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<a id="pvsmooth"></a>
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<a id="Indexpvsmooth" class="indexterm"></a>
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<h2>
<span class="refentrytitle">pvsmooth</span>
</h2>
<p>pvsmooth —
Smooth the amplitude and frequency time functions of a pv stream using parallel 1st order
lowpass IIR filters with time-varying cutoff frequency.
</p>
</div>
<div class="refsect1">
<a id="idm281472898282648"></a>
<h2>Description</h2>
<p>
Smooth the amplitude and frequency time functions of a pv stream using a 1st order
lowpass IIR with time-varying cutoff frequency. This opcode uses the same filter
as the <span class="emphasis"><em>tone</em></span> opcode, but this time acting separately on the amplitude and frequency
time functions that make up a pv stream. The cutoff frequency parameter runs at the
control-rate, but unlike <span class="emphasis"><em>tone</em></span> and <span class="emphasis"><em>tonek</em></span>, it is not specified in Hz, but as fractions
of 1/2 frame-rate (actually the pv stream sampling rate), which is easier to
understand. This means that the highest cutoff frequency is 1 and the lowest 0; the lower
the frequency the smoother the functions and more pronounced the effect will be.
</p>
<p>
These are filters applied to control signals so the effect is basically blurring the spectral evolution. The effects produced are more or less similar to <span class="emphasis"><em>pvsblur</em></span>, but with two important
differences: 1.smoothing of amplitudes and frequencies use separate sets of filters; and 2. there is
no increase in computational cost when higher amounts of 'blurring' (smoothing) are desired.
</p>
</div>
<div class="refsect1">
<a id="idm281472898208488"></a>
<h2>Syntax</h2>
<pre class="synopsis">fsig <span class="command"><strong>pvsmooth</strong></span> fsigin, kacf, kfcf</pre>
</div>
<div class="refsect1">
<a id="idm281472898206280"></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>kacf</em></span> -- amount of cutoff frequency for amplitude function filtering, between 0 and 1,
in fractions of 1/2 frame-rate.
</p>
<p>
<span class="emphasis"><em>kfcf</em></span> -- amount of cutoff frequency for frequency function filtering, between 0 and 1,
in fractions of 1/2 frame-rate.
</p>
<div class="warning" style="margin-left: 0.5in; margin-right: 0.5in;">
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<img alt="[Warning]" src="images/warning.png" />
</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 class="refsect1">
<a id="idm281472898200888"></a>
<h2>Examples</h2>
<p>
Here is an example of the pvsmooth opcode. It uses the file <a class="ulink" href="examples/pvsmooth.csd" target="_top"><em class="citetitle">pvsmooth.csd</em></a>.
</p>
<div class="example">
<a id="idm281472898199112"></a>
<p class="title">
<strong>Example 776. Example of the pvsmooth 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>
<div class="refsect1">
<a id="idm281472719076136"></a>
<pre class="programlisting">
<span class="nt"><CsoundSynthesizer></span>
<span class="nt"><CsOptions></span>
<span class="c1">; Select audio/midi flags here according to platform</span>
-odac <span class="c1">;;;realtime audio out</span>
<span class="c1">;-iadc ;;;uncomment -iadc if realtime audio input is needed too</span>
<span class="c1">; For Non-realtime ouput leave only the line below:</span>
<span class="c1">; -o pvsmooth.wav -W ;;; for file output any platform</span>
<span class="nt"></CsOptions></span>
<span class="nt"><CsInstruments></span>
<span class="vg">sr</span> <span class="o">=</span> <span class="mi">44100</span>
<span class="vg">ksmps</span> <span class="o">=</span> <span class="mi">32</span>
<span class="vg">nchnls</span> <span class="o">=</span> <span class="mi">2</span>
<span class="vg">0dbfs</span> <span class="o">=</span> <span class="mi">1</span>
<span class="kd">instr</span> <span class="nf">1</span>
k<span class="n">acf</span> <span class="o">=</span> <span class="nb">p4</span>
k<span class="n">fcf</span> <span class="o">=</span> <span class="nb">p5</span>
a<span class="n">sig</span> <span class="nb">soundin</span> <span class="s">"fox.wav"</span>
<span class="n">fsig</span> <span class="nb">pvsanal</span> a<span class="n">sig</span><span class="p">,</span> <span class="mi">1024</span><span class="p">,</span> <span class="mi">256</span><span class="p">,</span> <span class="mi">1024</span><span class="p">,</span> <span class="mi">1</span> <span class="c1">; analyse it</span>
<span class="n">ftps</span> <span class="nb">pvsmooth</span> <span class="n">fsig</span><span class="p">,</span> k<span class="n">acf</span><span class="p">,</span> k<span class="n">fcf</span>
a<span class="n">tps</span> <span class="nb">pvsynth</span> <span class="n">ftps</span> <span class="c1">; synthesise it </span>
<span class="nb">outs</span> a<span class="n">tps</span><span class="o">*</span><span class="mi">3</span><span class="p">,</span> a<span class="n">tps</span><span class="o">*</span><span class="mi">3</span>
<span class="kd">endin</span>
<span class="nt"></CsInstruments></span>
<span class="nt"><CsScore></span>
<span class="c1">; amp freq </span>
<span class="nb">i</span> <span class="mi">1</span> <span class="mi">0</span> <span class="mi">3</span> <span class="mf">0.01</span> <span class="mf">0.01</span> <span class="c1">;smooth amplitude and frequency with cutoff frequency of filter at 1% of 1/2 frame-rate (ca 0.86 Hz)</span>
<span class="nb">i</span> <span class="mi">1</span> <span class="o">+</span> <span class="mi">3</span> <span class="mi">1</span> <span class="mf">0.01</span> <span class="c1">;no smoothing on amplitude, but frequency with cf at 1% of 1/2 frame-rate (ca 0.86 Hz)</span>
<span class="nb">i</span> <span class="mi">1</span> <span class="o">+</span> <span class="mi">10</span> <span class="mf">.001</span> <span class="mi">1</span> <span class="c1">;smooth amplitude with cf at 0.1% of 1/2 frame-rate (ca 0.086 Hz)</span>
<span class="c1">;and no smoothing of frequency</span>
<span class="nb">e</span>
<span class="nt"></CsScore></span>
<span class="nt"></CsoundSynthesizer></span>
</pre>
</div>
</div>
</div>
<p><br class="example-break" />
</p>
<p>
The formula for calculating the cutoff frequency of the filter: frame rate / hopsize = new frame starts per second (in Hz), then the percentage of half the framerate.
For example, looking at the first note in the example, the frame rate is 44100 / 256 = 172,265625 Hz (= 172 new frame starts per
second). half of the frame rate is about 86 Hz, and one percent of this is 0.86 Hz.
</p>
</div>
<div class="refsect1">
<a id="idm281472898194120"></a>
<h2>Credits</h2>
<p>
</p>
<table border="0" summary="Simple list" class="simplelist">
<tr>
<td>Author: Victor Lazzarini</td>
</tr>
<tr>
<td>May 2006 </td>
</tr>
</table>
<p>
</p>
<p>New plugin in version 5</p>
<p>May 2006.</p>
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