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Video switching—more than a bandwidth saver

Wed, 05/31/2006 - 8:00pm
Staff

Switching video leads to the availability of a virtually infinite number of channels, makes it possible to target advertising to specific households, and can even mean faster channel changing. And, oh yeah, it can save bandwidth and money.

That's according to the panelists of a recent CED Webcast titled, "Gazing Beyond Bandwidth Efficiency—Exploring the Potential of Switched Broadcast." An archive of the event, underwritten by BigBand Networks, is available for free at www.cedmagazine.com.

Adi Kishore, director of media and entertainment at the Yankee Group, laid out the drivers for switched video, and one of the biggest remains more efficient bandwidth utilization—for competitive reasons.

Operators need to broadcast more high-definition content, in large part to counter the HD offerings of satellite TV providers, notably DirecTV. MSOs also need to continue to roll out video-on-demand, a differentiating service DBS rivals cannot match. Telcos, meanwhile, are rolling out switched services, though slowly. Nonetheless, operators will need to answer competitive challenges from the telcos, and can do so by migrating to switching.

Given Wall Street's dictum that no costly upgrades are allowed, Kishore noted, the cost of migrating to switched digital video is well within what financial analysts are willing to tolerate from MSOs.

Biren Sood, vice president product marketing at BigBand Networks, discussed the functional elements of a switching network, and explained they are all in place. "The technology is ready for primetime," he said.

The consumer experience cannot, and will not, be compromised. BigBand set out to have no more than a 200-millisecond delay with channel changes, but it turns out that in many cases, channels change faster in a switching environment, Sood said. There is no effect on either electronic program guides or on DVRs.

Cox Communications conducted a trial with switched digital a year and a half ago. John Hildebrand, vice president of video technology engineering at Cox, explained there are two types of switched broadcasting: multicasting and unicasting.

In unicasting (which is more directly analogous to strictly defined IPTV), every subscriber gets a dedicated program stream, even if multiple viewers are watching the same content at the same time. In multicasting, if there are multiple viewers of the same content at the same time, they share an MPEG stream.

The advantages of multicasting are that it conserves more bandwidth, and costs less. The advantages of unicast include faster channel changing, and the ability to personalize content at the subscriber level, Hildebrand said.

Time Warner Cable is planning on rolling out switched digital video throughout its entire footprint. Paul Brooks, senior network architect at Time Warner Cable, offered specific advice on making the transition.

For the pre-launch, for example, he recommended operators take steps such as preparing a QAM channel programmer lineup, rewiring distribution hubs for target service group sizes as needed, and modifying or enhancing the IP transport system and edge switch-routers if needed.

For the actual launch, Brooks cautioned that a mini-carousel be set up with a dynamic channel map that allows subscribers to view currently streaming programs even if there is no two-way connection to the set-top box.

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