Dolby Atmos & You
Dolby Atmos has risen rapidly from competitor
to main contender in the race for an objective
audio format to take cinema into a more
immersive and creative future. This isn’t just
a few extra speakers for cinemas. It could change the
way film sound is approached at a fairly fundamental
level, and therefore have a significant effect on the
market for audio post-production services in film.
Quite important then…
To work with Dolby Atmos, you have to understand
the basic concepts of channel (‘array’) beds, and
discrete objects. First, the more familiar channel
component (9.1, 7.1, and so on): Dolby’s Jurgen Scharpf
(Senior Product Engineer, Audio & Video) stresses
the idea of an array, as opposed to a point source:
“Channel tracks – or the bed – address arrays of speakers.
For example, if you pan something to the left surround
that lights up three to four speakers in the cinema.
It’s an array, and gives you a diffuse perception of where
that sound comes from, but it also gives you pretty
good universal coverage.
“An object track has a very discrete position. It pans
to an individual speaker, or it pans between individual
speakers. It comes more ‘forward’ in your surround mix.”
Yes, there are plenty of novelty moments to be had
here, but it goes deeper than that. Dolby’s Hubert Henle
(Senior Director, Content Services) provides an example
of a restaurant scene. The channel component might
be the music and a general background atmosphere.
Then you could use point-source dialogue objects to bring
some reality to the scene: “In a restaurant you can easily
follow all of the conversations around you if you want to.
With Atmos we can create that effect much better than
you can with a surround array. It is so unnatural for a
piece of dialogue to come from a surround array when
usually you would expect it to come from a point source…
If you do it right, you can either listen to them or filter
them out, as your brain does in the real world.”
T hose dialogue objects could be treated as ’phantom sources’, where the point source is positioned at a position in 3D space using a combination of more than one of the discrete speakers (in the same way as a stereo system reproduces a phantom centre), or you can use the
‘snap to speaker’ option, where Atmos picks the nearest speaker to your panning coordinates and uses that to reproduce the
sound object.
It is important to note that the panning positions of objects are not
‘printed’ as they would be in a channel-based mix. Metadata describes the position of the objects and
that panning is rendered at
the point of delivery (the cinema) and optimised
for the particular speaker array and speaker density at the venue.
So, how do you go about an Atmos mix in practice? At the time of writing, Dolby is using its
own Pro Tools panning plug-in to pan objects. This plug-in writes the information as Pro Tools automation and currently (cinema processor still in development) that is transmitted to the rendering unit, which renders the soundtrack in
real time.
Dolby has confirmed it is already working with a number of DAW and large-format console manufacturers to implement 9.1 and object panning into their platforms, and we should start hearing news of those implementations soon. It has already developed a number of automatic panning modes for single-handed 3D joystick
panning, but trials have shown that joystick-knob (height-position) or joystick-joystick panning are also perfectly workable. This third-party integrated approach is different to the IMM Sound approach,
which was to use its own external DAW to do the panning and encoding.
Of course, for now (remembering a full commercial release of Atmos is some way away), there has to be some shenanigans to fit Atmos into Pro Tools. This involves not only the object panner, but a 9.1 panner. Scharpf says, “We are pursuing an additional plug-in that would give you 9.1 panning in the standard channel-
based form. Currently Pro
Tools doesn’t support that.
We use a 7.1 buss plus
a stereo buss for the overhead arrays.” Scharpf notes that the current workflow for objects is basically to create a number of object tracks in Pro Tools, complete with the Dolby panner plug-in, and move
anything you want to treat
as an object from the main materials (pre-mixed stems, individual sound elements, and so on) into those object tracks.
Now We Can
Because Atmos does have this audio + metadata real-time rendering model, there is potential for all sorts of adaptive options for the Mix Engineer to dabble with. For now, one that will be attractive to many is the concept of ‘conditional mixing’ – a kind of ‘If-Else’ arrangement for your carefully crafted project. An actual implemented example might be conditional options for 7.1 or 5.1 outputs. “Let’s say you have a helicopter hovering over the screen,” explains
Scharpf. “In Atmos that’s pretty easy – you put it into the most front overhead surround speakers. Now, what’s happening in 7.1 and 5.1 renderings? Because it’s close to the screen it pulls some of that sound into the screen speakers when it renders it. That might not
be desirable if you can’t actually see the helicopter.” In this instance, you could deny the helicopter object access to any front speakers when a height array is not available. Clever, eh?
Scharpf: “It’s an automatable feature in the
panner, so you can do it for just one sound effect. That’s something that’s new. Mixing in one format and already s etting parameters for other renderings. That’s definitely new in Atmos.”
The next main development on Dolby’s list of things to do is to implement dispersion or spread of objects in the speaker array. At the time
of writing, objects are
restricted to pannable point sources and cannot be ‘spread’ as a sort of halfway point between array and point-source. This will be available by release date.
