3D's Cable Future is Still a Bit Fuzzy

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Cable's drive to 3D is slowly gaining momentum and should make the industry a major player -- if the service gains popularity in the home and more televisions capable of the advanced format are manufactured.It is clear that people love 3D in movie theaters, as evidenced by the success of Up, Avatar and, more recently, Piranha 3D. The content has taken the next step and entered the home via DVD, Blu-ray players and, to some extent, through cable and other service providers.But 3D success for the cable industry is anything but a foregone conclusion. The challenges are in the marketplace -- popularity in the theater is not synonymous with popularity in the den -- and in the creation of much greater efficiencies on the technical front. Indeed, it appears that the industry's initiatives are at a crossroads.A key realization is that cable's 3D signals, at least at the outset, will not match Blu-ray or even DVD's quality because they will be limited to the number of bits used by a 2D high definition TV signal. While the teeth of the piranhas may not be quite as sharp on a cable channel as on a Blu-ray display, signals with a bit less data is the only path forward, at least for now.

In addition to coming to grips with bandwidth limitations and a current dearth of programming, the industry is only at the beginning of the standardization process. Dr. Stefan Winkler, the chief scientist at Cheetah Technologies (www.cheetahtech.com), said that cable operators' initiatives still are in the experimental stages. He explained that ops are experimenting with various approaches and determining how well they coexist or conflict with other elements of their operations. "A lot of issues still have to be solved," he said. "Operators have to test in their environments and see if it interoperates with the equipment they have."

No Slam Dunk

For 3D to become a major cable play, certain things likely must happen. At least one of these elements -- inclusion of 3D circuitry in more televisions -- is not directly under the control of the cable industry (though operators' success or failure in 3D will impact set makers' plans). More directly within cable's control is settling on standards and creation of an end-to-end ecosystem. The ecosystem includes gear for processing and distributing the video, inserting ads, branding content, multiplexing and de-multiplexing signals with 2D video and other elements, wrote Ramin Farassat, the VP of product marketing and business development for RGB Networks (www.rgbnetworks.com) in response to emailed questions.A milestone on the road to proactively addressing these issues came with the release of specifications. On September 1, CableLabs (www.cablelabs.com) released the Content Encoding Profiles 3.0 Specification. 3D uses two images -- stereoscopy -- to create the illusion of depth. The CableLabs spec tells content creators, operators and the rest of the ecosystem how to do this when the images are at the left and right or at the top and bottom of the frame.

According to Farassat, the outstanding questions addressed by the CableLabs' specification focus on, among other things, bit rates, video/audio formats metadata specs, frame rates and closed captioning. "The CableLabs specifications address these and provide the guidelines for content providers to create the content appropriately, and for cable systems to adequately deliver this content," he wrote.It has repeatedly been proven that the industry works best when it draws from the same technical playbook, and the encoding specs are designed to use this approach to drive efficiency, David Broberg, CableLab's VP of consumer video technology, said. "Part of the problem with delivery today with a lack of a standard is that there is a wide range of implementations in use," he explained. "In order to accommodate them, more bandwidth is thrown at the problem instead of addressing the issues on the formatting side. This clarifies the ambiguities on formatting to get bandwidth to where it should be."This is, quite naturally, an extremely complex topic. One example is pixel grid alignment. Broberg said that the requirement that a 3D channel fit snuggly into a 6 MHz channel using 2D HDTV as a base reference point means that about half of the data must be removed. "When you reduce the number of pixels to half, the result is that you need to know how to reconstruct the picture so that the pixels don't shift. It's a detail, but it is important," Broberg said.There are two interrelated issues at play here. Broberg is referring to how best to paste the signal back together after the data is removed, which is a purely technical exercise. The other question is more subjective: What is the cost of taking out that data in terms of subscribers' perception? The worst possible outcome of the industry's overall 3D initiative is to expend the effort and investment -- and disappoint subscribers.Though preserving adequate quality is a key concern, it may only be a temporary one. Approaches to transmitting full 3D signals within the parameters of today's cable network are being discussed, said Roland Vlaicu, the director of technical marketing in the Broadcast Group at Dolby Laboratories (www.dolby.com).Vlaicu said that the specification's approach of facilitating the transmission of 3D content in which the duplicate image is over and under or left and right in the bandwidth currently carrying 2D HD images has two significant advantages. "It allows 3D to roll out quickly and it allows cable programmers and operators to continue to use equipment in the headend and in set-top boxes without modification," he said.

Clean Engineering Still Key

One of the biggest of cable's forays into 3D to date was Comcast Media Center's (www.comcastmediacenter.com) transmission in April of the 2010 Masters Golf Tournament from Augusta, GA. Richard Buchanan, CMC's VP and GM of content services said that one of the takeaways from the project was that the engineers learned how to tell if something is wrong with the 3D transmission by looking at it on 2D monitors.Buchanan said that many things were learned about 3D during the tournament, which broadcast the content in linear and VOD formats. Among the most important is that even small problems in the transmissions can lead to "horrendous" images. "Good clean engineering is even more important [than in 2D formats] in terms of maintaining signals all the way through," Buchanan said.While industry executives seem to be excited by 3D, as witnessed by the great amount of hardware and software on display at the Cable Show 2010 this spring in Los Angeles, the reality of whether 3D becomes a major services or a nice add-on still has not been determined.The bottom line is that the industry is doing what it must in the most efficient way possible. While those issues are decided in the marketplace, the industry is working hard to confront and alleviate technical hurdles. Peter Putnam, the Senior Contributing Editor to Pro AV and Editor of HDTVexpert.com, said that the industry is, in essence, taking care of business. "They are being as proactive as they have to be," he said. "They don't have a lot [of programming] to show people. They have identified the boxes it works with it and have a spec for encoding. They are building the infrastructure. As more channels are ready they will be too."Carl Weinschenk is the features editor at BGR. He can be reached at [email protected].