Cable Plant Can Deliver 3D, Now
Lack of standards and confusion about standards are often cited as obstacles to 3DTV deployment. So perhaps it will help that the person heading up 3DTV testing at CableLabs is also responsible for the SCTE’s 3D project.
David Broberg is vice president of consumer video technology at CableLabs. In addition, he said, "I’m the chairman of the committee in the SCTE that’s looking at these standards." CableLabs has announced expanded support for 3D testing, and the SCTE launched its 3D project nearly a year ago.
In February 2009, the SCTE Engineering Committee assigned the “3D over Cable” project to its Digital Video Subcommittee, part of the SCTE’s American National Standards Institute (ANSI)-accredited standards program.
Broberg said the need to develop 3D standards is actually less urgent for cable providers than it is for content creators and consumer equipment manufacturers. The reason is that cable providers can already deliver 3D using existing plant and set-top boxes.
In October 2009, CableLabs participated in a 3D pavilion at the SCTE’s CableTec Expo in Denver.
"We actually delivered 3D over the Denver Comcast cable plant to the convention center and several TV sets at the same time," said Broberg. "We can deliver today."
In this week’s announcement about its 3D testing, CableLabs said new HDMI 3D specifications add support for the "Top/Bottom" format and enable 3D to be delivered through legacy set-top boxes. (For the original announcement, click here). For more on 3D and HDMI, click here).
Top/bottom representation format is one type of single stream video layer multiplex format in which the left eye view is shown on the left side of the screen and the right eye view is shown on the right side. But there are several other types of single stream representation formats for 3D, including side-by-side panels, checker-board pattern and line interleaved. (For an in-depth look at 3D, click here).
"We’ve done some testing that favors the top/bottom solution," said Broberg. "That’s the preference at this point. Top and bottom preserves the full horizontal resolution. Side by side preserves the full vertical. With stereoscopic it is the horizontal offset between the two images that preserves the depth fidelity."
Some 3D aficionados claim that single stream resolution formats don’t provide the "wow" factor that viewers see at theaters.
"I would contend that is not true," said Broberg. "The demos at Tec Expo were high quality, stunning."
But he said there would be some quality improvements when cable is ready to move to dual stream resolution formats. However, those formats require more bandwidth and new equipment and set-tops.
"The cable industry is looking longer term at dual stream," he said. "The migration to that will take time. Single stream provides an immediate solution."
As for the beginning and ending of the 3D delivery chain, the Society of Motion Picture and Television Executives (SMPTE) is working on standards for the production of 3D content and the Consumer Electronics Association (CEA) is working on standards for TVs and 3D glasses.
-Linda Hardesty
