Real multicasting

Although using the digital television signal to transmit multiple standard-definition programs was a hot topic a few years ago, the idea has become somewhat lost in the shuffle amid DTV datacasting plans and the ongoing controversy over the 8-VSB transmission standard. But two DTV stations have launched around-the-clock multicasts as a way to bring new programming networks to their markets.

NBC affiliate WCYB-TV Bristol, Va., last fall announced plans to use its DTV spectrum to broadcast The WB network and Pax TV and has begun using a fiber-optic connection to feed The WB directly to cable operator Charter Communications, which has about 100,000 cable subscribers in the market. Since the launch of WCYB-DT on May 26, The WB (DT-2) is broadcast over the air as part of a DTV multiplex along with wcyb-tv's simulcast NBC programming (DT-1), Pax TV (DT-3), and a fourth channel consisting of locally produced cut-ins for MSNBC (DT-4).

DTV conversion gear that WCYB-TV installed at Charter's headends receives the DTV signals and converts them to analog for normal cable distribution.

The station has also signed deals with Comcast and Adelphia to carry WB and Pax TV programming, according to WCYB-TV Executive Vice President and General Manager Joe Macione. Viewers with DTV receivers can watch the multiplex over the air, of course, although the fourth channel currently fades to black between the local news cut-ins (Macione plans to fill those spaces with a Doppler radar loop).

The feeds are compressed at variable bit rates by a Harris Flexicoder encoding system, all four combined taking up 18 Mb/s of the 19.39-Mb/s DTV channel, says Macione. That extra 1.39 Mb/s will probably be used for broadcasting data, since WCYB-TV owner Lamco Communications has joined the Broadcasters' Digital Cooperative (see story opposite). Although the Cooperative is looking for a daily average of 4 Mb/s, Macione says WCYB-DT can probably make up the difference between the MSNBC cut-ins.

WCYB-TV contributes some local news programming to The WB stream as well as re-run and first-run syndicated programming. It also sells local advertising on the channel, though not yet on Pax TV.

"What we're waiting to do is get some Nielsen numbers and also get on some cable systems," says Macione.

WCYB-TV doesn't show any high-definition NBC programming since the network hasn't provided it with an HDTV satellite receiver yet, says Macione. NBC is currently showing only The Tonight Show With Jay Leno in HDTV, and Macione expects that, by the time NBC has an HDTV presence in the Tri-Cities market (DMA 92), compression will be good enough to allow WCBY-TV to broadcast one HDTV stream and three SDTV streams. If not, he'll drop the fourth channel with the MSNBC cut-ins to make space.

"We've been working with [NBC] on this thing," says Macione.

WCYB-TV won't be the only Lamco station to pursue multicasting, says Lamco President and CEO Marshall Noecker. He plans to launch a UPN feed at ABC affiliate wcti Greenville-New Bern, N.C., when it goes digital this year and is also considering multicasting with KTXS-TV Abilene-Sweetwater, Texas, a market where Lamco just purchased a low-power Telemundo station. Noecker doesn't expect that station to launch DTV until next spring. "I wouldn't be surprised if we put Telemundo on our digital in that market," he says.

Another station group that's a big believer in multicasting is Paxson Communications, which just launched a six-stream multicast with WCPX-DT Chicago. The station began broadcasting DTV officially from Sears Tower on June 8, showing the Pax Central time zone feed on DT-1, the Pax Eastern time zone feed on DT-2 and the Pax Pacific time zone feed on DT-3, and religious networks Worship Network on DT-4, Praise Television Network on DT-5 and The Total Living Network on DT-6.

Wcpx-dt's multiplex is compressed by DiviCom statistical multiplexing gear with an average bit rate of 3 Mb/s for each feed, according to Al Domescik, Paxson director of engineering for the Midwest region. "We do our main feed, the main Chicago rebroadcast, with a little more overhead for it than the other stations," he says. "Depending on what's going on, you may get one [stream] jump up as high as 6.5 Mb/s, such as at times when you get poor-quality video.The stat mux does a pretty good job of controlling all that, and we really haven't noticed too many problems."

WCPX-DT is currently only inserting local commercials on the main Pax feed, simply passing the other five streams through as received via satellite. The station generates PSIP (Program and System Information Protocol) data for all six streams. Although the station is broadcasting DTV from ch. 43, the PSIP identifies the programming as ch. 38-1, 38-2, etc., referring to its analog counterpart on ch.38.

WCPX-DT doesn't currently have any deals in place with AT & T or any other cable operator in the Chicago market. But Paxson Chairman Bud Paxson, a long-time champion of analog must-carry, has presented wcpx-dt's multiplex to the NAB and FCC as a way to obtain carriage for Pax's primary DTV channel. Paxson has requested that Chicago cable operators replace wcpx-tv's analog signal with wcpx-dt's primary digital signal (38-1), converting it to analog so that all basic subscribers who currently receive Pax's Central time zone feed will continue to receive it on the same channel.

He also suggests that cable operators carry the remaining five streams of the DTV multiplex on the digital portion of the cable system as free programming services. The PSIP data sent with the multicast streams would allow the digital set-tops (assuming they could handle PSIP) to take the five additional DTV feeds and align them with the WCPX-DT primary channel.

"It is the company's goal," he said in a statement, "to achieve must-carry under the current 1992 must-carry law using the processes available to us and, if needed, to seek compromises to effectuate a digital must-carry plan, which I feel is an absolute requirement for the successful transition on a nationwide basis from analog television to digital television."