A MIDI track's data may utilize any number of the 16 available <dfn>MIDI channels</dfn>, and it is useful to be able to filter out a subset of those or force the input or output to utilize only certain channels. The Channel Selector dialog allows for filtering or modification of both the input and output of any given MIDI track.
The Channel Selector dialog is activated by <kbdclass="mouse">right</kbd>-clicking on a MIDI track's header and selecting <kbdclass="menu">Channel Selector...</kbd> from the menu that appears. Filtering or modification of Inbound MIDI events for the given MIDI track is done by selecting among:
Selecting <kbdclass=menu>Record all channels</kbd> does no filtering of inbound MIDI events.
</p>
<p>
If simple filtering of incoming MIDI events is desired, <kbdclass=menu>Record only selected channels</kbd> should be selected. A 1-by-16 grid of squares with numbers in them will become sensitive to mouse clicks, and the desired channels to be allowed through the filter can then be selected by clicking on them. Channels that are allowed to pass through will be highlighted in green.
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<p>
<kbdclass=menu>Force all channels to 1 channel</kbd> will rewrite the channel number of all incoming events of the selected MIDI track to whichever channel is highlighted in the 1-by-16 grid of squares. When this option is chosen, one and only one channel can be selected.
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<p>
Filtering or modification of outbound MIDI events is done by selecting among:
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<ul>
<li><kbdclass=menu>Play only selected channels</kbd></li>
<li><kbdclass=menu>Use a single fixed channel for all playback</kbd></li>
</ul>
<pclass="note">
Selecting <kbdclass=menu>Playback all channels</kbd> does no filtering of outbound MIDI events.
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<p>
Simple filtering of outgoing MIDI events is done similarly to simple filtering of incoming MIDI events, and is done by selecting <kbdclass=menu>Play only selected channels</kbd>. Also similarly to the incoming case, <kbdclass=menu>Use a single fixed channel for all playback</kbd> will rewrite the channel number of all outgoing events of the selected MIDI track to whichever channel is selected.
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<p>
When either <kbdclass=menu>Record only selected channels</kbd> or <kbdclass=menu>Playback only selected channels</kbd> is selected, a group of three buttons, each appearing below their respective 1-by-16 grids, will become sensitive to mouse clicks. They perform the following functions:
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<table>
<tr>
<th>All</th>
<td>Selects all the channels in the 1-by-16 grid above it; all the squares become lit with green</td>
</tr>
<tr>
<th>None</th>
<td>Deselects all the channels in the 1-by-16 grid above it; all the squares become unlit</td>
</tr>
<tr>
<th>Invert</th>
<td>Any channel in the 1-by-16 grid that is lit green becomes unlit, and any unlit channel becomes lit with green</td>
The Patch Selector window is an easy way to set which instrument will be used on any of the MIDI channels. Although patches can be changed at any time using a <ahref="@@patch-change">patch change</a>, this dialog provides an easy and convenient way to preview patches in software and hardware instruments. It integrates fully with Ardour's support for MIDNAM (patch definition files), so Ardour can display named programs/patches for both General MIDI synths and those with MIDNAM files.
The window itself makes it easy to choose a channel, a bank number, optionally choosing a bank number through its <dfntitle="Most Significant Byte">MSB</dfn> and <dfntitle="Least Significant Byte">LSB</dfn> numbers (CC#00 and CC#32) for large banks, then choosing an instrument.
The keyboard at the bottom of the window allows for a quick preview of the selected instrument, either automatically (using the buttons on top of the keyboard) or manually by either clicking a note or using the computer keyboard as a piano keyboard.
