Chapter 3. Pro Tools Concepts; Hard Disk Audio Recording; The Digidesign Audio Engine - DigiDesign Pro Tools Reference Manual

Chapter 3: Pro Tools Concepts
This chapter explains the principles and con-
cepts that form the foundation of Pro Tools op-
eration and functionality.

Hard Disk Audio Recording

Tape-based recording is a linear medium—you
need to rewind or fast forward a tape to hear a
particular spot in a recording. To rearrange or re-
peat material in a linear system, you need to re-
record it, or cut and splice it.
Hard disk recording is a nonlinear (or random ac-
cess) medium—you can go immediately to any
spot in a recording without having to rewind or
fast forward.
Nonlinear systems have several advantages. You
can easily rearrange or repeat parts of a record-
ing by making the hard disk read parts of the re-
cording in a different order and/or multiple
times. In addition, this re-arrangement is non-
destructive, meaning that the original recorded
material is not altered.
Pro Tools is a nonlinear recording system that
lets you rearrange and mix recorded material
nondestructively.

The Digidesign Audio Engine

DAE (or Digidesign Audio Engine) is Digi-
design's real-time operating system for digital
audio recording, playback, and processing.
When you install Pro Tools, DAE is automati-
cally installed on your system.
In the same way that a computer's operating
system provides the foundation for programs
that run on the computer, DAE provides the
foundation for much of the hard disk recording,
digital signal processing, and mix automation
required by Pro Tools and other products from
Digidesign and its Development Partners.
The DAE Playback Buffer Size determines the
amount of memory DAE allocates to manage
disk buffers.
For information on configuring the DAE
Playback Buffer Size, see "DAE Playback
Buffer Size" on page 45.
The DAE Playback Buffer Size can be changed in
the Playback Engine dialog (see "Playback En-
gine Dialog" on page 14).
Chapter 3: Pro Tools Concepts 13