In May, ABC announced that it would be streaming HD TV shows on the Internet. However, the quality of that HD stream will not match that delivered by cable and satellite carriers, according to MultiChannel News on Thursday.

The HD shows that ABC has announced for July will technically be High Definition, that is a resolution of 720 x 1280 at 24 fps. However, the videos will be encoded and compressed at a bit rate substantially below those used by cable and satellite carriers.

Testing was conducted by ABC at bit rates from 850 Kbps to 2 Mbps. "We’re not talking 5 megabits per second or something crazy like that," said Skarpi Hedinsson, the V.P. of technology for the Disney-ABC Television Group.

In contrast, cable operators deliver HDTV at roughly 12 to 19 Mbps using MPEG-2. When using the more efficient compression algorithm of MPEG-4, the bandwidth would still be about 5 Mbps. Currently, ABC is transmitting SD at 1.5 Mbps on the Internet, and the planned HD stream will be at 2 Mbps.

Mr. Hedinsson said that they have been testing a video codec from On2 Technologies that provides better picture quality at lower bit rates. "Three or four months ago, I would have said we wouldn’t have been able to do this," he said.

Highly compressed video signal will exhibit artifacts and pixelation compared to less compressed video. In addition, fast motion tends to be affected by extreme compression.

One consideration ABC found was the limited CPU power of the typical PC to decompress the video. "It’s not going to be bandwidth that is the problem -- it’s going to be the horsepower on the PC end," Hedinsson said. "You do need quite a bit of CPU power to render 24 frames per second. We are going to do our best to educate users on what their experience will be like."

It seems we still have a ways to go before we all get out out of the OK HD and into excellent HD on the Internet. Hardware MPEG handling in our computers would certainly help.