Cable-TV slowly steps into stereo 3-D

SAN JOSE, Calif. – Cable-TV operators and their suppliers are stepping slowly into the new era of stereo 3-D television, but it could take years before they can handle full high definition content.

Some cable networks are broadcasting handling a growing schedule of 3-D events while vendors test interim standards using firmware upgrades to support partial high def signals. Set-top boxes, TVs and back-end encoders will need a new generation of video and interface chips to carry stereo-3D broadcasts in full high definition.

"It's coming in steps," said David Grubb, chief technology officer at set-top maker Motorola Home. "First we're making 3-D as compatible as possible with existing video infrastructure," he said.

"We've worked in past year on sorting out agreements on 3-D formats, making the consumer experience easy so when they tune into a 3-D channel the TV automatically switches to right mode and presenting 2-D graphics like closed captions and program guides in 3-D space," he said.

CableLabs, the R&D consortium of the cable-TV industry, expects to finish interoperability testing of its so-called frame-compatible approach in about six months. "We have lab prototypes of encoders and set-tops and we've seen end-to-end demos," said David Broberg, vice president of consumer video technology at CableLabs.

The group released in early September its specification for encoding stereo 3-D signals. It defines metadata to let set-tops identify 3-D content and its format type and pass that information to a 3-D capable TV over an HDMI version 1.4a interface.

That capability will let TV's automatically decode the signal. Today consumers need to manually select the correct 3-D mode on the TV after they tune into a 3-D channel.

Today CableLabs and HDMI 1.4a support three 3-D formats for packing signals for two eyes into one existing video channel—separate top and bottom formats for 720-progressive 60 Hz and 1080p 24 Hz signals and a side-by-side format for 1080-interlaced content. The result is a signal presented to the TV for decoding at something less than a full high definition resolution.

The metadata supplies information to a graphics engine about how to find and decode 2-D graphics data in the formats.