Atmos backgrounds, in the mixers’ words

Featured, Surround — By on February 12, 2013 11:15

Dolby’s much talked-about object-based Atmos surround format was first introduced late in 2012, with the release of ‘Brave’. More recently, this new, more immersive cinema audio experience has been enjoyed by an even wider audience with the release of the first of Peter Jackson’s ‘Hobbit’ trilogy,

In this piece, on the Designing Sound website, Jake Riehle interviews Chuck Michael (‘Taken 2′) and Craig Henighan (‘Chasing Mavericks’, above right) about how they mixed the backgrounds for those films in Atmos, at the Zanuck Theatre (above) on the Fox studio lot in Hollywood.

Jake Riehle, Designing Sound (JR): “How are background elements handled during the Atmos mix?”

Chuck Michael (CM): “Taken 2 was originally mixed in 5.1. So to create the Dolby Atmos mix, we worked with the original, virtual pre dubs in pro tools. This meant that we could “unwind” any of the predubs and get to the individual tracks that made up the mix. However, since it was cut for 5.1, it was particularly challenging to figure out how to spread the background material into the 9.1 Dolby Atmos “Bed” tracks, (Left, Center, Right, Left Surround, Right Surround, Left Rear Surround, Right Rear Surround, Left Overhead, Right Overhead and the rarely-used-for-BGs-Sub/LFE).

Ideally, there’d be more BG material cut for the additional channels, but since we wanted to preserve the integrity of the original mix as much as possible (which meant not adding any new sounds), we used a combination of techniques to spread the 5.1 BGs into 9.1. The tricks we used included slight delays, reverb returns and sometimes just a simple double bussing to bring different BG elements into the extra channels. Additionally, in a few cases, we were able to isolate BG elements and present them as “Objects” that we placed and or slowly moved in the sound field.”

Craig Henighan (CH): “During the final days of our 7.1 mix on Chasing Mavericks, sound effects editor Doug Jackson and I spotted the film for potential scenes that would be ideal Atmos. It became obvious that we’d need to hit all those scenes again with another layer of backgrounds. We did a couple days of cutting complimentary BG’s against our existing stems (Dialogue stem, Music stem, BG stem, SFX stem, Foley Stem and Wave Stem). When the units were turned over to me I reverted back to premix mode on the stage and did a pass of the backgrounds in Dolby Atmos. These new Atmos background beds were mixed against the 7.1 stems, listening to each element and then decide where to pan them, add eq or any other processing. Doug provided me with both stereo and mono tracks and together we worked through this premix pass. He designed winds, airs, BG activity, seagulls, etc. that worked extremely well with our existing 7.1 mix.”

JR: “What type of background elements shined in Atmos, what felt gimmicky or failed to translate?”

CM: “Certainly if anything felt gimmicky, I would quickly change it. I wasn’t making a demo, so my goal wasn’t to show off the Atmos system, but rather to use the system to make the movie going experience more immersive and intense. I don’t recall BG elements being much at risk of sticking out in the surrounds. The overheads however, were a different story. I found things like close-up traffics could not easily be put into the overheads – it’s just too direct and hearing that from above sounded odd. So, I think a much more reflective, indirect sound works best for the overhead channels in terms of BGs.

That said, we managed to get the 5.1 BGs sounding pretty good in a 9.1 environment. It blended well – to the point where I’d sometimes wonder, “are those additional channels even playing?” Flipping back to the 5.1, I’d hear what a big difference it made. I think this is what you want – the film just plays and feels natural and you don’t consciously notice the sound until you decide to compare to what you have before. And then you go, yeah, this is a big difference.
Just like 5.1, sounds with a sharp attack or that are recorded very closely can stick out if played behind the audience. So, I tried to avoid putting any transient heavy BG element directly into the surrounds and definitely wouldn’t put in the overheads unless it directly related to something on-screen. But again, this is pretty much the same precaution anyone would take in a 5.1 mix.”

