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Re: surround sound tech info?
Hermann Stemberger replied to Jim Stevenson:
There are many types of Surround: Dolby Stereo
channel), Dolby Surround (Analog - also called "Pro
Just to clarify; Dolby Stereo and Dolby Surround are two different
for the same encoding. Dolby Stereo was designed for the movie industry
uses Dolby A or SR noise reduction, whereas Dolby Surround was
to domestic applications and has no noise reduction (except
switching between stereo on surround will
be noticed because you're "switching on" (at least) one
(from the back!).
As a matter of fact switching _off_ the surround channels is more
detected, provided that the surround mix was properly done.
shouldn't be too detectable.
There are different socalled "upmix"
(=make e.g. 5.1 channels out of 2)
algorhythms available. The most known is the (already mentioned)
Pro Logic Encoder.
Dolby Pro Logic only applies to _decoding_ a Dolby Stereo/Surround
A Dolby Stereo/Surround encoder was designed to encode four
of audio into two channels. Yes, you can consider Dolby Stereo encoding
an upmix algorhythm, but originally it is just an encoding
As far as i know there is just one
professional headphone surround
system from STUDER that is in development stage.
That would be the BRS (Binaural Room Simulation) system, now
by IRT - Institut für Rundfunktechnik in Munich. More info at
The Dolby Headphone was originally developed by Lake DSP,
and many of
the original forms of it and the hardware used is very
The two mailing lists mentioned are probably the best sources for
about surround sound. Here's one more discussion group, which deals a
with practical things: