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<div class="refentry">
<a id="tvconv"></a>
<div class="titlepage"></div>
<a id="IndexTvconv" class="indexterm"></a>
<div class="refnamediv">
<h2>
<span class="refentrytitle">tvconv</span>
</h2>
<p>tvconv —
A time-varying convolution (FIR filter) opcode.
</p>
</div>
<div class="refsect1">
<a id="idm281472877041080"></a>
<h2>Description</h2>
<p>
An opcode that takes two incoming signals and
interprets one of them as the coefficients of linear
time-variable finite impulse response filter. This is
implemented via direct convolution (for partition sizes of
1 sample) or DFT-based partitioned convolution.
The signals can be 'frozen' (i.e. the filter coefficients are
kept the same) at any point in time, at a-rate or k-rate.
</p>
</div>
<div class="refsect1">
<a id="idm281472876984200"></a>
<h2>Syntax</h2>
<pre class="synopsis">ares <span class="command"><strong>tvconv</strong></span> asig1, asig2, xfreez1,
xfreez2, iparts, ifils</pre>
</div>
<div class="refsect1">
<a id="idm281472876981960"></a>
<h2>Initialization</h2>
<p>
<span class="emphasis"><em>iparts</em></span> -- partition size, for sizes > 1, a
DFT-based partitioned convolution process is used. Otherwise a
time-domain delay line FIR is implemented. Partition sizes > 1
are rounded to the nearest power-of-two.
</p>
<p>
<span class="emphasis"><em>ifils</em></span> -- filter size. For partition sizes >
1, filter sizes are rounded to the nearest power-of-two. With
partition size = 1, since direct convolution is used, filters
can be of any size.
</p>
</div>
<div class="refsect1">
<a id="idm281472876979096"></a>
<h2>Performance</h2>
<p>
<span class="emphasis"><em>ares</em></span> -- audio output.
</p>
<p>
<span class="emphasis"><em>asig1, asig2</em></span> -- audio inputs.
</p>
<p>
<span class="emphasis"><em>xfreez1</em></span> -- freeze switch for
asig1. Coefficients are only updated (ie. the signal is passing
into the convolution) if xfreez1 > 0. This input can take an
audio or a k-rate signal, or a constant.
</p>
<p>
<span class="emphasis"><em>xfreez2</em></span> -- freeze switch for
asig2, similar to xfreez1 in operation.
</p>
</div>
<div class="refsect1">
<a id="idm281472876974808"></a>
<h2>Examples</h2>
<p>
Here is an example of the tvconv opcode. It uses the file <a class="ulink" href="examples/tvconv.csd" target="_top"><em class="citetitle">tvconv.csd</em></a>.
</p>
<div class="example">
<a id="idm281472876972952"></a>
<p class="title">
<strong>Example 1035. Example of the tvconv 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="idm281472697553592"></a>
<pre class="programlisting">
<span class="nt"><CsoundSynthesizer></span>
<span class="nt"><CsOptions></span>
-odac
<span class="nt"></CsOptions></span>
<span class="nt"><CsInstruments></span>
<span class="kd">instr</span> <span class="nf">1</span>
a<span class="n">sig</span> <span class="nb">diskin</span> <span class="s">"fox.wav"</span><span class="p">,</span><span class="mi">1</span><span class="p">,</span><span class="mi">0</span><span class="p">,</span><span class="mi">1</span>
a<span class="n">ir</span> <span class="nb">diskin</span> <span class="s">"beats.wav"</span><span class="p">,</span><span class="mi">1</span><span class="p">,</span><span class="mi">0</span><span class="p">,</span><span class="mi">1</span>
a<span class="n">ir</span> <span class="nb">buthp</span> a<span class="n">ir</span><span class="o">/</span><span class="vg">0dbfs</span><span class="p">,</span><span class="mi">1000</span>
k<span class="n">1</span> <span class="nb">linseg</span> <span class="mi">0</span><span class="p">,</span><span class="nb">p3</span><span class="o">/</span><span class="mi">3</span><span class="p">,</span><span class="mi">0</span><span class="p">,</span><span class="mi">0</span><span class="p">,</span><span class="mi">1</span><span class="p">,</span><span class="mi">2</span><span class="o">*</span><span class="nb">p3</span><span class="o">/</span><span class="mi">3</span><span class="p">,</span><span class="mi">1</span>
a<span class="n">1</span> <span class="nb">oscili</span> k<span class="n">1</span><span class="p">,</span> <span class="mf">0.5</span><span class="p">,</span> <span class="mi">1</span>
a<span class="n">2</span> <span class="nb">oscili</span> k<span class="n">1</span><span class="p">,</span> <span class="mf">0.6</span><span class="p">,</span> <span class="mi">1</span>
a<span class="n">sig</span> <span class="n">tvconv</span> a<span class="n">sig</span><span class="p">,</span>a<span class="n">ir</span><span class="p">,</span><span class="mi">1</span><span class="o">-</span>a<span class="n">2</span><span class="p">,</span><span class="mi">1</span><span class="o">-</span>a<span class="n">1</span><span class="p">,</span><span class="mi">256</span><span class="p">,</span><span class="mi">1024</span>
a<span class="n">sig</span> <span class="nb">clip</span> a<span class="n">sig</span><span class="p">,</span><span class="mi">1</span><span class="p">,</span><span class="vg">0dbfs</span>
<span class="nb">out</span> a<span class="n">sig</span>
<span class="kd">endin</span>
<span class="nt"></CsInstruments></span>
<span class="nt"><CsScore></span>
<span class="nb">f</span><span class="mi">1</span> <span class="mi">0</span> <span class="mi">1024</span> <span class="mi">7</span> <span class="mi">0</span> <span class="mi">512</span> <span class="mi">0</span> <span class="mi">1</span> <span class="mi">1</span> <span class="mi">511</span> <span class="mi">1</span>
<span class="nb">i</span><span class="mi">1</span> <span class="mi">0</span> <span class="mi">30</span>
<span class="nt"></CsScore></span>
<span class="nt"></CsoundSynthesizer></span>
</pre>
</div>
</div>
</div>
<p><br class="example-break" />
</p>
</div>
<div class="refsect1">
<a id="idm281472876968664"></a>
<h2>See also</h2>
<p>
<a class="link" href="pconvolve.html" title="pconvolve"><em class="citetitle">pconvolve</em></a>,
<a class="link" href="convolve.html" title="convolve"><em class="citetitle">convolve</em></a>,
<a class="link" href="ftconv.html" title="ftconv"><em class="citetitle">ftconv</em></a>
</p>
</div>
<div class="refsect1">
<a id="idm281472876964696"></a>
<h2>Credits</h2>
<p>
</p>
<table border="0" summary="Simple list" class="simplelist">
<tr>
<td>Author: Victor Lazzarini </td>
</tr>
<tr>
<td>2017</td>
</tr>
</table>
<p>
</p>
<p>New in version 6.09</p>
</div>
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