Reactions Mixed on Astra’s Split 3D Transmission Standard

BERLIN -- SES Astra has not explained the reasoning behind its split standard for 3D TV (CED Sept 3 p2). It said, for the time being at least, satellite 3D transmissions will use either the side-by-side (for 1080i resolution) or top-bottom (for 720p resolution) formats, which make them compatible with existing HD set-tops. Free-to-air 3D services will be signaled using mechanisms defined under an updated DVB standard, which will allow automatic switching of the display from 2D to 3D and from 3D to 2D, Astra said.

Astra did not respond right away to our requests for a clear and simple written explanation of the reasoning for the split standard. But industry insiders we polled said they think the double standard was necessary because an interlaced 1080i signal can easily be vertically sliced precisely down the middle into two side-by-side halves. Continual changes in the picture line structure that are inherent in interlacing would upset accurate horizontal slicing into two equal halves, one on top of the other, the insiders said.

Sky in the U.K. welcomes the decision, said Chris Johns, Sky’s chief engineer for broadcast strategy. “I have been working with industry groups such as Astra in identifying the best resultant frame compatible formats,” Johns told us in an e-mail. “Astra’s announcement ratifies Sky’s position in the optimal format to deliver 3D to the consumer with minimal change to infrastructures."

Sky’s HD and 3D services are all 1080i/50, with side-by-side 3D transmission, Johns said. “The platform is capable of both 1080i and 720p,” Johns said. “But Sky identified the direction of flat panels to be 1080, and the resultant horizontal resolution (1920) was always superior to the lower 720 format (1280). The result is better images on the bigger screens with most content."

Sisvel and 3DSwitch, the Italian companies that have been jointly promoting a novel and newly patented method of dividing a broadcast picture frame into two halves by tiling, have less reason to be happy, a 3DSwitch executive told us. Tiling, which 3DSwitch is demonstrating at IFA, involves putting one eye image in the middle of the picture frame and slicing the other eye image into tiles that surround the center. “The major manufacturers like Samsung have been leading and the broadcasters like Astra are following,” said Dario Pennisi, 3DSwitch chief technology officer. “We have not been talking to individual broadcasters like Astra, we have been talking to bodies like DVB in Europe, CableLabs in the U.S. and with CEA, of course. “We fear this rush into 3D is going to create issues for consumers who will have to manually switch their sets to suit broadcast standards. Closed systems like Sky can control what happens by updating their boxes over the air, to support automatic switching. But the free-to-air broadcasters don’t have that control. It’s crazy to ask consumers to go through three levels of menus to change settings."

Sisvel/3DSwitch doubts the Astra decision will be the end of the matter, though, Pennisi said. “The MPEG-4/H.264 standard supports the picture-cropping flag that we use to control 3D tiling,” he said. All H.264 receivers, terrestrial or satellite, and IPTV boxes, too, must support the flag. They use it to control the size of the pictures they display. Our 3D tiling feature can be added by a firmware upgrade. So 2D sets will display 2D, and 3D sets generate depth. Tiling can also be used to control the depth display of captions, so that different people at different depths in a scene have their own captions. This is just the beginning.”