Most automation systems feature a centralized rack with one of each source type feeding several TVs. That means you only need one AppleTV, one or two satellite cable boxes, one centralized Blu-ray server, etc., cutting down on both the amount of equipment at each local video display and the overall cost of the installation. But what happens when 4K Ultra HD content becomes available en masse and 4K Ultra HD sets become affordable enough to put them not in just one but several rooms of your home? Will 4K content transmit as easily as HDTV? In a word, no. But Crestron is looking to make it all a little bit easier for those craving 4K Ultra HD in their homes, in every room and on every display.
In fact, yesterday the company premiered a new range of 4K DigitalMedia switching and video distribution devices at Integrated Systems Europe in Amsterdam. “Up until now, video distribution technology was not available to transmit 4K content throughout a home or business, to multiple rooms, or over long distances,” said Justin Kennington, Technology Manager for DigitalMedia.
The system consists of input/output cards and blades, the DM-RMC-4K-100-C Receiver/Room Controller, and the HD-XSPA 4K receiver. Explaining how this all works might be a challenge for me, not to mention a boring read for you, unless, that is, you are a custom integrator. However, the logic behind Crestron’s 4K initiative is fascinating as the company explores the issues behind distributing 4K Ultra HD throughout your home.
In a white paper at www.crestron.com/4k, the company delineated the issues with distributing 4K. I’ll try to sum it up without the technical-ese. First, there is the problem of mismatched resolutions. While most 4K displays are designed with 3840 x 2160 resolution (exactly twice that of current HDTVs), 4K DCI (Digital Cinema Initiatives, used in commercial theaters) resolution is slightly larger, at 4096 x 2160, meaning it has a slightly different shape, or aspect ratio (1.90:1 as opposed to standard 4K’s 1.78:1). There are also a lot of what Crestron is calling “tweener” resolutions–those resolutions somewhere between HDTV and 4K that also must be accounted for. Overall, it means that displays and sources have to be carefully matched in a 4K distribution system.
Additionally, varying frame rates present challenge for 4K residential system designers. Crestron explains that HDTV at 60 frames per second needs a data rate of 4.46 Gbit/s. But multiply that by four (UHD is, after all, four times the resolution of HDTV), and you’ll need at least 17.9 Gbit/s. HDMI 1.4 supports a maximum data rate of 10.2 Gbit/s. This means that today’s 4K devices are limited to 30 frames per second, or less. Incidentally, Crestron’s DigitalMedia supports the transmission of 4K content at 50 or 60 frames per second with 4:2:0 chroma subsampling–a technology that lowers the transmission of chrominance data, while fully transmitting luminance data–using HDMI 2.0, which has, ta-da!, a data rate of 18 Gbit/s.
It’s no secret that running cable over long distances results in degraded signal, or worse, signal loss. For 4K UHD, it’s even more extreme, with shorter cable runs necessary due to the higher bandwidth needed for signal integrity. Crestron also points out that interoperability between 4K devices is a crapshoot at best, considering that it’s nearly impossible to test such a thing with a technology in its infancy. The white paper states:
“As a result, when these new 4K sources and displays enter the market, compatibility between them is often imperfect. There can even be compatibility issues between products from the same company. This presents yet another new challenge for system designers.”
Crestron has created a 4K Certification program in which manufacturers submit their 4K sources and displays to Crestron to ensure that they are delivering on their promise, and will work within the company’s DigitalMedia system. While many of us are just starting to think about purchasing a 4K Ultra HD set for our living rooms, it’s nice to know someone out there has got our backs when it comes time to really trick out our homes with multiple 4K Ultra HD sets. For some of us, that might mean we need to win the lottery; for others, it’s just a matter of time as the technology becomes streamlined.
Who knows, perhaps we’ll be profiling the world’s first distributed 4K system here soon!