ET: SDV a big hammer in bandwidth toolbox
As cable operators rush to satiate customers’ appetites for more HD channels, and as they compete against telco and satellite operators’ growing HD channel lineups, switched digital video (SDV) is becoming one of the most used tools in the cable operators’ bandwidth toolbox.
“Switched digital video is the thing the industry is talking the most about,” said Nimrod Ben-Natan – Harmonic’s  VP of product marketing, solutions and strategy – during his “QAM Before the Storm” keynote address, which was prior to the “Seamless Streaming: The Future of Switched Digital Video” session.
SDV has been around since 2004, when the first trial took place in Austin with BigBand Networks  and Time Warner Cable . SDV sends just the programming that consumers in a service group or node are watching, instead of the entire slate of channels. While the technology also holds promise for sharing bandwidth resources between video silos such as video-on-demand (VOD) and SDV, switched digital’s biggest impact this year is reclaiming bandwidth in order to allow MSOs to deploy more HD channels.
Greg Hardy, Scientific Atlanta’s  VP of video development, said that switching HD channels, instead of the long-tail content that was previously typical in SDV deployments, will be big for cable operators throughout the next few years.
“[SDV] is not just recovering bandwidth but delivering HD,” Hardy told the session attendees.
While SDV is a great technology, Hardy said, cable operators need to be very mindful of the size of the service groups where channels are being switched. MSOs can add more QAMs, but Hardy said that the best bang for the buck was doing node splits.
The panel also discussed the time frame of going from an SDV multicast model to SDV unicast. Unicast would allow targeted advertising to be sent directly to a single viewer in a home, but the cost of having a tuner for each TV in a household makes unicast prohibitive in the near term.
Cable operators need to find a logical migration from multicast to smaller microcasts before reaching unicast, but BigBand’s chief cable architect, Doug Jones, said that advertising revenues will spur the migration along.
Arris’  CTO in Europe, Charles Cheevers, said that within two years he expects to see more sharing of bandwidth between SDV and VOD services via edge resource managers (ERMs), followed by those services sharing bandwidth with broadband services over unified ERMs. Cheevers predicted that by 2015, there will be 61 channels mapping in and out of SDV, and that unicast will be deployed in an on-demand mode.
Pragash Pillai, Bresnan’s VP of strategic engineering, said that SDV is “another tool in the tool kit” to manage bandwidth, which also includes MPEG-4 and node splits. SDV also provides a good tool for cable operators to monitor what their customers are watching.
Bresnan is working on offering 50 HD channels this year, but without technologies such as SDV and MPEG-4, Pillai said that Bresnan will run out of bandwidth next year.
More Broadband Direct:
• WSJ: Sprint layoffs coming 
• Broadband Briefs for 1/15/08