Looking for 4K Ultra HD content you can get over the air? It could be a while.

Ahead of IBC this week, the Ultra HD Forum has released the latest version of its UHD guidelines, known as the Phase A guidelines, to the public. Forum members previously had access to the Phase A document. But for the first time it's now available to any interested party, offering details on what's in and what's out in the early stages of 4K UHD TV development.

Beyond the technical elements of UHD video outlined by the Ultra HD Forum, the Phase A document also describes the use cases that are currently within the scope of the Forum's work. During Phase A, the Forum notes that it is only focusing on content delivered over the Internet (over the top, or OTT) and by multichannel video programming distributors (MVPDs). The Forum plans to expand its focus to include UHD video delivered over the air (OTA) in the future, but OTA broadcasts are not part of Phase A guidelines for development and interoperability work.

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Early development and distribution of UHD content have proceeded very differently from the introduction of high-definition television a decade or more ago. Not only are OTA broadcasts not a priority, but even among service providers, 4K UHD TV services are being delivered almost, if not entirely, over IP.

When the HD era began, cable companies had to stand up whole channels worth of linear HD content and carry out major upgrades to their QAM-based network infrastructure. But with IP, there is a lot more flexibility to perform incremental upgrades and deliver select UHD broadcasts, like coverage from the Rio Olympics. (See AT&T & Dish Mix 4K Into Olympics Coverage and Comcast Shows Off Rio in HDR... in Philly.)

"QAM to cable is kind of like TDM is to telco," noted Andy Smith, chief architect for cable MSOs at Juniper Networks Inc. (NYSE: JNPR) in a recent interview. "Any kind of new service that's introduced (like 4K TV)... won't leverage QAM."

Smith pointed out that the transition to HD TV required a major commitment on behalf of service providers.

"Now for them to introduce 4K as a service, they don't have to do that big lift and shift," said Smith. "They can introduce it as another application riding over [the network]."

The advantages of IP-based delivery may, ironically, reduce the industry's "all in" commitment to the next generation of TV technology, or at least lead to more of a phased delivery of new Ultra HD content. IP systems are certainly reducing the pressure to broadcast UHD content over the air or even over traditional cable networks.

At IBC, the Ultra HD Forum will further discuss its UHD development work. Within the Phase A guidelines just released, the Forum also describes the technical components that are currently defined as part of Ultra HD TV. The definition of UHD TV in its first incarnation includes: resolution up to 2160p, a wider palette of colors known as wide color gamut (WCG), high dynamic range (HDR) technology for greater brightness and picture contrast, 10-bit color offering more bits of color per pixel, next-generation audio with a preference for 5.1 or channel-based Immersive Audio and the inclusion of closed captioning and subtitles.

— Mari Silbey, Senior Editor, Cable/Video, Light Reading