Dolby Pro Logic

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Dolby Pro Logic is a surround sound processing technology developed by Dolby Laboratories, designed to decode soundtracks encoded with Dolby Surround. The terms Dolby Stereo and LtRt (Left Total, Right Total) are also used to describe soundtracks that are encoded using this technique. Dolby Stereo—also known as Dolby MP (Motion Picture) or Dolby SVA (stereo variable-area)—was developed by Dolby in 1976 for analog cinema sound systems. The format was adapted for home use in 1982 as Dolby Surround when HiFi capable consumer VCRs were introduced. It was further improved with the Dolby Pro Logic decoding system after 1987. The Dolby MP Matrix was the professional system that encoded four channels of film sound into two. This track used by the Dolby Stereo theater system on a 35mm optical stereo print and decoded back to the original 4.0 Surround. The same four-channel encoded stereo track was largely left unchanged and made available to consumers as "Dolby Surround" on home video. However...

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