# Long distance video (SDI vs cat6)



## Crash_Override

What is the best way to get video to projector? 
The video and projector are show dependent. Maximum distance should be 50m (160ft). 
I have been offered an HDMI to SDI converter and SDI to HDMI converter. But other people are suggesting an HDMI to cat5e/6 converter and cat5e/6 to HDMI converter. 
What to you suggest? SDI or Cat6? 

Signal is coming from QLab for our shows, or sometimes even from a powerpoint presentation. I will be buying an minidisplayport to HDMI, I already have minidisplayport to VGA but I would like to invest in better quality signal.


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## Joshualangman

We have discussed this extensively on various episodes of The Cue: http://thecueshow.com/site/.

Either can work. SDI limits you to broadcast resolutions, which may be problematic.


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## ruinexplorer

If you have a projector which is using broadcast resolutions as stated (such as 1920x1080), then you should be fine either way. If you are needing other computer resolutions, then you do not want to use SDI as it is limited, which will force the image into the closest resolution which may cause your image to lose clarity.

So, let's assume that it doesn't matter. What might be best? There are a couple factors. If you are going from a computer style signal (HDMI) to a broadcast type signal (SDI), you are not only changing the signal "language", but also the means of transport. When using a co-axial cable to distribute SDI over a distance as suggested, you need to make sure that you use digital grade cable. The older analog cables will suffice for short runs (similar to using a mic cable for short runs of DMX that use a 3-pin XLR). Generally, short to me is 25' or less. Also, you will get better results with double shielded cable.

With Ethernet cables and their adapters, the biggest "gotcha" is that many people try to use pre-installed cable. Unfortunately, you need to make sure that those don't go through any type of network system as generally, a balun (the converter you speak of) will not be changing the signal to an IP protocol. It is also critical to use the specified cables (i.e. don't use cat6 when cat5e is required). Ethernet cable is generally cheaper than digital co-ax. Quality of converter also makes a huge difference.


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## Crash_Override

At first I have a projector with native resolution of 1024 x 768, max would be 1600 x 1200. So I need to be able to send 4:3 or 16:10, depending on projector.


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## Chris15

16:10, and 4:3 to a lesser extent are going to be problematic in broadcast SDI land. The highest broadcast standard 4:3 signal is 576p.

I think you're looking at Video over CAT, my default recommendation would be for HDBaseT products...


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## Crash_Override

Update: If it changes anything. I don't have mini displayport. I have thunderbolt port.
I will be showing only pictures in that show. Picture resolutions vary a lot.


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## Crash_Override

Or should I stay with VGA and just get a 50m cable?

Found online these: Kramer PT-571 and PT-572. What about these?


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## Bubby4j

I'm actually in the same boat - we're redoing the video distribution in our church's main auditorium. I've not actually ordered anything quite yet, but I'm going to try the Kramer HDBaseT converters. The cheapest set is about $400 (transmitter & receiver pair) and is supposedly good for 230ft, though results may vary due to cabling & interference. The longer length one is good for 100m (330ft) or potentially further than that if you're just doing 1080p (instead of 4k).

To me it seems like a better solution than SDI, at least for our purposes, as the Cat5e/Cat6 cable is already in place, and HDBaseT supports stuff like nonstandard resolutions/framerates & HDCP.

VGA is pretty outdated, and only going to be more so within the next few years.
I wouldn't install anything analog unless you had a super low budget. If you really care about price, Extron has some VGA over cat5e/cat6 converters. Used sets of transmitters/receivers go for pretty cheap on ebay, and they're rock solid reliable. (Extron MTP is the series that I'm referring to.)


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## Morte615

If you are too the point of installing cable, always look at Cat 6 (you could run Cat 5e but Cat 6 will work with pretty much any Cat 5e equipment and the expanded bandwidth for Cat 6 will help you down the road) or even better fiber. Technology is moving more and more toward network topology and is just going to be more prevalent over the years. Also with Cat 6 or Fiber you can purchase (or rent depending on needs) converter boxes to go from just about anything (VGA, Component, Composite, HDMI, SDI, ect.) to anything, you can even convert from one source to another if needed (HDMI to VGA) though sometimes you may need special hardware but the cable run is the same. 

And if you are running the cable, always run more than you think you need now. If you can afford it I always try to run at least double the cable. That helps with broken cables/connections (especially during critical show time when you don't have time to re-terminate a new connector on {especially fiber} you can just move to another cable and fix it when you have time) as well as expansion down the road. And is much cheaper to run now than later when you end up needing it.

For flexibility I say Network is probably the way to go. Though for simplicity (and budget) it may not always be the best.


