<?xml version="1.0" encoding="UTF-8" standalone="no"?> <!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd"> <html xmlns="http://www.w3.org/1999/xhtml"> <head> <meta http-equiv="Content-Type" content="text/html; charset=UTF-8" /> <title>moogvcf</title> <link rel="stylesheet" type="text/css" href="csound.css" /> <meta name="generator" content="DocBook XSL Stylesheets V1.76.1" /> <link rel="home" href="index.html" title="The Canonical Csound Reference Manual" /> <link rel="up" href="OpcodesTop.html" title="Orchestra Opcodes and Operators" /> <link rel="prev" href="moogladder.html" title="moogladder" /> <link rel="next" href="moogvcf2.html" title="moogvcf2" /> </head> <body> <div class="navheader"> <table width="100%" summary="Navigation header"> <tr> <th colspan="3" align="center">moogvcf</th> </tr> <tr> <td width="20%" align="left"><a accesskey="p" href="moogladder.html">Prev</a> </td> <th width="60%" align="center">Orchestra Opcodes and Operators</th> <td width="20%" align="right"> <a accesskey="n" href="moogvcf2.html">Next</a></td> </tr> </table> <hr /> </div> <div class="refentry" title="moogvcf"> <a id="moogvcf"></a> <div class="titlepage"></div> <a id="IndexMoogvcf" class="indexterm"></a> <div class="refnamediv"> <h2> <span class="refentrytitle">moogvcf</span> </h2> <p>moogvcf — A digital emulation of the Moog diode ladder filter configuration. </p> </div> <div class="refsect1" title="Description"> <a id="idp32201216"></a> <h2>Description</h2> <p> A digital emulation of the Moog diode ladder filter configuration. </p> </div> <div class="refsect1" title="Syntax"> <a id="idp32201896"></a> <h2>Syntax</h2> <pre class="synopsis">ares <span class="command"><strong>moogvcf</strong></span> asig, xfco, xres [,iscale, iskip]</pre> </div> <div class="refsect1" title="Initialization"> <a id="idp32242560"></a> <h2>Initialization</h2> <p> <span class="emphasis"><em>iscale</em></span> (optional, default=1) -- internal scaling factor. Use if <span class="emphasis"><em>asig</em></span> is not in the range +/-1. Input is first divided by <span class="emphasis"><em>iscale</em></span>, then output is mutliplied <span class="emphasis"><em>iscale</em></span>. Default value is 1. (New in Csound version 3.50) </p> <p> <span class="emphasis"><em>iskip</em></span> (optional, default=0) -- if non zero skip the initialisation of the filter. (New in Csound version 4.23f13 and 5.0) </p> </div> <div class="refsect1" title="Performance"> <a id="idp32244768"></a> <h2>Performance</h2> <p> <span class="emphasis"><em>asig</em></span> -- input signal </p> <p> <span class="emphasis"><em>xfco</em></span> -- filter cut-off frequency in Hz. As of version 3.50, may i-,k-, or a-rate. </p> <p> <span class="emphasis"><em>xres</em></span> -- amount of resonance. Self-oscillation occurs when <span class="emphasis"><em>xres</em></span> is approximately one. As of version 3.50, may a-rate, i-rate, or k-rate. </p> <p> <span class="emphasis"><em>moogvcf</em></span> is a digital emulation of the Moog diode ladder filter configuration. This emulation is based loosely on the paper <span class="quote">“<span class="quote">Analyzing the Moog VCF with Considerations for Digital Implementation</span>”</span> by Stilson and Smith (CCRMA). This version was originally coded in Csound by Josep Comajuncosas. Some modifications and conversion to C were done by Hans Mikelson. </p> <div class="warning" title="Warning" style="margin-left: 0.5in; margin-right: 0.5in;"> <table border="0" summary="Warning"> <tr> <td rowspan="2" align="center" valign="top" width="25"> <img alt="[Warning]" src="images/warning.png" /> </td> <th align="left">Warning</th> </tr> <tr> <td align="left" valign="top"> <p>This filter requires that the input signal be normalized to one. This can be easily achieved using <a