Features The complete guide to Dolby Atmos
FROM MOVIES TO MUSIC, HOME ENTERTAINMENT HAS WHOLLY EMBRACED DOLBY ATMOS. BUT WHAT DOES IT OFFER ABOVE REGULAR SURROUND SOUND, AND IS NOW THE BEST TIME TO UPGRADE?
GEORGE LUCAS FAMOUSLY said that sound was 50% of the movie-watching experience. With Dolby Atmos, we think it could be a good deal more.
Basically 3D for your ears, it’s the biggest thing in home cinema audio since the launch of Dolby Digital 5.1, and has opened up a completely new way for TV and films to deliver sound.
A big change in Dolby Atmos is that sounds become ‘object-based’, rather than ‘channelbased’ as in Dolby 5.1. With channel-based tech, the engineers could direct sounds to specific speakers. In an object-based system, however, audio designers can place individual sonic elements inside a 3D soundfield, with their movement and position reflected by the speaker arrangement. This technology, says Dolby, creates an “illusion of an infinite number of speakers” and can fully immerse you in the action.
ATMOS ORIGINS
Of course Dolby Atmos, like so many proprietary Dolby sound formats, made its debut in the cinema. The award-winning Disney Pixar’s Brave was the first movie released with an Atmos soundtrack, and the sound system has since become a common attribute of premium screens.
The loudspeaker array embraces a 360-degree configuration in a Dolby Atmos cinema. Enclosures reach right to the edge of the screen, bolstered by additional speakers overhead. Within a Dolby Atmos-encoded soundtrack, every element within a frame can effectively become a separate sound object. Adaptive rendering in the cinema’s audio decoder determines exactly where a sound should be heard in any particular theatre. So while the number of loudspeakers in a screen may vary, mandated by its size and layout, the listening experience will be uniform.
Dolby Atmos arrived in the home on the back of Blu-ray, but it’s since been adopted by streaming services and — in some countries — even premium TV providers. Atmos isn’t just for movies and TV shows, though: it has added a whole new level of realism to live broadcasting, and even some video games. Sport led the way, but more recently Sky transmitted the Royal wedding in Dolby Atmos, and pumped out 19 hours of live music from the Isle of Wight Festival 2018.
Crucuially, Netflix now streams Dolby Atmos-encoded movies through its app on multimedia devices, and this spring Apple will
bring Dolby Atmos to Apple TV 4K with tvOS 12, and promises that iTunes will have the largest collection of Dolby Atmos movies to date.
HOME ATMOS-SPHERE
In its domestic guise, Dolby Atmos comes in all shapes and sizes. Home cinema systems, built around an AV receiver, offer the nearest you can currently get to that fully immersive theatrical experience, through a combination of regular surround sound, with either five or seven speakers, plus either two or four height channels (depending on available amplification).
A Dolby Atmos surround system with 5.1 surround and two-height 5.1 channels is commonly referred to as 5.1.2, while a 7.1 system with four-height channels is 7.1.4. Add a second subwoofer and this becomes 7.2.4, and so on.
Dolby Atmos height is commonly delivered via dedicated upfiring speakers (although if you have pro-style in-ceiling speakers, they’ll work too). By reflecting sound off the ceiling, these Dolby-enabled speakers fool your brain into thinking that audio is genuinely coming from above. This tends to be how things work for either a surround system or a soundbar, which will have the upfiring speakers built into its driver array.
You can get a Dolby Atmos soundbar with separate rear speakers, such as the Samsung HW-K950, which is designed to offer the best of both worlds, adding a level of true 3D sound without taking up the space of a big set of speakers. But many models have all of the speakers included in the single unit, as found on the Sony HT-Z9F or LG SK10Y. Ultimately, your choice of hardware will be driven by the space you use it in and the level of complexity you want.
Of course, compromises need to be made when keeping things simple. While an AV receiver, with a full complement of speakers, offers the most accurate Dolby Atmos experience, a soundbar will generally only be able to create a sense of width and height, without a matching sense of overhead audio. But when compared to a stereo soundbar, this improved scale should make the entire upgrade worthwhile.
