Specifications
Pro Tools Reference Guide502
LCRS for Dolby Surround
Dolby Surround (Pro Logic) is a four-channel
format that is one of the most widely installed
consumer surround formats.
This format, which requires Dolby encoding
and decoding technology, provides three full-
range front speakers left, center, and right, plus
a mono surround channel (often split and mon-
itored through pairs of satellite speakers, but a
single “rear” channel nonetheless).
Surround Format Example
The goal of Dolby Surround encoding is to make
a four-channel mix (LCRS) more portable, by
transforming it into an encoded two-channel
mix referred to as Lt/Rt. Lt and Rt represent
Left Total and Right Total, respectively. When-
ever you see Lt/Rt, it refers specifically to mate-
rial that has been processed by a Dolby Sur-
round Encoder (such as the Dolby SEU4 or
Dolby Surround Tools plug-in).
The Lt/Rt mix can then be transported, trans-
mitted, or played as a stereo mix, making it
compatible with most home and theater sys-
tems. Alternately, the Lt/Rt pair can be decoded
back into an LCRS mix in home theater systems
where the required decoding hardware is avail-
able.
5.1 for Dolby Digital and DTS
Both Dolby Digital and DTS formats are six-
channel, 5.1 formats. Both provide five full-
range speakers and a sub. These two surround
formats use different track layouts, filtering, and
compression as part of their specifications.
.1 Formats
The “.1” in any multichannel mix format indi-
cates an LFE (Low Frequency Effects) track in the
mix. Whenever a decimal is part of a surround
format, it indicates a discrete Sub channel in the
surround playback system that is intended for
playback through a subwoofer speaker. For ex-
ample, Dolby Digital is a 5.1 format intended for
playback through systems with five full-range
speakers and one subwoofer speaker. Dolby Sur-
round EX is a 6.1 format, with six full-range
speakers and one subwoofer speaker. SDDS is a
7.1 format, with seven full-range speakers and
one subwoofer speaker.
Sub content will include the LFE channel of a
“.1” format mix, as well as the effects of any bass
management in the playback system. See “LFE”
on page 503.
.0 Formats
The “.0” formats (5.0, 6.0, 7.0), while not associ-
ated with any specific surround formats, are use-
ful in many mixes as sub-paths. For example,
not all tracks will have content that needs to be
routed to the LFE channel (the “.1” channel).
Assigning such tracks to a 5.0 path provides a
360° panner without LFE controls.
For professional results, always use profes-
sional-level products (such as the Dolby
Model SDU4 Decoder, Model DP564 De-
coder, or Dolby Surround Tools plug-in)
when mix monitoring. Pro Logic-equipped
consumer products have auto-balancing
features which, if used for mix monitoring,
may contribute to inappropriate mixing de-
cisions