DigiDesign DigiRack Plug-ins User manual

DigiRack
™
Plug-ins
Version 7.3

Copyright
© 2007 Digidesign, a division of Avid Technology, Inc. All rights
reserved. This guide may not be duplicated in whole or in part
without the express written consent of Digidesign.
AudioSuite, Avid, Avid DNA, Avid Xpress, Digi 002, Digi 002
Rack, Digidesign, Mbox, Mbox 2, Mbox 2 Mini, Mbox Pro,
MultiShell, Pro Tools, Pro Tools|HD, Pro Tools LE, Pro Tools
M-Powered, and RTAS are either trademarks or registered
trademarks of Avid Technology, Inc. in the US and other
countries. All other trademarks contained herein are the
property of their respective owners.
Product features, specifications, system requirements, and
availability are subject to change without notice.
PN 9329-55974-00 REV A 01/07

Contents iii
contents
Chapter 1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1
Plug-in Formats . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1
System Requirements . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2
Conventions Used in This Guide . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3
About www.digidesign.com . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3
Chapter 2. Installation and Configuration . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5
Installing Plug-ins . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5
Organizing Plug-ins . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5
Chapter 3. Working with Real-Time Plug-ins . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9
Processing Power Requirements of TDM and RTAS Plug-ins . . . . . . . . . . . . . . . . . . . . . . . . . . 9
Delay in Signal Processing . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 13
Plug-ins as Inserts . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 15
Inserting Plug-ins on Tracks . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 16
The Plug-in Window . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 18
Clip Indicators . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 22
Using the Side-Chain Input . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 22
Tempo Sync . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 23
Automating Plug-ins . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 24
Instrument Plug-ins . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 27
RTAS Plug-ins on Auxiliary Input and Master Fader Tracks . . . . . . . . . . . . . . . . . . . . . . . . . . . 27
HTDM Plug-in Conversion to RTAS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 29

DigiRack Plug-ins Guide iv
Chapter 4. Working with AudioSuite Plug-ins . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 31
The AudioSuite Menu . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 31
The AudioSuite Window . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 32
AudioSuite Processing Preferences . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 37
Using AudioSuite Plug-ins . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 39
Chapter 5. Adjusting Plug-in Controls . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 41
Adjusting Plug-in Controls . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 41
Chapter 6. DigiRack Real-Time TDM and RTAS Plug-ins . . . . . . . . . . . . . . . . . . . . . . . . 43
EQ III . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 43
EQ II . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 57
Click . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 58
Dither . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 59
POW-r Dither . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 61
D-Verb . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 62
Dynamics III . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 64
Dynamics II . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 79
Mod Delay II . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 79
Signal Generator . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 81
SignalTools . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 82
Pitch . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 87
TimeAdjuster . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 90
Trim . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 92

Contents v
Chapter 7. DigiRack AudioSuite Plug-ins . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 95
EQ III . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 95
EQ II . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 95
Dynamics III . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 96
Dynamics II . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 96
Chorus . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 97
Flanger . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 98
Multi-Tap Delay . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 99
Ping-Pong Delay . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 100
Invert . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 101
Duplicate . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 101
Delay . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 101
Normalize . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 102
Gain . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 103
Reverse . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 103
Signal Generator . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 103
DC Offset Removal . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 104
Time Compression/ Expansion . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 104
Pitch Shift . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 106
Time Shift . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 107
Chapter 8. Plug-in Settings . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 115
Using the Librarian . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 115
Plug-in Settings Dialog . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 118
DigiBase and Plug-in Settings Files . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 119
Chapter 9. Using ReWire with Pro Tools . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 121
ReWire Requirements . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 122
Using ReWire . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 122
Tempo and Meter Changes . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 123
Looping Playback . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 124
Automating ReWire . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 124

DigiRack Plug-ins Guide vi
Appendix A. DSP Requirements for TDM Plug-ins . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 125
DSP Requirements . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 125
Appendix B. DSP Delays Incurred by TDM Plug-ins . . . . . . . . . . . . . . . . . . . . . . . . . . . 129
Index . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 131

