DigiDesign Mbox 2 Pro Getting Started Manual page 28

The maximum available CPU Usage Limit de-
pends on the number of processors in your com-
puter and on the number of processors you
specify with the RTAS Processor setting. This
value can be up 99 percent for single-processor
computers or 90 percent for multi-processor
computers.
Increasing the CPU Usage Limit may slow
down screen response on slower computers.
To change the CPU Usage Limit:
Choose Setup > Playback Engine.
1
From the CPU Usage Limit pop-up menu, se-
2
lect the percentage of CPU processing you want
to allocate to Pro Tools.
Click OK.
3
RTAS Engine (RTAS Error Suppression)
The RTAS Engine options determine RTAS error
reporting during playback and recording. This is
especially useful when working with instrument
plug-ins.
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 a final mix.
20 Mbox 2 Pro Getting Started
There are two RTAS Engine 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, 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 this option is disabled,
the buffer is half the H/W Buffer Size, or at least
128 samples (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.
The Minimize Additional I/O Latency option is
only available if the Ignore Errors During Play-
back/Record option is enabled.
To enable RTAS error suppression:
Choose Setup > Playback Engine.
1
Select Ignore Errors During Playback/Record.
2
If available, you can also select Minimize Ad-
3
ditional I/O Latency.
Click OK.
4