Inching to datacast specs

ATSC's S13 standard specifies structures, protocols for inserting data into TV streams

The Advanced Television Systems Committee is close to formalizing a standard for broadcasting data applications within the digital television spectrum.

The proposed S13 Data Broadcasting standard would establish specific data structures and protocols for inserting data into 19.39-Mb/s digital television streams, allowing different DTV stations to broadcast data applications in a consistent way and giving receiver manufacturers a benchmark for building datacasting-friendly TVs and PCs.

Ratifying such a standard is essential for data-enabled DTV receivers to hit the market in volume and, consequently, for broadcasters' datacasting dreams to come to fruition.

Although Menlo Park, Calif.-based Geocast plans to broadcast its multimedia content to proprietary DTV data receivers, other datacasting proponents such as iBlast and the Broadcasters' Digital Cooperative are betting on the mass proliferation of standardized DTV receivers, particularly PCs.

The S13 standard, named after the ATSC technology specialist group that drafted it, has been "out for ballot" to the ATSC's Technology Group on Distribution (T3) for two months. Those ballots from T3's roughly 200 members were tallied last week, and a majority were in favor of the proposed standard.

Now the standard will be put out to a vote by the entire ATSC membership. The final letter ballot on an ATSC standard takes six weeks, and two-thirds of the members voting will have to approve of S13 for it to be adopted.

"This is a very important issue, and it's attracted a great deal of interest," says ATSC Executive Director Mark Richer. "The broadcast side, the TV set manufacturers and the computer industry are all eager to get it done.

"[S13] is a very comprehensive standard. It's agnostic to the type of content, but it defines multiple different protocols to allow broadcasters to transmit data in a way that would be more universal and let people develop generic receivers to capture that data."

Content would be covered by another proposed standard, DASE (DTV Application Software Environment), which is yet to be voted on.

The DASE standard governs a layer of software that would enable datacasting applications to run on different types and brands of DTV receivers. For example, it would allow a programmer to create multimedia content once and be assured that it would work on both a Samsung HDTV set and a Compaq PC.

The specialist group on data broadcasting, which met outside Boston last week, will now spend the next few weeks responding to comments on the S13 standard. The comments related to "mostly very detailed technical issues," says Richer.

"We'll look at the comments and address the comments," he says. "Either way, we'll now move forward, and it will be balloted to the complete ATSC membership."

Richer adds that the ATSC task force formed in March to tackle DTV transmission issues is making "a lot of progress." The full task force, which includes groups focusing on VSB performance, broadcasters' DTV requirements and field-testing methodology, will meet June 8 in Arlington, Va.