<?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>User Defined Opcodes (UDO)</title> <link rel="stylesheet" type="text/css" href="csound.css" /> <link rel="stylesheet" type="text/css" href="syntax-highlighting.css" /> <meta name="generator" content="DocBook XSL Stylesheets Vsnapshot" /> <link rel="home" href="index.html" title="The Canonical Csound Reference Manual" /> <link rel="up" href="OrchTop.html" title="Syntax of the Orchestra" /> <link rel="prev" href="OrchNamedInstruments.html" title="Named Instruments" /> <link rel="next" href="Orchtab.html" title="K-Rate Vectors" /> </head> <body> <div class="navheader"> <table width="100%" summary="Navigation header"> <tr> <th colspan="3" align="center">User Defined Opcodes (UDO)</th> </tr> <tr> <td width="20%" align="left"><a accesskey="p" href="OrchNamedInstruments.html">Prev</a> </td> <th width="60%" align="center">Syntax of the Orchestra</th> <td width="20%" align="right"> <a accesskey="n" href="Orchtab.html">Next</a></td> </tr> </table> <hr /> </div> <div class="section"> <div class="titlepage"> <div> <div> <h2 class="title" style="clear: both"><a id="OrchUDO"></a>User Defined Opcodes (UDO)</h2> </div> </div> </div> <p> Csound allows the definition of opcodes inside the orchestra header using the opcodes <a class="link" href="opcode.html" title="opcode"><em class="citetitle">opcode</em></a> and <a class="link" href="endop.html" title="endop"><em class="citetitle">endop</em></a>. The defined opcode may run with a different number of control samples (<a class="link" href="ksmps.html" title="ksmps"><em class="citetitle">ksmps</em></a>) using <a class="link" href="setksmps.html" title="setksmps"><em class="citetitle">setksmps</em></a>. </p> <p> To connect inputs and outputs for the UDO, use <a class="link" href="xin.html" title="xin"><em class="citetitle">xin</em></a> and <a class="link" href="xout.html" title="xout"><em class="citetitle">xout</em></a>. </p> <p> An UDO looks like this: </p> <pre class="programlisting"> <span class="oblock">opcode</span> Lowpass, a, akk <span class="opc">setksmps</span> 1 <span class="comment">; need sr=kr</span> ain, ka1, ka2 <span class="opc">xin</span> <span class="comment">; read input parameters</span> aout <span class="opc">init</span> 0 <span class="comment">; initialize output</span> aout <span class="op">=</span> ain<span class="op">*</span>ka1 <span class="op">+</span> aout<span class="op">*</span>ka2 <span class="comment">; simple tone-like filter</span> <span class="opc">xout</span> aout <span class="comment">; write output</span> <span class="oblock">endop</span></pre> <p> This UDO called <span class="emphasis"><em>Lowpass</em></span> takes 3 inputs (the first is a-rate, and the next two are k-rate), and delivers 1 a-rate output. Notice the use of <a class="link" href="xin.html" title="xin"><em class="citetitle">xin</em></a> to receive inputs and <a class="link" href="xout.html" title="xout"><em class="citetitle">xout</em></a> to deliver outputs. Also note the use of <a class="link" href="setksmps.html" title="setksmps"><em class="citetitle">setksmps</em></a>, which is needed for the filter to work properly. </p> <p>To use this UDO within an instrument, you would do something like:</p> <pre class="programlisting"> afiltered Lowpass asource, kvalue1, kvalue2</pre> <p>See the entry for <a class="link" href="opcode.html" title="opcode"><em class="citetitle">opcode</em></a> for detailed information on UDO definition. </p> <p> You can find many ready made UDO's (or contribute your own) at <a class="ulink" href="http://www.csounds.com/" target="_top"><em class="citetitle">Csounds.com</em></a>'s <a class="ulink" href="http://www.csounds.com/udo/" target="_top"><em class="citetitle">User Defined Opcode Database</em></a>. </p> </div> <div class="navfooter"> <hr /> <table width="100%" summary="Navigation footer"> <tr> <td width="40%" align="left"><a accesskey="p" href="OrchNamedInstruments.html">Prev</a> </td> <td width="20%" align="center"> <a accesskey="u" href="OrchTop.html">Up</a> </td> <td width="40%" align="right"> <a accesskey="n" href="Orchtab.html">Next</a></td> </tr> <tr> <td width="40%" align="left" valign="top">Named Instruments </td> <td width="20%" align="center"> <a accesskey="h" href="index.html">Home</a> </td> <td width="40%" align="right" valign="top"> K-Rate Vectors</td> </tr> </table> </div> </body> </html>