Introduction:
	There is a small about of people in our industry that truly understand surround sound. It is sure to play an ever growing role in the media technologies; knowing and understanding surround sound could enhance job opportunities. If you expand your opportunities they could increase your client base and prestige in the field of mixing music as well as soundtracks for movies or gaming. By investing in a surround monitoring system , learning the basic tools and techniques of mixing and mastering you can give your career a marketing age.

Past to Present:
	Up until the 1940's all of the soundtracks were played back in mono. On November 13th of 1940, Walt Disney's Fantasia opened up the sound field to stereo. Fantasia was the first to introduce multi-channel sound to the public. In the early 1950's Cinemascope and Todd-AO both used magnetic tracks that existed alongside the release print picture, and required the projector be fitted with special playback heads, amps, and speakers. With popularity and audio quality increasing in the 1970's came the development of Quadraphonic sound (Quad). In 1982 Dolby labs introduced "Dolby Surround". By 1987 millions of homes were listening thru high end audio systems. It wasn't until 1992 were discrete 5.1 surround sound became possible with Dolby's AC3 surround encode/decode system (Dolby Digital).

Sound Interfacing:
	Surround requires at least 6 output channels, it logically follows your interface with at least two inputs and six outputs or a multichannel audio interface. The various output buses of a DAW are designed to route to the first six outputs in a L/R/C/S/LS/RS configuration. A number of USB /Firewire interfaces have come into the market that fully support surround sound. These devices allow audio to be easily and cost efficiently routed from your host DAW or application to an external amp or active monitor system. These audio cards might include a driver that has extensive monitor controls for varying setup levels switching between modes such as mono, stereo, and surround.

                             SURROUND MASTERING AND DELIVERY FORMATS 

Dolby Digital:
	Also known as AC3, this is a popular codec thats used to encode digital audio into a multichannel bit stream through the use of perceptual coding techniques. This code eliminates unused audio that is masked or imperceptible, the amount of data that's encoded within the bitstream can can be greatly reduced when compared to its uncompressed counterpart.

DTS (Digital Theater System):
	An audio encoding scheme that supports up to 6.1 channels of discrete audio from a single data stream for use in cinema sound DVD/Home theatre and multimedia. The DTS codec exists in several format flavours. DTS is used to encode audio data at rates of 1.5 Mbit/ sec or 754 Kbit/ Sec. DTS stores the encoded data on separate CD-Rom discs.

Dolby Pro Logic:
	A common delivery format for getting surround sound into the masses is through the use of Dolby Pro Logic. Its able to derive a surround soundscape from a standard pair of stereo channels. When Dolby Pro Logic is switched in, it's possible to listen to a stereo program (of any type) in surround. 

SRS:
	The circle surround format forms SRS technologies, it also makes use of matrix signal processing and phase steering technology to encode and decode surround sound. When listening to Circle Surround encoded material, a number of "spatial " enhancements can be taken advantage of from a stereo or surround setup.

WMA:
	The Windows Media Audio codec was designed for digital download and multimedia formats, has been optimized for streaming or "download and play" delivery at bit rates of ranging from 28 Kbit/Sec. True sound can be played from a standard window XP computer. It is also possible to play back surround encoded files from a stereo computer or media player through the use of a down mix codec that mixes the canter and rear channels into L-R channels.

MP4:
	Essentially based on Apple's Quicktime MOV format and is capable of containing audio, video and subtitle data streams in various bit stream formats including surround sound. This format allows for the distribution of audio and video content over download and other data transmission media in a way that can be protected using an optical digital rights management scheme. 

Mixing in Surround:
	Any device having a number of multiple bus consoles can be used to create a surround sound mix (typically having eight or more buses). Whether working in an analog hardware, digital hardware, or DAW mixing environment, the ability to pan mono or stereo sources into a surround soundscape without difficulty can make the difference between a difficult compromised mix and one that lifts spirits.

Reissuing Back Catalog Material:
	One of the unintended by products of older, classic projects that are being reissued into surround sound by the record companies is the resurrection and the rescue of their older analog (and digital) masters that are aging to point that restoration becomes a monumental task. Listening to a well crafted surround project over killer speakers in the studio home playback or a home theater system can rank way up there with the best.