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<a id="liveconv"></a>
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<a id="IndexLiveconv" class="indexterm"></a>
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<h2>
<span class="refentrytitle">liveconv</span>
</h2>
<p>liveconv —
Partitioned convolution with dynamically reloadable impulse response
</p>
</div>
<div class="refsect1">
<a id="idm281472919821816"></a>
<h2>Description</h2>
<p>
Computationally efficient, partitioned convolution, using a function table as impulse response (IR) source,
similar to the <a class="link" href="ftconv.html" title="ftconv"><em class="citetitle">ftconv</em></a> opcode.
The <span class="emphasis"><em>liveconv</em></span> opcode allows dynamic reload of IR data at any time
while the convolution is running, controlled by the <span class="emphasis"><em>kupdate</em></span> parameter.
Due to the manner in which the IR is updated, the operation can be done without audio artifacts in the convolution output.
</p>
<p>
The IR table is read partition by partition after signalling an update.
The first <span class="emphasis"><em>ksmps</em></span> samples must be available when the update flag is set.
The rest of the table can be continuously filled in consecutive passes. There may be a new update
for every partition, allowing as many as <span class="emphasis"><em>ftlen/iplen</em></span> simultaneous updates
(ftlen is the length of the IR table).
</p>
<p>
The low-latency, dynamic behavior of <span class="emphasis"><em>liveconv</em></span> makes it ideal for
convolution with live sampled impulse responses, and/or real-time impulse response transformations and modifications.
</p>
</div>
<div class="refsect1">
<a id="idm281472919773336"></a>
<h2>Syntax</h2>
<pre class="synopsis">ares <span class="command"><strong>liveconv</strong></span> ain, ift, iplen, kupdate, kclear</pre>
</div>
<div class="refsect1">
<a id="idm281472919771112"></a>
<h2>Initialization</h2>
<p>
<span class="emphasis"><em>ift</em></span>
-- table number for storing the impulse response (IR) for convolution. The table may be filled with new
data at any time while the convolution is running.
</p>
<p>
<span class="emphasis"><em>iplen</em></span>
-- length of impulse response partition in samples; must be an
integer power of two. Lower settings allow for shorter output delay, but
will increase CPU usage.
</p>
</div>
<div class="refsect1">
<a id="idm281472919768248"></a>
<h2>Performance</h2>
<p>
<span class="emphasis"><em>ain</em></span>
-- input signal.
</p>
<p>
<span class="emphasis"><em>ares</em></span>
-- output signal.
</p>
<p>
<span class="emphasis"><em>kupdate</em></span>
-- flag indicating whether the IR table should be updated.
If kupdate=1 the IR table ift is loaded partition by partition, starting with the next partition.
If kupdate=-1 the IR table ift is unloaded (cleared to zero) partition by partition, starting with the next partition.
Other values have no effect.
</p>
<p>
<span class="emphasis"><em>kclear</em></span>
-- flag for clearing all internal buffers.
If kclear has any value != zero, the internal buffers are cleared immediately. This operation is not free of artifacts.
</p>
</div>
<div class="refsect1">
<a id="idm281472919763592"></a>
<h2>Example</h2>
<p>
Here is an example of the liveconv opcode. It uses the file <a class="ulink" href="examples/liveconv.csd" target="_top"><em class="citetitle">liveconv.csd</em></a>.
