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<div class="refentry" title="midichannelaftertouch">
<a id="midichannelaftertouch"></a>
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<h2>
<span class="refentrytitle">midichannelaftertouch</span>
</h2>
<p>midichannelaftertouch —
Gets a MIDI channel's aftertouch value.
</p>
</div>
<div class="refsect1" title="Description">
<a id="id3017973"></a>
<h2>Description</h2>
<p>
<span class="emphasis"><em>midichannelaftertouch</em></span> is designed to simplify writing instruments that can be used interchangeably for either score or MIDI input, and to make it easier to adapt instruments originally written for score input to work with MIDI input.
</p>
<p>
In general, it should be possible to write instrument definitions that work identically with both scores and MIDI, including both MIDI files and real-time MIDI input, without using any conditional statements, and that take full advantage of MIDI voice messages.
</p>
<p>
Note that correlating Csound instruments with MIDI channel numbers is done using the <a class="link" href="massign.html" title="massign"><em class="citetitle">massign</em></a> opcode for real-time performance,. For file-driven performance, instrument numbers default to MIDI channel number + 1, but the defaults are overridden by any MIDI program change messages in the file.
</p>
</div>
<div class="refsect1" title="Syntax">
<a id="id3018621"></a>
<h2>Syntax</h2>
<pre class="synopsis"><span class="command"><strong>midichannelaftertouch</strong></span> xchannelaftertouch [, ilow] [, ihigh]</pre>
</div>
<div class="refsect1" title="Initialization">
<a id="id3018639"></a>
<h2>Initialization</h2>
<p>
<span class="emphasis"><em>ilow</em></span> (optional) -- optional low value after rescaling, defaults to 0.
</p>
<p>
<span class="emphasis"><em>ihigh</em></span> (optional) -- optional high value after rescaling, defaults to 127.
</p>
</div>
<div class="refsect1" title="Performance">
<a id="id3018665"></a>
<h2>Performance</h2>
<p>
<span class="emphasis"><em>xchannelaftertouch</em></span> -- returns the MIDI channel aftertouch during MIDI activation, remains unchanged otherwise.
</p>
<p>
If the instrument was activated by MIDI input, the opcode overwrites the value of <span class="emphasis"><em>xchannelaftertouch</em></span> with the corresponding value from MIDI input. If the instrument was <span class="emphasis"><em>NOT</em></span> activated by MIDI input, the value of <span class="emphasis"><em>xchannelaftertouch</em></span> remains unchanged.
</p>
<p>
This enables score p-fields to receive MIDI input data during MIDI activation, and score values otherwise.
</p>
<div class="note" title="Adapting a score-activated Csound instrument." style="margin-left: 0.5in; margin-right: 0.5in;">
<table border="0" summary="Note: Adapting a score-activated Csound instrument.">
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<td rowspan="2" align="center" valign="top" width="25">
<img alt="[Note]" src="images/note.png" />
</td>
<th align="left">Adapting a score-activated Csound instrument.</th>
</tr>
<tr>
<td align="left" valign="top">
<p>See the <a class="link" href="MidiInterop.html" title="MIDI/Score Interoperability opcodes"><em class="citetitle">MIDI interop opcodes</em></a> section for details on adapting score driven instruments for MIDI or vice-versa.</p>
</td>
</tr>
</table>
</div>
</div>
<div class="refsect1" title="Examples">
<a id="id3018729"></a>
<h2>Examples</h2>
<p>
Here is an example of the midichannelaftertouch opcode. It uses the file <a class="ulink" href="examples/midichannelaftertouch.csd" target="_top"><em class="citetitle">midichannelaftertouch.csd</em></a>.
</p>
<div class="example">
<a id="id3018746"></a>
<p class="title">
<b>Example 361. Example of the midichannelaftertouch opcode.</b>
</p>
<div class="example-contents">
<p>See the sections <a class="link" href="UsingRealTime.html" title="Real-Time Audio"><em class="citetitle">Real-time Audio</em></a> and <a class="link" href="CommandFlags.html" title="Csound command line"><em class="citetitle">Command Line Flags</em></a> for more information on using command line flags.</p>
<pre class="programlisting">
<span class="csdtag"><CsoundSynthesizer></span>
<span class="csdtag"><CsOptions></span>
<span class="comment">; Select audio/midi flags here according to platform</span>
<span class="comment">; Audio out Audio in No messages MIDI in</span>
-odac -iadc -d -M0 <span class="comment">;;;RT audio I/O with MIDI in</span>
<span class="csdtag"></CsOptions></span>
<span class="csdtag"><CsInstruments></span>
<span class="comment">; Initialize the global variables.</span>
<span class="ohdr">sr</span> <span class="op">=</span> 44100
<span class="ohdr">kr</span> <span class="op">=</span> 4410
<span class="ohdr">ksmps</span> <span class="op">=</span> 10
<span class="ohdr">nchnls</span> <span class="op">=</span> 1
<span class="comment">; Instrument #1.</span>
<span class="oblock">instr</span> 1
kafter <span class="opc">init</span> 0
<span class="opc">midichannelaftertouch</span> kafter
<span class="comment">; Display the aftertouch value when it changes and when key is pressed</span>
<span class="opc">printk2</span> kafter
<span class="oblock">endin</span>
<span class="csdtag"></CsInstruments></span>
<span class="csdtag"><CsScore></span>
<span class="comment">; Play Instrument #1 for ten seconds.</span>
<span class="stamnt">i</span> 1 0 10
<span class="stamnt">e</span>
<span class="csdtag"></CsScore></span>
<span class="csdtag"></CsoundSynthesizer></span>
</pre>
</div>
</div>
<p><br class="example-break" />
Its output should include lines like:
</p>
<pre class="screen">
i1 127.00000
i1 20.00000
i1 44.00000
</pre>
<p>
</p>
</div>
<div class="refsect1" title="See Also">
<a id="id3018793"></a>
<h2>See Also</h2>
<p>
<a class="link" href="midicontrolchange.html" title="midicontrolchange"><em class="citetitle">midicontrolchange</em></a>,
<a class="link" href="mididefault.html" title="mididefault"><em class="citetitle">mididefault</em></a>,
<a class="link" href="midinoteoff.html" title="midinoteoff"><em class="citetitle">midinoteoff</em></a>,
<a class="link" href="midinoteoncps.html" title="midinoteoncps"><em class="citetitle">midinoteoncps</em></a>,
<a class="link" href="midinoteonkey.html" title="midinoteonkey"><em class="citetitle">midinoteonkey</em></a>,
<a class="link" href="midinoteonoct.html" title="midinoteonoct"><em class="citetitle">midinoteonoct</em></a>,
<a class="link" href="midinoteonpch.html" title="midinoteonpch"><em class="citetitle">midinoteonpch</em></a>,
<a class="link" href="midipitchbend.html" title="midipitchbend"><em class="citetitle">midipitchbend</em></a>,
<a class="link" href="midipolyaftertouch.html" title="midipolyaftertouch"><em class="citetitle">midipolyaftertouch</em></a>,
<a class="link" href="midiprogramchange.html" title="midiprogramchange"><em class="citetitle">midiprogramchange</em></a>
</p>
</div>
<div class="refsect1" title="Credits">
<a id="id3018887"></a>
<h2>Credits</h2>
<p>Author: Michael Gogins</p>
<p>Example written by Kevin Conder.</p>
<p>New in version 4.20</p>
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