Chapter 1: Introduction 1
chapter 1
Introduction
Plug-ins are special-purpose software compo-
nents that provide additional signal processing
functionality to Pro Tools
®
.
The DigiRack™ plug-ins included with
Pro Tools provide a comprehensive suite of dig-
ital signal processing effects that include EQ, dy-
namics, delay, and other essential functions.
Plug-in Formats
There are three formats of plug-ins:
• TDM plug-ins (real-time, DSP-based)
•RTAS
®
plug-ins (real-time, host-based)
• AudioSuite™ plug-ins (non-real-time, file-
based processing)
TDM Plug-ins
(Pro Tools HD Only)
TDM (Time Division Multiplexing) plug-ins
function as track inserts, are applied to audio
during playback, and process audio non-de-
structively in real time. TDM plug-ins are de-
signed for use with Pro Tools HD software on
Pro Tools|HD
®
systems, and rely on the process-
ing power of Digidesign DSP cards.
The number and variety of TDM plug-ins that
you can use simultaneously in a session are lim-
ited only by the amount of DSP available. You
can increase available DSP by installing addi-
tional DSP cards (such as HD Core, HD Accel, or
HD Process cards) in your computer. This
power-on-demand aspect is a significant advan-
tage of Pro Tools|HD systems.
References to Pro Tools LE™ in this guide
are usually interchangeable with Pro Tools
M-Powered™ or Pro Tools Academic™, ex-
cept as noted in the Pro Tools M-Powered
and Academic Getting Started Guides.

DigiRack Plug-ins Guide 2
RTAS Plug-ins
RTAS (Real-Time AudioSuite) plug-ins provide
features and functionality similar to their TDM
counterparts, but unlike TDM plug-ins, they rely
on and are limited by the processing power of
your computer. The more powerful your com-
puter, the greater the number and variety of
RTAS plug-ins that you can use simultaneously.
Because of this dependence on the CPU or
host
processing
, the more RTAS plug-ins you use con-
currently in a session, the greater the impact it
will have on other aspects of your system’s per-
formance, such as maximum track count, num-
ber of available voices, the density of edits pos-
sible, and latency in automation and recording.
RTAS plug-ins can be used with Pro Tools HD,
Pro Tools LE™.
AudioSuite Plug-ins
AudioSuite plug-ins are used to process and
modify audio files on disk, rather than nonde-
structively in real time. Depending on how you
configure a non-real-time AudioSuite plug-in, it
either creates an entirely new audio file, or alters
the original source audio file. Audio-Suite plug-
ins can be used on all Pro Tools systems and
Avid software.
System Requirements
To use DigiRack plug-ins you need any the fol-
lowing:
• A Digidesign-qualified Pro Tools system
running Pro Tools
• A Digidesign-qualified Pro Tools system
and a third-party software application that
supports the Digidesign TDM, RTAS, or
AudioSuite plug-in standards
• A qualified Avid
®
Xpress
®
, Avid Xpress DV,
or Avid DNA™ system (AudioSuite only)
• A qualified Digidesign VENUE system
(TDM only)
For complete system requirements visit the
Digidesign website (www.digidesign.com).
Compatibility Information
Digidesign can only assure compatibility and
provide support for hardware and software it
has tested and approved.
For a list of Digidesign-qualified computers, op-
erating systems, hard drives, and third-party de-
vices, visit the Digidesign website
(www.digidesign.com).

Chapter 1: Introduction 3
Conventions Used in This
Guide
All Digidesign guides use the following conven-
tions to indicate menu choices and key com-
mands:
:
The following symbols are used to highlight im-
portant information:
About www.digidesign.com
The Digidesign website (www.digidesign.com)
is your best online source for information to
help you get the most out of your Pro Tools sys-
tem. The following are just a few of the services
and features available.
Registration Register your purchase online. See
the registration form included with your system
for instructions.
Support Contact Digidesign Technical Support
or Customer Service; download software up-
dates and the latest online manuals; browse the
Compatibility documents for system require-
ments; search the online Answerbase or join the
worldwide Pro Tools community on the Digide-
sign User Conference.
Training and Education Study on your own using
courses available online or find out how you can
learn in a classroom setting at a certified
Pro Tools training center.
Products and Developers Learn about Digidesign
products; download demo software or learn
about our Development Partners and their plug-
ins, applications, and hardware.
News and Events Get the latest news from
Digidesign or sign up for a Pro Tools demo.
To learn more about these and other resources
available from Digidesign, visit our website
(www.digidesign.com).
Convention Action
File > Save Choose Save from the
File menu
Control+N Hold down the Control
key and press the N key
Control-click Hold down the Control
key and click the mouse
button
Right-click Click with the right
mouse button
User Tips are helpful hints for getting the
most from your Pro Tools system.
Important Notices include information that
could affect your Pro Tools session data or
the performance of your Pro Tools system.
Shortcuts show you useful keyboard or
mouse shortcuts.
Cross References point to related sections in
this guide and other Digidesign guides.

