Dolby's "object-based" surround sound encoding technology, introduced in 2012. In contrast to channel-based systems, audio objects can be positioned anywhere in 3D space. Atmos supports 128 audio tracks and up to 64 speakers in the cinema, while home theaters require at least a 5.1 system plus two "height speakers," resulting in a 5.1.2 system. The height speakers can be in or on the ceiling, or they can be "upward firing" units built into or placed on top of the front speakers. However, Dolby recommends four height speakers for the best realism (a 5.1.4 configuration). Transformers: Age of Extinction was the first Atmos Blu-ray movie. Both Dolby Atmos and DTS:X introduced object-based surround sound (see DTS
). See surround sound
A 5.1.2 Atmos Configuration
Atmos requires at least two "height" speakers that are ceiling mounted. However, upward-firing speakers can be built into or placed on top of the front speakers.