Apple Logic Pro 9 - Manual (Page 1186)

SACD: Super Audio Compact Disc
Basically, the Sony-Philips version of DVD-A. SACD audio is stored in a format called Direct
Stream Digital, which has a sampling rate of 2.8224 MHz. SACD discs must contain a stereo
mix, but usually also offer a 5.1 mix (although this is optional).
Pro Logic II
Pro Logic II uses two full-range rear channels, unlike the original Pro Logic (LCRS) format.
It does not, however, use the LFE channel. In other words, this is a 5.0 format, so simply
disable the LFE channel in Logic Pro if you want to deliver a Pro Logic II soundtrack.
DTS (Digital Theater Systems)
Soundtracks generally sound better than Dolby Digital EX equivalents because they use
a 3:1 compression ratio, whereas Dolby uses a 12:1 ratio. Less compression obviously
means more storage space is required on the delivery medium.
1186 Chapter 39 Working with Surround