Beyond channels
Traditional surround formats are channel-based: the soundtrack is mixed for fixed speaker positions such as 5.1 or 7.1. Dolby Atmos adds object-based metadata, allowing sounds to be positioned and moved through a three-dimensional space that includes height. In a home cinema, the AV receiver renders those objects to the speakers you actually have, whether that is 5.1.2, 5.1.4 or a larger layout. The advantage is not only overhead effects; it is smoother movement, better ambience and a more convincing soundfield when the room is designed properly.
