Specifications

Chapter 3: Working with Real-Time Plug-Ins 9
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 allow
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 Setups > Playback Engine.
2 From the H/W Buffer Size pop-up menu, select
the audio buffer size, in samples.
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 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. (On dual-processor Mac-
intosh computers, this setting controls the allo-
cation of a single processor.)
3 Click OK.
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 MIDI tracks.
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.