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.
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 the 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.
Dolby Atmos technology allows up to 128 audio tracks plus associated spatial audio description metadata (most notably, location or pan automation data) 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 ambiance 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 (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 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 fronts, surround, and even ceiling-mounted height channels for the precise panning of select sounds such as a helicopter or rain.