A surround sound processing technology that can extract center, left, right, bass and stereo surround channels from a stereo source. Pro Logic IIx can additionally extract two rear surrounds from either stereo or 5.1 sources, and Pro Logic IIz further extracts front stereo height channels.
Multiple modes may be offered by the system: Movie mode, Music mode and Game mode.
PLII works fundamentally as a matrix decoder with servos that accentuate the directionality of the current determined dominant signal by negative feedback in the other channels. The surround channels are fed by signals of inverted phase while the height channels contain uncorrelated, ambient signals.
Although PLII works from basically any stereo source, stereo programmes can be specifically encoded for surround decoding by PLII with matrix encoding. These programmes may be branded with the "Dolby Stereo" or "Dolby Surround" logo.
DO NOT believe Eazy-X's definition. It sucks so bad.
"This song is encoded by Dolby Pro Logic II!"
"No, Pro Logic II is a decoder only."