IN THE ACTION
Dolby’s 3D audio format isn’t just about movies and television shows, however. It’s transformative for sports too. Examples from the UK show what’s possible with sports — in particluar soccer — and other events. The object-based soundsystem is uniquely able to bring home the true atmosphere of a large stadium event. In a live context, Dolby Atmos is used to convey the atmosphere of a match and the way a crowd can utterly envelop you.
Mixing Atmos audio for live events is fundamentally different from creating 3D audio for films. For one thing, the number of audio objects is far lower. Between two or four are assigned to atmosphere and crowd noise, while the commentary and PA system in the ground also become individual elements. Crowd chants or singing could also become an individual object. Clever use of ambiance will help to create a sense of stadium seating, so you really feel as if there are people sat around and above you.
The delivery of Dolby Atmos from set-top boxes is also rather different from that on Blu-ray. The latter presents Dolby Atmos as an extension of the Dolby True HD format, however Atmos from a set-top box or streaming service is delivered via Dolby Digital Plus, a more bandwidth-friendly conduit. Dolby Digital Plus, as we reveal later
on, will be the key to taking Dolby Atmos to another level.
If you’re an Xbox One owner, you can also avail yourself of Dolby Atmos games. All you need is the Dolby Access app installed on your console, and an encoded game, such as Gears of War 4, Rise of the Tomb Raider, or Assassin’s Creed Origins. You can then route an Atmos bitstream from your Xbox console to an AV receiver or soundbar. In addition, there are a number of Dolby Atmos enabled headphones that can also be used with the Dolby Access app. Those headphones include the Turtle Beach Stealth 700 gaming headset and the Plantronics RIG line of gaming headsets (the 500 PRO series and 800LX are standouts).
Both LG and Sony offer a selection of screens with integrated Dolby Atmos audio decoding. These can unfold Atmos audio from Netflix, as well as from external sources such as a set-top box or Blu-ray player. The TV itself doesn’t do anything clever with the Atmos track; the important thing is that it can send the bitstream of audio out over HDMI (using the set’s audio return channel, or ARC), where it can be decoded by an AV receiver or soundbar.
THE HEIGHT OF MUSIC
Dolby Atmos is slowly finding an active role within the music industry, and can now be experienced in all its live glory. In fact, the object-based sound technology already has a home on the dance club circuit: Ministry of Sound became the first venue in the world to install a Dolby Atmos sound system. The club’s 600-capacity Dolby-equipped space, called The Box, features a truly ear-busting 60 speakers, 22 channels and a synchronised lighting system.
With movies, object-based audio enables individual items to be steered with precision around a soundstage. In its club guise, Dolby Atmos enables a DJ to pan audio dynamically in real time. Multiple stems of music can be washed in any direction around a venue, creating a unique listening experience.
If clubbing isn’t your idea of a good time, there are other musical options on offer. Last year R.E.M issued a Dolby Atmos remix of Automatic for the People, to celebrate the album’s 25th anniversary. If you’re looking for something a little more esoteric, you might want to check out Prometheus: The Dolby Atmos Experience by symphonic metal band Rhapsody. It’s the kind of thing Thor would chill to between quests, while polishing his mighty hammer.
Dolby hasn’t had a clear run at the next- gen audio market, however. A competing system, Auro-3D, created by Belgium-based Auro Technologies, has recently garnered a smattering of studio support. Beyond some isolated appearances on Blu-ray (such as Adam Sandler’s film Pixels, of all things), it hasn’t really amounted to much.
Dolby Atmos’ biggest rival, therefore, is DTS:X. This is a soundalike object-based system from the makers of DTS-HD Master Audio, a format that dominated soundtracks on regular Blu-ray. DTS has been far less successful in getting DTS:X off the ground, but there is still studio support for it, and consequently all Dolby Atmos AV receivers, and some soundbars, offer compatibility.