# Need advice on video with distances of 200 ft or more



## gauss1spl (Jan 19, 2010)

I don't normally take jobs in areas of limited experience, but a friend of mine is pleading with to take this on ( I suggested hire a professional). 
The boat company he works for wants to run 10 to 12, 37 inch screens from their mac mini to run a promo video at boat shows. 
The are a couple sets of problems i need to address. What type of cabling do I need ? would i use rg6, cat5, other suggestions you may have that would give the best quality video for these long runs. These line would also need to pass audio as well. Some type of multi cable would probably make this job easier and clean. 
I realize that it will require a distribution amplifier, something in a 19" rackmount would be ideal.
Any help or advice would be greatly appreciated.

Thanks


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## museav (Jan 20, 2010)

The current Mac minis come with mini-DVI and mini-DisplayPort outputs along with a mini-DVI to DVI cable. And you can buy separate adapters or cables to get to DisplayPort, HDMI or VGA, although not all of the ones out there seem to work as well as may be desired. Which format you decide to use and distribute may depend upon what the displays accept.

Since you also want to send audio then theoretically both DisplayPort and HDMI could carry video and audio on the same cable. However, you will probably find few displays having DisplayPort inputs and it seems that with mini-DisplayPort to HDMI adapters you actually need to take the audio from the USB port on the Mac mini and properly configure it for that. With DVI or VGA via an adapter you would need to separately distribute the analog audio.

So that leads to a few questions. What inputs do the displays support? When you say "200 ft or more" what is the maximum distance they see that "or more" representing? Are the displays going to be individual displays distributed over a large area or might there be displays that are back-to-back or in close proximity (if they did go UTP/CAT5 there are some dual output devices that could save money in such situations)?


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## gauss1spl (Jan 22, 2010)

The displays haven't been purchased by the company as of yet. I will assume that they will all hdmi in. As far as the maximum length will probably be around 350 - 400 feet.

Since these shows are never the same lay out it will be hard to project the configuration of the displays. The only constant is the one arch the have which will contain 4 displays, 2 on either side back to back and all the rest over a large area.

Do i need to run sheilded cat5 for this? low skew cable? run a distribution center (receiver) with a skew?


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## Chris15 (Jan 24, 2010)

The other prudent question at this point is going to be the expected maximum resolution. If we are going to look at running HDMI around, then what degree of "high definition" is desired will significantly affect the maximum distances between repeaters and such things...

Oh and because it's HDMI, anyone know what the HDCP maximum of the Mac mini is?


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## fx120 (Jan 24, 2010)

HDMI distribution is probably the worst way you could go for something that needs to be robust and road-ready. HDMI was designed as a consumer level interface that would be used in semi-permanent installs over cable lengths of a few feet. While there is "pro-grade" distribution equipment out there, it's expensive and frankly I don't like the connectors. Long distances can be a problem as well. Audio is a moot point because your Mac Mini won't embed audio if you're using a HDMI adapter, so you would still have to run a separate line for that. 

The industry standard for distributed video is still RGBHV and SDI. In your case you're probably best off going with RGBHV unless the budget is there to go digital. At lower resolutions the quality over long (300'-500') distances can be very acceptable with good cable and amplifiers. Many LCD TV's have HD-15 VGA inputs on the back so you could input directly into the TV's without needing adapters, and use common computer displays as well. The cables and distribution gear are available from a number of different manufacturers, and is common enough it can be rented in pretty much any major city if you need to supplement for a bigger job. 

As far as RGBHV-CAT5 baluns go, they are an OK solution that can allow you to pass both video and audio down one inexpensive cable, but they don't provide the greatest video quality and skew becomes quite apparent over long distances. They are an increased cost, and the ones that work the best are also the most expensive, almost to the point where you can purchase SDI converters for only a little bit more. 

Which brings me back to SDI. Specifically HD-SDI. SDI is a professional level standard that is currently most commonly used in broadcast, but is seeing a growth in the touring and corporate AV markets as the equipment comes down in price. It is by far the best way to go for long distance runs where picture quality is important. Audio can also be embedded easily into the digital stream, then decoded on the other end. The cable used is RG-6 coax rated for use with digital signals, and can be distributed using amplifiers, or often daisy-chained out of one device and on down to the next. 

