How TV's Leading Mixers Play the 5.1 Sound Field

[Gregg Lengling]

By Dan Daley
Contributing Writer
Film & Video Magazine
 
Mixer Michael Giacalone at Comcast's SSL C100 board.
Videographers should be happy we don't have eyes in the backs of our heads. The audio world is having a hard enough time figuring out where to put what as it enters a broadcast world where viewers hear everything in a 360-degree sound field.  While multichannel music mixing has begun to suss itself out, broadcast  sports mixers are finding that they still have an uncharted landscape before them, retaining many of the conventions of the stereo arena but still leaving them a lot of choices to make. What sports doesn't offer them is a lot of time to make those decisions.

"There's a lot of things we could try if we only had the time," laments Jonathan Freed as he drives to the Detroit airport in the wake of the Pistons' championship upset over the L.A. Lakers last June, at which he mixed audio effects. For instance, panning the main point source in a 5.1 sound field as it moves across a court, field or gridiron might make for exciting viewing.

But getting audio switching to follow the video during fast-paced cuts from camera to camera would require its own preseason of training. "It can be done," Freed says. "It involves creating tallies based on which cameras are being switched to and from at any given moment. Theoretically, it can work. But who has the time to figure it out?"

 


Even without that kind of complexity, mixing audio for live sporting events is complicated. As mixers push the envelope of discrete 5.1, they still have to make sure that broadcasts work for viewers who are listening through matrixed surround codecs like Dolby Pro Logic and SRS's Circle Sound, or standard stereo and even mono broadcasts.

 
 
A good mix, most sports audio mixers agree, establishes a pleasant-sounding and cerebrally logical soundfield. In  5.1 for HDTV, this is preset by the mixer, who places each element into the 360-degree field afforded by the technology. Some conventions everyone adheres to: the announce talent always goes down the center channel; crowd noise and other ambient audio goes into a combination of left and right channels and the rear channels. Effects sounds get the most play. Fox's famous "whooshes" can circle the room as replays are wiped on screen and box-score bugs appear during lulls in the action.

"In discrete 5.1, the rear channels have to be anchored by something," says Phil Adler, a freelance mixer who did many of CBS's NFL games last season in 5.1. "I put crowd noises and music tracks in the rears and bleed them into the left and right channels, along with effects. The same goes for the bumper music to commercial. It's a nice transition effect. But during the games, anything too specific from the rears is distracting."

Some of the most advanced 5.1 sports mixing is being done by Comcast Sports in Philadelphia, where the Wachovia Stadium broadcast center was completely revamped for HDTV. The center, home to the Flyers and 76ers, is about a block and a half from the Phillies baseball stadium, where all the games this year are in 5.1 and HD. Signal runs to the center over 6000 feet of fiber cable in two pairs, one for audio and one for control data, interfacing with a new SSL C100 console with a stage box for the fiber inputs and 5.1 faders that consolidate control of the multiple discrete channels and, via software algorithms, do automated downmixes of the 5.1 mix for the stereo feed. Mixer Michael Giacalone says that kind of automation is absolutely necessary. "I've got 107 channels of DSP alone coming in during Phillies games now," he says.

Giacalone's sound field for hockey is fairly straightforward: the audio image is centered on camera 1, which accounts for the majority of air time. Of the 10 Crown PCC-160 boundary-layer microphones set up around the rink, he blends the ones closest to the camera position — known as the "nearboards" — subtly into rear channels. The rest of the audio is sent left and right. One thing that 5.1 has changed is the microphones used for crowd noise, he says. "We use a lot more of them now, and we're using Shure VP88 stereo microphones. I hang them pretty far up around the first balcony level to avoid getting any individual voices, and I use them in a mid-side configuration, which I find opens the sound up a lot more than an X-Y set-up."

Phillies baseball games are a different story. Giacalone uses the center-field camera as a primary reference point, placing sound from first base into the left channel and from third base into the right — the reverse of the stadium crowd perspective but the same as the home viewers' POV. While most sports move too quickly to allow live panning, Giacalone creates the sensation of that on, for instance, a pick-off move by the pitcher to first base by increasing the gain on the left channel. Natural crowd reaction to the play jumps in the rear channels following the play, giving the soundfield a sense of movement.

   
Freelance mixer
Phil Adler.
 
Comcast's sound effects are in stereo, but other audio prerecord elements, such as music, are now delivered in 5.1, played back from 360 Systems' Digicart decks. Replays are also now all in 5.1, thanks to the installation this year of three EVS multichannel hard-disk recorders that can play back eight channels of AES audio — six for HDTV and two for stereo. This replaces Dolby E codecs that had been used in conjunction with taped replays before, resulting in a two-frame delay.

The future of 5.1 sports sound might be ESPN's X Games. Consultant Ron Scalise, who has picked up 14 Emmys for mixing in 20 years, concocted the "Xducer," a piezo-electric contact microphone not unlike the ones used on acoustic guitars years ago, and has 90 of them perched along a skater's half-pipe run, each of which is panned across the SRS Circle Sound soundfield the network uses for 5.1 broadcasts. As the broadcast takes place, the audio is fed into an AVID system using a Unity server for editing later replays in stereo stems for 5.1.


X Games crowd placement in the soundfield is different from conventional sports. "We want the viewer to hear individual voices cheering Tony Hawk on," says Scalise.

Scalise confirms that the X Games are sweetened during the live broadcast, using a MIDI keyboard or Pro Tools system loaded with sound effects that enhance BMX bike landings and other action. "Mixing X Games is like listening to Jimi Hendrix play guitar," says Scalise. "You want the thing to sound bigger than life."

 

There is virtually no panning during sports broadcasts. The pervasive wisdom is that microphone placement is the best way to provide viewers with localization cues. Adler prefers to use stereo microphones or stereo microphone pairs in creating the stems for sports audio.

This approach is an acknowledgment of matrixed surround audio. Systems such as Dolby Surround and SRS Circle Sound are codecs in which the algorithms are designed to identify mono elements and automatically route them to the center channel. It might be fine to let an occasional individual sound source slip down the middle, but there are so many potential mono sources in a game that they would soon cause a distraction from the commentaries.

The solution is to make them stereo synthetically, using off-the-shelf boxes from Orban and TC Electronic. Jonathan Freed uses the SRS BSP broadcast signal processor for the task.

"We're basically trying to fool the codec," he explains. "You're always at the mercy of the decoder in a matrixed system, which wants to put anything that's discrete into the center channel. So we make everything stereo except the announcers."

Scott Pray, a freelance mixer who has worked major-league games for ESPN and ABC, likes the way the codecs work, noting the algorithmic allocation of audio averages the distribution of sound out automatically. Pray employs little other processing, usually just a touch of compression and limiting using internal processing on the Calrec Alpha console and outboard dbx comp/limiters on the Calrec Q2. He establishes the sound field early on and defines it using microphone choices.

"For crowd microphones, I use hypercardioid mikes, like the Sennheiser 416, in an X-Y pattern," he says. "That gives you the stereo image you want to both sound wide and full and to deal with the codecs. But it also reflects the fact that, with surround audio, we have to pay more attention to the way each element in the soundfield sounds. We're paying more attention to the crowd sounds now because viewers are able to pick elements like that out of the mix at home. People are listening more critically, whether they realize it or not."