NBC expands 5.1 coverage
ATHENS, GREECE
Athens saw the most extensive capture and broadcast of 5.1 surround sound audio at an Olympics to date.
Although this wasn't the first Olympics with 5.1, the broadcast was "proof of concept" preparation for the more extensive HD coverage planned for the Torino Winter Olympics in 2006.
"We've used Dolby ProLogic II before, but never with the care and the amount of energy we used this time," said Bob Dixon, project manager, sound design for NBC Olympics.
NBC really wants to please the home theater audience by the time the next Olympics rolls around, and Dixon said the broadcaster used some expensive equipment and a good amount of setup preparation to capture the sounds these audiophiles expect with their HDTV.
In Athens, the breadth of the expanded audio capture was limited to three venues where NBC decided to go beyond host broadcaster AOB's stereo audio--athletics, gymnastics and diving. AOB did cover the opening and closing ceremonies in 5.1, however, and NBC took this feed.
FEELING THE SPACE
"The whole job of the surround is to capture the place where the event was going on, so people at home can experience what the space feels like for the athletes or the spectators," Dixon said.
To that end, NBC used some very specialized microphones from UK-based SoundField.
"They've got one microphone with a capsule design that goes through a series of different control boxes... you can end up with not only a 5.1 coverage, but you can steer the microphone electronically so that it looks like it's pointing straight down, or straight ahead or straight up and you can set your 5.1 to be at any plane you wish."
"It's a really good sounding microphone," he said. "It's like using one of the best studio condensers but in an array that lets you capture 5.1, and the remote controls are very nice."
Using these mics required a bit of reconnaissance to find possible locations that would capture the right feel and yet still be acceptable to AOB. What kind of audio "feel" was NBC seeking?
"Diving, for example, is a big hall with a lot of reflections--it sounds like any place you've been where there's an indoor pool except way bigger," Dixon said. "You have the sounds of the crowd within this reflective space, you have the sounds of the water, not just the diving splash but also the little ripples and things like that. Then, before a dive the whole place is deathly quiet, and after the dive everyone bursts into applause."
Capturing that is very different from capturing the ambience of the much larger athletics stadium, or the multiple-events-at-once nature of a gymnastics hall, Dixon said.
NBC took the mic outputs and put them through a Dolby ProLogic II encoder, because the network was a two-channel medium. Most consoles do not accept 5.1 inputs yet, and transmission paths all the way to the consumer are still two-channel. Events broadcast in 5.1 were automatically decoded by consumers' ProLogic II decoders.
Dixon was happy with the Athens "proof of concept" for 5.1, calling it "something to build on."
EXPANDED STUDIOS
At a more basic level than 5.1, the addition of so many NBC-owned cable channels in NBC's facility at the International Broadcast Center (IBC) and the expanded coverage of smaller events prompted the network's planners to re-evaluate the way some things were done.
NBC added another studio to the three used at its 2000 Sydney effort to handle all the cable traffic. For the first time Calrec Zeta consoles were used for two of the smaller studios. "They are smaller consoles--and we pushed them right to their maximum," said Dixon.
Calrec's larger Alpha consoles also made an Olympic appearance for NBC. "They are really made to do television... it's a matter of how logically they are laid out for the operator and the kind of metering that is available so an operator can more quickly tell what's happening; like where things are going and where things are coming from," Dixon said.
This was the first time digital consoles of any kind were used in an NBC Olympics facility, according to Dixon. "It had a great impact on us," he said. "The re-engineering was fun, but it was lots and lots of new details to consider."
Because NBC had several operators who had never worked on the Calrec digital consoles--and some who had never worked on any digital console--a lot of communication and time for training was built into the schedule, both in New York and in Athens immediately before the Games.
REFINEMENTS
NBC's expanded coverage of all the events meant that a lot more commentator positions were needed, and the network took the opportunity to refine some of the equipment used here.
The commentary design at several venues--beach volleyball, athletics (track and field), boxing, diving, gymnastics, swimming and tennis--was changed to better handle long cable runs, some of which were several thousand feet long.
"You can't just run a mic level signal down all that cable," Dixon said. "In the past we've had to resort to something called mic-to-line amps, which are pre-amplifiers that boost the microphone at the commentator positions."
BACKUP POWER
Although this solution was adequate and not terribly expensive or difficult, setting up the control on how loud the mics were was done at the commentator booth. If done incorrectly, the announce mic might have produced too hot of a signal, and this required a lot of back-and-forth between the truck and the booth A-2 until it was correct.
Beyond this level of complexity, the need to provide backup power to the mic-to-line amps and all the cable and extra gear needed became somewhat unwieldy.
According to Dixon, NBC engineers thought that the situation really didn't demand bringing the signal up to full-line level--a little boost was all that was needed, and NBC engineers, Matt Adams and Chris Jorgensen, found a small U.K. company called Fel Communications to help solve the problem.
Fel's microphone-line boosters are phantom-powered, so when power is on in the console the device increases gain by 30 dB, which was enough for this application.
"So now at the console those beautiful, expensive mic preamps that we bought can still be used... you're not going to the line level input, you're still going to a mic level input so you can make up the rest of the gain you need right at the console," Dixon said. "The guy in the truck has full control again, and if a wire goes out and you lose phantom power you only lose that mic."
Audio also played a part in the great expansion of coverage of what NBC called "pure world" feeds--events where commentary was put in over host broadcaster pictures and host sound.
Although it sounds simple, it really wasn't. For these events the commentators were at the venue, but the producer controlled the audio at the IBC.
Historically in these situations NBC has had challenges related to audio distortion, and the existing design only had a single line back to the two announcers. The latter could be problematic when one of the commentators is an ex-athlete who just isn't used to having audio in his ear when he was on-air. The solution involved hiring Australian-based TieLine, which already had an ISDN codec product that did about 60 percent of what NBC was looking to do.
"We made some phone calls and they agreed to work with us and develop what we wanted," Dixon said.
What was developed--housed in a small portable kit with associated equipment--allowed producers to remotely control the gain and the mix of the announcers at the venues.
"We have a 15 kHz bandwidth coming from the venue to the IBC for their program, and for the return of that channel we send them an IFB channel with data that tells the box which announcer should hear this," Dixon said.
SOUND EFFECTS
A second 15 kHz bandwidth channel from venue to IBC allowed the announcers to keep their mics from being heard over-the-air, so they could talk to a producer privately. On the return of that channel, IBC personnel could send them a mix minus which wouldn't get interrupted. All of this was via a single ISDN line.
NBC also brought a mono feed of the sound effects from the host that went to the announcer's TieLine. Announcers could bring this up as loud as they wanted and it only went to their own ears, so they had something to talk against and got a feel of the action.
At the IBC, the TieLine setup had everything a producer might need, including a mixer and a speaker panel for remote monitoring of the host sound effects.
"The producer adds the sound of his announcers to those speakers--not the on-air mix, just the announcers' mix, but this is a representation of what somebody at home ought to be hearing," said Dixon.
Giving producers so much control over audio was a concern. "What we had to do was make sure the producer was staying on top of the mix," said Dixon. "We gave them a training course with manuals and hands-on work here in the building."
The TieLines also dovetail nicely with NBC's long-range goal of keeping more people at home. "There's no technical reason that the producer could not have been in New York," said Dixon. "There are philosophical and pragmatic issues about the producers and talent being on-site and face-to-face, but not technical issues."