Food For Thought
All these extra options must surely be a double-edged sword? It’s going to give Re-Recording Mixers, Sound Designers, Editors, and Sound Supervisors a lot more to think about. It may even fundamentally change the creative process as objects begin to be planned into the sound design. But that also means we should get more options and more creative opportunity, right? As long as we get more time?
In any case, there’s a lot to think about.
Though when you do think about it, you’ll realise how obvious and intuitive it should be. Scharpf has been involved with training – working with Mixers from Europe, the US, China, and New Zealand – and has been impressed with the speed of uptake:
“The learning curve was never longer than a day,” he says.
“It’s very intuitive. It’s really what mixers have wanted to do for a long time… and now they can.”
Dolby’s Doug Darrow (SVP Cinema) is now on a count down to the first major commercial
release for Atmos, which has started with the limited ‘prototype’ release of Pixer’s Brave with Atmos.
“We’ll do additional prototype deployments this year,” he confirms, “With hopefully-soon-to-be-announced titles that will be released into them… And then the commercial release of the product will be early
next year.”
So far, he’s pleased with the feedback from the limited release of Brave: “The reaction’s been outstanding.
We’ve had great consumer reaction, great exhibitor interest. There’s a lot of excitement right now in the industry. In some sense, you could look at the last several decades of movie-going and theatrical movie technology as a progression towards a more immersive entertainment experience, going back to the original days of widescreen.
I might even argue stadium seating, and digital projection and 3D and surround sound are all sort of elements of a more immersive experience, and this is another way to take that to another level. “
Also, with the creatives, Darrow says it has set a new benchmark for positive reaction:
“I’ve been demoing digital cinema technology for 15 years, and I’ve never seen a technology that was immediately embraced by the creative community the way this one has been. They get it instantly, it’s like,
‘I never want to do another movie another way than like this’. It’s really been amazing to see that kind of interest and support. So, we’re pretty excited about it, we think it’s an innovation that’s going to be firmly embraced by the industry and is going to deliver an overall much better experience to the movie going audience, and we know we’ve got to get it right, but we’re really excited about the potential of it.”
House On Soho Square
The centre of the Atmos push in the UK is at Dolby’s new offices in Soho Square, London. With the help of Munro Acoustics, the company has created a new 70-seat preview theatre inside the building and has been busily getting
excessive weight could compromise the isolation
properties, and this had to be taken into consideration
at the design stage.
This does pose an interesting question for cinemas
as well. Large ceiling speakers will have to be hung
safely, which would normally mean hanging them from
the main building structure. In this, multi-purpose
theatre/cinemas might have an advantage as they
generally have well-specified lighting
bars and exposed structural features.
Also, smaller rooms require
fewer speakers to meet the Dolby
specification. Dolby specifies that
speaker density has to be such
that from every seating position in
the critical listening area the angle
between adjacent speakers should not
be more than 30 degrees.
Hubert Henle was able to confirm
that Dolby will be certifying mix
rooms for Atmos at Feature and
Premier levels, and that a number of
post facilities in the UK and Europe
were already in the planning stages of
converting for Dolby Atmos.
Other considerations for both cinemas and dubbing
theatres include a step up in the quality of sound
speakers. Henle: “For the front [in the Dolby theatre]
we’re using typical screen speakers – three way systems
– but the surround speakers are not typical surround
speakers. We’re still in a phase of defining what is a
good surround speaker for Atmos, but it needs to be
full range because it could be an individual source, so we
need a better quality speaker compared to the average in
today’s cinemas. At the same time, you have to have cost
in mind in a commercial theatre. You can’t expect that a
commercial theatre is all of a sudden installing surround
sound speakers that are three or four times the cost of
what they have installed already.”
The new Dolby Theatre is a triumph,
so don’t pass up the opportunity to go and
listen if such an opportunity presents itself.
The combination of Atmos and Munro Acoustics
makes for a special experience. The space is
marked for a range of functions. Henle: “First of all
it’s a cinema that we can use for demonstrations of
our technology. …It is the ideal opportunity to
demonstrate the technology right at the heart of the
Soho community.
“The other purpose is we to offer it to our customers
for their own screenings. It’s designed as a reference
room for both sound and picture. You would expect
a Dolby theatre to have a perfect sound system – and
we did our best to achieve that with the help of Munro
Acoustics – but we’ve also had a look at the image side
of things. The room design is very colour-neutral so that
there is no impact on the perception of colours coming
off the screen – which is what colour graders require.”
In the press release regarding the theatre opening,
Munro’s Technical Director, Chris Walls, was quoted:
“The Soho Square building presented some architectural
and acoustic challenges, but our design team certainly
rose to the occasion. The result is an incredibly accurate
theatre that demonstrates the potential of the Dolby
Atmos format.”
So, Dolby Atmos is a big deal for film companies,
post production services, cinemas, and (hopefully)
cinema audiences. There’s still a little while to go
before full commercial release, so the fine details of the
spec and implementation may well change a little bit.
Hopefully we’ll start to see the fruits of the IMM Sound
acquisition soon, which might include more than just
panning. Spatial information such as reverb and EQ
could well become part of the Atmos experience.