DigiRack Plug-ins Guide4

Chapter 2: Installation and Configuration 5
chapter 2
Installation and Configuration
Installing Plug-ins
The Digidesign DigiRack plug-ins are installed
when you install Pro Tools. For more informa-
tion about installing Pro Tools, see the Getting
Started Guide that came with your system.
If installing multiple packages of plug-ins, do so
in the following order:
1 DigiRack plug-ins (installed with Pro Tools).
2 Packs and other bundles included with your
Digidesign system.
3 Any additional plug-ins. Check with the man-
ufacturer of your plug-ins for compatibility in-
formation and support.
Organizing Plug-ins
You can customize how plug-in lists (plug-in
menus) are organized in the Insert selector and
Plug-in selector.
Use the “Organize Plug-in Menus By” pop-up
menu in the Pro Tools Display Preferences page
to organize plug-in menus in a Flat List (with
plug-ins in alphabetical order), Category, Manu-
facturer, or Category and Manufacturer.
Plug-ins organized by categories
Plug-ins organized by manufacturer

DigiRack Plug-ins Guide6
“Organize Plug-in Menus By” Option
Flat List Organizes plug-ins in a single list, in al-
phabetical order.
Category Organizes plug-ins by process category
(such as EQ, Dynamics, Effects, and Delay), with
individual plug-ins listed in the category sub-
menus. Plug-ins that do not have a Category de-
fined will appear in the Other Category folder.
Plug-ins can appear in more than one category.
Plug-in categories include:
•EQ
• Dynamics
• Pitch Shift
• Reverb
• Delay
• Modulation
• Harmonic
• Noise Reduction
• Dither
• Sound Field
• Hardware
• Instrument
• Other
• Wrapped Plug-ins
• Effects
Manufacturer Organizes plug-ins by their manu-
facturer (such as Digidesign, Eventide, Line 6,
McDSP), with individual plug-ins listed in the
manufacturer submenus. Plug-ins that do not
have a Manufacturer defined will appear in the
“Other” manufacturer folder.
Most Digidesign Development Partner plug-ins
will be sorted as Digidesign when view by man-
ufacturer is enabled.
Category and Manufacturer Organizes plug-ins
in two levels of menus. The top menus display
plug-ins by process category (such as EQ, Dy-
namics, and Delay), with individual plug-ins
listed in the category submenus. The bottom
menus display plug-ins by their manufacturer
(such as Digidesign, Eventide, Line 6, McDSP),
with individual plug-ins listed in the manufac-
turer submenus.
To select how plug-ins are organized:
1 Open or create a session.
2 Choose Setup > Preferences, and click the Dis-
play tab.
3 Click the “Organize Plug-in Menus By” pop-
up menu, and select one of the view options.
4 Click Done.
The current Organize Plug-in Menus By setting
is saved with Pro Tools preferences (it is not
saved with the Pro Tools session file).
Plug-in Favorites
To find a plug-in faster, a plug-in can be desig-
nated as a favorite. Favorite plug-ins are shown
at the top of the plug-in menu.
Choosing Category view for plug-in menus

Chapter 2: Installation and Configuration 7
When a plug-in becomes a favorite, it is still
shown in plug-in category and/or manufacturer
sub-menus (if enabled) and its name appears in
bold.
To designate a plug-in as a favorite:
■Control-click (Windows) or Command-click
(Mac) on a plug-in Insert button, and select a
plug-in from the menu (or sub-menus, if en-
abled) to designate it as a favorite.
To change the status of a plug-in favorite:
1 Control-click (Windows) or Command-click
(Mac) on a plug-in Insert button, a nd select a
plug-in favorite that you no longer want to des-
ignate as a favorite.
2 When selecting the plug-in favorite to change,
you can select the plug-in from the list of favor-
ites at the top of the plug-in menu, or in its plug-
in category/manufacturer sub-menu (where the
plug-in appears in bold).
Default Plug-ins
You can set a default EQ plug-in and Dynamics
plug-in, which places them at the top of the In-
sert selector pop-up menu on-screen, and first in
the list of menu choices when assigning inserts
on ICON worksurfaces.
To set a default plug-in:
1 Choose Setup > Preferences and click Mixing.
2 Under Setup, choose a plug-in from the De-
fault EQ or Default Dynamics pop-up menu.
3 Click OK to close the Preferences window.
Menu display of favorite plug-ins (Category view shown)
Favorite plug-ins
Plug-in categories
Default plug-in display in Insert selector menu
Default EQ plug-in
Default Dynamics
plug-in

