Dolby Pro-Logic

• Pro-Logic is the original and still dominant technology.
• An analog decoding processor that will extract the four channels from any source (Videotape, DVD, Satellite, Stereo Cable of Laser Disc) with Dolby Surround encoding.
• The information is embedded in the two channels of stereo sound.

Dolby Digital or AC-3

• Six channel technology and the choice of the mew DBS satellite braodcasters.
• On film the digital information is iptically placed in a highly compressed format in the spaces between the spricket holes.
• This technology is not available on videotapes (which are analog).
• AC-3 is becoming standard in many audio processors.

DTS

• Six channel technology.
• In a therater system, the digital informationis stored on a CD that is synchronized with an optical time code on the film.
• This technology is not restricted by the meager space available on a reel of film and xontains more information in a less compressed mode.
• The relatively low upgrade cost for movie theaters has made this a very popular technology and there are many who feel that DTS does sound better.
• While the future of DTS appears bright, the technology is just becoming available in higher end consumer electronic products.

SDDS from Sony

• An eight channel technology that is not availble in the home.