# video over Cat5



## GXander (Aug 8, 2015)

I am designing projections for a production this fall that will use rear projection onto the cyc for backgrounds. Ideally, our projection operator will be in the booth with lights and sound, rather than behind the cyc where they can't see what is happening. To make this possible and avoid signal degradation over this long distance, I am looking at running the video signal over Cat5 cable. I have a Cat5 cable that will be long enough, and I found several adapters like this one online, but I also found adapters that are more expensive and look more complex (like this). Should I take this to mean that, if I use a cheap, simple, adapter, it will not transmit the signal correctly? And if so, is there a way I can make a simple adapter work correctly rather than having to buy an expensive adapter?


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## Amiers (Aug 8, 2015)

well it all depends on the length of the cat5 run. If you already have the adapters that is a positive. The other think is if it is a VGA adapter then you will be limited to A 4:3 ratio with your content. 

I would assume that if you already have this set up that it has been used already. So I would think it should work fine.


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## Colin (Aug 8, 2015)

Let us know how long a run you need, but in general I would be very skeptical of anything passive like the first option you found. The second looks better.

I have had good luck with the Monoprice extenders for HDMI over 100' runs (they claim to do much more) but that could be a different story than VGA. 

If it is worth getting an extender for, I would wager it is worth getting something that plugs into the wall though.


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## FMEng (Aug 8, 2015)

VGA over Cat 5 is done in the analog domain. 
The different twist rate per pair in conventional Cat 5 affects the velocity of propagation, causing the colors of the image not to line up exactly. You will either need to use special, low skew cable, or use an expensive extender that allows active correction for skew.

My understanding is that the HDMI extenders send the signal digitally over Cat 5, which reduces should not degrade the image until the maximum distance is exceeded. HD Base-T should also be lossless.


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## GXander (Aug 9, 2015)

Thank you all for the advice. The length of the run is going to be 100', since that's the length of the cable we have that's long enough. The projector we're going to be using has a maximum resolution of 1024x768, so limiting the aspect ratio to 4:3 isn't a problem. We actually have not done this before. The last time we used rear projection like this, the operator was next to the projector, and we will do this again if it turns out to be necessary. Looking at the cable, it appears I was wrong when I said cat5. It is actually a cat6 cable, I had just assumed it was cat5 because it was an ethernet cable. Will cat6 be any better? Also, if it would be better to use HDMI-ethernet adapters here than VGA, I believe that would be possible. I just need to find out what computer we're using and make sure it has an HDMI port. I really cannot afford one of the active extenders, but I'm ok with buying a passive one even if it turns out not to be usable for this application. However, if you think there's no chance of the passive extender working well enough, we'll stick to having the operator behind the cyc.


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## ruinexplorer (Aug 9, 2015)

CAT6 will be worse with skew than CAT5 cable. With 100' run, why not just use a good VGA cable? With that resolution, you should be fine.


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## rhedgehog (Aug 28, 2015)

Depending on your show, it might also be possible to have the computer running the projections act as a media server of sorts, and have a second computer in your booth to act as the controller. This way you could use the cat6 cable just as a network cable, which it should be fine for at 100'. This adds complexity, though, and more points of failure, so take it with a grain of salt.


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## MikeJ (Aug 29, 2015)

Kind of old thread, but to clarify an above post, for the next person with a similar setup, VGA is not limited to 4:3 ratio or to SD resolutions, for that matter.

Also 100' runs of VGA or 5 wire, will be fine. And while we are on the subject, I have used the cheap, $16-20 HDMI to dual cat5 baluns on amazon, that get 3+ stars, and they work just fine at 100'(most of the bad review are from people plugging in the 2 cat5s reversed, writing a bad review BEFORE trying to switch the cables, and then not being able to change their rating). I only used these to get signal to a couple TVs in a bar; for professional use in a live show, I would get something better, but for a penny pinching school or community theater project, they will work, but they are built very cheaply, not like at all like a professional device.


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