Introduction|
Mono|
Dolby Stereo|
Dolby Surround|
Dolby Surround Pro-Logic II
Dolby Surround Pro-Logic II is an analogue format based on the original, but has a
number of new features that addresses the previous limitations of Dolby Pro-Logic
in an environment where the '5.1' channel format is commonplace. The existing format
has four channels - left, right, centre and surround. The surround channel is a
single, limited-bandwidth channel played back through two rear speakers that adds
atmosphere to a soundtrack. This channel, plus the centre, is matrixed within the
two-channel stereo recording for the left and right front speakers. The new encoding
and decoding system uses the same matrixed Dolby Surround soundtrack, but processes
it in a different way. Using new decoding technology, the rear channels can operate
independantly of the front channels and with each other, so the surround speakers
work in stereo rather than mono. They can also be presented with full-bandwidth
signals that enable the rear channels to go as loud as the front speakers. The new
decoder also does a better job of creating a dedicated sub-woofer channel for bass.
Dolby Pro-Logic|
Dolby Pro-Logic II|
Dolby Digital|
Dolby Digital Surround-EX|
DTS|
DTS-ES|
THX|
Sony SDDS|
Since the introduction of Dolby Surround Pro-Logic in the late 1980's, cinema
sound has been developed a great deal. With Laserdisc and the recent DVD-video
format offering the latest 5.1 channel digital surround formats like Dolby Digital
and dts, the original analogue surround system is often considered as a 'second-best'
alternative
