Dolby Laboratories Atmos User Manual

Dolby Atmos

October 2014

®

for the Home Theater

Dolby Atmos®, the revolutionary cinema sound technology, has come to home theaters.
With Dolby Atmos, content creators can precisely place and move sounds anywhere in your
living room, including overhead, to make entertainment incredibly immersive and lifelike.

This white paper is designed to explain how Dolby Atmos will work in home theaters and
how you can build a Dolby Atmos enabled system or upgrade your existing system to
support Dolby Atmos. This paper also explains the technological components of Dolby Atmos
in home theater and the tools that content creators and broadcasters will use to create and
deliver Dolby Atmos content to homes.

Why replace channel-based surround sound?

Dolby Atmos is a revolutionary technology that moves beyond the paradigm of channel­based audio, which has gone as far as it can in the home.

Dolby has led home theater technology since the late 1980s, when we introduced four-

®

channel Dolby

Pro Logic®. We led the development of 5.1 and then introduced 7.1

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surround sound in the home and the cinema. But as home theater expanded to 9.1 and
even 11.1 systems, the problems of pursuing more and more channels became clear. Home
theater content often originates from theatrical content that is mixed, at best, in 7.1 sound
and many times in 5.1. That meant that 9.1 or 11.1 systems reached a point of diminishing
returns in parsing and upmixing that limited signal to serve more and more channels.

In addition, the ability to recreate reality using channel-based audio is inherently limited. In
real life, sounds move in specific and sometimes complicated ways—a hummingbird flies off
a tree branch, hovers in front of a pair of blossoms, and then dives down to a fountain for a
drink. Simply moving the hummingbird’s sound from the Left Height channel to the Right
Front channel can’t possibly recreate the detail of th at bird’s flight. And when you lose those
details, it detracts from the brain’s sense that what it’s watching is real.

A cinema solution

Dolby first started investigations into a solution to the problems of channel-based audio in
the cinema. Our goal was to free filmmakers from the limitations of audio channels by
developing a system that allowed them to determine exactly where a sound should be and
where it should move in three dimensions—that is, to fait hfully recreate that hummingbird’s
flight in all its complexity.

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Dolby Atmos in home theater

Dolby has now developed the technology required to translate the Dolby Atmos experience
in cinema to home theaters. In the case of the home theater, every sound in the mix is
represented as an audio object. What happens when you play a Dolby Atmos film, whether
from a Blu-ray Disc™ or a streaming video service, is quite remarkable. When you set up
your Dolby Atmos enabled A/V receiver (AVR), you’ll have informed your receiver how many
speakers you have, what type of speakers they are (large, small, overhead, and/or Dolby
Atmos enabled), and where they’re located. Your receiver will decide—in real time—exactly
which speakers it needs to use from moment to moment in order to reproduce the sounds
of the car careening across the screen and the child fleeing up the stairs. That detailed, very
specific movement of sound helps your brain suspend disbelief and feel as if what you’re
watching is real.

The flexibility of Dolby Atmos object-based sound makes it incredibly adaptable. A Dolby

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Atmos movie can be played back on nearly any speaker configuration in the home. You’ll be
able to hear the placement and movement of sound in a Dolby Atmos movie whether you
have a system with five speakers on the floor and two overhead, or 24 speakers on the floor
and 10 overhead (the current maximum for a Dolby Atmos supersystem). The more
speakers you have, the more precise the audio positioning becomes.

And you have lots of flexibility to upgrade your system. If you add more speakers, your AVR
can use them to provide you with even more detailed, richer sound.

Delivery of Dolby Atmos movies

Major Hollywood studios are partnering with Dolby to create Dolby Atmos home video
versions of current box office releases and previously released favorites. In addition to
global studio partnerships, Dolby is partnering with game, music, and broadcast content
creators to take advantage of Dolby Atmos technology for future home theater use.

We wanted to ensure that entertainment fans could get Dolby Atmos movies in the same
ways they get movies now, on Blu-ray Disc or through streaming video services.

We invented a new, scalable algorithm as well as new extensions for our existing
technologies, Dolby TrueHD, which is Dolby’s lossless Blu-ray™ format, and Dolby Digital
Plus™, which is used by leading streaming video providers or for secondary languages on

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Blu-ray Disc. Both formats now support Dolby Atmos sound, meaning that you’ll be able to
play Dolby Atmos movies from your Blu-ray player or streaming device.

A Blu-ray player that fully conforms to the Blu-ray specification can play a Dolby Atmos
movie without a firmware update. The player will need to be connected to an AVR capable
of supporting Dolby Atmos and set to audio bitstream out. Note that some Blu-ray players
default to secondary audio, a playback mode in which third-party content is mixed with the
primary soundtrack and output as a Dolby Digital signal; be sure to turn this feature off to
ensure decoding and playback of Dolby Atmos content by your AVR.

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There’s also no need to buy new HDMI
supports Dolby Atmos audio.

Dolby Atmos audio tracks (both Dolby TrueHD and Dolby Digital Plus) are backward
compatible. If you play a movie mixed in Dolby Atmos on a non Dolby Atmos system, you’ll
experience traditional 5.1 or 7.1 audio, depending on the layou t of your system. This means

cables. The current HDMI spec (v1.4 and later) fully

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content providers don’t need to maintain separate Dolby Atmos and non Dolby Atmos
mixes.

Setting up your Dolby Atmos home theater

Although Dolby Atmos is a revolutionary new home theater format, it doesn’t require that
you start from scratch. Although you will need a new AVR, in most cases, you’ll be able to
keep most, if not all, of your existing speakers.

Many people now have 5.1 or 7.1 systems with a subwoofer and either five or seven
speakers positioned at about ear level. Many of these speakers will work wit hout a problem
in a Dolby Atmos system.

The importance of overhead sound

In real life, sounds come from all around us, including overhead. Having the ability to
recreate overhead sounds is a key element in making Dolby Atmos sound so realistic. If we
see a helicopter take off onscreen and then hear its blades cutting through the air above our
heads, the experience makes us feel like we’re really in the scene, not just watching it.

Dolby Atmos cinemas recreate these overhead sounds with an array of overhead speakers
above the audience. Some home theater enthusiasts will also be able to install speakers in
or on their ceilings, but you don’t have to.

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