We switched over to HD-SDI distribution for our corporate gigs a few months back when we upgraded one of our seamless switchers to a unit that has HD-SDI output and have had great luck with the Black Magic Design mini-converters for "breaking out" of SDI and back to analog YUV or HDMI when we need to use a older piece of gear that doesn't have SDI inputs like a LCD TV. So far we have had great success using them and the quality of the image is fantastic.

Black Magic makes a converter that takes DVI and a analog audio input and converts it to HD-SDI, which could then be converted back to HDMI and analog audio at each TV using one of their mini-converters, then daisy-chained to the next display. The DVI-SDI converter is about $400, and each SDI-HDMI converter is about $500 so it does get expensive pretty quick, but it would offer the best picture quality and the easiest setup/ strike.


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## SHARYNF (Jan 24, 2010)

I think you need to look at budget, and also consider what signal type is going to give you the level of quality you need. HDMI is great, but what is your signal source? is it a looping dvd? Bluray HD? or ??? A 37 inch display at a trade show probably does not need to be full hd and it would probably be difficult for the typical viewer to tell the difference.

The simplest is probably going to be to use cat5 from S video with audio like the Extron MTP units, being fed from a s-video/audio distro. 

Moving up from there you could use a s video distro, convert to dual RG6 using s video din to dual bnc connectors and then run your coax

Up from there you could look at a full component feed, but you are going to have to run a lot of cable, and IMO the quality on a 37 inch monitor is not going to be all that different, if you were using a much larger monitor then using a HD signal source and a full component distro etc might make a difference but your cost is going to rise substantially. I would NOT use a component to cat 5 converter for this, I think the loss in quality from the cat5 would offset the move to component.

Again IMO at this level of monitor and distances, I think your best option would be s video over rbg 6 

Personally I think that all the added expense of going hd-sdi on 37 inch monitor is not worth it if you were running high end projectors or very large displays yes but IMO 37 inches is just about the point where the standard def and high def sort of meet, 

Sharyn


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## museav (Jan 25, 2010)

Conversions also affect the quality so multiple conversions to SDI and back seems to make little sense in this application. Any issues with skew on longer runs can be addressed through using skew free or low skew cable or by using receivers with skew compensation.

RGBHV might be a good choice but 300'-500' runs of any reasonable resolution is pushing it and long runs of bundled RG-6 cable is hardly the friendliest thing to work with in a portable show setup. For that type of setup, RGBHV, DVI or HDMI over twisted pair cable probably makes the most sense. However, HDMI over twisted pair is currently limited to shorter runs, so that may not be practical. Also keep in mind the digital sunset, at the end of this year the analog output on some 'HD' sources, especially Blu-Ray players, may be limited to 480i SD video.

Magenta Research offers a HDCP compliant, DVI and stereo audio over twisted pair system that is rated for full HD resolution up to 600' over a single CAT6 cable, Infinea DVI Transmitter. There are a number of manufacturers for RGBHV and stereo audio over CAT5/6 transmitters and receivers, but be sure to match the run distance and resolution, many times an "up to X feet" spec for some video over CAT5/6 devices represents the maximum run with a lower resolution signal.

HDMI, DVI or RGBHV over fiber is another option that can allow for very long runs. Magenta Research and Extron offer such systems but they are still a significant cost increase compared to UTP/STP based systems.


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## Expoman55 (May 13, 2010)

In our new church facility we had the need to control distribute video from the control booth out to large screens throughout the facility hundreds of feet and to switch the output. We used a switcher to control the video into an encoder to send DV and DA over over Cat 5/6. At each monitor we have a decoder box ( tiny little box with wall wart adapter) to pull the audio and video components apart for the monitor.. each box has little alignment pots for signal, and alignment.. Works well. Nice clean 720 pic on each side.. as limited by one monitor will only do 720


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