DigiRack Plug-ins Guide8

Chapter 3: Working with Real-Time Plug-ins 9
chapter 3
Working with Real-Time Plug-ins
Real-time plug-ins process audio nondestruc-
tively in real time. They do not alter the original
source audio, but only apply their effect during
playback.
There are two formats of real-time plug-ins:
TDM Plug-ins Rely on the processing power of
Digidesign DSP cards. TDM plug-ins run only on
Pro Tools|HD systems.
RTAS Plug-ins Rely on the processing power of
your computer. RTAS plug-ins run on
Pro Tools|HD and LE systems.
Processing Power
Requirements of TDM and
RTAS Plug-ins
TDM and RTAS plug-ins differ in their process-
ing power requirements.
TDM Plug-ins
Each real-time TDM plug-in that is inserted in a
Pro Tools session uses a portion of your system’s
total available DSP resources.
Since these DSP resources reside on the cards
that make up your particular Pro Tools hard-
ware configuration, the amount of DSP avail-
able depends entirely on the number and type
of DSP cards in your system.
You can add more mixing and processing power
to your system by installing additional DSP
cards, provided you have unused PCI (or PCIe)
expansion slots in your computer or use a
Digidesign-approved Expansion Chassis.
The System Usage window (Window > System
Usage) shows how much DSP is available on
your system, and gives an approximation of
how it is currently being used.
For more information on the System Usage
window, see the Pro Tools Reference Guide.
System Usage window
See Appendix A, “DSP Requirements for
TDM Plug-ins” for relative numbers of in-
stances of each DigiRack TDM plug-in that
can be powered by a single DSP chip. DSP
capacity differs with card type.

DigiRack Plug-ins Guide10
DSP Sharing Between TDM Plug-ins
With Digidesign’s MultiShell™ II technology,
different types of TDM plug-ins can share the
same DSP chip at the same time. This lets you si-
multaneously use a greater variety of plug-ins by
efficiently managing the DSP available on each
chip in your system.
To take advantage of this capability, plug-ins
must be MultiShell II compatible. All
DigiRack TDM plug-ins with the exception of
Pitch are MultiShell II compatible.
Some third-party plug-ins may not be Multi-
Shell II compatible. To check compatibility,
contact the manufacturer.
RTAS Plug-ins
RTAS plug-ins rely on and are limited by the pro-
cessing power of your computer’s CPU. The
more RTAS plug-ins you use concurrently in a
session, the greater the impact it will have on
other aspects of your system’s performance,
such as maximum track count, the density of
edits possible, and latency in automation and
recording.
The CPU meter in the System Usage window
(Window > System Usage) shows how much of
your computer’s processing power is currently
being used by Pro Tools, and how much is still
available.
Improving RTAS Plug-in
Performance
You can increase the number of RTAS plug-ins
your system can use concurrently by increasing
the Hardware Buffer Size and CPU Usage Limit.
Hardware Buffer Size
The Hardware Buffer Size (H/W Buffer Size) con-
trols the size of the hardware cache used to han-
dle host processing tasks such as monitoring la-
tency and using Real-Time AudioSuite (RTAS)
plug-ins.
◆Lower Hardware Buffer Size settings reduce
monitoring latency, and are useful when you are
recording live input.
◆Higher Hardware Buffer Size settings provide
more audio processing and effects, and are use-
ful when you are mixing and using more RTAS
plug-ins.
To change the Hardware Buffer Size:
1 Choose Setup > Playback Engine.
2 From the H/W Buffer Size pop-up menu, select
the audio buffer size, in samples.
3 Click OK.
For more information on the System Usage
window, see the Pro Tools Reference Guide.
In addition to causing slower screen re-
sponse and monitoring latency, higher
Hardware Buffer Size settings can affect the
accuracy of plug-in automation, mute data,
and timing for Instrument or MIDI tracks.

