Dolby Atmos: Movie sound takes to the 3D stage

The name Dolby Laboratories has long been associated with innovative and world-leading sound reproduction. Its latest creation, Atmos, has come at the perfect time to augment the unprecedented immersive experience of big screen 3D stereoscopic images.

The principle behind Atmos is one of constructing a 3D framework of independently controlled speakers completely lining the cinema, including the ceiling, to provide pinpoint accuracy for the origin and movement of individual sounds. By combining traditional channel-based audio (5.1 or 7.1 surround) with individual audio "objects" the Atmos system has now launched movie soundtracks into the world of true 3D.

Disney, Fox, Pinewood Group, Sony Pictures, Skywalker Sound, Paramount and ToddAO are just some of the movie post production facilities to have recently installed Atmos mixing suites. While the first Atmos release was Pixar’s Brave in 2012, uptake in cinemas will take a little more time as, naturally, an investment in speaker and hardware upgrades is needed but many have already taken the plunge.

Gizmag attended a demonstration of the Dolby Atmos system as a guest of Soundfirm, Australia's Oscar nominated audio post production facility, and we spoke with Soundfirm’s Bruce Emery (Technical Manager, Sydney) and Chris Goodes (Mixer/Sound Designer), as well as Dolby’s Stuart Bowling (Director of Market Development) and David Gould (Senior Product Manager) who conducted the demo.

Inside Atmos – what the specs mean

The system comprises mixing software with 3D panning to X/Y/Z coordinates and decoding hardware that stores the audio and processes the mixing metadata to deliver discrete signals to up to 128 simultaneous and lossless audio streams (channels or sound elements) in real time, and allows for up to 64 discrete speaker feeds. The system is all about discrete audio elements, which Dolby calls “objects”, that are positioned and moved within a 3D space.

So how do theses “objects” relate to the traditional channel based multi-track session?

"Objects sort of sit on top of that," says David Gould. "They can be seen as just another stem. You already have your dialogue stem, your music stem, your effects stem that add together to make your overall soundtrack which are channel based aspects, and on top of that you have your objects which are almost just another 'food group' added into that mix. The difference is they’re not mixed together to a channel-based layout. They are kept discrete throughout the process and then the metadata is how they play back. They are PCM audio, 48khz at 24bit, but it’s just not 'mixed together.' It’s rendered on playback so we say it’s the best of both worlds. Things that are suited to being part of a channel, such as your LCR (left/centre/right), can still be part of a channel and yet you can add a sharp, dynamic, discrete sound that you want to sit on top of that channel based content and that will be an object.

"They don’t have to be moving, they can be static objects, like putting things just off screen. One of the things that Atmos has is these extra speakers between the side array and the screen so you can pull things slightly off screen.

"No manufacturer has released an official Atmos reverb (reverberation FX plugin) yet but those who have mixed in the format have used reverbs very successfully by taking an extra stereo return and adding it to your overhead array, for example. Just using the tools available to you today, be it a convolution reverb or an artificial reverb, you can use them in a different way and create these really compelling soundscapes."

How is Atmos being received by the film making community?

Directors of the caliber of Peter Jackson (Lord of the Rings series, The Hobbit series, King Kong and Michael Bay (Transformers series, Armageddon, Pearl Harbour) have been quoted in interviews saying that if they’d known about Atmos earlier, they would have incorporated its use at the conceptual stage of their projects. "The film making cycle is long so we’re seeing more mixers come back and do their second and third mix in Dolby Atmos," says Gould. "Certainly people who’ve already worked with Atmos have said that next time they’ll approach it differently, but it’ll take two or three years before they’ll be able to see it happen."

Bruce Emery’s clients’ first question is usually about the cost. "Between the director and the producer, suddenly they see something new, the director is immediately sold," he explains. "They get it straight away. The producer’s first question is, of course, 'Well, how much is this going to cost me?’ Here’s something that they’ve just found out about and they haven’t budgeted for it so they want to know how much extra it’ll cost and how are they going to distribute the content."

With cost obviously being a critical factor, how much extra time does it take to do an Atmos mix vs a 7.1 surround mix? “Well that’s a question that’s becoming more difficult to answer," says Emery. "The difference between the old standards and mixing in Atmos can’t be a sudden break. The way films are made just doesn’t allow for mistakes. You can’t say ‘Oh gee, that didn’t work. I’ll take it back and fix it and release it again.’ That’s why equipment develops the way it does. You can spend a week more doing an Atmos mix from an existing mix."

"The first Dolby Atmos release was Pixar’s Brave in 2012 (which won many awards including the Oscar, Gloden Globe and BAFTA awards for Best Animated Feature Film), says Gould. "After they finished the 7.1 mix they went back and spent three and a half weeks doing the Atmos mix. Oblivion, on the other hand, a movie they mixed natively in Atmos, had the Atmos mix, the 5:1 mix and the 7.1 mix all within a few days. Using the DFC implementation and the Harrison implementation where they are working natively from the start and getting comfortable with the process and only an extra day or so for the deliverables, the creative and mixing part is virtually the same now."

