As surround sound became more widespread and well known, the quality and consistency started to vary considerably from one theatre and film to another. When George Lucas, the creator of Star Wars, started making the films, he wanted the film's quality to reflect that of his story and effort that went into producing the film. This meant a new standard in technical filmmaking. He founded Lucasfilm, a separate company that consisted only of skilled professionals, dealing with creating minimum standards a movie theatre, production studio and all equipment had to conform to before they could show his films, to ensure consistently high standards no matter where the film was shown. This was patented as the "bureau of standards" for film-related matters. It is known as Lucasfilm THX. THX literally stand for Tomlinson Hollmann Experiment!
More technological developments
In later years, further advances in digital signal processing have enabled soundtrack producers to add more channels to the standard 5.1 channel mix.
Two formats are now capable of delivering 7 channels discreet (6.1) or 8 channel matrixed (7.1) surround mixes off conventional DVD's. These formats are DTS-es and Dolby Digital EX. DTS-es adds a centre channel at the back to create more realistic surround signal placement and is a 6.1 channel system. The Dolby Digital-EX system adds two extra surround speakers, which results in two back surround speakers and two side surround speakers. These systems are referred to as extended surround systems. This was done to create more realistic fly-over and fly-across effects. Sound can now be sent across, over, through or between only the surrounds! This results in even more spectacular and realistic surround sound, as the more speakers there are, the less stress each speaker is subjected to and the more natural the sound becomes. Unfortunately, this also dramatically increases the cost of producing the soundtrack, so do not expect to find too many of these soundtracks. Luckily, if a customer invested in a 6- or 7.1 surround system, any modern processor will create sound to go to those channels.
The latest addition to surround formats is Dolby Pro Logic II. This new format is a drastic departure from the original Pro Logic, but retains the same genetic roots of Dolby Pro Logic by using non-encoded material (normally stereo) to produce surround sound. This new format is produced digitally and makes use of the complex digital processor, to afford the user a more realistic and natural sounding surround experience from stereo signals. Because of this there is no need for having a specially encoded soundtrack for Pro Logic II and can be obtained from any stereo recording. Most new surround receivers will be able to process this format.
There is also a new version of DTS that works with any stereo signal. This format called DTS neo:6 and is very similar in it's functioning to the way Pro Logic II works. It is said to be DTS's answer to Pro Logic and is included in most surround processors now. Both Pro Logic II and DTS neo:6 operate digitally and deliver staggering levels of realism and precision, despite being converted from stereo recordings. Both formats also offer two versions of their format for optimal use with different programme material. The two versions of neo: 6 and Pro Logic II are music and movie, with independent setups for both. These two different versions optimize the decoding software for the type of programme material used and results in more natural music reproduction and more vivid movie soundtracks.
Both Pro Logic II and neo:6 can also be extended to incorporate the newly added "extended surround" speakers, respectively called Pro Logic IIx and neo:6x, designed to make full use of the complete package of speakers in the system.