Chapter 3: Working with Real-Time Plug-ins 11
RTAS Processors
The RTAS Processors setting determines the
number of processors in your computer allo-
cated for RTAS plug-in processing.
With computers that have multiple processors,
or that feature multi-core processing or hyper-
threading, this setting lets you enable multi-pro-
cessor support for RTAS processes. Used in com-
bination with the CPU Usage Limit setting, the
RTAS Processors setting lets you control the way
RTAS processing and other Pro Tools tasks are
carried out by the system.
◆A higher number of processors reserves more
CPU processing capacity for RTAS plug-in pro-
cessing. This is useful for sessions with large
number of RTAS plug-ins.
◆A lower number of processors leaves more
CPU processing capacity for automation, screen
redraws, and video playback in Pro Tools, or for
other application running at the same time as
Pro Tools.
To set the number of RTAS Processors:
1 Choose Setup > Playback Engine.
2 From the RTAS Processors pop-up menu, select
the number of available processors you want to
allocate for RTAS plug-in processing.
3 Click OK.
CPU Usage Limit
The CPU Usage Limit controls the percentage of
CPU resources allocated to Pro Tools host pro-
cessing tasks such as RTAS plug-in performance
and screen redraws.
◆Lower CPU Usage Limit settings limit the ef-
fect of Pro Tools processing on other CPU-inten-
sive tasks, such as screen redraws, and are useful
when you are experiencing slow system re-
sponse, or when running other applications at
the same time as Pro Tools.
◆Higher CPU Usage Limit settings allocate
more processing power to Pro Tools, and are
useful for playing back large sessions or using
more real-time plug-ins.
To change the CPU Usage Limit:
1 Choose Setup > Playback Engine.
2 From the CPU Usage Limit pop-up menu, se-
lect the percentage of CPU processing you want
to allocate to Pro Tools. (On dual-processor Mac
computers, this setting controls the allocation
of a single processor.)
3 Click OK.
Increasing the CPU Usage Limit may slow
down screen response on slower computers.
For more information on the Hardware
Buffer Size and CPU Usage Limit, refer to
the Pro Tools Reference Guide.

DigiRack Plug-ins Guide12
RTAS Error Suppression
You should only enable RTAS error suppression
if you are experiencing frequent RTAS errors
that are interrupting your creative workflow.
When RTAS error suppression is enabled, you
can experience a degradation of audio quality.
However, this may be acceptable in order to
avoid interrupting playback and recording
when working with instrument plug-ins. Be sure
to disable RTAS error suppression when you
need to ensure the highest possible audio qual-
ity, such as for the final mix or audio layback.
To enable RTAS error suppression:
1 Choose Setup > Playback Engine.
2 Select Ignore Errors During Playback/Record.
3 If available, you can also select Minimize Ad-
ditional I/O Latency.
4 Click OK.
RTAS Error Suppression Options
Ignore Errors During Playback/Record When en-
abled, Pro Tools continues to play and record
even if the RTAS processing requirements ex-
ceed the selected CPU Usage Limit. This can re-
sult in pops and clicks in the audio during play-
back and recording, but does not stop the
transport.
Minimize Additional I/O Latency When enabled,
any additional latency due to suppressing RTAS
errors during playback and record is minimized
to 128 samples. Suppressing RTAS errors re-
quires at least 128 samples of additional buffer-
ing on some systems. If the Minimize Addi-
tional I/O Latency option is disabled, the buffer
is half the H/W Buffer Size, or at least 128 sam-
ples (which ever is greater). If you are on an
older, slower computer, you may not want to
enable this option since doing so can adversely
affect performance.
Enabling Ignore Errors During Play-
back/Record only suppresses error reporting.
RTAS errors can result in pops and clicks in
the audio during playback and recording. To
avoid this, try increasing the CPU Usage
Limit and the HW Buffer Size, and reduce
the number of RTAS plug-ins in use in the
session.
Playback Engine dialog, Mbox 2 (Mac OS)

