Setup guide

Appendix F: TDM Mixing and DSP Usage 103
DSP Cache
Pro Tools HD also maintains a Plug-in and Mixer
cache for allocated DSP when closing and open-
ing sessions. While this does not change the
time it takes to open the first session after you
launch Pro Tools, it does result in being able to
open and close all subsequent Pro Tools sessions
quickly, especially when using the Revert To
Saved command or when opening similarly con-
figured sessions.
As long as Pro Tools is running, the DSPs will
only be completely purged if you open a session
with a different sample rate or one with differ-
ent Playback Engine settings.
When using DSP caching, the System Usage
window may not always accurately show the
DSP resources your session is currently using.
For an accurate display of current DSP usage,
you can either disable DSP caching or purge the
DSP cache.
To enable (or disable) DSP Caching:
1 Open the System Usage window (Windows >
System Usage).
2 Click the DSP Cache pop-up menu and select
(or deselect) Use DSP Cache.
To purge the DSP cache:
1 Open the System Usage window (Windows >
System Usage).
2 Click the DSP Cache pop-up menu and select
(or deselect) Purge Cache. This refreshes the Sys-
tem Usage display.
Setting Up Sessions to Use DSP
Efficiently
The dynamically configurable mixing environ-
ment in Pro Tools lets you make choices based
on the type of setup you want to have—such as
how many inputs you want for your mixer, how
many plug-ins you want to use, or how many
sends you need.
For example, you could allocate all of your DSP
power to create a large mixer with dozens of
channels—but you would not be able to use as
many busses, sends, or TDM plug-ins. Alterna-
tively, you could create a mixer with a smaller
number of mixer channels plus some sends and
Auxiliary Inputs for returns, and TDM plug-ins
on several tracks.
You can set up your session by choosing one of
the session templates supplied with your system
as a starting point, or by building it from
scratch. If you are starting from scratch, a good
rule of thumb is to start by building your mixer
first, since at least one of the DSPs in your sys-
tem is automatically dedicated to mixing. Start
with audio tracks, then add sends and Auxiliary
Inputs, and finally add plug-ins as available DSP
allows. Master Faders do not use additional DSP
power.
Another feature available for DSP manage-
ment is Active and Inactive switching. See
the Pro Tools Reference Guide for more in-
formation.
RTAS (Real-Time AudioSuite) plug-ins, as
well as AudioSuite
plug-ins, do not use DSP
and are always available. Refer to your
Di-
giRack Plug-Ins Guide
for more information.