Whats the difference between Pro Logic, Pro Logic II, and Dolby Digital 5.1?
Dolby Pro Logic is a matrix decoder that decodes the four channels of surround sound that have been encoded onto the stereo soundtracks of Dolby Surround program material such as VHS movies and TV shows. Dolby Surround is a matrix encoding process that in essence folds Left, Center, Right, and Surround channels onto stereo soundtracks. A Pro Logic decoder unfolds the four channels on playback (without a Pro Logic decoder, the encoded program plays in regular stereo). Dolby Pro Logic II is an advanced matrix decoder that derives five-channel surround (Left, Center, Right, Left Surround, and Right Surround) from any stereo program material, whether or not it has been specifically Dolby Surround encoded. On encoded material such as movie soundtracks, the sound is more like Dolby Digital 5.1 (see below), while on unencoded stereo material such as music CDs the effect is a wider, more involving soundfield. Among other improvements over Pro Logic, Pro Logic II provides two full-range surroun
