DigiDesign Pro Tools, Справочное руководство

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Chapter 29: Plug-in and Hardware Inserts 683
Using a Side-Chain Input
The side-chain input is the split-off signal used
by a plug-in's detector to trigger dynamics pro-
cessing, and is generally drawn internally from
the input signal. However, some plug-ins let you
switch between internal and external side-chain
processing.
With external side-chain processing, a plug-in's
detector is triggered by an external signal (such
as a separate reference track or audio source)
known as the
key input .
A typical use for external side-chain processing
is to control the dynamics of one audio signal
using the dynamics of another signal (the key
input). For example, a kick drum track could be
used to trigger gating of a bass track to tighten it
up, or a rhythm guitar track could be used to
gate a keyboard pad.
Side-Chain Filters
Some plug-ins feature key high-pass and low-
pass filters. These controls let you define a spe-
cific frequency range in the side-chain signal
with which to trigger the plug-in effect. A com-
mon production technique is to use these con-
trols to filter a drum track so that only specific
high frequency sounds (such as a hi-hat) or low
frequency ones (such a tom or a kick) trigger the
effect.
Using a Key Input for External Side-
Chain Processing
To use a key input for external side-chain
processing:
1
Click the plug-in’s Key Input selector and se-
lect the input or bus carrying the audio you
want to use to trigger the plug-in.
2
Click the External Key to activate external
side-chain processing.
3
Press the Spacebar to begin playback. The
plug-in uses the input or bus that you chose as a
key input to trigger its effect.
4
During playback, do any of the following to
fine-tune key input triggering:
• To hear the audio source you have selected
to control the key input, enable Side-Chain
Listen or Key Listen (depending on the
plug-in). When finished, disable Side-
Chain Listen/Key Listen to resume normal
plug-in monitoring.
• To filter the key input so that only specific
frequencies trigger the plug-in, use the fil-
tering controls (if available) to select the
frequency range.
5
Adjust the plug-in’s Threshold control (if
available) and other controls as needed.
Choosing a Key Input