class="link" href="Zerodbfs.html" title="0dbfs"><em class="citetitle">0dbfs</em></a>, like this: </p> <div class="literallayout"> <p>ares <span class="command"><strong>moogvcf</strong></span> asig, kfco, kres, 0dbfs</p> </div> <p>You can also use <a class="link" href="moogvcf2.html" title="moogvcf2"><em class="citetitle">moogvcf2</em></a> which defaults scaling to <a class="link" href="Zerodbfs.html" title="0dbfs"><em class="citetitle">0dbfs</em></a>. </p> </td> </tr> </table> </div> </div> <div class="refsect1" title="Examples"> <a id="idp32250832"></a> <h2>Examples</h2> <p> Here is an example of the moogvcf opcode. It uses the file <a class="ulink" href="examples/moogvcf.csd" target="_top"><em class="citetitle">moogvcf.csd</em></a>. </p> <div class="example"> <a id="idp32251808"></a> <p class="title"> <strong>Example 492. Example of the moogvcf 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> <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> -odac <span class="comment">;;;realtime audio out</span> <span class="comment">;-iadc ;;;uncomment -iadc if realtime audio input is needed too</span> <span class="comment">; For Non-realtime ouput leave only the line below:</span> <span class="comment">; -o moogvcf.wav -W ;;; for file output any platform</span> <span class="csdtag"></CsOptions></span> <span class="csdtag"><CsInstruments></span> <span class="ohdr">sr</span> <span class="op">=</span> 44100 <span class="ohdr">ksmps</span> <span class="op">=</span> 32 <span class="ohdr">nchnls</span> <span class="op">=</span> 2 <span class="ohdr">0dbfs</span> <span class="op">=</span> 1 <span class="oblock">instr</span> 1 <span class="comment">; iscale does not need to be set here because already 0dbfs = 1 </span> aout <span class="opc">vco</span> .3, 220, 1 <span class="comment">; Use a nice sawtooth waveform.</span> kfco <span class="opc">line</span> 200, p3, 2000 <span class="comment">; filter-cutoff frequency from .2 to 2 KHz</span> krez <span class="opc">init</span> p4 asig <span class="opc">moogvcf</span> aout, kfco, krez <span class="opc">outs</span> asig, asig <span class="oblock">endin</span> <span class="csdtag"></CsInstruments></span> <span class="csdtag"><CsScore></span> <span class="comment">;a sine wave</span> <span class="stamnt">f</span> 1 0 16384 10 1 <span class="stamnt">i</span> 1 0 3 .1 <span class="stamnt">i</span> 1 + 3 .7 <span class="stamnt">i</span> 1 + 3 .95 <span class="stamnt">e</span> <span class="csdtag"></CsScore></span> <span class="csdtag"></CsoundSynthesizer></span> </pre> </div> </div> <p><br class="example-break" /> </p> </div> <div class="refsect1" title="See Also"> <a id="idp32254088"></a> <h2>See Also</h2> <p> <a class="link" href="moogvcf2.html" title="moogvcf2"><em class="citetitle">moogvcf2</em></a>, <a class="link" href="biquad.html" title="biquad"><em class="citetitle">biquad</em></a>, <a class="link" href="rezzy.html" title="rezzy"><em class="citetitle">rezzy</em></a> </p> </div> <div class="refsect1" title="Credits"> <a id="idp32256064"></a> <h2>Credits</h2> <p> </p> <table border="0" summary="Simple list" class="simplelist"> <tr> <td>Author: Hans Mikelson</td> </tr> <tr> <td>October 1998</td> </tr> </table> <p> </p> <p>New in Csound version 3.49</p> </div> </div> <div class="navfooter"> <hr /> <table width="100%" summary="Navigation footer"> <tr> <td width="40%" align="left"><a accesskey="p" href="moogladder.html">Prev</a> </td> <td width="20%" align="center"> <a accesskey="u" href="OpcodesTop.html">Up</a> </td> <td width="40%" align="right"> <a accesskey="n" href="moogvcf2.html">Next</a></td> </tr> <tr> <td width="40%" align="left" valign="top">moogladder </td> <td width="20%" align="center"> <a accesskey="h" href="index.html">Home</a> </td> <td width="40%" align="right" valign="top"> moogvcf2</td> </tr> </table> </div> </body> </html>