What is Dolby Atmos?

Posted Fri Apr 21, 2017 at 02:29 PM PDT by
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Keeping track of the latest audio and video tech can be daunting. Thankfully, High-Def Digest has you covered. Welcome to our new Home Theater 101 series, where we'll be explaining emerging technologies while also recommending the very best possible A/V gadgets n' gear you can buy at your particular budget level. 

When it comes to recent audio advancements, few are as buzzworthy as the new DOLBY ATMOS and DTS:X immersive surround sound formats.

But just what exactly is Dolby Atmos and how does it work? And what do A/V enthusiasts mean when they throw around words like object-based mixing and up-firing drivers? Well, fret not! If you don't know the difference between a 5.1 setup and a 7.1.4 configuration, this guide is here to breakdown the ins and outs of the Dolby Atmos format. So, without further ado, let's dive right into

HOME THEATER 101
WHAT IS DOLBY ATMOS?

THE BASICS


At its core, Dolby Atmos is an immersive surround sound format which utilizes object-based mixing over traditional channel-based mixing. But what's the difference between the two methods?

With channel-based mixing, movie tracks are designed with audio designated directionally to specific speakers through a predetermined number of discrete channels. For instance, in a 5.1 setup, all sound placement is limited to specific left, center, right, left surround, right surround, and LFE speaker channels (the .1).

But with Dolby Atmos object-based mixing, core channels are now joined by individual audio objects (sound effects, dialogue, etc.). These objects are mixed in a virtual environment, allowing sound designers to place up to 128 separate sounds anywhere in the space at any given time -- not just within a select number of fixed locations. For instance, if a mixer is placing a buzzing bee into a movie soundtrack, they can now move that sound anywhere within the environment, not just between specific speakers. This allows the mix to organically scale up or down to a wide variety of speaker setups and locations, mapping the sounds to the appropriate speaker based on where the effects should be in the movie's virtual environment.

Dolby Atmos first debuted in theaters with the 2012 release of Disney•Pixar's Brave. Since then, over 2,000 Dolby Atmos enabled theater screens have been installed and over 500 theatrical movie titles have been mixed in the format.

Likewise, Dolby Atmos is now an integral part of the Dolby Cinema process, which also incorporates the Dolby Vision laser projection system to deliver high dynamic range images with expanded colors and enhanced contrast. Currently, there are more than 50 Dolby Cinema locations around the globe (HERE is a list of Dolby Cinema at AMC locations here in the US). 

IN THE HOME THEATER


Building off of Atmos' initial cinema success, Dolby launched Atmos support for the home theater in September of 2014. Much like the format's cinema implementation, Dolby Atmos for the home theater uses the same object-based mixing tech, allowing sound designers to position individual effects and groupings of sounds anywhere they desire -- free from conventional channel restrictions. Special metadata is then paired with each sound, giving information about its location and movement throughout the room. The Dolby Atmos renderer built into an Atmos A/V receiver then takes that metadata and places the sounds exactly where they are supposed to go as scaled to a user's specific speaker setup.

And because mixers now have expanded freedom when it comes to sound placement, this also means that audio can come from locations previously unavailable in traditional home theater surround sound setups -- most notably from above

With that in mind, the most substantial benefit of Dolby Atmos in the home is through the addition of overhead audio. While the Atmos home theater spec can technically support up to a 24.1.10 speaker configuration, most current consumer products offer support for 5.1.2, 5.1.4, 7.1.2, 7.1.4, and 9.1.2 configurations -- with the first number representing the amount of ear-level surround sound speakers used, the middle number designating a subwoofer or two, and the last number signifying the amount of height speakers used.

REQUIREMENTS FOR DOLBY ATMOS


In order to properly play a Dolby Atmos enabled soundtrack, users will need an A/V receiver with Dolby Atmos support connected via HDMI to a Blu-ray player, Ultra HD Blu-ray player, or other media device capable of bitstreaming the Dolby Atmos track to the receiver. 

Meanwhile, in order to actually add overhead sound to a home theater setup, users have several options. First, customers can simply install traditional in-ceiling speakers or mount speakers on their ceilings. While this is the most effective method, it won't be suitable for everyone's home and setup.

Thankfully, Dolby has teamed up with several manufacturers to release Dolby Atmos-enabled speakers. These speakers feature an additional up-firing driver positioned on top in order to reflect sound off of the ceiling. This simulates the effect of audio coming from above without the hassle of actually mounting a height speaker. In addition, some companies have even released separate Dolby Atmos modules that can be placed on top of current floor-standing and bookshelf speakers, giving them an upward firing driver without having to buy a whole new speaker. Finally, there are several Dolby Atmos sound bar options on the market now as well, offering a simpler, all-in-one solution for simulated overhead audio. 

For a detailed rundown of recommended Dolby Atmos speaker configurations and installations, check out Dolby's Official Atmos Speaker Setup Guide

DOLBY ATMOS CONTENT


Dolby Atmos soundtracks are now featured on a growing collection of Blu-ray and Ultra HD Blu-ray discs, along with streaming services like VUDU, and even video games. In total, there are now over 150 home titles available with Atmos, including movies and TV shows from studios like Lionsgate, Warner Bros., HBO, Universal, and Paramount, covering major releases like La La Land, Game of Thrones, Mad Max: Fury Road, Gravity, and more.

And in addition to native Dolby Atmos content, Atmos receivers also offer a mode called Dolby Surround. This option allows users to up-mix standard stereo, 5.1 and 7.1 soundtracks to create Atmos-like effects with simulated overhead audio objects.

RECOMMENDED GEAR


There's currently a wide variety of Dolby Atmos-enabled gear on the market, including over 75 A/V components and over 45 sound bar and speaker models. Here's a rundown of some recommended Atmos products available now.

5.1.2 Onkyo HT-S7800 All-In-One Home Theater System ($899.99) - Perfect for customers looking for a complete Atmos package on a budget. Includes 5 surround speakers and 1 subwoofer (with 2 Dolby Atmos-Enabled height speakers), and a 5.1.2 AV receiver with Dolby Atmos and DTS:X support. Full review here!

Yamaha RX-A3060 9.2 Channel AVR ($1,999.95) - Geared toward users who want to setup more extensive Atmos configurations with expandable support for up to 7.1.4 or 9.1.2 speaker layouts. 9.2 channel AV receiver (11.2-ch expandability with 2-ch amplifier) with 150 W (8 ohms, 20Hz-20kHz, 2ch driven, 0.06% THD), MusicCast technology, Dolby Atmos, and DTS:X. Full review here!

SVS Prime Elevation Speakers ($399.98 per pair) - Designed to serve as a versatile Dolby Atmos or DTS:X height speaker with flexible placement options. Likewise, the unit can also be used as a center, front, LCR, side surround and/or rear surround speaker when ideal placement in a room isn't possible. Full review here!


So, there you have it. Those are the basics of the Dolby Atmos immersive audio format. If you still have any other questions about Atmos, please let us know in the forums! 

MORE HOME THEATER 101 ARTICLES

-What is DTS:X?
-Best Sound Bars
-Up-mixed: Dolby Surround vs DTS:Neural:X

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