"The last film we worked on was The Monkey King, a Chinese film which I co-mixed in Dolby Atmos with Steve Burgess," says Chris Goodes. "It was incredibly rushed, unfortunately, but we mixed natively. The downmixing into 7.1 and 5:1 is done automatically using the DMC and the results were incredible. We didn’t have to touch a thing. We literally hit 'play,' watched the whole film in 5:1 and thought 'Wow!'. It contained all the elements and a lot of that surround base was kept under control for a 5:1 environment where you don’t have that “space”, that level of movement. It sucks it in a little bit – but in a good way. You feel it, like, 'plastered to the walls' a little bit when you flick between Atmos and 5:1, but it’s not unpleasant. There’s no 'OMG, now we have to go and change everything!' It felt very good on the 5:1 and 7.1 mixdown and it was good to hear they were so close to the (Atmos) soundtrack.

"It’s a big action film so there’s a lot of sword fighting and a little bit of the traditional swishing and clanging but there was also a lot of specialized sound design that was done by Steve Burgess and James Ashton where there were large creatures, like dragons and massive monsters, as well as more “magical” elements there were not just straight action but also a little bit more fantasy based things.”

How will Atmos change the way films are made?

“When film makers realize what they can do with sound, they might shoot something in a completely different fashion or edit something completely differently to what they would have done," continues Goodes. "With sound, perspectives can be shifted. You can use your atmospheres differently and you can use perspectives in quite a different manner."The integration of music with other elements in the soundtrack is becoming more common. Music as sound effects is a trend that will only grow with the uptake of the Dolby Atmos system. Music has traditionally been heard coming from one place – even in stereo that space is quite focused. But the 3D audio stage of Atmos also begs for some creative music mixing. Chris has already experienced working in Atmos that way on The Monkey King: "The music stems came to us quite 'wide,' about 60 tracks or so, and we were pulling elements 'off screen' and putting them in different spaces to make more room 'on screen' for elements like dialogue and any effects that maybe needed a little bit more room. Your space can be just so precise now. If you’ve got enough time, you could mix it like you were sitting in the middle of the orchestra with instruments coming from discrete locations rather than banks of speakers."

“As sound designer/mixers, you’re thinking more about what you can do from the outlay. Atmospherically, I think, is the main thing. It’s the subtle things that you can now really play with and get more control over than you’ve ever had before. You now have incredible control of where you can put things in a space. That’s really where it’s leaps and bounds ahead. Of course the big stuff can also be better in Atmos because you’re not bombarded with it from the front any more, you can have it spread around. They can be all around you so there can be more (relative) level but not as loud.

"It is, essentially, a higher resolution of movement – more resolution down the wall. You can pull things out and put them somewhere else to get them out of the way. Especially in the overheads. For example, say you’re in a jungle, you can have the rustling leaves coming from above you. You don’t have to compromise. Creatively it’s pretty amazing. If a director asks for anything, you can pretty much do it. There’s no excuses any more!”

Audio facilities such as Soundfirm have traditionally built up huge libraries of sound effects and background ambiance that they have either recorded themselves or made up from pre-recorded collections. How does their library of effects get updated now for Atmos?

"We do a lot of multitrack recording, we’ve been doing that for may years, now, says Goodes. "We’ll go out and record 5:0 or 5:1 and they are adaptable to Atmos. To record in overhead we’ll have to experiment with, as that’s really the new thing from 5:1 or 7.1. Now you’re not so much capturing a space, you’re creating a space – which is what we do anyway. Even in 5:1 the space is layered from so many different elements so I’ll mainly be using the same techniques we’ve used in the past. With overhead and sides you can add extra 5:1 Atmos in a slightly different position or add more stereos or even mono for 'objecting' things in your soundtrack. Underwater is a perfect example, you have the bubbles you can feel coming from directly above you and something slightly more 'washy' coming from the surrounds. It’s where you really have that separation of what’s happening 'up.' It’s a proper 3 dimensional platform."

There are so many different sizes of cinema, can they all use Atmos effectively?

We know Atmos can serve discrete audio to up to 64 speakers, so what’s the minimum speaker configuration for Atmos? “Well really it’s dependent on the size of the room," explains Goodes. "It’s to do with the angle between the speakers. You wouldn’t want less than five down the side walls, then you’ve got two rows of five on the ceiling and possibly four along the back and you can have only three along the front in a small room. You’ve also got your bass managed subs."

What other technologies are Dolby employing to develop Atmos?

The end game with sound is, of course, the speaker by which it’s ultimately transmitted. With sound dispersion angles being different for different makes of speakers, we asked if they’d collaborated with any of the speaker manufacturers to develop an Atmos-friendly design? "We’ve worked with companies like JBL, Klipsch, QSC, etc., and for the overheads we typically want a wider dispersion than we normally have on the side or rear wall surround speakers," says Dolby’s Stuart Bowling. "So companies like JBL, Christie and Klipsch have started to design and release specific overhead surround speakers that have that wider dispersion pattern. We like 100˚ x 100˚or greater dispersion pattern. They are also manufacturing those speakers with regards to helping mounting them in ceilings as well."

We also asked what's recommended for cinemas in terms of sub woofers for LFE (low frequency effects) and sub bass response?

“In a theater, typically in the back third, or the sides or the ceiling we put the additional subs, or even on the rear wall for theaters that can’t accommodate those scenarios," says Bowling. "We’ve had theaters that have actually put them behind the screen, but left and right – away from the main LFE. Each configuration, or array, is, understandably, specifically tailored to suit the particular room in which it’s installed."

When will my local cinema have Atmos?

For a regularly updated list of which cinemas near you have installed Atmos, as well as a list of Dolby Atmos movies, check out the Dolby website.