Dolby Digital Surround EX

A development to Dolby Digital by Dolby and Lucasfilm THX. It was first released in 1999 for the film Star Wars Episode I: The Phantom Menace.

In this system, the rear channel is matrixed, to offer a more enclosing surround sound experience. The result can be played without loss of information on standard 5.1 systems, or played in 6.1 or 7.1 on systems equipped with Surround EX decoding and additional speakers.