Is Your VOD Interface Nasty?

Cable operators appear increasingly eager to get the Data Over Cable Service Interface Specification (DOCSIS) into the set-top box. The potential benefits include efficiency, flexibility and new revenue. What’s acting as the proverbial nose of the camel in the tent is the DOCSIS Set-top Gateway (DSG), a two-year-old specification from CableLabs designed for the specific task of handling communication between set-top and headend. "It didn’t really get a lot of immediate attention," Ralph Brown, CableLabs vice president of broadband access, says. "But now it’s really gaining in attention as more and more of our (MSO) members begin to take advantage of that approach, and move from their proprietary out-of-band (OOB) communication channel to an open one." (For more on CableLabs, see related story.) Turning up the heat Something has revved up this category, leading to what Brown calls a "big bulge of activity across the board, products being developed, specs being refined." Something is probably a lot of things, such as the evolution of the set-top, the idea of a Sony Passage-type enabler of alternative conditional access (CA), the maturity of the OpenCable application platform (OCAP) specification, the ubiquity of DOCSIS, the drive toward all-digital (or all-IP) and underlying economics. Key drivers include the opportunity "to move away from the lock on CA" and "to enable more two-way services off the set-top," Bruce McLelland, vice president of engineering at Arris, says. "By adopting DSG, you get to reuse the existing infrastructure," John Chapman, Cisco Systems distinguished engineer and key contributor to the specification, says. Specifically, that would include the cable modem termination system (CMTS) and related high-speed data gear. The near-term objective is very practical, Chapman continues. "It’s all economics and network management and getting to the next stage of VOD," he says. "Other things will evolve." How does it operate? Putting a cable modem into a set-top box yields a key enabler of video-on-demand (VOD): a two-way IP connection. "DSG is really an extension to IP multicast," Chapman explains. "We have a different way for endpoints to join a session. We take multicast in, we propagate it down the network, call it a tunnel, and then we have rules for how to associate set-top boxes with tunnels." Ongoing refinements to DSG include ways to "advertise" multicast sessions to endpoints and to increase flexibility and scaling efficiency. "DSG is like static addressing. And second generation DSG is like dynamic addressing," Chapman says. (For more details on DSG, see Chapman’s paper in the Proceedings Manual from SCTE’s Conference on Emerging Technologies; a good primer on DSG also can be found in Ron Hranac’s May 2003 column. See www.broadband-pbimedia.com/archives/ct/0503/0503_broadband.html.) Work continues Acknowledging that the committee working on DSG is "getting a lot of pressure to turn over," Chapman says that it could be as late as mid-May before the baseline, advanced mode DSG specification is ready for the CMTS. That still leaves the MIBs (management information bases), test suite and, moreover, the set-top specification, which could take another four to six months, he says. Don Dulchinos, CableLabs vice president for advanced platform and services, the department that includes the OCAP project, suspects that the specification will be completed more quickly. What is required is that Scientific-Atlanta, Motorola and other stakeholders in the set-top arena nail down DSG in the advanced host. "I don’t think that’s several months of work, but we’ll see," Dulchinos says. Proving that it works to everyone’s satisfaction is another matter. "We’re still working out the details on how to run the testing itself." -Jonathan Tombes While the cable industry has benefited from the popularity of video-on-demand (VOD), the inadequacy of the user interface is a constant concern. N2 Broadband and ICTV are championing one effort to alleviate the problem. The project-which features N2’s OpenStream middleware and ICTV’s HeadendWare centralized interactive software-is rolling out this quarter at the Mayo Clinic in Rochester, MN. The clinic’s requirements for a user interface are highly unique, but the base technology needed to create it can be used for any number of scenarios, according to Jonathan Symonds, ICTV’s vice president of business development. In addition to normal entertainment fare, patients at the clinic must have access to educational materials on their conditions. Patients are likely to use the VCR functionality more often for reviewing materials on their condition than they would when viewing entertainment. The videos also are targeted on a department-by-department basis: Parents of newborns have no need to see videos on recovering from bypass surgery. Linking servers to interface Serving this micro-community requires a sophisticated user interface. N2/ICTV is orchestrating a three-tiered approach. "We basically provide open interfaces to the VOD server as well as the application layer, which is the user interface," says Raj Amin, N2’s vice president of business development. The trick is allowing servers from any manufacturer-Mayo uses Concurrent-to respond to commands from radically different user interfaces. The glue linking those servers to the user interface is N2’s OpenStream. The N2/ICTV user interface is based on the Interactive Services Architecture (ISA) that the industry developed at the behest of Time Warner Cable. The Common Object Request Broker Architecture (CORBA) manages ISA. This language, according to Symonds, is difficult to use. Therefore, the ICTV and N2 platform employs a trio of Web interfaces to allow programmers to create the desired user interface. Mayo surveyed about 200 patients and found that respondents liked the system and would recommend its use. Survey feedback led to some simplification of the remote control. In July, Mayo will start a two-year rollout that eventually will see the system deployed to several thousand in-patient beds, waiting and out-patient areas where people spend a lot of time, such as the kidney dialysis rooms, according to Diane Wottreng, a consultant in the Mayo Clinic’s communications division. -Carl Weinschenk