In case you missed it, Home Box Office just plunked a massive milestone into the developing tale that is advanced video compression.
At a breakfast panel during the annual Society of Cable Telecommunications Engineers’ Cable-Tec Expo last month, HBO’s chief technology officer, Bob Zitter, said that the 26 HDTV channels it announced on June 12 will only be compressed for transmission using MPEG-4.
In other words, those channels won’t be sent in two formats — the existing MPEG-2, and the newer MPEG-4.
This matters in a big way, and on at least two levels. First: HBO makes it part of its business to lead with advanced technologies. The premium kingpin’s moves tend to be emulated by other program networks. That means we can expect more and more networks to shift exclusively to MPEG-4 compression for their growing HD lineups.
Second, and more troublesome, is that U.S. cable providers are not geared — at their headends or in their aggregate deployed base of 35 million digital boxes — to handle an MPEG-4 stream. The HD channels cable operators are so gallantly streaming right now are nearly exclusively done in MPEG-2.
AT&T, by contrast, can only do MPEG-4, because HD streams compressed with MPEG-2 are just too hefty for its pipes — especially in homes with more than one HDTV display. Ditto for France Telecom, with its 1 million Internet Protocol-TV customers.
Oops.
On the register of facial surprise, the cable operators on the June 20 panel — Marwan Fawaz, chief technical officer of Charter Communications; John Schanz, executive vice president of national engineering and technical operations at Comcast; and Jim Ludington, senior vice president of program management and divisional support for Time Warner Cable — came in somewhere between “did I hear that correctly?” and “pardon me while I start adding up what this is going to cost me.”
Again: It was not yet eight o’clock in the morning.
The immediate consensus, paraphrased, went like this: We’d like it better, HBO, if you’d simulcast your HD in MPEG-2 and MPEG-4, but we certainly understand your decision-making process. High definition is fat. Satellite transmissions are expensive — north of $125,000 per month, per transponder.
On the whole, and with the time that has passed since the panel, it’s clear that the issue here is more about cost than technology.
TRANSCODE THIS
What happens now? Most operators are planning to deploy boxes with MPEG-2/4 combo chips. That activity starts coincident with the new boxes dictated by the removable security deadline (as in the one that hit July 1), and gains momentum in 2008.
But for that hefty installed base of digital set-tops, operators will need a thing called a “transcoder,” to take that incoming MPEG-4 stream, and convert it into an MPEG-2 stream. Actually, they’ll need lots of them — one per multiplex of three or four HD channels.
Estimates vary — widely — on how much that will cost. Some say it’s in the hundreds of dollars per channel; others say it’s around $2,500 per multiplex.
The good news is, there’s no shortage of competition among the many companies making transcoders. The National Association of Broadcasters’s April show was crawling with them: Envivio, Modulus (since purchased by Motorola), Grass Valley Group, Tandberg, and Scientific Atlanta, among others.
Transcoders work by taking an incoming stream of video, decoding (unsquishing) it, and then re-encoding (resquishing) it into the desired format. In other words, there’s no real way to make an MPEG-4 stream into an MPEG-2 stream, on the fly.
HBO’s HD channels will be encoded (squished) to a rate of 8 Megabits per second, which was also news to the panel: Zitter had said at NAB that he’d make his encoding rate decision by the time of the SCTE Expo, and he made good on that promise.
If nothing else, it’s a good time to be in the video squish business.
Stumped by gibberish? Visit Leslie Ellis atwww.translation-please.com.
