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<span class="refentrytitle">reson</span>
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<p>reson —
A second-order resonant filter.
</p>
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<div class="refsect1" title="Description">
<a id="id3159263"></a>
<h2>Description</h2>
<p>
A second-order resonant filter.
</p>
</div>
<div class="refsect1" title="Syntax">
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<h2>Syntax</h2>
<pre class="synopsis">ares <span class="command"><strong>reson</strong></span> asig, kcf, kbw [, iscl] [, iskip]</pre>
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<div class="refsect1" title="Initialization">
<a id="id3159490"></a>
<h2>Initialization</h2>
<p>
<span class="emphasis"><em>iscl</em></span> (optional, default=0) -- coded scaling factor for resonators. A value of 1 signifies a peak response factor of 1, i.e. all frequencies other than kcf are attenuated in accordance with the (normalized) response curve. A value of 2 raises the response factor so that its overall RMS value equals 1. (This intended equalization of input and output power assumes all frequencies are physically present; hence it is most applicable to white noise.) A zero value signifies no scaling of the signal, leaving that to some later adjustment (see <a class="link" href="balance.html" title="balance"><em class="citetitle">balance</em></a>). The default value is 0.
</p>
<p>
<span class="emphasis"><em>iskip</em></span> (optional, default=0) -- 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>
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<div class="refsect1" title="Performance">
<a id="id3159540"></a>
<h2>Performance</h2>
<p>
<span class="emphasis"><em>ares</em></span> -- the output signal at audio rate.
</p>
<p>
<span class="emphasis"><em>asig</em></span> -- the input signal at audio rate.
</p>
<p>
<span class="emphasis"><em>kcf</em></span> -- the center frequency of the filter, or frequency position of the peak response.
</p>
<p>
<span class="emphasis"><em>kbw</em></span> -- bandwidth of the filter (the Hz difference between the upper and lower half-power points).
</p>
<p>
<span class="emphasis"><em>reson</em></span> is a second-order filter in which <span class="emphasis"><em>kcf</em></span> controls the center frequency, or frequency position of the peak response, and <span class="emphasis"><em>kbw</em></span> controls its bandwidth (the frequency difference between the upper and lower half-power points).
</p>
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<div class="refsect1" title="Examples">
<a id="id3160139"></a>
<h2>Examples</h2>
<p>
Here is an example of the reson opcode. It uses the file <a class="ulink" href="examples/reson.csd" target="_top"><em class="citetitle">reson.csd</em></a>.
</p>
<div class="example">
<a id="id3160155"></a>
<p class="title">
<b>Example 522. Example of the reson 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</span>
-odac -iadc -d <span class="comment">;;;RT audio I/O</span>
<span class="comment">; For Non-realtime ouput leave only the line below:</span>
<span class="comment">; -o reson.wav -W ;;; for file output any platform</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
<span class="comment">; Generate a sine waveform.</span>
asine <span class="opc">buzz</span> 15000, 440, 3, 1
<span class="comment">; Vary the cut-off frequency from 220 to 1280.</span>
kcf <span class="opc">line</span> 220, p3, 1320
kbw <span class="opc">init</span> 20
<span class="comment">; Run the sine through a resonant filter.</span>
ares <span class="opc">reson</span> asine, kcf, kbw
<span class="comment">; Give the filtered signal the same amplitude </span>
<span class="comment">; as the original signal. </span>
a1 <span class="opc">balance</span> ares, asine
<span class="opc">out</span> a1
<span class="oblock">endin</span>
<span class="csdtag"></CsInstruments></span>
<span class="csdtag"><CsScore></span>
<span class="comment">; Table #1, an ordinary sine wave.</span>
<span class="stamnt">f</span> 1 0 16384 10 1
<span class="comment">; Play Instrument #1 for 4 seconds.</span>
<span class="stamnt">i</span> 1 0 4
<span class="stamnt">e</span>
<span class="csdtag"></CsScore></span>
<span class="csdtag"></CsoundSynthesizer></span>
</pre>
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<p><br class="example-break" />
</p>
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<div class="refsect1" title="See Also">
<a id="id3160192"></a>
<h2>See Also</h2>
<p>
<a class="link" href="areson.html" title="areson"><em class="citetitle">areson</em></a>,
<a class="link" href="aresonk.html" title="aresonk"><em class="citetitle">aresonk</em></a>,
<a class="link" href="atone.html" title="atone"><em class="citetitle">atone</em></a>,
<a class="link" href="atonek.html" title="atonek"><em class="citetitle">atonek</em></a>,
<a class="link" href="port.html" title="port"><em class="citetitle">port</em></a>,
<a class="link" href="portk.html" title="portk"><em class="citetitle">portk</em></a>,
<a class="link" href="resonk.html" title="resonk"><em class="citetitle">resonk</em></a>,
<a class="link" href="tone.html" title="tone"><em class="citetitle">tone</em></a>,
<a class="link" href="tonek.html" title="tonek"><em class="citetitle">tonek</em></a>
</p>
</div>
<div class="refsect1" title="Credits">
<a id="id3160275"></a>
<h2>Credits</h2>
<p>Example written by Kevin Conder.</p>
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