Specifications
Chapter 3: Working with Real-Time Plug-Ins 7
CPU Usage Limit
The CPU Usage Limit controls the percentage of
CPU resources allocated to Pro Tools host pro-
cessing tasks.
◆ 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 Setups > 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.
3 Click OK.
Delay in Digital Signal
Processing
DSP processing in digital audio systems incurs
signal delay of varying amounts. Such delays
can vary from as short as few samples to as long
as several hundred samples, depending 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
Pro Tools TDM 6.4 and higher provides Auto-
matic Delay Compensation, which utilizes a
portion of your system resources to delay signals
as needed for tim- aligned output. For details on
Automatic Delay Compensation, see the
Pro Tools Reference Guide.
When using earlier versions of Pro Tools, you
need to compensate for these delays manually
to avoid phase correlation problems.
Use the following methods, as available, to com-
pensate for processing delay.
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.
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.