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Chapter 6: DigiRack Real-Time TDM and RTAS Plug-ins 69
About Limiting
Limiting prevents signal peaks from ever ex-
ceeding a chosen threshold, and is generally
used to prevent short-term peaks from reaching
their full amplitude. Used judiciously, limiting
produces higher average levels, while avoiding
overload (clipping or distortion), by limiting
only some short-term transients in the source
audio. To prevent the ear from hearing the gain
changes, extremely short attack and release
times are used.
Limiting is used to remove only occasional
peaks because gain reduction on successive
peaks would be noticeable. If audio material
contains many peaks, the threshold should be
raised and the gain manually reduced so that
only occasional, extreme peaks are limited.
Limiting generally begins with the ratio set at
10:1 and higher. Large ratios effectively limit
the dynamic range of the signal to a specific
value by setting an absolute ceiling for the dy-
namic range.
Compressor/Limiter III Controls
This section describes controls for the Compres-
sor/Limiter plug-in.
Input/Output Level Meters
The Input and Output meters show peak signal
levels before and after dynamics processing. See
“Levels Section” on page 65 for more informa-
tion.
Unlike scales on analog compressors, metering
scales on a digital device reflect a 0 dB value that
indicates full scale (fs)—the full-code signal
level. There is no headroom above 0 dB.
Compressor/Limiter Graph Display
The Dynamics Graph display lets you visually
see how much expansion or gating you are ap-
plying to your audio material. See “Dynamics
Graph Display” on page 67.
Threshold
The Threshold control sets the level that an in-
put signal must exceed to trigger compression or
limiting. Signals that exceed this level will be
compressed. Signals that are below it will be un-
affected.
This control has an approximate range of
–60 dB to 0 dB, with a setting of 0 dB equivalent
to no compression or limiting. The default value
for the Threshold control is –24 dB.