Digital Video Distribution -- Are We There Yet? -

Digital Video Distribution -- Are We There Yet?

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I get a lot of calls from rental people, especially owners and management, about video signal distribution and switching systems for shows. The first question is usually When do we go all digital?

Most shows today are hybrids, with digital signals from some sources, but an analog distribution and switching system. This is a result of both emerging digital signal standards, and a lack of comprehensive digital switching and distribution gear.

Among the many digital signals and connectors competing currently for our attention are DVI, HDMI, SDI and FireWire (IEEE 1394). DVI has become the de-facto output standard for newer computers and lots of high-end consumer video formats. Most of our display devices have DVI inputs now, as well. SDI has been in the market a few years now, and is seen as both input and output on lots of high-end professional decks, displays, projectors and switchers. HDMI is a comer, and is currently being seen mostly in the high-end home entertainment and HDTV market. And FireWire has become the standard for video acquisition and desktop editing systems, which clients often want to use as nonlinear video sources for shows. All of these digital interfaces have available signal extenders, switchers and processing, but those boxes are mostly limited to a single signal type. The products, such as interfaces, DAs and basic switchers are available to do most things, but were lacking the kind of finished products that would bring a show together digitally, such as switching systems with effects and previews that accommodate all the necessary digital formats directly.

A CAT5 Solution?
However, when talking about this issue to one of my colleagues in the industry, she announced that she had a solution to digital distribution: CAT5. She was adopting one of the CAT5 interfacing and distribution systems that is currently on the market, believing it to be digital. I had to point out that, while some of the higher-end CAT5, CAT5E and CAT6 distribution systems employ digital processing, their distribution is analog over twisted pair. In the better systems, this signal is very well processed for distribution in this manner. The lower-end systems use a passive balun for input and attempt to compensate in the receivers, and the results Ive seen from them are plainly terrible.
CAT5 distribution is making great inroads in the installation segment of the business, where common and pre-installed cable formats are important, and you can inexpensively future-proof a building by pulling lots of extra CAT5e.

Is there any advantage to the rental company for adopting one of the video-over-twisted-pair systems? There are lots of opinions, but Im not one of the ones that think so. If Im going to distribute video as analog anyway, I see no reason to add twisted pair transmitters/receivers to the long list of distribution boxes Im shipping to the show. They add powered components, power drops in some locations I didnt originally need them, and new components that can fail. Im not willing to do that just to get savings in cable weight and expense. Besides, I can buy a lot of nice, heavy-duty (read: Banquet-cart proof) RGB cable for the price of the twisted pair transmitters and receivers Id need to complete a show. My personal belief is that when clients ask for video over CAT5 they mean video over my network, which is a fast-developing market but not yet ready for rental prime time.

No, for show distribution Im left with a tried-and-true choice to bring all my signals into the show in a common format: Analog RGB. Its only here that I can currently get the complete range of universal products I need to produce a show--interfaces, distribution, switching, edge-blending, and effects, from multiple manufacturers, that operate well together. We do some shows, using laptops and plasmas or small projectors in DVI, and we do some high-end shows involving mostly video using SDI. But when we bring it all together, we fall back to the stable analog standard.

Do I think the rental and staging market will adopt digital distribution and switching on a widespread basis? Yes I do. But I believe it will take development of more universal standards, and more of the bridge products that we now have in analog. And I believe that its final form will come not in a distribution-and-switching model, but as a true mixed-data network, when those products are ready.

There are lots of early experiments out for this model, and well see more at shows like InfoComm this year. The handwriting is on the wall, so to speak, and the traditional arguments against it are falling silent as the multi-billion dollar manufacturers of the computer, networking and video industries chase the idea, along with the most progressive manufacturers in the AV industry.

In the meantime, while Im waiting, Ill help make sure that the manufacturers of high-quality coax cable dont starve.


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