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<div class="refentry" title="pdclip">
<a id="pdclip"></a>
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<a id="IndexPdclip" class="indexterm"></a>
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<h2>
<span class="refentrytitle">pdclip</span>
</h2>
<p>pdclip —
Performs linear clipping on an audio signal or a phasor.
</p>
</div>
<div class="refsect1" title="Description">
<a id="idp35863208"></a>
<h2>Description</h2>
<p>
The <span class="emphasis"><em>pdclip</em></span> opcode allows a percentage of the input range of a signal to be clipped to fullscale. It is similar to simply multiplying the signal and limiting the range of the result, but <span class="emphasis"><em>pdclip</em></span> allows you to think about how much of the signal range is being distorted instead of the scalar factor and has a offset parameter for assymetric clipping of the signal range. <span class="emphasis"><em>pdclip</em></span> is also useful for remapping phasors for phase distortion synthesis.
</p>
</div>
<div class="refsect1" title="Syntax">
<a id="idp35907944"></a>
<h2>Syntax</h2>
<pre class="synopsis">aout <span class="command"><strong>pdclip</strong></span> ain, kWidth, kCenter [, ibipolar [, ifullscale]]</pre>
</div>
<div class="refsect1" title="Initialization">
<a id="idp35909008"></a>
<h2>Initialization</h2>
<p>
<span class="emphasis"><em>ibipolar</em></span> -- an optional parameter specifying either unipolar (0) or bipolar (1) mode. Defaults to unipolar mode.
</p>
<p>
<span class="emphasis"><em>ifullscale</em></span> -- an optional parameter specifying the range of input and output values. The maximum will be <span class="emphasis"><em>ifullscale</em></span>. The minimum depends on the mode of operation: zero for unipolar or -<span class="emphasis"><em>ifullscale</em></span> for bipolar. Defaults to 1.0 -- you should set this parameter to the maximum expected input value.
</p>
</div>
<div class="refsect1" title="Performance">
<a id="idp35911048"></a>
<h2>Performance</h2>
<p>
<span class="emphasis"><em>ain</em></span> -- the input signal to be clipped.
</p>
<p>
<span class="emphasis"><em>aout</em></span> -- the output signal.
</p>
<p>
<span class="emphasis"><em>kWidth</em></span> -- the percentage of the signal range that is clipped (must be between 0 and 1).
</p>
<p>
<span class="emphasis"><em>kCenter</em></span> -- an offset for shifting the unclipped window of the signal higher or lower in the range (essentially a DC offset). Values should be in the range [-1, 1] with a value of zero representing no shift (regardless of whether bipolar or unipolar mode is used).
</p>
<p>
The <span class="emphasis"><em>pdclip</em></span> opcode performs linear clipping on the input signal ain. <span class="emphasis"><em>kWidth</em></span> specifies the percentage of the signal range that is clipped. The rest of the input range is mapped linearly from zero to ifullscale in unipolar mode and from -ifullscale to ifullscale in bipolar mode. When <span class="emphasis"><em>kCenter</em></span> is zero, equal amounts of the top and bottom of the signal range are clipped. A negative value shifts the unclipped range more towards the bottom of the input range and a positive value shifts it more towards the top. ibipolar should be 1 for bipolar operation and 0 for unipolar mode. The default is unipolar mode (ibipolar = 0). ifullscale sets the maximum amplitude of the input and output signals (defaults to 1.0).
</p>
<p>
This amounts to waveshaping the input with the following transfer function (normalized to ifullscale=1.0 in bipolar mode):
</p>
<p>
</p>
<div class="literallayout">
<p><br />
1| _______ x-axis is input range, y-axis is output<br />
| / <br />
| / width of clipped region is 2*kWidth<br />
-1 |/ 1 width of unclipped region is 2*(1 - kWidth)<br />
-------------------- kCenter shifts the unclipped region<br />
/| left or right (up to kWidth)<br />
/ |<br />
/ |<br />
------ |-1<br />
</p>
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<p>
</p>
<p>
Bipolar mode can be used for direct, linear distortion of an audio signal. Alternatively, unipolar mode is useful for modifying the output of a phasor before it is used to index a function table, effectively making this a phase distortion technique.
</p>
</div>
<div class="refsect1" title="See Also">
<a id="idp35916888"></a>
<h2>See Also</h2>
<p>
<a class="link" href="pdhalf.html" title="pdhalf"><em class="citetitle">pdhalf</em></a>,
<a class="link" href="pdhalfy.html" title="pdhalfy"><em class="citetitle">pdhalfy</em></a>,
<a class="link" href="limit.html" title="limit"><em class="citetitle">limit</em></a>,
<a class="link" href="clip.html" title="clip"><em class="citetitle">clip</em></a>,
<a class="link" href="distort1.html" title="distort1"><em class="citetitle">distort1</em></a>
</p>
</div>
<div class="refsect1" title="Examples">
<a id="idp35919864"></a>
<h2>Examples</h2>
<p>
Here is an example of the pdclip opcode. It uses the file <a class="ulink" href="examples/pdclip.csd" target="_top"><em class="citetitle">pdclip.csd</em></a>.
</p>
<div class="example">
<a id="idp35920832"></a>
<p class="title">
<strong>Example 579. Example of the pdclip 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>
<span class="comment">; Audio out Audio in</span>
-odac -iadc <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 abs.wav -W ;;; for file output any platform</span>
<span class="csdtag"></CsOptions></span>
<span class="csdtag"><CsInstruments></span>
<span class="comment">; test instrument for pdclip opcode</span>
<span class="oblock">instr</span> 3
idur <span class="op">=</span> p3
iamp <span class="op">=</span> p4
ifreq <span class="op">=</span> p5
ifn <span class="op">=</span> p6
kenv <span class="opc">linseg</span> 0, .05, 1.0, idur <span class="op">-</span> .1, 1.0, .05, 0
aosc <span class="opc">oscil</span> 1.0, ifreq, ifn
kmod <span class="opc">expseg</span> 0.00001, idur, 1.0
aout <span class="opc">pdclip</span> aosc, kmod, 0.0, 1.0
<span class="opc">out</span> kenv<span class="op">*</span>aout<span class="op">*</span>iamp
<span class="oblock">endin</span>
<span class="csdtag"></CsInstruments></span>
<span class="csdtag"><CsScore></span>
<span class="stamnt">f</span>1 0 16385 10 1
<span class="stamnt">f</span>2 0 16385 10 1 .5 .3333 .25 .5
<span class="comment">; pdclipped sine wave</span>
<span class="stamnt">i</span>3 0 3 15000 440 1
<span class="stamnt">i</span>3 + 3 15000 330 1
<span class="stamnt">i</span>3 + 3 15000 220 1
<span class="stamnt">s</span>
<span class="comment">; pdclipped composite wave</span>
<span class="stamnt">i</span>3 0 3 15000 440 2
<span class="stamnt">i</span>3 + 3 15000 330 2
<span class="stamnt">i</span>3 + 3 15000 220 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="Credits">
<a id="idp35923104"></a>
<h2>Credits</h2>
<p>
</p>
<table border="0" summary="Simple list" class="simplelist">
<tr>
<td>Author: Anthony Kozar</td>
</tr>
<tr>
<td>January 2008</td>
</tr>
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<p>
</p>
<p>New in Csound version 5.08</p>
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