Dolby Atmos


Dolby Atmos is a surround sound technology developed by Dolby Laboratories. It expands on existing 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, a variety of 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 4,400 locations as of April 2019. Dolby Atmos has also been adapted to a home theater 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 major 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 to be distributed to theaters for optimal, dynamic rendering to loudspeakers based on the theater capabilities. Each audio track can be assigned to an audio channel, the traditional format for distribution, or to an audio "object." Dolby Atmos by default, has a 10-channel 7.1.2 bed for ambience stems or center dialogue, leaving 118 tracks for objects.
Dolby Atmos home theaters can be built upon traditional 5.1 and 7.1 layouts. For Dolby Atmos, the nomenclature differs slightly: a 7.1.4 Dolby Atmos system is a traditional 7.1 layout 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 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 theater for each sound, as a three-dimensional rectangular coordinate relative to the defined audio channel locations and theater boundaries.
During playback, each theater's Dolby Atmos system renders the audio objects in real-time such that each sound is coming from its designated spot with respect to the loudspeakers present in the target theater. By way of contrast, traditional multichannel technology essentially 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 theater. 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, the Dolby Atmos system can also give each loudspeaker its own unique feed based on its exact location, thereby enabling many new front, 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 theaters.
Among them were several established manufacturers of audiovisual home entertainment devices announcing new products that have now brought Dolby Atmos into home theaters across the globe. Products offered range from premium home cinema receivers and preamplifiers to mid-range home-theater-in-a-box 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 will support Dolby Atmos when released in Fall 2018.
The first movie to be released on Blu-ray with Dolby Atmos was . 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 Audio-Visual 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 it could only be enjoyed 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. Compatible streaming players include the Apple TV 4K, Fire TV Stick 4K, Fire TV Cube, Fire TV Stick, Fire TV, and NVIDIA Shield TV.

Implementation and differences from commercial implementations

Because of limited bandwidth and lack of processing power, Atmos in home theaters 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. This is not a matrix-encoded channel, but a spatially-encoded digital signal with panning metadata. Atmos in home theaters can support 24.1.10 channels, it also can do up to 118 dynamical simultaneous objects with 10 bed channels and uses the spatially-encoded object audio substream to mix the audio presentation to match the installed speaker configuration.
In order to reduce the bitrate, nearby objects and speakers are clustered together to form aggregate objects, which are then dynamically panned in the process that Dolby calls spacial coding. The sound of the original objects may be spread over multiple aggregate objects to maintain the power and position of the original objects. The spatial resolution 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 is an improvement on 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 both Windows Sonic for Headphones and Dolby Atmos for Headphones. Dolby Atmos for headphones requires a licence to function which can be 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, 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.