CH: “In Mavericks there were lots of scenes in the ocean or on the beach. Sounds that really shined in those scenes were seagulls, winds, airs and distant activity. I was striving to make Atmos put the audience further into the movie by subtly using every surround channel, sometimes discreetly, other times diffused. One particular scene that worked well was when Jay asks Frosty to help him surf Mavericks. It’s early morning; the town is barely awake so I played with the placement of specific distant activity to make it feel like everything is slowing waking up. I put some seagulls on the side walls while sending a bit of that signal into an aux using Echoboy. In the return of that aux I set up a short street slap that I could pan around independently. The subtle delay of the seagulls gave the scene a layer of believability that worked quite well. The Atmos engine smooth pans and connected the front, back, overhead and sides of the theatre in a way that 7.1 can’t accomplish.

That said, there were things that felt gimmicky in the first day of Atmos mixing simply because I was having fun with the format and testing boundaries! As I got more comfortable, I reeled a few things in. Some wind tracks that I put in the overheads started to call attention to themselves, so I reined them in a bit. Though with the right elements, the overheads are extremely useful in adding a layer of believability to the soundtrack.”

JR: “Every film brings unique challenges but after mixing in Atmos how would you prepare/design background units and or predubs differently for the next time you mix in it?”

CM: “There are a couple things I would do editorially if I knew early on that the film was going to be mixed in Dolby Atmos. First, I’d cut more BG tracks, with specific attention to using an indirect, washy ambience overhead. When recording BGs in the future, I’ll probably try to record a couple tracks normally, then maybe a couple tracks more distant, off-mic and/or reflecting off a surface – something specifically designed for the overhead speakers.
Second, I’d play around a bit more with Wallas and any sort of group/crowd BG material. I would like to experiment with the idea of building up more tracks of fewer people, placed as objects around the room, instead of just sending a few tracks of busy crowd to the bed channels.

There was one point in Taken 2 where we had the opportunity to try this. It was a foreign walla track recorded on location with just a couple people talking. I moved this out of the beds and placed it about halfway down the left wall. That, by itself, definitely stuck out. It felt like an effect played out of a speaker on the side wall – probably because that’s what it was! So, I added a few reverbs, giving it a little slap, which I returned to the surrounds and overheads – using slightly different reverb settings for each bed channel. This ended up sounding very realistic. Since I hadn’t had the opportunity to use this technique elsewhere in the film, I was concerned about it standing out, so I ultimately decided to back it off a bit so it wasn’t so present. It’s a very short sequence, but really makes you feel like you’re there on the street.

It turns out there’s a big difference between just using the 9.1 beds vs. placing an audio object in the sound field and using the beds to create realistic reflections for that object. Granted, it’s a bit of work, but I think in some areas, definitely worth it. Imagine 6 or 7 specific BG or Walla objects placed around the room with their reflections going back to the bed channels, creating a fuller, more realistic crowd bed (and maybe sitting on top of a thinner crowd bed bussed to the 9.1 bed channels so it blends better). I haven’t had the chance to try this, but it’s something I’d really like to experiment with to see if this technique can help build a more immersive and realistic sonic environment.”

CH: “I can see backgrounds and atmospheres becoming much more detailed in this format. The eventual goal is to cut and mix from the ground up in Atmos. I hope that I’ll be able to set up my editing room in a “baby” Atmos set up soon, so that I can monitor in Atmos from the beginning of design through editorial. Dolby has made Atmos scalable and is working on a system so editors can monitor Atmos in edit suites. Ultimately it’s going to be more work, more “sound” will have to be cut with “filling out” the Atmos format in mind. Of course this will be film dependent and needs to be done tastefully, Dolby Atmos will bring the collaboration of mixers and editors even closer together as working within the format allows a much higher level of attention and detail to the sound track but will need to be planned for from sound editorial, through the mix and into deliverables.”

As well as the films mentioned above, ‘Life of Pi’, the second instalment of ‘The Hobbit’, ‘The Desolation of Smaug’, scheduled for release on Dec 14th. 2013, ‘Star Trek Into Darkness’, ‘Pacific Rim’, and ‘Gravity’ have been, are going to be, or are, at least, planned to be, released with Atmos mixes.


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