As for the future? Well, Atmos for the domestic
market is not being ruled out, but it’s not ‘on the
road map’ yet either. SRS Labs has already signalled its intention to address the domestic market with its MDA
object-based platform and future cloud-based streaming
capabilities. Of course, Dolby has never been shy of the
broadcast market either.
This is mostly conjecture though. What does matter is that Dolby Atmos looks like it might be the dominant
player in objective audio for cinema. And the Atmos ‘switchover’, if (when?) it comes, could separate audio professionals and facilities into winners and losers. We should probably plan to win.
ATMOS AT A GLANCE
Dolby Atmos is a developing audio format, initially aimed at commercial cinema releases. It introduces ceiling speaker arrays for a height element and combines channel and object-based audio components. Array panning is like the traditional channel-based panning with
addition of the two height channels. Height channel arrays are currently spec’d as as two lines of speakers down the left and right sides of the auditorium.
• Beds (channel-based components) support up to 9.1 audio, (Left,
centre, right, left surround, right surround, left rear, right rear,
overhead left, overhead right).
• Objects (‘point-source’) positioning supports up to 64 discrete
speaker positions for vector/co-ordinate-based ‘phantom positions
or ‘snapped to speaker’ positions.
• Atmos supports up to 128 simultaneous channel and object
components (10-channel beds + 118 objects, for example)
• Object panning stored as metadata and rendered at point of
delivery
• First full commercial release expected early 2013
IN WITH THE IMM CROWD
Last month, Dolby confirmed its buy-out of Barcelona-based IMM Sound, which was developing an objective audio format of it own, in competition with Dolby. The news of the purchase may disappoint those who were rubbing their hands in preparation for another format war, but for some it simply shortened a battle that was lost before it was begun, probably to the benefit of object-based sound itself. We asked Dolby’s Doug Darrow (SVP Cinema) about the IMM Sound episode…
Doug Darrow: “…We didn’t really view what they [IMM Sound] were doing as a competitive threat. Because of the stature and long history that Dolby has in the entertainment industry, it was never about being overly concerned about IMM sound gaining a lot of market share. It was more about getting to a solution that would allow for rapid deployment in the industry, and that was about delivering a common format for the best object-based next-gen sound solution. …We felt like we had the best solution and IMM sound had the second best, and so if you combine the two best solutions, you give the market something that it can really get behind – a single format for object-based audio mixing.
“…At the same time, we would get a really skilled engineering team that had been thinking about this kind of problem for the last seven years, that we felt would be a good complement to the people inside Dolby. We were right about that. We’ve been extremely pleased with how the early phases of the integration have gone.”
Paul Mac: What relative strengths of Atmos and IMM Sound are going to come to the fore as development continues?
DD: “They had some relatively developed authoring tools…They had some reverb enhancements and technology, and some equalisation solutions that could be nice additions to what we’re doing. We had other approaches, and they were a little further along in some of those areas. So it’s one of those things where it can be a nice fit. They had a different overhead speaker arrangement than we had, so what we’ll do is look at both solutions and take the best of what both are doing.
It’s really a way to look at how somebody else approached the problem and share learning, and come up with an even better solution. That’s the early view of it.”
DEFINITION
• The term ‘Objective Audio’ has its root in
the name of the popular object-orientated
programming language, Objective
C. We’ve used it to describe any system
of mixing where audio is considered as
a set of objects and metadata is used to
describe panning and other information.
BRAVE NEW WORLD
The first film to have limited release with a Dolby Atmos soundtrack has been Pixar’s Brave. Will Files (Madagascar 3, Compliance, Mission: Impossible – Ghost Protocol) was Re-Recording mixer for the Atmos mix, taking on the tough job of satisfying both Gary Rydstrom (Re-Recording Mixer and Sound Designer on the commercial release) and the film’s directors. At the time of writing, Brave with Atmos is screening at 14 cinemas in
the US and one in Barcelona.
Jurgen Scharpf, Senior Product Engineer, Audio & Video for Dolby was involved in the Brave mix and and tells a story of a constructive, iterative process that ultimately had to remain true to the commercial release, yet take advantage Atmos. “it kind of went through a three-phase mix,” explains Scharpf, “Because there was a lot of experimenting done… The first version of the mix maybe went a little too far…” It had deviated too far from the original mix, so they went back to the mix room. Scharpf: “The second edition was
a very conservative Atmos mix. We played it again for Gary [Rydstrom]
and he missed a lot of things that we did in the first pass… The third pass ended up being the ideal one.
An example of a moment in Brave where Atmos really makes sense
is when Princess Merida overshoots an archery target and goes into the
forest to retrieve the arrow. Creatures of the forest, including birds and
‘wisps’ were assigned as Atmos objects and so came from discrete point sources surrounding the audience. “I think was much better in Atmos
than it was in 7.1,” says Scharpf. “…You definitely feel this is a new sound format, but it’s not distracting and I don’t think people really notice that there are a ton of new speakers… People notice it’s a great soundtrack.”
