What’s new with DSL TV?

In our last column, we discussed the growing trend of DSL and satellite TV partnerships. In the U.S., larger telcos seem to have settled on this solution and forgone any TV-over-DSL alternatives in the near term. Outside of these carriers, however, DSL-based TV continues to grow.

In our last column, we discussed the growing trend of DSL and satellite TV partnerships. In the U.S., larger telcos seem to have settled on this solution and forgone any TV-over-DSL alternatives in the near term. Outside of these carriers, however, DSL-based TV continues to grow.

Within in the U.S., a number of independent (mainly rural) telcos have deployed video over ADSL solutions, combining local content, “cable” channels and digital audio programming with high-speed Internet and voice services. The real action, of course, has been outside of the U.S., where providers in Japan, Korea, Italy, and elsewhere have launched commercial video over DSL services.

In some of these locations, providers are able to leverage very high-speed DSL connections to offer their video services, eliminating perhaps the biggest hurdle providers must overcome for DSL TV - bandwidth limitations that obstruct both the reach of the service to customers and the number of channels offered. Remember that a “broadcast quality” MPEG-2 TV channel can eat up 4M bit/sec or more all by itself, while U.S. DSL providers are just now announcing new “faster” DSL services topping out at 3M bit/sec.

Eventually FTTH, or at least fiber to the neighborhood, with faster DSL variants like ADSL2+ or VDSL to the customer, will give U.S. telcos the bandwidth they need. But in the near term, providers need two things to get around these bandwidth limitations: more efficient codecs, and video headend systems that can transcode (and also transrate) MPEG-2 broadcast TV signals on the fly, in real time.

On the codec front, many vendors and providers are beginning to look at MPEG-4/H.264 and Microsoft’s Windows Media codec as solutions that can provide broadcast quality at ADSL-friendly bit rates. Neither of these codecs is completely cooked, but both are being adopted by hardware vendors, and both show great promise for standard definition TV (SDTV).

To take advantage of these codecs, a service provider needs to find a headend that can handle the real-time encoding or transcoding and rate shaping of incoming analog, satellite, MPEG-2 (or other codec) video signals to one of these next-gen codecs. For SDTV, many of the headend systems on the market today can handle this task - though not all yet support both Windows Media and H.264 codecs.

As more television content moves towards HDTV however, the problem is intensified by the sheer raw bandwidth of HDTV content. HD MPEG-2 streams require almost 20M bit/sec. Windows Media and H.264 can both potentially decrease this bandwidth requirement significantly, but the hardware to perform such transcoding is not yet widely available. One vendor recently told us that with today’s chipsets, it requires up to 16 chips to build a card that can transcode a single HDTV channel. This problem will be solved, but it will probably be several years before generally available hardware can make HDTV transcoding a reality.

We recently had a chance to catch up with Optibase, an Israeli headend vendor that’s been having some success in the “telco TV” market. We were intrigued by a new product they’re launching as a companion to their flagship MGW 5100 headend product (deployed in the U.S., Japan, and Italy, among other places). Optibase is expanding their product range down with the new MGW 1100 - designed for small-scale deployments like MDU/MTU, very small operators and even enterprise video streaming.

Perhaps the most interesting application for this new headend is in what Optibase is calling “local head-end.” While the MGW 1000 can handle the encoding/transcoding for only 12 channels (not enough for a full cable-competitive lineup), it can be deployed inexpensively in local COs for insertion of truly local channels into the overall channel lineup. Such a set-up would make it easy for a telco to add local college or K-12 educational and city government channels into a complete channel lineup being fed into the system from a larger regional headend. It could enable a telco to provide a truly differentiated service - TV programming that satellite or large cable MSOs simply don’t offer their customers.

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Copyright © 2004 IDG Communications, Inc.

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