Election's HD Capacity Crunch
Networks tap into new techniques
By Glen Dickson -- Broadcasting & Cable, 12/2/2007 7:00:00 PM
For the big television networks, finding enough transmission capacity is always a challenge during an election year. The swirl of primaries and daily campaign stops, along with multi-day events like the Democratic and Republican national conventions, requires a steady diet of satellite and fiber paths for transmitting both live feeds and taped packages.
In 2008, the networks' move to high-definition coverage of the political conventions is upping the ante, as HD video can use up to four times the bandwidth of a standard-definition feed. Delivering HD pictures requires buying new production and transmission equipment and can create some thorny format conversion issues for pool feeds, as different networks use different HD formats. And, of course, the high-definition feed also needs to be downconverted to support existing standard-definition networks, as well as streaming video for broadband news services.
“Doing it in HD just complicates it exponentially, besides all the money and the manpower to do it,” says Mel Olinsky, director of bureau operations for CBS News.
For example, says Olinsky, a hi-def serial digital signal from an HD camera can't be transmitted over standard copper cable; that means running fiber links on-site to every camera to transmit video and control the camera.
Monitoring pictures onsite is also more difficult. In standard-def, CBS would feed the video into an RF system to distribute it to producers and technical directors; now the video has to be downconverted first. Multichannel audio remains a challenge with HD—CBS News' first live HD broadcast of the State of the Union address earlier this year had an audio encoding problem that placed the primary audio on the rear channels.
The tight timing of major events like the Iowa caucuses and the New Hampshire primary (Jan. 3 for Iowa; Jan. 8 in New Hampshire), and the Democratic and Republican conventions in late summer, adds to the technical hurdles and operational costs of election coverage. With such back-to-back events, networks like CBS and ABC will have to maintain “mirrored” operations with separate on-site production staff and transmission gear.
“Bandwidth is probably going to be the No. 1 issue—both bandwidth and physical equipment—and where we're going to get our hands on this much equipment,” says Chris Myers, director of operations for ABC News Services.
The news service will use a mix of satellite and fiber capacity, and is planning well in advance to meet the needs of its internal clients—the ABC network, and ABC-owned stations and affiliates—as well as external clients like the BBC and Univision. Myers is working with Intelsat, ABC's primary satellite provider, and others to secure leases for extra transponder capacity early in the game.
ABC has been experimenting with sending video over fiber between its bureaus using high-bandwidth Dynamic Transfer Mode (DTM) transmission technology, which allows ABC to treat the bureaus as “one cohesive unit,” says Myers. It plans to ramp up its use of DTM transmission in 2008.
On the satellite side, some ABC affiliates and owned stations have successfully tested high-definition satellite newsgathering using JVC Pro HD cameras and Miranda converter boxes, which produce an ASI feed that can be fed into a standard satellite modulator.
“It's cost-effective,” says Myers. “But you still have a bandwidth issue. You need 20 megahertz of satellite [capacity] to do that. We've also had quite a bit of success in MPEG-2 just compressing it down to 12 Mbps. We're finding that to be just fine for talking heads and typical newsgathering. It's looking all right.”
ABC is also investigating advanced compression systems like MPEG-4, as well as advanced satellite modulation schemes such as DVB-S2 that can deliver more usable bits per transponder. Myers notes that advances in satellite technology are expensive, as they require new receive equipment in multiple locations.
Transmission provider Level 3 Communications is looking to meet broadcasters' hi-def needs by extending the footprint of its Vyvx fiber network to connect directly to its biggest customers where it's feasible, says Derek Smith, senior VP of content markets for Level 3.
“When you have to change from an OC-3 [155 megabits per second] to an OC-12 [622 Mbps], you can do it very seamlessly, and it helps reduce some of the costs that are out there,” says Smith.
For example, Level 3's fiber runs right past the Pepsi Center in Denver, site of the Democratic Convention. So, the company is extending its fiber backbone directly into the building, allowing it provide not only broadcast video but a host of voice and data services.
“That's a big change for us, where we said we're going to make the investment,” says Smith. “Because it's not something we can undo—the parking lot that we dug up to take the fiber all the way in there.”
For its coverage of the 2004 conventions, CBS developed a system of bringing the video and audio paths back to the CBS Broadcast Center and switching the show there, which allowed it to eliminate an on-site production truck (it has a satellite truck for backup) and some on-site routing equipment. Olinsky worried he would have to scrap that model for HD because of its higher bandwidth requirements. But this fall CBS has been successfully testing advanced compression gear, including an MPEG-4 encoder from Fujitsu that Olinsky believes will allow CBS to send high-definition pictures along some of its existing transmission paths.
Using a fiber link between Washington and New York, CBS was able to unplug an SD encoder from an existing multiplex and plug in the Fujitsu encoder at the same data rate of 8 Mbps and deliver good-quality 1080-line-interlace video. It has also successfully tested the Fujitsu system in satellite transmissions.
“The nice thing about it is it's an MPEG-4 encoder, but it uses an MPEG-2 transport stream,” says Olinsky. “So, I'm now leaning back toward doing the next convention in HD using the same model of bringing everything back to New York and decoding it in New York. We're still looking at the other vendors to see what they can come up with, but it's looking very promising.”
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