CABL Forum - the H20

DirecTV's first MPEG-4-ready receiver, the H20, and a new companion satellite dish. The antenna is a bit larger and more complicated than previous models because it tunes in localized ("spot beam") MPEG-4 signals from orbiting satellites spread farther apart than the system's core satellites.

For now, DirecTV is deploying MPEG-4 to deliver high-definition versions of ABC, CBS, FOX and NBC to select local markets, including Philadelphia. While a little slower out of the gate, rival Dish Network has the same agenda, and just this week turned on the same four Philadelphia HD local channels in MPEG-4.

Next year, DirecTV will push out with national MPEG-4 HD channels, promising to offer 150 eventually. That will surely force cable companies to start upgrading their delivery systems to MPEG-4.

Because it will take a while before even all of its current HD customers can be converted to the new boxes, DirecTV continues to deliver national high-def feeds of the same four networks via its original, less-efficient MPEG-2 format. (Customers who don't want to go high-def won't have to swap out equipment.)

Exploiting this dual-carriage situation, I've been able to flip back and forth between the MPEG-4 and MPEG-2 versions of the high-def networks fed by satellite. Making for an even more interesting comparison, the DirecTV H20 box also boasts an exceedingly good tuner for over-the-air broadcasts of the same four digital channels (and a lot more that aren't on the satellite feed).

THE PROOF IS IN THE PUDDING: So what have I learned? Viewing even fast-action, system-taxing events like the Olympic bobsled competitions and Daytona 500 on a high-resolution (720p) Pioneer plasma screen, I could not detect any difference in picture quality between the MPEG-2 and MPEG-4 satellite feeds! So yes, the new compression technology works very well.

When I compared the over-the-air HD versions, the broadcast picture did appear a tad sharper, though. Especially when viewed at close range, the satellite versions suffered from more background image blurring (aka "pixelization") in scenes with lots of movement.

It's long been murmured that satellite (and cable) services do a bit of compression of their high-def signals for efficiency's sake. While maintaining the demanded, 1,080 lines of picture resolution, the systems cut the number of distinguishable pixels making up each line from 1,920 to less than 1,300.

Truthfully, very few high-def TVs sold to date can reveal every last pixel in an optimum, 1080-by-1920 transmission. Mine can't. But this year, a bunch of pricey new displays will be up to potential, with Sony touting its worthiest as "full HD."

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the H20