Whole-Building Video Distribution

[sdpiowa]

Hello everyone!
I'm a volunteer with the media team at New Hope, and I have been asked to do research concerning video distribution. We recently had a lightning strike that destroyed some of our main video equipment, and we are looking at revamping our system now instead of later.

We are looking to centralize our video system into our tech room instead of running multiple point-to-point feeds across the building. We currently run two video lines from our auditorium to our chapel (one drives two large TVs and one drives the main screen), VGA lines to all our hall monitors, and coax to the rest of the building. We would like to digitally transmit as many of these lines as possible, but we are also looking to implement a system that allows us to centrally choose which transmission goes to each monitor. None of us has much hands-on experience in this area. We currently do our auditorium-to-chapel lines over Cat5 cable, though only one is "truly" digital (the other just uses two pins on the cable).

We would like to run multiple feeds from the same system, though I understand that it might be cost-prohibitive to do so. We are currently running several feeds to other rooms in the church by using different channels on our coax distribution system, but we are wanting to transition to a centrally-controlled digital system, if possible.

Thanks! If this is confusing, let me know, and I'll try to explain in more detail.

Stephen

[tdangelo]

Stephen,


There are really two discussions you are touching upon. The first question (not in order of importance) is what cabling type and scheme should you use between your central distribution point and each destination? Secondly, how do you select the content which appears at a specific destination?


Let’s look at the second question first (how do you select the content which appears at a destination?).


There are only two options here:


A) A system which allows any user at the destination to choose his own content. To accomplish this all content choices available should be present at the destination full-time (whether visible or not). Currently (short of running multiple cables to each destination, or putting a video router head at each destination) the only way to allow any user at any destination to choose his own content is some form of a modulated signal system allowing each content item to be on it’s own channel selectable at the display device. Modulated systems can be analog, or digital, standard definition or high definition. Typically, an end-user would use the channel selector in his TV, or a tuner connected to his monitor, projector or display to choose the content they want to see.


B) A system which forces all users at each destination to rely on a centralized hardware device (typically a video router) to choose content. To accomplish this only one signal needs to be present at the destination full-time. All content sources however would be available to the video router. You’re A/V technician then selects the content to appear at the destination. Typically this is done on what is called an X/Y router panel (although software control can/will do the same thing). Router-to-destination systems can also be analog, or digital, standard definition or high definition.

OK, now for the first question (what cabling type and scheme should you use between your central distribution point and each destination?).
This is usually driven by what the distances are to each destination, what resolutions are needed at each destination and what connectivity issues pre-exist for each destination.

Would you prefer a system which allows any user at the destination to choose his own content? Or, would you prefer a system which forces all users at each destination to rely on a centralized hardware device (and sometimes a centralized person) to choose content?

[sdpiowa]

I think the distance from the auditorium to the chapel is somewhere around 360 ft. The runs for the hallway monitors are slightly shorter, I believe. I'm guessing that those are (at max) somewhere between 250-300 ft. As far as the coax runs at the far side of the building...I really don't know the distances for that. Our tech room is near the center of the L-shaped building, so I can't imagine that the distance is over 400-450 ft.

For resolution, we will be broadcasting SD. The majority of our equipment cannot handle HD video. The coax feeds primarily connect to TVs, while one feed to the chapel drives a projector. That feed would be the one that we are primarily concerned about concerning quality.


I think that the centralized option is what our tech director is looking for. As a general rule, I don't anticipate that the transmission feeds will change much, but we want to have a system that allows us to control what is being fed to each monitor. It would also be beneficial to use the system to allow us to bypass broken equipment (projector feed can be "pushed" to chapel monitors if the projector breaks, for instance).

