<?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>butterhp</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="OpcodesTop.html" title="Orchestra Opcodes and Operators" /> <link rel="prev" href="butterbr.html" title="butterbr" /> <link rel="next" href="butterlp.html" title="butterlp" /> </head> <body> <div class="navheader"> <table width="100%" summary="Navigation header"> <tr> <th colspan="3" align="center">butterhp</th> </tr> <tr> <td width="20%" align="left"><a accesskey="p" href="butterbr.html">Prev</a> </td> <th width="60%" align="center">Orchestra Opcodes and Operators</th> <td width="20%" align="right"> <a accesskey="n" href="butterlp.html">Next</a></td> </tr> </table> <hr /> </div> <div class="refentry"> <a id="butterhp"></a> <div class="titlepage"></div> <a id="IndexButterhp" class="indexterm"></a> <div class="refnamediv"> <h2> <span class="refentrytitle">butterhp</span> </h2> <p>butterhp — A high-pass Butterworth filter. </p> </div> <div class="refsect1"> <a id="idm281472948579784"></a> <h2>Description</h2> <p> Implementation of second-order high-pass Butterworth filter. This opcode can also be written as <a class="link" href="buthp.html" title="buthp"><em class="citetitle">buthp</em></a>. </p> </div> <div class="refsect1"> <a id="idm281472948577496"></a> <h2>Syntax</h2> <pre class="synopsis">ares <span class="command"><strong>butterhp</strong></span> asig, kfreq [, iskip]</pre> <pre class="synopsis">ares <span class="command"><strong>butterhp</strong></span> asig, afreq [, iskip]</pre> </div> <div class="refsect1"> <a id="idm281472948512424"></a> <h2>Initialization</h2> <p> <span class="emphasis"><em>iskip</em></span> (optional, default=0) -- Skip initialization if present and non-zero. </p> </div> <div class="refsect1"> <a id="idm281472948510632"></a> <h2>Performance</h2> <p> These filters are Butterworth second-order IIR filters. They are slightly slower than the original filters in Csound, but they offer an almost flat passband and very good precision and stopband attenuation. </p> <p> <span class="emphasis"><em>asig</em></span> -- Input signal to be filtered. </p> <p> <span class="emphasis"><em>kfreq</em></span>/<span class="emphasis"><em>afreq</em></span> -- Cutoff or center frequency for each of the filters. </p> </div> <div class="refsect1"> <a id="idm281472948506648"></a> <h2>Examples</h2> <p> Here is an example of the butterhp opcode. It uses the file <a class="ulink" href="examples/butterhp.csd" target="_top"><em class="citetitle">butterhp.csd</em></a>. </p> <div class="example"> <a id="idm281472948504872"></a> <p class="title"> <strong>Example 100. Example of the butterhp 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="idm281472782238664"></a> <pre class="programlisting"> <span class="nt"><CsoundSynthesizer></span> <span class="nt"><CsOptions></span> <span class="c1">; Select audio/midi flags here according to platform</span> -odac <span class="c1">;;;RT audio out</span> <span class="c1">;-iadc ;;;uncomment -iadc if RT audio input is needed too</span> <span class="c1">; For Non-realtime ouput leave only the line below:</span> <span class="c1">; -o butterhp.wav -W ;;; for file output any platform</span> <span class="nt"></CsOptions></span> <span class="nt"><CsInstruments></span> <span class="vg">sr</span> <span class="o">=</span> <span class="mi">44100</span> <span class="vg">ksmps</span> <span class="o">=</span> <span class="mi">32</span> <span class="vg">nchnls</span> <span class="o">=</span> <span class="mi">2</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> <span class="c1">; White noise </span> a<span class="n">sig</span> <span class="nb">rand</span> <span class="mf">0.5</span> <span class="nb">outs</span> a<span class="n">sig</span><span class="p">,</span> a<span class="n">sig</span> <span class="kd">endin</span> <span class="kd">instr</span> <span class="nf">2</span> <span class="c1">; filtered noise</span> a<span class="n">sig</span> <span class="nb">rand</span> <span class="mf">0.6</span> a<span class="n">hp</span> <span class="nb">butterhp</span> a<span class="n">sig</span><span class="p">,</span> <span class="mi">500</span> <span class="c1">;pass frequencies above 500 Hz</span> <span class="nb">outs</span> a<span class="n">hp</span><span class="p">,</span> a<span class="n">hp</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">2</span> <span class="nb">i</span> <span class="mi">2</span> <span class="mf">2.5</span> <span class="mi">2</span> <span class="nb">e</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="idm281472948500648"></a> <h2>See Also</h2> <p> <a class="link" href="butterbp.html" title="butterbp"><em class="citetitle">butterbp</em></a>, <a class="link" href="butterbr.html" title="butterbr"><em class="citetitle">butterbr</em></a>, <a class="link" href="butterlp.html" title="butterlp"><em class="citetitle">butterlp</em></a> </p> </div> <div class="refsect1"> <a id="idm281472948496616"></a> <h2>Credits</h2> <p> </p> <table border="0" summary="Simple list" class="simplelist"> <tr> <td>Author: Paris Smaragdis</td> </tr> <tr> <td>MIT, Cambridge</td> </tr> <tr> <td>1995</td> </tr> </table> <p> </p> <p>Existed in 3.30</p> <p>Audio rate parameters introduced in version 6.02</p> <p>October 2013.</p> </div> </div> <div class="navfooter"> <hr /> <table width="100%" summary="Navigation footer"> <tr> <td width="40%" align="left"><a accesskey="p" href="butterbr.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="butterlp.html">Next</a></td> </tr> <tr> <td width="40%" align="left" valign="top">butterbr </td> <td width="20%" align="center"> <a accesskey="h" href="index.html">Home</a> </td> <td width="40%" align="right" valign="top"> butterlp</td> </tr> </table> </div> </body> </html>