Matters Concerning Audio - A Practical Guide to Video and Audio Compression - page 165

Table 7-2 Audio Track Arrangements (Continued)

Tracks Speakers Description

Dolby 3 front and An analog-matrixed signal is decoded to create the

Surround 1 rear extra surround channels. Too much compression

will destroy the matrix information. Separate them
out and then encode each independently.

Quadraphonic 2 front and An experimental analog surround format used for

2 rear music in the 1970s. Not much content survives in

this format.

5.0 surround 3 front and A modern surround format used for music

2 rear applications and lacking the low frequency channel.

Dolby Digital 3 front, Surround systems constructed according to the

(AC-3) 2 rear, and 1 Dolby model are configured in a variety of ways

low-frequency with anything from 1 to 6 channels being used.

channel There are also complex matrix-encoding signals that

must be preserved so the older Dolby Surround
systems will work. This is critical, and you must
have some knowledge of how this system works to
be able to encode it competently. Most important, the
sample rate must be high enough to preserve the
surround information. There are many versions and
variants of this system, and it is only Dolby Digital
5.1 if it says so on the box.

DTS Digital 3 front, An alternative to the Dolby system is the Digital

Surround 5.1 2 rear, and 1 Theatre Sound system. This is often presented on

low-frequency major DVDs containing Hollywood blockbuster

channel movies as an alternative to the Dolby sound track. It is

not unusual for DVD video files to have 10 or more
audio tracks associated with them. Every one has to be
carefully encoded and precisely synchronized.

THX 3 front, This extends the DTS system from 5.1 channels

Surround ES™ 3 rear, and 1 to 6.1. All the earlier caveats apply. You must be

low-frequency confident about what you are doing when encoding

this sort of channel complexity. Also known as DTS-
ES 6.1.

THX Surround 3 front, 3 rear, and This is also known as Dolby Digital EX and

EX™ 1 low-frequency supports 6.1 audio channels.

channel

Sony SDDS 5 front, 2 rear, and This is used in large cinema auditoriums and has

1 low-frequency 2 additional speakers on either side of the screen.

channel

Continued