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<h2>
<span class="refentrytitle">dcblock</span>
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<p>dcblock —
A DC blocking filter.
</p>
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<div class="refsect1" title="Description">
<a id="idp17686744"></a>
<h2>Description</h2>
<p>
Implements the DC blocking filter
</p>
<div class="literallayout">
<p><br />
Y[i] = X[i] - X[i-1] + (igain * Y[i-1])<br />
</p>
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<p>
</p>
<p>
Based on work by Perry Cook.
</p>
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<div class="refsect1" title="Syntax">
<a id="idp17688304"></a>
<h2>Syntax</h2>
<pre class="synopsis">ares <span class="command"><strong>dcblock</strong></span> ain [, igain]</pre>
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<div class="refsect1" title="Initialization">
<a id="idp17713912"></a>
<h2>Initialization</h2>
<p>
<span class="emphasis"><em>igain</em></span> -- the gain of the filter, which defaults to 0.99
</p>
</div>
<div class="refsect1" title="Performance">
<a id="idp17714856"></a>
<h2>Performance</h2>
<p>
<span class="emphasis"><em>ain</em></span> -- audio signal input
</p>
<div class="note" title="Note" style="margin-left: 0.5in; margin-right: 0.5in;">
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<th align="left">Note</th>
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<td align="left" valign="top">
<p>The new <a class="link" href="dcblock2.html" title="dcblock2"><em class="citetitle">dcblock2</em></a> opcode is an improved method of removing DC from an audio signal.</p>
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<div class="refsect1" title="Examples">
<a id="idp17716656"></a>
<h2>Examples</h2>
<p>
The result can be viewed in a graphical audio editor program like <span class="emphasis"><em>audacity</em></span>. <span class="emphasis"><em>audacity</em></span> is available for Linux, Windows, and the MacOS and may be downloaded from <a class="ulink" href="http://audacity.sourceforge.net/" target="_top"><em class="citetitle">http://audacity.sourceforge.net</em></a>.
</p>
<p>
Here is an example of the dcblock opcode. It uses the file <a class="ulink" href="examples/dcblock.csd" target="_top"><em class="citetitle">dcblock.csd</em></a>, and <a class="ulink" href="examples/beats.wav" target="_top"><em class="citetitle">beats.wav</em></a>.
</p>
<div class="example">
<a id="idp17719288"></a>
<p class="title">
<strong>Example 156. Example of the dcblock 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">;;;RT audio out</span>
<span class="comment">;-iadc ;;;uncomment -iadc if RT audio input is needed too</span>
<span class="comment">; For Non-realtime ouput leave only the line below:</span>
<span class="comment">;-o dcblock.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="oblock">instr</span> 1 <span class="comment">;add DC to "beats.wav"</span>
asig <span class="opc">soundin</span> "beats.wav"
asig <span class="op">=</span> asig<span class="op">+</span>5000 <span class="comment">;adds DC of 5000</span>
<span class="opc">outs</span> asig, asig
<span class="oblock">endin</span>
<span class="oblock">instr</span> 2 <span class="comment">;dcblock audio</span>
asig <span class="opc">soundin</span> "beats.wav"
asig <span class="op">=</span> asig<span class="op">+</span>5000 <span class="comment">;adds DC</span>
adc <span class="opc">dcblock</span> asig <span class="comment">;remove DC again</span>
<span class="opc">outs</span> adc, adc
<span class="oblock">endin</span>
<span class="csdtag"></CsInstruments></span>
<span class="csdtag"><CsScore></span>
<span class="stamnt">i</span> 1 0 2
<span class="stamnt">i</span> 2 2 2
<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="idp17721600"></a>
<h2>See also</h2>
<p>
<a class="link" href="dcblock2.html" title="dcblock2">
<em class="citetitle">dcblock2</em>
</a>
</p>
</div>
<div class="refsect1" title="Credits">
<a id="idp17722520"></a>
<h2>Credits</h2>
<p>
</p>
<table border="0" summary="Simple list" class="simplelist">
<tr>
<td>Author: John ffitch</td>
</tr>
<tr>
<td>University of Bath, Codemist Ltd.</td>
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<td>Bath, UK</td>
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<p>
</p>
<p>New in Csound version 3.49</p>
<p>February 2003: Thanks to a note from Anders Andersson, corrected the formula.</p>
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