The broadcaster panel has become a staple at the HPA Tech Retreat, typically drawing engineers from the Big Four, plus PBS, the National Association of Broadcasters, Sinclair and vendor Roundbox at this week’s event. Each provided a summary of what they were working on. None, as an audience member noted afterward, mentioned 3DTV.
“We don’t have enough bandwidth,” Fox’s Jim DeFilippis said.
That’s the short of it. The long if it involves the DTV transmission standard and how currently available 3DTV sets display stereoscopic images. Today’s 3DTV sets generally use a frame-compatible format by which dual images are displayed side-by-side and viewed through shutter glasses that rapidly block out one and then the other. The slightly different views create an illusion of three dimensionality. If broadcasters transmitted content in frame-compatible 3D, everyone with a non-3DTV would see dual images on the screen. To accommodate everyone, they’d have to squeeze both a 2D and a 3D video feed into their 6 MHz channels. It’s not impossible per se, but at an undesirable loss to image quality because broadcasting effectively is tied into MPEG-2 video compression under the Advanced Television Systems Committee standard.
The other most common way of conveying 3DTV is more bandwidth efficient. This “service-compatible” format supports 3D through the addition of data to the 2D signal. One popular form of service-compatible is called “2D Plus Delta,” says video expert and HPA Tech Retreat Program Maestro, Mark Schubin. “Everyone gets the left-eye view. The right-eye view gets electronically ‘subtracted’ from the left-eye-view to create a difference signal or delta. The delta gets encoded and transmitted.”
European broadcasters use the service-compatible format to deliver HDTV, and supported it for delivery of 3DTV. Broadcasters in the United States are in the meantime dealing with headwinds in the form of the National Broadband Plan, which calls for opening 40 percent of the TV spectrum for wireless broadband.
Nonetheless, said the NAB’s Art Allison, “terrestrial transmission is here to stay,” in the form of HDTV, HD Radio, multicasting and Mobile DTV. Interactivity is on the horizon. Allison said the ATSC standard for non-real-time file transfer services is expected “any day.” The body is also working on advanced codecs, ’Net-connectivity in TVs, content protection and . . . broadcast 3DTV!
Jim DeFilippis of Fox also gave broadcasting a general shout-out. Addressing the federal campaign to relieve broadcasters of spectrum, he proposed a “new metric” for determining spectrum efficiency: “Viewers per hertz.”
“There’s a notion broadcasters are spectrum hogs,” he said. “Broadcasting can provide approximately 1 viewer/Hz. LTE proposes using 10 MHZ for 1,500 viewers, or 150 microviewers.”
The metric proved popular in a ballroom full of engineers.
DeFilippis later said Fox is focusing on launching Mobile DTV this year in 20 TV markets “with a MCV ATSC Mobile DTV signal.” MCV being Mobile Content Venture, the consortium of networks and TV station groups promoting the platform. Fox will launch Mobile with a simulcast of the main channel, and set aside bandwidth for possible new services.
Mark Ruston of Roundbox rounded up Mobile DTV during the panel session. He said that content rights were still being worked out for the platform, but that agreements were being reached. PBS’s Jim Kutzner said three public stations are on the air with mobile signals and another 20 would be up by mid-2011. NBC’s Jim Starzynski said the network had 10 owned-and-operated stations on the air as well as five Telemundos. CBS’s approach to new platforms is measured, or rather, it must be.
“For alternative distribution, if CBS can authenticate the audience, it will participate,” the network’s Robert Seidel said. “We do not give our content away.”
See the original post here: http://tvtechnology.com/article/114048