Dolby Atmos

**Dolby Atmos** is a surround sound technology developed by Dolby Laboratories. It expands on decreasing surround sound systems by adding height channels, allowing sounds to be interpreted as three-dimensional objects. Following the release of Atmos for the cinema market, various consumer technologies have been released under the Atmos brand, using in-ceiling and up-firing speakers.

## History

The first Dolby Atmos installation was in the Dolby Theater in Los Angeles, for the premiere of *Brave* in June 2012. Throughout 2012, it saw a limited release of about 25 installations worldwide, with an increase to 300 locations in 2013. There were over 6,000 locations as of July 2020. Dolby Atmos has also been adapted to a home theatre format and is the audio component of Dolby Cinema. Most electronic devices since 2016, as well as smartphones after 2017, have been enabled for Dolby Atmos recording and mixing. The full set of technical specifications for Dolby Digital Plus with Dolby Atmos are standardized and published in ETSI TS 103 420.

*Game of Thrones* was the first television show mixed in Atmos, beginning with its 2016 Blu-ray reissue. R.E.M.'s 1992 album *Automatic for the People* was the first significant music release with its 25th-anniversary reissue in 2017.

## Technology

Dolby Atmos technology allows up to 128 audio tracks plus associated spatial audio description metadata (most notably, location or pan automation data) with being distributed to theatres for optimal, dynamic rendering to loudspeakers based on the theatre capabilities. Each audio track can be assigned to an audio channel, the traditional format for distribution, or an audio "object." By default, Dolby Atmos has a 10-channel 7.1.2 bed for ambience stems or center dialogue, leaving 118 tracks for objects.

Dolby Atmos home theatres can be built upon traditional 5.1 and 7.1 layouts. For Dolby Atmos, the terminology differs slightly: a 7.1.4 Dolby Atmos system is a conventional 7.1 structure with four overhead or Dolby Atmos-enabled speakers.

With audio objects, Dolby Atmos enables the re-recording mixer using a Pro Tools and Nuendo plugin (available from Dolby) or a Dolby Atmos equipped large format audio mixing console such as AMS Neve's DFC or Harrison's MPC5, to designate the apparent source location in the theatre for each sound, as a three-dimensional rectangular coordinate relative to the defined audio channel locations and theatre boundaries.

During playback, each theatre's Dolby Atmos system renders the audio objects in real-time. Each sound is coming from its designated spot for the loudspeakers present in the target theatre. By way of contrast, traditional multichannel technology nearly burns all the source audio tracks into a fixed number of channels during post-production. This has traditionally forced the re-recording mixer to make assumptions about the playback environment that may not apply very well to a particular theatre. The addition of audio objects allows the mixer to be more creative, to bring more sounds off the screen, and be confident of the results.

The first-generation cinema hardware, the "Dolby Atmos Cinema Processor," supports up to 128 discrete audio tracks and up to 64 unique speaker feeds. The technology was initially created for commercial cinema applications and was later adapted to home cinema. In addition to playing back a standard 5.1 or 7.1 mix using loudspeakers grouped into arrays, Dolby Atmos also gives each loudspeaker its unique feed based on its exact location. They enable many new fronts, surround, and even ceiling-mounted height channels for the precise panning of select sounds such as a helicopter or rain.

## Consumer implementations

### Home theater version

At the end of June 2014, Dolby Labs' hardware partners announced that Dolby Atmos would soon be coming to home theatres. Dolby Atmos-enabled movies are available with Kaleidescape's movie players.

Several established manufacturers of audiovisual home entertainment devices were announcing new products that have now brought Dolby Atmos into home theatres across the globe. Products offered range from premium home cinema receivers and preamplifiers to mid-range home-theatre-in-a-box (HTiB) packages of well-known brands such as Denon, Marantz, Onkyo, Pioneer and Yamaha, plus further models from lesser-known manufacturers and brands. On June 4, 2018, Apple announced that tvOS 12 for AppleTV 4K would support Dolby Atmos when released in Fall 2018.

