Creative Audio - Dolby Atmos With Glenn Stilwell
It’s still early days for live Dolby Atmos broadcasting in the United States, but Glenn Stilwell, senior audio engineering and operations manager for the Pac-12 Networks, is ready for it. Indeed, not only has Stilwell been experimenting with creating Dolby Atmos mixes in preparation for its more widespread use in live broadcasting, but he is also helping to train A1s in the technical aspects of the immersive format.
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Stilwell has worked in sports broadcasting for the past 35-plus years at the regional, national and international level, including five Olympic games for Olympic Broadcast Services. “Just for my own education, I started teaching after learning all the technical parts of the Atmos mix, using the Dolby lab around the corner,” he says. Pac-12 Networks, which is owned by the 12 universities of the Pac-12 Conference, broadcasts hundreds of live football, basketball and Olympic sport events annually and, like Dolby Laboratories, is headquartered in San Francisco.
The Pac-12’s one national and six regional TV networks produce audio in 5.1, Stilwell says. “But we’ve always done 5.1, so we’ve become very good at it.” Many of the events are produced using REMI or at-home workflows.
For his Dolby Atmos mixes, he says, “I’m taking the philosophy of the 5.1 mix and just expanding it. I want to make my mix as if I was at the 50-yard line of the football game. I’m transporting you acoustically to the stadium, so I have to think, what does it sound like when you sit at the 50-yard line?”
Adding The Vertical Plane
A 5.1 mix already surrounds the listener in the horizontal plane, of course, so how does the Dolby Atmos mix allow the A1 to kick things up a notch? Atmos mixing is still new for Americans, Stilwell observes. “Not so much for the Europeans, so they’re getting used to it and playing with it and making some very interesting and very good mixes in Atmos. They’re starting to incorporate some of that ear candy, as I refer to it.”
During a football game, the in-house announcer keeps up a steady matter-of-fact commentary that follows the on-field action through the P.A. system, which is usually, although not always, installed in the stadium roof. “One piece of ear candy is to take that audio stem and place it in the overheads, so I feel as I would at the stadium, with the sound coming from above me,” he says.
At Arrowhead Stadium in Kansas City, Missouri or Oakland Coliseum in California the P.A. is a single source in the camera-left end zone, he notes. “But if you put that in the ceiling speakers, you’re making it better, in my opinion.”
The crowd can also go in the overheads, placing listeners at field level with the bleachers and VIP boxes above them. For NBC’s Notre Dame football home game coverage, for example, one of the few events regularly broadcast in Dolby Atmos currently, “They’ve got four mono or stereo XLR drops on the roof. You take a simple shotgun and put it on the roof, angle it down to the stadium and now you have your overheads. That is the most basic thing you can do,” Stilwell says.
“What you’re listening for is that overhead sound of the stadium. The important technical thing to remember is that those four microphones, those four points, have to be decoupled from any of the field of play.”
Beyond football, he says, “If you’re tight on time but still want that overhead sound, we’ve experimented with putting a pair of shotguns on the back side of a basketball stanchion, pointing straight up. You’re getting the overhead, but it’s a reflection off the roof.”
Using a variety of source material and experimenting with remixing it for the immersive format, Stilwell says, “One of the interesting things I’ve found was that when you put the P.A. feed in the overheads, I know for a fact that the P.A. sound is getting into every effects mic that I have open on the field, but psycho-acoustically, my brain tells me that the P.A. announcement is coming from above and behind me. My mind cancels it out from the field of play microphones, and the effects seem better. That was a fun realization.”
There are other possibilities for adding ear candy, he says. Graphics are not yet being created with 10-channel (5.1.4) Dolby Atmos audio, but the possibilities could be limitless. For example, he says, “When you do a big show open graphic, you could have a bumblebee flying around your head and over the top of you. You can separate things like ‘the capper,’ where, going into commercial, you’re showing the last great play; when the play is over, a big graphic comes onscreen to put a bookend on it. You can take that capper sound, delay it, and now it’s going left to right and front to back over your head. The more experienced we get with it, the more it will start to sound better and cooler.”
For many presentations, the ear-level component of the audio, whether in 5.1 or Dolby Atmos, tends to be effects fed to the four corners, with the center channel reserved for the announcers and commentators, for clarity and intelligibility. In Dolby Atmos soundtracks for feature films, some mixers will bring certain elements off the screen and into the room—music, say—for better separation, and potentially so could sports broadcast A1s. “We could draw our announcers maybe higher up in that front plane,” Stilwell suggests. “We don’t have enough experience yet to do that on a consistent basis.” That said, “Some broadcasters are not going to want that; some are,” he adds.
But by and large, unlike a film mix, a broadcast mix of a sport event is largely static in terms of movement. “There is a philosophy that says it’s like a stereo show. You put out the microphones and if all the levels are set correctly, the show is going to mix itself to some degree. Because as somebody gets closer to a microphone, you’re going to hear more of that. Or you hear the concessions guy yelling, or maybe he’s in the back, halfway up overhead. Maybe that’s what you want as a natural feeling.”
One sporting event that has benefitted greatly from dynamic movement in the Dolby Atmos mix was the NHRA’s drag racing. The NHRA was a very early pioneer of Atmos mixing, teaming with Dolby in 2018 to experiment with the format, though the mix was not sent to air. “The NHRA guys are able to do that because they have a submixer who is dedicated to moving objects within the live environment,” Stilwell points out, something that won’t necessarily align with the staffing or budget plans for every sport event.
A couple of European mixing console manufacturers already offer mixing aids that can follow the ball in football matches, so it seems a distinct possibility that A1s wishing to add dynamic movement to their mixes might get some support as technology advances. “In 10 years, there’s going to be some AI that is going to allow us to do that,” Stilwell predicts. “They’re going to be able to take an object and, using AI, move it anywhere within the soundfield.”
One of Stilwell’s training points for would-be Dolby Atmos mixers is the creation of reference monitoring for the 5.1 and stereo downmixes that the majority of viewers will experience. Mixers are generally adept at maintaining a specific loudness level while barely glancing at their meters, and the same is true of monitoring the immersive, 5.1 or stereo mix and intuitively knowing how it sounds in the other formats. “Some people monitor the stereo mix more than the 5.1, some people monitor the Atmos more. Once you do enough games and you’re good enough at it, you can listen to the stereo and, if you hear something, you know exactly what’s wrong in the Atmos mix,” Stilwell says.
Keeping It Simple
Plus, in a remote truck, where the A1’s attention is constantly being pulled in numerous directions, it’s almost impossible to listen to any mix for any significant length of time. “From a practical standpoint, as Doug Deems [former A1 for Notre Dame’s home games and current Fox NFL mixer] showed in the videos he did a while back, there’s so much going on that you don’t have any more bandwidth to listen, other than spot-checking the mix,” Stilwell says.
The bottom line, he says, is that Dolby Atmos is a step above 5.1. “And it’s super simple, the way I look at it, but it makes such a significant difference. When I turn on games here at home, I will flip back and forth between Atmos and stereo and the difference is just night and day.”
Even his dog can get immersed in a Dolby Atmos mix, he says. “The way our TV room is set up, the front door is down a breezeway behind us. Our dog will hear something in Atmos and think somebody is coming through the door!”
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