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<a id="mvclpf4"></a>
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<h2>
<span class="refentrytitle">mvclpf4</span>
</h2>
<p>mvclpf4 —
Moog voltage-controlled lowpass filter emulation.
</p>
</div>
<div class="refsect1">
<a id="idm281472911535240"></a>
<h2>Description</h2>
<p>
Mvclpf4 is an digital implementation of the 4th-order (24 dB/oct) Moog ladder filter
originally written by Fons Andriaensen. It is a version of the
mvclpf3 opcode with four outputs, for 6dB, 12dB, 18dB, and
24 dB/octave responses.
</p>
</div>
<div class="refsect1">
<a id="idm281472911533800"></a>
<h2>Syntax</h2>
<pre class="synopsis">asig1,asig2,asig3,asig4 <span class="command"><strong>mvclpf4</strong></span> ain, xcf, xres[, istor]</pre>
</div>
<div class="refsect1">
<a id="idm281472911471192"></a>
<h2>Initialization</h2>
<p>
<span class="emphasis"><em>istor</em></span> --initial disposition of internal
data space. Since filtering incorporates a feedback loop of
previous output, the initial status of the storage space used is
significant. A zero value will clear the space; a non-zero
value will allow previous information to remain. The default
value is 0.
</p>
</div>
<div class="refsect1">
<a id="idm281472911469256"></a>
<h2>Performance</h2>
<p>
<span class="emphasis"><em>asig1</em></span> -- 6dB/oct low-pass response output.
</p>
<p>
<span class="emphasis"><em>asig2</em></span> -- 12dB/oct low-pass response output.
</p>
<p>
<span class="emphasis"><em>asig3</em></span> -- 18dB/oct low-pass response output..
</p>
<p>
<span class="emphasis"><em>asig4</em></span> -- 24dB/oct low-pass response output.
</p>
<p>
<span class="emphasis"><em>ain</em></span> -- input signal.
</p>
<p>
<span class="emphasis"><em>xcf</em></span> -- filter
cutoff frequency. The useful range is around six octaves below
and above middle C (pch 8.00).
</p>
<p>
<span class="emphasis"><em>xres</em></span> --
resonance, limited to the interval [0,1].
</p>
</div>
<div class="refsect1">
<a id="idm281472911462408"></a>
<h2>Examples</h2>
<p>
Here is an example of the mvclpf4 opcode. It uses the file <a class="ulink" href="examples/mvclpf4.csd" target="_top"><em class="citetitle">mvclpf4.csd</em></a>.
</p>
<div class="example">
<a id="idm281472911460552"></a>
<p class="title">
<strong>Example 592. Example of the mvclpf4 opcode.</strong>
</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>
<div class="refsect1">
<a id="idm281472734891272"></a>
<pre class="programlisting">
<span class="nt"><CsoundSynthesizer></span>
<span class="nt"><CsOptions></span>
-odac
<span class="nt"></CsOptions></span>
<span class="nt"><CsInstruments></span>
<span class="vg">0dbfs</span> <span class="o">=</span> <span class="mi">1</span>
<span class="kd">instr</span> <span class="nf">1</span>
a<span class="n">sig</span><span class="p">[]</span> <span class="nb">init</span> <span class="mi">4</span>
k<span class="n">env</span> <span class="nb">linen</span> <span class="nb">p4</span><span class="p">,</span><span class="mf">0.1</span><span class="p">,</span><span class="nb">p3</span><span class="p">,</span><span class="mf">0.1</span>
a<span class="n">in</span> <span class="nb">rand</span> k<span class="n">env</span>
k<span class="n">fr</span> <span class="nb">expon</span> <span class="mi">220</span><span class="p">,</span> <span class="nb">p3</span><span class="p">,</span> <span class="mi">1760</span>
a<span class="n">sig</span><span class="p">[</span><span class="mi">0</span><span class="p">],</span>a<span class="n">sig</span><span class="p">[</span><span class="mi">1</span><span class="p">],</span>a<span class="n">sig</span><span class="p">[</span><span class="mi">2</span><span class="p">],</span>a<span class="n">sig</span><span class="p">[</span><span class="mi">3</span><span class="p">]</span> <span class="nb">mvclpf4</span> a<span class="n">in</span><span class="p">,</span>k<span class="n">fr</span><span class="p">,</span><span class="mf">0.9</span>
<span class="nb">out</span> a<span class="n">sig</span><span class="p">[</span><span class="nb">p5</span><span class="p">]</span>
<span class="kd">endin</span>
<span class="nt"></CsInstruments></span>
<span class="nt"><CsScore></span>
<span class="nb">i</span><span class="mi">1</span> <span class="mi">0</span> <span class="mi">5</span> <span class="mf">0.9</span> <span class="mi">0</span>
<span class="nb">i</span><span class="mi">1</span> <span class="o">+</span> <span class="mi">5</span> <span class="mf">0.9</span> <span class="mi">1</span>
<span class="nb">i</span><span class="mi">1</span> <span class="o">+</span> <span class="mi">5</span> <span class="mf">0.9</span> <span class="mi">2</span>
<span class="nb">i</span><span class="mi">1</span> <span class="o">+</span> <span class="mi">5</span> <span class="mf">0.9</span> <span class="mi">3</span>
<span class="nt"></CsScore></span>
<span class="nt"></CsoundSynthesizer></span>
</pre>
</div>
</div>
</div>
<p><br class="example-break" />
</p>
</div>
<div class="refsect1">
<a id="idm281472911456360"></a>
<h2>Credits</h2>
<p>
</p>
<table border="0" summary="Simple list" class="simplelist">
<tr>
<td>Author: Fons Andriaensen, </td>
</tr>
<tr>
<td> ported to Csound by Victor Lazzarini</td>
</tr>
<tr>
<td>January 2016</td>
</tr>
</table>
<p>
</p>
<p>New in version 6.07</p>
<p>January 2016.</p>
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