</p>
<div class="example">
<a id="idm281472919761816"></a>
<p class="title">
<strong>Example 473. Example of the liveconv 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="idm281472746567080"></a>
<pre class="programlisting">
<span class="nt"><CsoundSynthesizer></span>
<span class="nt"><CsOptions></span>
-odac <span class="c1">;realtime audio out</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">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="c1">; empty IR table</span>
gi<span class="n">IR_record</span> <span class="nb">ftgen</span> <span class="mi">0</span><span class="p">,</span> <span class="mi">0</span><span class="p">,</span> <span class="mi">131072</span><span class="p">,</span> <span class="mi">2</span><span class="p">,</span> <span class="mi">0</span>
<span class="c1">; Record impulse response</span>
<span class="kd">instr</span> <span class="nf">13</span>
<span class="nb">p3</span> <span class="o">=</span> <span class="nb">ftlen</span><span class="p">(</span>gi<span class="n">IR_record</span><span class="p">)</span><span class="o">/</span><span class="vg">sr</span>
i<span class="n">skip</span> <span class="o">=</span> <span class="nb">p4</span>
i<span class="n">rlen</span> <span class="o">=</span> <span class="nb">p5</span>
a<span class="n">1</span> <span class="nb">diskin2</span> <span class="s">"fox.wav"</span><span class="p">,</span> <span class="mi">1</span><span class="p">,</span> i<span class="n">skip</span>
<span class="c1">; Fill IR table with segment from audio file</span>
a<span class="n">mp</span> <span class="nb">linseg</span> <span class="mi">0</span><span class="p">,</span> <span class="mf">0.1</span><span class="p">,</span> <span class="mi">1</span><span class="p">,</span> i<span class="n">rlen</span><span class="p">,</span> <span class="mi">1</span><span class="p">,</span> <span class="mf">0.1</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">0</span>
a<span class="n">ndx_IR</span> <span class="nb">line</span> <span class="mi">0</span><span class="p">,</span> <span class="mi">1</span><span class="p">,</span> <span class="mi">1</span><span class="o">/</span><span class="p">(</span><span class="nb">ftlen</span><span class="p">(</span>gi<span class="n">IR_record</span><span class="p">)</span><span class="o">/</span><span class="vg">sr</span><span class="p">)</span>
<span class="nb">tablew</span> a<span class="n">1</span><span class="o">*</span>a<span class="n">mp</span><span class="p">,</span> a<span class="n">ndx_IR</span><span class="p">,</span> gi<span class="n">IR_record</span><span class="p">,</span> <span class="mi">1</span>
<span class="nb">outch</span> <span class="mi">1</span><span class="p">,</span> a<span class="n">1</span><span class="o">*</span>a<span class="n">mp</span> <span class="c1">; output the IR</span>
k<span class="n">trig</span> <span class="nb">init</span> <span class="mi">1</span>
<span class="k">if</span> k<span class="n">trig</span> <span class="o">></span> <span class="o">-</span><span class="mi">1</span> <span class="k">then</span>
<span class="nb">chnset</span> k<span class="n">trig</span><span class="p">,</span> <span class="s">"conv_update"</span>
k<span class="n">trig</span> <span class="o">-=</span> <span class="mi">1</span>
<span class="k">endif</span>
<span class="kd">endin</span>
<span class="c1">; The convolver</span>
<span class="kd">instr</span> <span class="nf">14</span>
a<span class="n">in</span> <span class="nb">diskin2</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>
k<span class="n">update</span> <span class="nb">chnget</span> <span class="s">"conv_update"</span>
a<span class="n">conv</span> <span class="n">liveconv</span> a<span class="n">in</span><span class="p">,</span> gi<span class="n">IR_record</span><span class="p">,</span> <span class="mi">2048</span><span class="p">,</span> k<span class="n">update</span><span class="p">,</span> <span class="mi">0</span>
<span class="nb">outch</span> <span class="mi">2</span><span class="p">,</span> a<span class="n">conv</span><span class="o">*</span><span class="mf">0.009</span> <span class="c1">; output the convolution response</span>
<span class="kd">endin</span>
<span class="nt"></CsInstruments></span>
<span class="nt"><CsScore></span>
<span class="c1">; record impulse response</span>
<span class="c1">; skip IR_dur</span>
<span class="nb">i</span><span class="mi">13</span> <span class="mi">0</span> <span class="mi">1</span> <span class="mf">0.0</span> <span class="mf">0.5</span>
<span class="nb">i</span><span class="mi">13</span> <span class="mi">2</span> <span class="mi">1</span> <span class="mf">0.5</span> <span class="mf">0.5</span>
<span class="nb">i</span><span class="mi">13</span> <span class="mi">4</span> <span class="mi">1</span> <span class="mf">1.0</span> <span class="mf">0.5</span>
<span class="nb">i</span><span class="mi">13</span> <span class="mi">6</span> <span class="mi">1</span> <span class="mf">1.5</span> <span class="mf">0.5</span>
<span class="nb">i</span><span class="mi">13</span> <span class="mi">8</span> <span class="mi">1</span> <span class="mf">2.0</span> <span class="mf">0.75</span>
<span class="nb">i</span><span class="mi">13</span> <span class="mi">10</span> <span class="mi">1</span> <span class="mf">2.38</span> <span class="mf">0.25</span>
<span class="c1">; convolve</span>
<span class="nb">i</span><span class="mi">14</span> <span class="mf">0.0</span> <span class="mf">11.65</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>
</div>
<div class="refsect1">
<a id="idm281472919757528"></a>
<h2>See also</h2>
<p>
<a class="link" href="ftconv.html" title="ftconv"><em class="citetitle">ftconv</em></a>
<a class="link" href="tvconv.html" title="tvconv"><em class="citetitle">tvconv</em></a>
<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>,
</p>
</div>
<div class="refsect1">
<a id="idm281472919752632"></a>
<h2>Credits</h2>
<p>
</p>
<table border="0" summary="Simple list" class="simplelist">
<tr>
<td>Author: Sigurd Saue, Oeyvind Brandtsegg</td>
</tr>
<tr>
<td>2017</td>
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