Installation guide

Chapter 4: Configuring Core Audio (Mac OS X Only) 29
Avid Core Audio Manager cannot be accessed
under the following circumstances:
• When Pro Tools is running
• When another application is using
Direct IO
Preventing an Application from Accessing the
Avid Core Audio Driver
You can prevent an application from accessing
the Avid Core Audio Driver by holding down the
Shift key just before the application would ac-
cess the Avid Core Audio Driver, typically when
launching the application. Certain applications
(such as Apple Mail and iChat), do not access
the Avid Core Audio Driver until they first play
a sound, so you will need to hold down the Shift
key just prior to sound playback in order to pre-
vent the use of your Avid hardware for playback.
Using the Avid Core Audio
Manager
Use the Avid Core Audio Manager to change the
Core Audio Buffer Size setting, access the Hard-
ware Setup dialog for your Avid hardware, and
control volume and mute for the Avid Core Au-
dio Driver. The Avid Core Audio Manager also
identifies your Avid hardware, the supported
number of Input and Output Channels and the
number of attached clients (applications).
Buffer Size
You can select from the following buffer sizes
(depending on your Avid hardware):
• 64 samples
• 128 samples
• 256 samples
• 512 samples
• 1024 samples
• 2048 samples
Changing the Buffer Size for the Avid Core Au-
dio Driver does not affect the
H/W Buffer Size
setting in the Pro Tools Playback Engine dialog.
To configure Avid Core Audio Hardware Buffer
Size:
1 Double-click the Avid Core Audio Manager file
(located in /Applications/Avid/).
2 From the Buffer Size pop-up menu, select the
desired Core Audio buffer size (in samples).
Generally, smaller buffer sizes are preferable.
However, if you experience any problems with
performance (such as clicks and pops during re-
cording or playback), try increasing the Core
Audio
Buffer Size setting. You can also change
the buffer size from within the client application
if it is the only client attached to the Core Audio
Driver. Once two or more clients are active, you
will not be able to change the sample rate or the
buffer size.
To ensure proper playback with the Avid
Core Audio Driver, launch the Avid Core
Audio Manager first, making sure that its
status is “Connected.”