The first movie to be released on Blu-ray with Dolby Atmos was *Transformers: Age of Extinction*. The first video game to use Dolby Atmos was *Star Wars: Battlefront*, with a special agreement between EA and Dolby Laboratories. This game uses HDMI bitstreaming from the PC to deliver Atmos audio to consumer Audiovisual Receivers. Overwatch and Battlefield 1 for PC also have Atmos audio. On the Xbox One, Crackdown 3 and Gears of War 4 also support Atmos.

Dolby Atmos for Music, an audio-only iteration of the format, was adopted by streaming music services Tidal and Amazon Music in December 2019. However, Many could only enjoy it via headphones, a compromise at best. In May 2020, Tidal announced that the Dolby Atmos bitstream would be available over HDMI, allowing Dolby Atmos Music to be enjoyed on home theatre AV systems with a Dolby Atmos decoder and compatible soundbars. Dolby Atmos Music is only available to Tidal HiFi tier subscribers. Consistent streaming players include the Apple TV 4K, Fire TV Stick 4K, Fire TV Cube, Fire TV Stick (second-gen), Fire TV (third-gen), and NVIDIA Shield TV.

Sennheiser launched a new state of art Soundbar with built-in Dolby Atmos technology named AMBEO Soundbar in 2019 CES, Las Vegas. Soundbar has a 5.1.4 surround experience from a single device positioned for home entertainment. Sennheiser AMBEO Soundbar technology uses the reflection of sounds off the wall and roof surfaces, thus creates a spatial sonic experience with immersive 5.1.4 sound.

#### Implementation and differences from commercial implementations

Because of limited bandwidth and lack of processing power, Atmos in home theatres is not rendered the same way as in cinemas. A spatially-coded substream is added to Dolby TrueHD or Dolby Digital Plus or is present as metadata in Dolby MAT 2.0, LPCM like format. This substream is an efficient representation of the full, original object-based mix. It's not a matrix-encoded channel but a spatially-encoded digital signal with panning metadata. Atmos in home theatres can support 24.1.10 channels. It can also do up to 118 simultaneous dynamical objects with ten-bed channels and use the spatially-encoded object audio substream to mix the audio presentation to match the installed speaker configuration.

Nearby objects and speakers are clustered together to form aggregate objects to reduce bitrate, which is then dynamically panned in the process that Dolby calls spatial coding. Many may spread the original items' sound over multiple aggregate objects to maintain the actual objects' power and position. The spatial resolution (and hence the clustering's strength) can be controlled by the filmmakers when they use the Dolby Atmos Production Suite tools. Dolby Digital Plus has also been updated with Atmos extensions.

### Headphone and smartphone implementations

Dolby Atmos also has headphone implementations for PCs, the Xbox One, and mobile phones. They work by using audio processing algorithms to convert the Atmos object metadata into a Binaural 360° output using the usual two headphone speakers. This technique improves the previous Dolby Headphone technology, allowing for infinite channels of sound to be processed into a virtual surround experience.

Windows 10 Version 1703 Creators Update added platform-level support for spatial sound processing, including Windows Sonic for Headphones and Dolby Atmos for Headphones. Dolby Atmos for headphones requires a licence to function, purchased or redeemed inside the Dolby Access app.

Dolby Atmos has smartphone implementations for devices including but not limited to the iPhone XS/XR and later (when running iOS 13 or later), the Razer Phone and Razer Phone 2, the ZTE Axon 7, Samsung Galaxy S8/S8+, Samsung Galaxy S9/S9+, Samsung Note 9, Galaxy Note 8, Samsung Galaxy J8, Samsung Galaxy J6, Galaxy S10 series, Samsung Galaxy Tab, Samsung Galaxy A20, Samsung Galaxy A30 Samsung Galaxy A10, Samsung Galaxy M20, Samsung Galaxy M30, Samsung Galaxy M30s, Sony Xperia 1, Lenovo K8 Note, Lenovo K5 Note, Huawei Mate P20 Pro and Nokia 6. This implementation uses both the binaural headphone technology and a dual loudspeaker virtual surround sound implementation.

## See also

* Ambisonics, a similar spatial sound encoding technique. Nowadays used for some games and VR Audio
* Auro-3D, a similar, completely channel-based 3D surround system
* DTS:X, a competing fully object-based system
* Creative Super X-Fi, a competing surround sound "audio holography" system for headphones tuned to ear shape.