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## Bubby4j

@Morte615

What do you mean by Network? Do you mean some kind of video transport over IP?
I don't necessarily think it's impossible, but for live situations (IMAG) I would think that IP would have too much latency.

I absolutely agree with you about running Cat6 though.


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## Morte615

Not so much over IP as the cabling. My terminology was slightly mixed up. Though with using Fiber interfaces (expensive one mostly so take that into account) we have had no issues with latency on Imag. We routinely go anywhere from 25' upwards of 200' and have no had issues. Though in general the Cameras are Triax to the switcher (SDI in) then the switcher outputs to Fiber to our Video Matrix which goes to our screens and other outputs through Fiber or SDI (mostly Fiber)


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## ruinexplorer

Crash_Override said:


> Or should I stay with VGA and just get a 50m cable?
> 
> Found online these: Kramer PT-571 and PT-572. What about these?



I've not used those specific models, but they should be acceptable, especially with the resolution being sent. 

As for a 50m VGA cable, I'd stay away from it unless you are amplifying the signal before the run. The signal will degrade over that long of a run. To get around that with analog signals, we would use a 5-wire coaxial bundle for RGB-HV. This is the same signal as the VGA, so if you had to connect to something that used a D-sub 15 connector (commonly known as a VGA connector), there was a simple adapter. Many projectors actually had the 5-wire built in, so you didn't have to adapt there. This could be run 100m without noticeable degradation.

If you plan on permanently installing a system then, I would definitely agree that you should go Cat6 or fiber. If you go Cat6, make sure that the converter is set up to use that grade cable. As the twist pattern is different between categories of Ethernet cable, you can get errors if you don't use the right cable. I have seen converters that completely scramble the signal and others that can compensate. As an analog signal converter, I have found those that have skew correction as an option, then you can get the best results. Basically, the twist patterns are different to minimize interference. However, with the analog video signal, then the information is arriving at different times. The result is that the convergence gets messed up. However, if the converter is creating a digital signal (such as the one you were asking about), then there shouldn't be a problem with skew.


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## Crash_Override

Well for this show they didn't let me get anything fancy.
So will be using our old 4:3 projector and we bought second hand Extron VTR001 and VTT001. Now I need to get cable between those for touring. Rental company who sold me the Extron boxes used this cable (stranded, cat5e, outdoor, patchable, http://yeint.ee/image/data/incomingPdf/138495/VKBOX OUTDOOR.pdf ).
I'm unable source something like that from cat6 cable locally. But I want at least the cable to bee future proof if going for HDBaseT. So I tried looking in the HDBaseT standard and on some places it says I can use cat5e for it also? Is it true? My cat5e would be mounted on a drum, will it be very bad to the signal if I have it coiled up on the drum to some extent? Getting a 50m cable so let's say maybe 10m would be coiled.


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## Bubby4j

Crash_Override said:


> Well for this show they didn't let me get anything fancy.
> So will be using our old 4:3 projector and we bought second hand Extron VTR001 and VTT001. Now I need to get cable between those for touring. Rental company who sold me the Extron boxes used this cable (stranded, cat5e, outdoor, patchable, http://yeint.ee/image/data/incomingPdf/138495/VKBOX OUTDOOR.pdf ).
> I'm unable source something like that from cat6 cable locally. But I want at least the cable to bee future proof if going for HDBaseT. So I tried looking in the HDBaseT standard and on some places it says I can use cat5e for it also? Is it true? My cat5e would be mounted on a drum, will it be very bad to the signal if I have it coiled up on the drum to some extent? Getting a 50m cable so let's say maybe 10m would be coiled.



Yes, cat5e will work for HDBaseT. However, the distance and resolution that you'll be able to get will be dependent on the cable. Cat6 will go farther and/or higher resolution. At 50m I think regular cat5e will probably work at some resolutions, but it depends on interference. It appears that cable is shielded, which will help. It's hard to absolutely know if it'll work until you try it, otherwise you can look at the specific HDBaseT equipment and see the estimates they have.


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## ruinexplorer

As this is one of the Extron models which does not offer skew correction, here is advice from their site.


> When using data grade twisted pair cable for sending high-resolution video signals long distances, a problem called skew can cause a distortion in the image, resulting in visible color separation. Extron offers two options for solving this problem and restoring image quality. The first option is to place an SEQ 100 BNC Skew Equalizer at the receiving end of any cable run where skew is a problem. The second option is to use Extron's Enhanced Skew-Free™ AV UTP cable to make system connections.



I have seen this happen, even with 1024x768 resolution. Essentially you have a timing difference due to the different specs of twist in normal data cable. If you are looking for future proofing, I would go with Cat6 and get their skew equalizer.


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