Dolby® Pro Logic® II is an advanced matrixing technology that allows broadcasters to deliver convincing, realistic surround sound on stereo-only services.
Brings compelling surround sound to your listeners simply and economically via stereo broadcasts
Delivers surround-encoded audio, compatible with mono, stereo, and all generations of Dolby Pro Logic surround playback
Makes minimal impact on stereo broadcast infrastructure
Complements discrete 5.1 audio on your other services
Offers encoding tools to create matrix-encoded stereo from discrete 5.1-channel content for broadcast program preparation
Dolby Pro Logic II encoding can transform ordinary two-channel audio into realistic and engrossing surround sound for your listeners with multichannel audio systems and televisions including this technology, while your other listeners experience entirely normal mono or stereo.
During program production, a Dolby Pro Logic II encoder combines as many as five input signals—Left, Center, Right, Left Surround, and Right Surround—into a matrix-encoded, two-channel Left total/Right total (Lt/Rt) signal. The encoded signal is thereafter treated as conventional two-channel stereo audio throughout the broadcast distribution chain.
Stereo audio encoded with Dolby Pro Logic II can be decoded by any form of Dolby Pro Logic. Listeners with Pro Logic II decoding in particular (now standard on the vast majority of home surround systems) will benefit from three front channels, full-bandwidth stereo surrounds, advanced steering technology, and an exceptionally stable soundfield. With conventional stereo and mono playback, listeners experience no loss of critical soundtrack content.
Why Dolby
Dolby offers broadcast solutions that include the DP563 Dolby Surround and Pro Logic II Encoder and the DP564 Multichannel Audio Decoder.
With the DP563 encoder, you can create either a Dolby Pro Logic II (Lt, Rt) or a Dolby Surround (Lt, Rt) stereo mix directly from any discrete 5.1 mix for broadcast on stereo services. With Dolby E 5.1 content, metadata authored during production can enable the DP563 to create an Lt/Rt stereo mix automatically, with parameters exactly as specified by the program producers.
With the DP564 decoder, you can decode and monitor Dolby Digital, Dolby Digital Surround EX™, Dolby Pro Logic, and Dolby Pro Logic II programs, as well as regular two-channel PCM soundtracks.
We also license Dolby Pro Logic II encoding technology to professional audio manufacturers for use in products and systems that incorporate such other functions as video encoding and transport stream multiplexing.
Dolby Pro Logic II matrix encoding was developed to allow a listening experience closer to that provided by the discrete Dolby Digital 5.1-channel format used for DVDs, digital cable, HDTV and DTV, satellite, and the most sophisticated video games. Pro Logic II delivers five full-range channels, including two surround channels, matrix-encoded onto an otherwise standard (and compatible) stereo transmission.
Critical to Dolby Pro Logic II is its decoder design. In previous logic decoders, including the original Dolby Pro Logic technology, the control circuit looks at the relative level and phase between the input signals. This information is sent to the variable output matrix stage to adjust VCAs controlling the level of antiphase signals. The antiphase signals cancel the unwanted crosstalk signals, resulting in improved channel separation. This is called a feed-forward design.
Dolby Pro Logic II looks at the same input signals and employs a servo loop to match their levels. These matched audio signals are sent directly to the matrix stages to derive the various output channels. Because the same audio signals that feed the output matrix are themselves used to control the servo loop, it is called a feedback logic design. Incorporating global feedback around the logic steering process improves steering accuracy and dynamic behavior.
Dolby Pro Logic II
Sophisticated, matrix decoding technology that expands any two-channel source audio, such as CDs and stereo-encoded videocassettes, video games and TV broadcasts, to a five-channel full bandwidth (range) playback (Left/Center/Right/Left surround/Right surround), resulting in a surround experience.
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