Orlando, Fla. --- Todd Bowen, director of digital systems for Time Warner Cable’s Austin, Texas, division, delivered a key piece of wisdom for those deploying switched digital video: Be sure to get the right channels in the mix.
“The most important decision you’re going to make is which channels to switch,” Bowen said. “If you don’t pick the right channels, it’s going to bite you.”
That’s because if those channels are too popular -- that is, if they’re being watched by someone virtually all of the time -- those will potentially eat up all of the space set aside for the SDV pool, defeating the whole purpose of the technology.
Bowen gave a presentation here at the Society of Cable Telecommunications Engineers’ Cable-Tec Expo 2007 on “lessons learned” from his SDV rollout over the past three years.
The MSO initiated its first beta-test in July 2004 in Austin. The division launched SDV systemwide in spring 2006. It now switches 175 standard-definition channels -- having added 75 during the past year -- and eight HD channels, using BigBand Networks' switched-digital servers.
“Before SDV, we were bandwidth-sparse,” Bowen said. Moving to switched digital, he added, “allowed us to launch digital simulcast.”
Time Warner, an early proponent of the technology, is betting big on SDV to let it keep pace on HDTV. It expects to increase the rollout from eight divisions at the end of 2006 to at least one-half of its 23 divisions this year. SDV will let the MSO offer “virtually unlimited” HD capacity, chief operating officer Landel Hobbs said at a Wall Street conference earlier this month.
At the operational level, the key question for Bowen was: Which to switch? He offered a few insights from Austin's experience. First, he said, anything in a tier -- like a sports tier or a non-English-language tier -- is a good candidate, because obviously, not everyone takes that tier of service. Alternate-time-zone feeds and pay-per-view channels are also likely to be among the least-viewed channels.
“Event pay-per-view, sports pay-per-view, that’s low-hanging fruit,” he added. “Those are 8-10 channels that are wasted when there are no events.”
But there are exceptions to the rules. For example, in Austin, the West Coast feed of a certain kids’ channel (“the channel’s company has a large theme park up the road,” Bowen noted) happens to be extremely popular. “It’s the babysitting channel,” he said. “It’s always on.”
Then there are blockbuster PPV events, like high-profile boxing matches. For one such bout recently, Bowen said, customers who subscribed to the event hadn’t followed Time Warner’s instructions to boot up their SA set-tops to download the SDV client from the BigBand servers, so they couldn’t tune to the PPV channel. The call center was swamped with irate subscribers. “It was a classic example of, ‘Whoops,’” Bowen said.
Time Warner Austin has since moved its main PPV-events channel back into regular digital broadcast, although Bowen added that other PPV channels work very well in a switched environment.
In the final analysis, in selecting the channels to be switched, “There’s no magic chart that goes, ‘yes-no-yes-no,’” he said. “It’s a case-by-case basis.”
Another of Bowen's findings: Some video with lots of motion, like live sporting events, needs more than the 3.75 megabits per second that ordinary SDV streams can comfortably be limited to. “Some channels take up six, seven, eight megabits, so rather than rate-shape those, we take up two channels -- 7.5 megabits -- so we don’t have video issues,” Bowen said.
To offer the 175 SD and eight HD channels in the switched group, Time Warner Austin dedicated eight quadrature-amplitude-modulation channels for SDV. “We put [the QAMs] on the high end of the spectrum, adjacent to VOD,” Bowen said.
He added that he doesn’t let QAM utilization for SDV rise more than 70%. If usage is consistently around that much for a given service group, he said, his team will reconfigure the group or do a node split to minimize the chance that SDV channels will be blocked.
All things considered, Time Warner Austin encountered relatively few customer-service issues with the SDV rollout, according to Bowen, who added, “We thought there would be 20,000-30,000 service calls in Austin, but we didn’t have that at all.”
