CBS brings the music in Surround Sound
NEW YORK
The biggest audio show in the business got even bigger in February when CBS broadcast the 45th Grammy Awards live from Madison Square Garden in high-definition television with 5.1 Surround Sound, the first major awards show produced in the advanced audio and video formats.
"If you had an HDTV set in your home theater, you were in for quite a treat," said Eric Duke, president, All Mobile Video, which supplied most of the mobile production trucks used for the show.
The HD/5.1 production was done separately from and simultaneously with the SD/stereo job. Needless to say, it was a complex undertaking, involving All Mobile Video's Resolution and Crossroads mobile units and B trucks and Effanel Music's L7 and OSR trucks.
All Mobile Video also supplied its Celebrity trucks for MTV's pre-show red carpet coverage.
Phil Ramone served as the broadcast's audio supervisor with Michael Abbott handling the audio coordination tasks as well as acting as the database asset manager. "Audio production has always been the core of the Grammy Awards," said Abbott.
FOUR-TRUCK CONNECTION
A big challenge for Abbott in the system design was to keep the audio connectivity in the AES domain to maintain the least amount of time latency between the four audio trucks. After the various sources that were to be distributed among all the trucks were decided, it was then up to the engineers to configure their consoles to accommodate the required feeds. In the truck interconnect alone there were 400-plus audio signal paths.
Resolution was the primary facility for the HD/SD audio/video production. "Having Crossroads as the SD facility allowed us the luxury of splitting the production tasks between the two trucks," Abbott said.
Don Worsham, one of three engineers in the Crossroads truck used 360 Systems DigiCarts for the audio playback of the music tracks of the nominees on the truck's AMS Neve Libra Live II, while Fritz Lang handled the voice-overs, incidental music, and musical bumpers using an Akai DD1000 hard disk player/editor in another location in Crossroads. Dick Maitland provided the audience sweetening in the Crossroads audio booth.
The audio playback and sweetening stems (audio sub-mixes) from Crossroads fed the Sony Oxford R3 in Resolution where broadcast production mixer Ed Greene provided the final SD/stereo feed. Grass Valley HD/SD Profiles located in a Gelco Trailer served as video/audio playback devices via AES and analog to Resolution for integration to the 5.1 and SD/stereo mixes.
Resolution also served as the transmission hub for both the 5.1 and SD/stereo broadcast video/audio feeds, using Resolution's NVision routing switchers.
The 5.1 Surround music mix was done in Effanel Music's L7 expando mobile recording studio with an AMS Neve Capricorn. "The Grammy Awards featured 16 elaborate live performances," said Randy Ezratty, Effanel's owner. "Each act was miked separately and pre-wired, then rolled into place."
5.1 music mixing was engineered by John Harris and Jay Vicari, each taking turns. More than 230 Audio Technica wired and wireless microphones were used for the show in addition to those by Shure, Sennheiser, and Neumann, Ezratty said.
Ezratty, who has done numerous 5.1 projects for DVDs, was the 5.1 sound designer for the Grammy Awards and the 5.1 composite mixer in Effanel's secondary OSR truck. Using a Yamaha DM2000 digital console, Ezratty took the 5.1 music mix from L7, plus show elements and stems from Resolution and Crossroads, and did the composite 5.1 mix for the HD broadcast that was fed to CBS.
"I used a Lexicon 960 for spatial effects on everything but the live music performances, and a T.C. Electronics 6000 six-channel bus limiter," Ezratty said. "With all the channels we had, we had so much headroom that we didn't have to do much to compress the output."
Ezratty supplemented the production audio feeds with Audio Technica 4051 microphones placed in the rear of Madison Square Garden, and mixed them into the surround channels "to taste."
The house sound was provided by ATK/Firehouse, which used a fiber drive system for signal distribution from the front-of-house position (in the audience) to the various speaker clusters in the arena. ATK provided a total of four Yamaha PM1D digital consoles, two at the foldback positions (for monitors) and two at the front of house position. The mic signals were split and distributed in the analog format, with the exception of a digital audio fiber link from the splitters on-stage to Effanel L7.
All production and performance vocal mics were distributed at line level via Aphex 1788 mic preamplifiers and then put through an Audiotek/Whirlwind three-way splitter with ATK-spec Jensen transformers. "This allowed for a low noise floor and transient headroom," Abbott said.
Redundancy was an important factor in the overall signal distribution with emergency back-up feeds provided and cross-patched between all mix positions. "The audio infrastructure is failsafe as we can make it with all mix position having redundant feeds," Abbott said.
ALL IN THE TIMING
A major issue of concern was maintaining lip sync and timing between the stereo and 5.1 mix.
Greg Coppa, director of Engineering and Advanced Technology at CBS Engineering, said that CBS for the first time used Dolby E compression for the transmission mechanism for 5.1 audio, and did preliminary work to understand all the issues related to two Dolby E compression cycles.
"We established a method to quantify and measure lip sync," he said. "The Dolby E encoder and decoder each have a one-frame delay, so if you are not careful with how you account for that, you could wind up with multiple frames of delay and loss of lip sync."
CBS developed a test tape that contains a tone and a flash of video, with timing measurements performed on an oscilloscope.
"The methodology is very simple and very accurate," Coppa said. Because of the nature of the test, it can't be done during the live broadcast, "but we spent many hours doing end-to-end testing and setting everything up. ... We ran the tape over the distribution network before the event for the stations to quantify well in advance and account for [the delay], and we knew it wasn't going to drift."
The composite 5.1 mix from the OSR truck was routed via Resolution to the CBS Dolby E encoders on-site, embedded in the HD signal, and transported via fiber to the CBS Broadcast Center on 57th Street, a little over 20 blocks north of the Garden.
Considering the diverse paths the audio and video took, "We had to ensure that the 5.1 audio mix was in sync with the HD video," Coppa noted. "From a transmission perspective, our philosophy is if we receive a signal in time, we will give it back in time."
In the CBS Broadcast Center, the audio was de-embedded and decoded so that commercials and other elements could be integrated.
The HD broadcast and the SD broadcast needed to be in sync, Coppa said, because the commercial inserts in the HD side came from the SD network.
CBS also used a five-second delay on both the HD and SD feeds to catch anything inappropriate. In the case of the HD delay, additional calculations had to be made to take into account the extra delay caused by the Evertz 777OCS-HD encoder and 777ODS-HD decoder before and after the video passed through the HD delay server.
For the 5.1 feed to the stations, CBS once again used Dolby E encoding to transmit eight channels (5.1 plus the stereo channels-left and right).
Coppa said that the stereo signals accommodated those stations with older MPEG receivers without 5.1 capability.
"We worked with Harris in the development of features in their integrated receiver/decoder [IRD]," Coppa said. "With the new IRD, we can enter a delay value in the MPEG video that matches the Dolby E delay. This way, audio and video come out of the IRD in time."
Rocky Graham, manager of DTV Applications at Dolby Laboratories Inc. said CBS did extensive testing to determine metadata values like dialnorm and dynamic range compression and manually entered them in their ATSC encoders for terrestrial transmission.
Abbott credits Supervising Producer John Cossette for going forth with this level of technical production.
"He provided the platform to produce the Broadcast and has now established the level of quality for future HD/5.1 broadcasts," he said.
CBS didn't wait long before delivers its next set of 5.1 programs, a number of the HD broadcasts of NCAA tournament basketball games.
"It was a big challenge, but we were really ecstatic on how it came about," Abbott said. "If more productions attampt to do this, it will become more cost-effective and an incentive for HD to become mainstream."
