With the launch of ESPN's new 3D network on June 11, 3DTV took a huge step forward, as Comcast Corp. (Nasdaq: CMCSA, CMCSK) and DirecTV Group Inc. (NYSE: DTV) began offering the service to more than 40 million digital cable and satellite subscribers across the US. Further, such other major TV players as Discovery Communications Inc. (Nasdaq: DISCA, DISCB, DISCK) and DirecTV itself are developing 3D programming as well.

But while 3DTV may be all the rage in some circles, its implementation will not exactly be a piece of cake. Many challenges remain before 3DTV can gain the mass adoption that HDTV now enjoys.

At a Cable Show panel in Los Angeles last month, four tech experts spelled out just some of the major barriers to making 3DTV a popular mass-market product. They stressed that it will take a lot of work to boost the viewing quality and experience of stereoscopic video images beamed to the home.

For instance, the experts outlined cable's initial approach of offering "frame-compatible" 3DTV signals to viewers. Using this approach, cable operators send the separate left-eye and right-eye images to homes either in a side-by-side format or stacked top to bottom. While this method doesn't require major changes in the industry's existing video-delivery infrastructure, the signals don't offer the full-resolution images promised by 3D.

The next phase of development calls for offering full-resolution 3DTV pictures through two separate information channels. To do so, cable providers will either use a frame-compatible signal with an additional channel of information or a single-image signal with a second channel of 3D data. However, the experts noted, both approaches will require expensive new video-delivery equipment and digital set-tops, making them a pricey proposition for most MSOs.

"The endgame is, of course, to deliver full-resolution [3D]," noted David Broberg, VP of consumer video technology for Cable Television Laboratories Inc. (CableLabs) . But he said it will likely take another two years for the industry to develop digital set-top boxes with the required processing power to deliver full 1080i HD resolution in 3D mode.

Kevin Murray, a systems architect with NDS Ltd. , said it may not be technically necessary to offer such other enhancements as the ability to deliver on-screen graphics in 3D and direct TV sets to switch between 2D and 3D modes. But he argued that enhancements such as these would significantly improve the viewing experience. "You don't need to do anything to an HD set-top to get 3D video on a 3D display," he said. "But the experience you get isn't as seamless, isn't as clean."

Furthermore, Murray said, such "trick modes" as fast forwarding could be quite problematic in 3D. For example, he noted, it could be "very disconcerting" to watch a 3D video of somebody throwing a baseball at you in fast-forward mode.

Walt Husak, director of image technologies for Dolby Laboratories Inc. (NYSE: DLB), said it's still not clear how popular 3DTV programming will be. Nor, he said, is it clear whether many programmers will pay the higher production costs to develop 3D content any time soon. "How many hours will people spend viewing 3DTV?" he asked. "Five to six hours per day? Or will it be a couple hours per week? We'll have to wait and see."

Besides these issues, glasses-free 3DTV displays, considered 3D's Holy Grail by most experts, may still be many years away from becoming a reality.

Independent TV technology consultant Mark Schubin described a demo by Japan's NHK showing an "absolutely great" 3D parallax-barrier display, with no need for special glasses. But, even with an ultra-HD camera, he said, "the quality was less than YouTube," because the technology displays images from multiple viewpoints. He said it would take 100 times the information currently transmitted for 3DTV for a parallax-barrier display to produce a high-quality video.

With the cable industry now seeking to draft its own tech standards for 3D delivery, we will be addressing these questions (and more) at our third annual Cable Next-Gen Video Strategies event on June 24. We'll also be tackling such provocative topics as TV Everywhere, cable IPTV, and interactive TV.

So, if you can make it to Atlanta on Thursday, please join us at the Westin Buckhead Hotel. Hope to see you there!

— Alan Breznick, Senior Analyst, Heavy Reading