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<h2>
<span class="refentrytitle">downsamp</span>
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<p>downsamp —
Modify a signal by down-sampling.
</p>
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<div class="refsect1" title="Description">
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<h2>Description</h2>
<p>
Modify a signal by down-sampling.
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<div class="refsect1" title="Syntax">
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<h2>Syntax</h2>
<pre class="synopsis">kres <span class="command"><strong>downsamp</strong></span> asig [, iwlen]</pre>
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<div class="refsect1" title="Initialization">
<a id="idp18632528"></a>
<h2>Initialization</h2>
<p>
<span class="emphasis"><em>iwlen</em></span> (optional) -- window length in samples over which the audio signal is averaged to determine a downsampled value. Maximum length is <span class="emphasis"><em>ksmps</em></span>; 0 and 1 imply no window averaging. The default value is 0.
</p>
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<div class="refsect1" title="Performance">
<a id="idp18633840"></a>
<h2>Performance</h2>
<p>
<span class="emphasis"><em>downsamp</em></span> converts an audio signal to a control signal by downsampling. It produces one kval for each audio control period. The optional window invokes a simple averaging process to suppress foldover.
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<div class="refsect1" title="Examples">
<a id="idp18635056"></a>
<h2>Examples</h2>
<p>
Here is an example of the downsamp opcode. It uses the file <a class="ulink" href="examples/downsamp.csd" target="_top"><em class="citetitle">downsamp.csd</em></a>.
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<p class="title">
<strong>Example 186. Example of the downsamp 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 downsamp.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
ifrq <span class="op">=</span> <span class="opc">cpspch</span>(p4)
ain <span class="opc">diskin2</span> "beats.wav", 1
aenv <span class="opc">follow</span> ain, .001 <span class="comment">;take the amplitude every 1/1000th of a second</span>
alow <span class="opc">tone</span> aenv, 25 <span class="comment">;lowpass-filter (25 Hz) for a clean signal</span>
kenv <span class="opc">downsamp</span> alow
asig <span class="opc">pluck</span> kenv, ifrq, 15, 0, 1
<span class="opc">outs</span> asig, asig
<span class="oblock">endin</span>
<span class="csdtag"></CsInstruments></span>
<span class="csdtag"><CsScore></span>
<span class="stamnt">i</span> 1 0 2 9
<span class="stamnt">i</span> 1 + . 7
<span class="stamnt">i</span> 1 + . 5
<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" />
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<div class="refsect1" title="See Also">
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<h2>See Also</h2>
<p>
<a class="link" href="diff.html" title="diff"><em class="citetitle">diff</em></a>,
<a class="link" href="integ.html" title="integ"><em class="citetitle">integ</em></a>,
<a class="link" href="interp.html" title="interp"><em class="citetitle">interp</em></a>,
<a class="link" href="samphold.html" title="samphold"><em class="citetitle">samphold</em></a>,
<a class="link" href="upsamp.html" title="upsamp"><em class="citetitle">upsamp</em></a>
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