Hi guys, I’m not such an expert on managing video signals, and I don’t miss only the knowledge but also the terminology. I would like to split a SDI signal into two TV screens, each one gets a different half. I never done it, how would you go about it? Do I need to upscale it first then split? What boxes do that?
Checked some posts about Video Walls controllers, or Video Multiplexers, but I have the feeling this is maybe an easier case and don’t need all that.
well a couple of things off the bat
if you want to spilt an sd video signal into two screens you are probably going to have either some aspect ratio issues or have to crop a good chunk of the viewable signal to make it fit.
if you want to try any kind of DIY method (for either live or prerecorded signals) you are going to have to have some kind of computer/framebuffer unit per screen, and probably have some difficulty with synchronization of the two units.
if you can live with HDMI solutions, there are reasonably cheap HDMI based video wall controllers out there in the world.
a very punk method that i think bill turk mentioned on some board a while back was very brute force: use a series of security cameras to rescan different chunks your video off a largish screen and then have each camera going out to a different monitor. probably the main tricky thing there is arranging the cameras in some kind of a way to make it easy to move them in x/y space to make sure each chunk of the image is properly arranged.
unless anyone else has an SDI specific solution they can recommend, might be good to fold this post into a general purpose VIDEO WALL WIKI type post, as this is one of the eternal internet questions re: video art/vj stuffs
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Hey the rescanning might be a good solution, simple but did not think about that! You can move the post… Thanks Andrei!
On the cheap (I think, I haven’t checked in a couple years but when I was picking them up in 2016-17 they were easy to find online for around $5 each) Avermedia AverKey 300 VGA to composite converters can do some basic pan and scan stuff and has VGA passthrough, so if you got four of them and an SDI to VGA converter you could daisychain the VGA ports of the Averkeys and use the “normal zoom” (200% zoom witha freely movable area) on each one to zoom and pan to four different quadrants of your input and patch the composite outs from each one to four different SD TV sets. Or in your case, you could make your source material 8:3 and letterbox it, and then zoom in on the left and right halves with two AverKeys. You could also theoretically do a 3x3 wall the same way with 9 AverKeys running in “area zoom” mode. They take input up to 1600x1200 (and I think the AverKEy Gold might be able to go a little higher), though, so you have more than enough resolution to do a 2x2 wall with standard def TV.
I’ve never tried daisy chaining them and only own two myself, so I have no idea if there would be any signal loss or anything, and the quality isn’t going to be amazing but it’s not actually too bad - I actually used one on the VGA port of an old laptop as an emergency backup to dump a 1080p source to VHS for a paying job when my good downscaler broke and it was more than adequate. There are much better ways to do what you’re trying to do, but this isn’t the worst and it’s probably one of the cheapest.
If it works, I haven’t actually done it myself.
Relevant manual page:
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