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<h2>
<span class="refentrytitle">pvstencil</span>
</h2>
<p>pvstencil —
Transforms a pvoc stream according to a masking function table.
</p>
</div>
<div class="refsect1" title="Description">
<a id="idp39302096"></a>
<h2>Description</h2>
<p>
Transforms a pvoc stream according to a masking function table;
if the pvoc stream amplitude falls below the value of the function
for a specific pvoc channel, it applies a gain to that channel.
</p>
<p>
The pvoc stream amplitudes are compared to a masking table, if
the fall below the table values, they are scaled by <span class="emphasis"><em>kgain</em></span>. Prior
to the operation, table values are scaled by <span class="emphasis"><em>klevel</em></span>, which can be
used as masking depth control.
</p>
<p>
Tables have to be at least fftsize/2 in size; for most GENS it is
important to use an extended-guard point (size power-of-two plus
one), however this is not necessary with GEN43.
</p>
<p>
One of the typical uses of <span class="emphasis"><em>pvstencil</em></span> would be in noise
reduction. A noise print can be analysed with <span class="emphasis"><em>pvanal</em></span> into a PVOC-EX
file and loaded in a table with <span class="emphasis"><em>GEN43</em></span>. This then can be used as
the masking table for <span class="emphasis"><em>pvstencil</em></span> and the amount of reduction would
be controlled by <span class="emphasis"><em>kgain</em></span>. Skipping post-normalisation will keep the
original noise print average amplitudes. This would provide a good
starting point for a successful noise reduction (so that <span class="emphasis"><em>klevel</em></span>
can be generally set to close to 1).
</p>
<p>
Other possible transformation effects are possible, such as
filtering and `inverse-masking'.
</p>
</div>
<div class="refsect1" title="Syntax">
<a id="idp39358008"></a>
<h2>Syntax</h2>
<pre class="synopsis">fsig <span class="command"><strong>pvstencil</strong></span> fsigin, kgain, klevel, iftable</pre>
</div>
<div class="refsect1" title="Performance">
<a id="idp39359088"></a>
<h2>Performance</h2>
<p>
<span class="emphasis"><em>fsig</em></span> -- output pv stream
</p>
<p>
<span class="emphasis"><em>fsigin</em></span> -- input pv stream.
</p>
<p>
<span class="emphasis"><em>kgain</em></span> -- `stencil' gain.
</p>
<p>
<span class="emphasis"><em>klevel</em></span> -- masking function level (scales
the ftable prior to `stenciling') .
</p>
<p>
<span class="emphasis"><em>iftable</em></span> -- masking function table.
</p>
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</td>
<th align="left">Warning</th>
</tr>
<tr>
<td align="left" valign="top">
<p>
It is unsafe to use the same f-variable for both input and output of pvs opcodes. Using the same one might lead to undefined behavior on some opcodes. Use a different one on the left and right sides of the opcode.
</p>
</td>
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</div>
<div class="refsect1" title="Examples">
<a id="idp39362336"></a>
<h2>Examples</h2>
<p>
</p>
<div class="example">
<a id="idp39362800"></a>
<p class="title">
<strong>Example 677. Example</strong>
</p>
<div class="example-contents">
<pre class="programlisting">
fsig <span class="opc">pvsanal</span> asig, 1024, 256, 1024, 1
fclean <span class="opc">pvstencil</span> fsig, 0, 1, 1
aclean <span class="opc">pvsynth</span> fclean</pre>
</div>
</div>
<p><br class="example-break" />
</p>
</div>
<div class="refsect1" title="Credits">
<a id="idp39364760"></a>
<h2>Credits</h2>
<p>
</p>
<table border="0" summary="Simple list" class="simplelist">
<tr>
<td>Author: Victor Lazzarini</td>
</tr>
<tr>
<td>November 2004 </td>
</tr>
</table>
<p>
</p>
<p>New plugin in version 5</p>
<p>November 2004.</p>
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distrib
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Mageia
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5
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x86_64
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media
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core-release
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b707d9a4ee443103660a75ccb6e51334
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files
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