--- /dev/null
+---
+layout: default
+title: Sidechaining
+---
+<p>
+ Dynamic Processors – such as compressors – in general use the the original
+ input signal for analysis and operate on the same signal.
+ Side-chaining uses the signal level of <em>another input</em> to control
+ the compression level of the original signal.
+</p>
+<p>
+ Effect Processors which have a side-chain input (sometimes also called <em>key input</em>)
+ have an additional input pin to receive a signal from an external input.
+ In Ardour that extra input can be connected in the plugin's <kbd class="menu">Pin Configuration</kbd>
+ dialog: the signal from one track can be tapped off and used as an input to a
+ plugin on a different track. This dialog is
+ accessed via the plugin's context-menu > <kbd class="menu">Pin Connections…</kbd>.
+</p>
+<p>
+ In case a plugin has a dedicated sidechain input, Ardour automatically
+ creates a port for the input. This is a normal I/O port which can be fed by any
+ external signal.
+ The <kbd class="menu">Pin Configuration</kbd> dialog is not limited to
+ processors with a dedicated sidechain input, it also allows to manually create
+ (or remove) a sidechain input port and provides for flexible connection of the
+ signal to plugin pins.
+</p>
+<p>
+ The operational flow in the Ardour GUI starts at the processor which is to receive
+ the signal: a sidechain source is selected, and Ardour creates a dedicated send-processor in the
+ source processor box, the level of which can be adjusted either in the Pin Configuration window
+ or directly on the source's send.
+</p>
+
+<h2>A simple example: Sidechain compression</h2>
+
+<p>
+ One example is the use of a bassdrum track to trigger
+ the compression on a bass track. The sidechain compressor (a-Compressor) will be placed on
+ the bass track, and will need to receive the signal from the bassdrum track as
+ a way to trigger the compression.
+</p>
+
+<figure>
+ <img src="/images/sc-comp-pin.png" alt="Sidechain compression: Pin configuration">
+ <img src="/images/sc-comp-mixer.png" alt="Sidechain compression: Mixer view">
+ <img src="/images/sc-comp-editor.png" alt="Sidechain compression: Editor view">
+ <figcaption>
+ A sidechain compression: Pin configuration, mixer view and editor view.
+ </figcaption>
+</figure>
+
+<p>
+ Here, on the bass track, an <em>a-Compressor</em> has been added, and the
+ Drum track has been set as the sidechain source. The mixer reflects this
+ by showing an <em>SC</em>-send processor in the drum track, very similar to a <a href="/signal-routing/aux-sends/">send</a>
+ The bass track also shows an arrow as one of the a-compressor input.
+</p>
+<p>
+ As a result, in the editor, each peak in the kick drum track triggers the compression on the bass track
+ and the resulting track shows the compression kicking in on each kick drum peak, hence
+ reducing the gain. The compression is applied to the bass, but only based on the level of the drum track.
+</p>
+<p>
+ This is commonly used for <em>ducking</em> effect, when e.g. a radio speaker's voice triggers the
+ compression on the audio playing.
+</p>
+
+<h2>MIDI Sidechaining</h2>
+
+<p>
+ Ardour allows the sidechain sources to be either audio or MIDI tracks/busses. This is
+ particularly useful when a MIDI signal is used to control an audio effect, like a
+ vocoder or an auto-tuner, like <a href="https://github.com/x42/fat1.lv2">fat1</a>,
+ the LV2 port of Fons Adriaensen's <a href="http://kokkinizita.linuxaudio.org/linuxaudio/zita-at1-doc/quickguide.html">Zita AT1</a>
+ by Robin Gareus:
+</p>
+
+<figure>
+ <img src="/images/pin-connection-autotune.png" alt="MIDI Sidechain">
+ <figcaption>
+ MIDI sidechainig example: fat1.lv2.
+ </figcaption>
+</figure>
+
+<p>
+ Here, the MIDI track is inputed to the plugin's MIDI IN pin through a sidechain,
+ indicating to the plugin what note should the source audio be corrected to.
+</p>
+
+<p class="note">
+ Notice that in the example above, the output of the "Vocals" track is connected
+ to the input of the "Corrected" track. We could have chosen to insert the "Vocals" track
+ content as an audio sidechain too, totally disconnecting the input from the plugin, and
+ connecting the plugin's input pin to the audio sidechain port.
+</p>
+
+<h2>Pre-processing the sidechained signal</h2>
+
+<p>
+ Sometimes, the effects of a sidechain signal on a plugin can be enhanced by
+ pre-processing the signal.
+</p>
+<p>
+ In the first example above, if the entire drum part is on one track,
+ then compressing with this signal as a sidechain will result in every peak triggering the compression,
+ be them bass drum kicks or snare, cymbals, etc.
+</p>
+<p>
+ In this case, adding an EQ to the drum track with a low pass filter would filter out the peaks
+ created by the high pitched instruments of the drum kit, and allow for a better triggering, though to
+ avoid damaging the original drum track, a send to an intermediary track would be better suited
+ to place the EQ on. This track won't be connected to the Master, as its content is of no musical
+ interest except for it's use as a trigger, allowing for some extreme EQ.
+</p>
projects / ardour-manual-diverged / blobdiff