ABC Plans Compressed HD Downloads: The "high-definition" TV shows ABC.com plans to debut in early July will be extremely compressed versions that -- while saving on bandwidth -- will not be comparable to the HDTV services cable or satellite providers currently offer.
The HD video on the broadcaster's Web site would technically meet a basic definition of HDTV: It will be delivered at a screen size of 1280 by 720 pixels at 24 frames per second.
But the video will be encoded at bit rates far below the MPEG-based HD streams from cable operators, and compression has a bearing on the visual quality of the picture.
Skarpi Hedinsson, vice president of technology for the Disney-ABC Television Group, said his group has tested HD-resolution video compressed at between 850 kilobits per second and 2 megabits per second. "We're not talking 5 megabits per second or something crazy like that," he added.
Cable providers typically encode HD streams at roughly 12-19 mbps using the MPEG-2 format, but even the more-efficient MPEG-4 standard requires at least 5 mbps for HD video displayed on large-screen TV sets.
ABC.com uses a video codec from On2 Technologies, a small New York video-software developer, and Hedinsson said the latest versions of its codecs provide better quality at lower bit rates. "We have invested in a facility that has very sophisticated encoding," he added. "Three or four months ago, I would have said we wouldn't have been able to do this."
The site already provides standard-definition video encoded at 1.5 mbps, Hedinsson said, so the step up to 2 mbps seemed feasible: "For us, the delta between HD and SD is not really that great."
(Read Original Article - Via HDTV Magazine - Industry News (Beta).)