[petereit]

Well, this is a great opportunity to start moving everything to current digital technology. I would start by replacing all TVs with HDTVs. Use a SDI matrix router like the BlackMagic VideoHub which will let you patch any source to any destination (even using an iPad if you like. Imagine sitting in your service and your projector fails. You don't even leave your pew--you just swipe over to your VideoHub app on your iPad and reroute your video to your large TVs). Use BlackMagic mini-converters to get your video sources to SDI and run SDI cable everywhere. At the destination end, to feed your HDTVs, use a BlackMagic SDI-to-HDMI mini converter into a Geffen HDMI distribution hub and run HDMI cables to your HDTVs.

The beauty of running SDI is that you get absolutely no degradation of your video quality up to 300 feet (essentially unlimited distance if you add equalizing, reclockng SDI repeaters or use fibre optic runs), it's virtually impervious to RFI interference and it's completely future-proof for the day you eventually switch to HD.

[sdpiowa]

Thank you very much! I will certainly look into that.

[Arlin]

I would also consider a packet based (video over IP) CAT5 distribution like Just Add Power or voLANte. Basically sending video over a computer network.

[sdpiowa]

Very cool. We actually just installed our gigabit switches yesterday morning. I'll have to look at those.

[sdpiowa]

Is the Blackmagic SDI receiving equipment interchangable with receivers made by other companies? Also, what do we need to watch for if we end up purchasing other SDI equipment (switchers, analog to SDI for our cameras, etc.)? Should they all natively work with each other?

The whole concept of SDI is relatively new to me. I was only first exposed to it at a Willow Creek conference a few months ago.

[tdangelo]

sdpiowa,

Any SDI device will connect to any other SDI device assuming the following:

Both devices are 525/60 or 625/50 standard definition or have the ability to convert.
Both devices are 1280x720/60 or 1280x720/50 or have the ability to convert.
Both devices are 1920x1080/60(59.94) or 1920x1080/50 or have the ability to convert.
Both devices are 1920x1080/24(23.9 or 1920x1080/25 or have the ability to convert.
The cable distance between the two devices is within the tolerances of the cable.

All this sounds much more complicated than it is. SDI is pretty plug-and-play. If there are issues between two devices it usually has to do with a miss-match between the resolution/frame rates above and/or cable specs.

[petereit]

Good info, Tom. SDI is a professional broadcasting standard, so most SDI products conform well to the spec. BlackMagic and Aja SDI mini-converters are pretty universal, and will configure to just about any resolution and frame rate you throw at them.

In the US, the SD video standard is 525/60, HD standards are 720/60 and 1080/60 (or /24 if you're shooting for "that film look". )

Generally you will set your video switcher to one standard (for us it's 720/60) and everything else in your chain will need to be set to that standard.

[Brad Weber]

The SDI based solution addresses the 'digital' aspect but seems rather awkward otherwise as it would require converting any sources to SDI as well as a home run from each device or group of devices for which you would want to be able to select the content. An IP based video distribution system such as is increasingly common for hospitals, hotels, etc. might be a better option, especially if you want the people at the receiving end to be able to select the content they view.

It depends upon the sources involved, however another potential consideration with SDI is that SDI is a production oriented format and does not address DRM or HDCP. This is actually getting to be a real problem in some applications as I am encountering situations where there is an HD-SDI based production system for which one of the sources is one or more outputs from a presentation system and while you can now address sources with Digital Rights Management and HDCP within the presentation system, getting those signal to any form of SDI is problematic. You can get DVI-to-SDI and HDMI-to-SDI converters but they will not be HDCP compliant as that would then allow creating a digital version of the content with the DRM removed. Solutions such as using component analog or VGA/RGBHV outputs for sources such as computers with Blu-Ray drives or standalone Blu-Ray players are no longer a viable option due to the analog sunset aspects. I have yet to find a good way to legally get source signals with DRM into an SDI based production system and don't see that changing unless the DRM involved changes.

[petereit]

We've been running SDI for almost two years now and haven't experienced a single problem due to DRM. Honestly, I can't even think of any scenario where DRM even enters the picture.