Techies use many different connectors every day, yet they're always changing. Somebody is always trying to come up with the next best thing. In today's ever-changing environment, one of the most commonplace connectors, the BNC, or bayonet-style coax connector, is morphing into another widely used item, HDMI.
What is HDMI? The next best thing. HDMI stands for High Definition Multimedia Interface. In short, it takes high-definition video and digital audio and puts them together in one place.
But wait, so does coax cable with a BNC connector. It's called an embedded signal. So, putting any preferences or deep discussions into everything else HDMI does aside, let's look at the two options and their pros and cons.
HDMI is very cool!
What it's done to reduce cable clutter is exciting enough. The fact that all of those digital signals, ie HD video, audio, HDCP protocols, etc., can travel together down one cable is a great thing. Reminds me of fiber optics, but that's a different article.
HDMI has now become a very popular connection point on many different devices. We first saw it on consumer products, and it has now infiltrated the prosumer and professional markets. So, what are the advantages of HDMI? I already mentioned the first, and most obvious advantage: reduction of cable clutter. Just look behind your TV and you'll see the difference.Even in the house-of-worship market, cable management is affected, and if you read my article on cable management , you know the subject is near and dear to my heart. A similar advantage with HDMI, is that your hookup is one and done. No yellow, red, white configuration, or RGBHV. Just one HDMI and you walk away.
But....
Uh-oh, here he goes, you're saying. While HDMI is great in certain applications, it can't be considered for use in every situation that allows for it.
Why not?
There are a few reasons. First, is durability. The connector itself can be flimsy on cheaper cables. Even on the heftier connectors, you'll need to provide strain relief to protect the connection point on the cable/connector. Also, the HDMI jack on the device isn't designed for frequent plugging and unplugging. While it's very convenient for your portable projector or TV, I recommend that HDMI applications be considered only for permanent installations. HDMI cables are also not repairable, just replaceable.
Distance is another issue. After roughly 100 feet, an HDMI cable becomes useless, and you now have to extend over CAT5/6, which then requires conversion on both ends using an HDMI-to-Ethernet converter. While CAT5 is cheap, and will probably go to your projectors, the extra converter becomes a point of failure.
So, now the BNC connector!
Versatile is the operative word here. The BNC connector is a mainstay of the broadcast and production world. Why? It is durable. Under normal use, it will not break. In fact, unless you step on it or run over it with something, it won't break. If the cable is pulled, the crimp may fail, and you'll have to do a field repair. A what? Yes, a field repair! Grab your crimper, snips, and replacement connector and go fix that cable! In two minutes, you're done.
Obviously in an installation scenario, repairs are less frequent, but knowing you can is a great thing, and remember to still create a strain relief loop.
Also, distance is not an issue in most cases. An analog signal can push 1000 feet on good cable, SD/SDI 600-700 feet, and HD/SDI around 150 feet. Many of these distances will encompass the majority of scenarios you'd encounter.
Distribution of HD/SDI signals over 150 feet or so will likely need to be converted to a fiber or CAT5 solution anyways. In the majority of these cases, quality coax cable will be all that's needed to complete the path to the device. Out of the switcher or DA (distribution amplifier) straight to the projector.
So if you buy a projector with HDMI only, you're going to have to do some sort of conversion, whether it's from CAT5 to HDMI, or coax to HDMI unless your runs are very short.
What's the big deal with that you may ask? It's added cost for one thing. As stewards of God's money in our church, it's our job to manage our budgets accordingly. Am I suggesting being cheap? No, but I am suggesting that there are ways to maximize what we do by shopping smart. Conversion also creates additional points of failure. If you have to check for a failure in your signal path, do you want to have to test a path full of converters?
In a coax scenario, you have two places to check: the beginning of the path, and the end.
Again, if you are dealing with embedded audio, then BNC, or coax will also handle your embedded audio signals much like HDMI. You just don't have the HDCP protocol capability.
The marketplace is heavily pushing HDMI as a one-and-done solution, but it just might not be right for your particular application. You have other options. Talk to your vendors and integrators. Consider your situation carefully to see what works best for you.