Chapter 3: Working with Real-Time Plug-ins 13
The Minimize Additional I/O Latency option is
only available if the Ignore Errors During Play-
back/Record option is enabled.
This option is only available on Pro Tools sys-
tems that require additional buffering for RTAS
error suppression, as follows:
• Windows XP:
• Mbox®2 Pro
• Digidesign-qualified M-Audio interfaces
with Pro Tools M-Powered or Pro Tools Ac-
ademic
• Mac OS X:
• Mbox
• Mbox 2
• Mbox 2 Pro
• Mbox 2 Mini
• Digi 002®and Digi 002 Rack
• All Pro Tools M-Powered systems
• All Pro Tools Academic systems
RTAS Plug-ins on Auxiliary Inputs or
Master Faders
With Pro Tools HD, RTAS plug-ins can be in-
serted on Auxiliary Input and Master Fader
tracks, or after TDM plug-ins on any kind of
track.
This can affect voice usage and total latency,
and limitations on inserting or removing plug-
ins during playback. For more information, see
“RTAS Plug-ins on Auxiliary Input and Master
Fader Tracks” on page 27.
Delay in Signal Processing
DSP and host-based processing in digital audio
systems incurs signal delay of varying amounts.
Such delays can vary from as short as few sam-
ples to as long as several hundred samples, de-
pending on the type of processing applied.
If you have recorded an instrument on multiple
tracks using multiple microphones (a drum kit
for example) and process the different tracks
with different plug-ins, the tracks may go out of
phase. You will then need to compensate for
these delays to avoid phase cancellation prob-
lems.
Compensating for Delay
Use the following methods, as available, to com-
pensate for processing delay.
Delay Compensation
Use Delay Compensation to automatically cal-
culate and compensate for processing delay. For
more information on Delay Compensation, see
the Pro Tools Reference Guide.
See Appendix B, “DSP Delays Incurred by
TDM Plug-ins” for information on delays
inherent in specific DigiRack TDM plug-
ins. See the Pro Tools Reference Guide for a
guide to calculating DSP-induced delays.
Delay Compensation is automatically en-
abled on Pro Tools LE systems and cannot
be turned off.

DigiRack Plug-ins Guide14
TimeAdjuster
You can compensate for TDM or RTAS plug-in-
induced delays by using the TimeAdjuster plug-
in. This plug-in lets you apply a specific number
of samples of delay to the signal path of a
Pro Tools track. TimeAdjuster provides settings
files that apply the correct compensation time
in samples for delay introduced by one or more
plug-ins. See “TimeAdjuster” on page 90 for
more information about the TimeAdjuster plug-
in.
Manual Delay Compensation
You can manually compensate for processing
delay by first calculating the amount of delay on
each track, and then nudging other track’s play-
lists later or earlier in time. This method is useful
when Delay Compensation is unavailable, or
when you want to conserve resources.
Low-Latency Recording with
Instrument Plug-ins
When an Instrument track containing an in-
strument plug-in (or a MIDI track routing MIDI
data to an instrument plug-in) is record enabled,
Pro Tools automatically suspends delay com-
pensation through the main outputs of the au-
dio track, Instrument track, or Auxiliary Input
on which the instrument plug-in is inserted. This
allows for latency-free monitoring of the instru-
ment plug-in during recording.
MIDI and Audio Processing Plug-ins
Some plug-ins, such as Bruno and Reso, process
audio while allowing MIDI data to control pro-
cessing parameters. When you record enable an
Instrument or MIDI track that is controlling an
Audio processing plug-in, the track the plug-in
is inserted on will go into low-latency mode, ef-
fectively making the processed audio play early.
To keep audio time-aligned when using a MIDI
controlled plug-in on an audio track:
■Start-Control-click (Windows) or Command-
Control-click (Mac) the Track Compensation in-
dicator for the audio track to apply delay com-
pensation.
To keep audio time-aligned when using a MIDI
controlled plug-in on an Auxiliary Input:
1 Start-Control-click (Windows) or Command-
Control-click (Mac) the Track Compensation in-
dicator for the Auxiliary Input to bypass delay
compensation.
2 Enter the total system delay into the User Off-
set field.
For information about TimeAdjuster in
Delay Compensation sessions, see the
Pro Tools Reference Guide.
You can also compensate for offsets in-
curred by processing delays by using the
same plug-ins on all tracks.
Delay Compensation for instrument plug-
ins works only when all MIDI and audio
connections take place inside of Pro Tools.
For example, Pro Tools does not suspend
delay compensation when you are using Re-
Wire to connect software synthesizers and
samplers.