Surround Sound for Stereo Broadcast Transmissions

Transform ordinary two-channel audio into realistic and engrossing surround sound for your television broadcast audience with Dolby Pro Logic™ II and Dolby Surround technologies. Matrix surround sound is possible on any two-channel analog or digital television service or entertainment media, including programs destined for over-the-air and stereo-only television, PC and console games, or VHS tapes.

During creation, Dolby Pro Logic II and Dolby Surround programs are matrix-encoded onto two audio outputs. They are treated as two-channel or stereo audio throughout the broadcast distribution chain, then decoded back into surround sound by the viewer's home receiver. Dolby Pro Logic II and Dolby Surround broadcasts perfectly complement the Dolby Digital 5.1 broadcasts available on DTV services.

Dolby Pro Logic II is incorporated into nearly every Dolby Digital home theater system, and offers five full-range channels (including stereo rear channels), advanced steering logic for maximum channel separation, and an exceptionally stable soundfield. Dolby Pro Logic II programs provide five-channel playback on consumer systems equipped with Dolby Pro Logic II decoding, and are fully backward-compatible with Dolby Surround Pro Logic, stereo, or mono systems.

During program production, the Dolby Pro Logic II encoder combines five input signals-Left, Center, Right, Left Surround, and Right Surround-into the matrix-encoded, two-channel Lt/Rt signal.

Dolby Surround Pro Logic, the original Dolby professional matrix-surround encoding technology, is featured in millions of home A/V receivers worldwide. Dolby Surround Pro Logic decoding in consumer products features four-channel playback: Left, Center, and Right, plus a mono surround channel that's usually split between two rear speakers.

During program production, the Dolby Surround encoder combines four channels-Left, Center, Right, and mono Surround-into a two-channel Lt/Rt output for recording or distribution on any two-channel analog or digital medium.

More information:
Technical Library
Dolby Surround and Dolby Pro Logic II products
Broadcast Engineering, November 2003
Dolby Pro Logic II vs. SRS Circle Surround.