The Long Haul: Moving HDMI Over Network Wires
HDBaseT was created to overcomes distance limitations of moving HDMI around homes. But you may already be using HDBaseT in commercial installs without knowing it.
If we accept the fact that hdmi, the consumer-electronics-driven, awkwardly performing, distance-limited format for transporting high-definition video with audio, is a fact of life in pro AV (and it is for the foreseeable future), the question then becomes, how do we do what AV integrators do best? Namely, switch and route HDMI signals to devices such as digital signs and overhead projectors that are necessarily installed far from their sources? One way is by using HDBaseT technology.
You don't know HDBaseT? No matter, you may be using it anyway. If you've ever deployed some of the latest Crestron's DigitalMedia (DM) 8G gear, or AMX's UTPro family of HDMI matrix switchers, or even HDMI extension equipment from companies such as Atlona or Gefen, then chances are you've used HDBaseT. If an equipment manufacturer tells you that it can transmit HDMI up to 330 feet over a single Cat-5 cable, it's probably talking about HDBaseT.
"We hesitated to go out and promote it at first because there's a lot more we layer on top of HDBaseT," says Dan Jackson, Crestron's lead engineer for integrating the technology into its DM line. "We didn't want to get lumped in with everyone who threw a chip down."
HDBaseT is based on chip-technology developed by Valens Semiconductor. With Valens chips at either end of a Cat-5e or Cat-6 cable, you can transmit uncompressed HDMI video and audio, 100Base-T Ethernet, control signals, and power roughly 330 feet at speeds up to 10.2 Gbps. The chips take HDMI 1.4 with HDCP, Ethernet, and other signals, process them as HDBaseT, send them over the wire, then turn them back into HDMI and Ethernet at the receiving end.
An industry body—the HDBaseT Alliancewas formed to promote the technology, led primarily by major HDTV manufacturers that want a way to overcome the distance limitations of standard HDMI cabling in the home. The eventual end game is to have devices such as Blu-ray players, media servers, and HDTVs with built-in Valens chips speaking HDBaseT over long distances. So far, no commercially available HDBaseT endpoint exists. But that hasn't stopped makers of switchers and routers from adopting the technology and doing for AV integrators and their clients what today's displays and sources can't—build solutions that put HDBaseT into real-world applications.
"We see the technology being adopted much more in the commercial space than in homes," says Chris Bundy, marketing director for Atlona, which recently added a pair of HDBaseT matrix switchers to its line. "We're working on a digital signage project in Las Vegas using HDBaseT. If you think about digital signage, people these days don't just want to see content, they want to interact with it. And the fact that you can take that much data and control, as well as HD video and audio, down a single Cat-5 cable is perfect for things like kiosks and touchscreens."
In interviews with manufacturers that have adopted HDBaseT, they all tell a very similar story: They were in serious development of their own technology for transmitting HDMI long distances, but they shelved those efforts after they spent time testing the Valens chipset. AMX had been working on a solution using technology that it obtained when it acquired media distribution manufacturer Endeleo in 2006, according to Robert Noble, AMS's chief technology officer. Then Valens came knocking. "They've really hit a sweet spot," Noble says. "As you move into buildings that already have a network cabling infrastructure, it [HDBaseT] makes a lot of sense."
Early versions of Crestron's DigitalMedia used a technology that the company developed itself to transmit HDMI over twisted-pair wires using Crestron's homegrown DigialMedia cabling. The company says it still sells a lot of the original DM equipment. (The newer DM 8G products are based on HDBaseT.) The first DM cable was basically three cables in one and could only go about 150 feet. Crestron hooked up with Valens in fall 2009.
"They make the wire itself better," says Crestron's Jackson. "There's a lot of stuff with HDMI, like EDID and HDCP, that they don't touch. As a manufacturer we still need to manage those pieces, because 75 percent of the problems with HDMI are due to incompatibilities between equipment. But Valens has solved the problem of getting a signal a long distance when there's no HDMI cable that can do that in a good way."