Windows XP display to 640x480 though. I think 800x600 is the lower limit.
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Slaughterer 2005-06-02 12:06
I keep thinking of more to add. Sorry about the multiple posts.
Remember that regardless of the actual resolution of your desktop, you can scale a movie. So let's say you decide to do a 1920x480 movie. You can't set your desktops to 640x480 under XP, so set them to 800x600 and let your player scale up to fill the screen. I try to avoid scaling, and some formats scale better than others, so you'll have to experiment. Get the PC, the graphics card, and three monitors NOW and start working with it. Some combination of 2 or 3 monitors, video resolutions, and scaling will do the trick.
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XSIra 2005-06-03 23:58
Slaughterer, thanks so much for all the input! I'll be talking to our A/V guys and video editor this week, and all of your info has been extremely helpful. I will test the various scenarios and post the results here, in case anyone else has a similar challenge.
BTW, the PC playing the video is an HP dual-core, 64-bit workstation with 8GB of RAM, so I suppose it should be able to play any video resolution without any hickups (I hope...) ;)
Cheers,
Ira
Ira
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