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<h2>
<span class="refentrytitle">vco2init</span>
</h2>
<p>vco2init —
Calculates tables for use by vco2 opcode.
</p>
</div>
<div class="refsect1" title="Description">
<a id="idp51031560"></a>
<h2>Description</h2>
<p>
<span class="emphasis"><em>vco2init</em></span> calculates tables for use by <a class="link" href="vco2.html" title="vco2"><em class="citetitle">vco2</em></a> opcode. Optionally, it is also possible to access these tables as standard Csound function tables. In this case, <a class="link" href="vco2ft.html" title="vco2ft"><em class="citetitle">vco2ft</em></a> can be used to find the correct table number for a given oscillator frequency.
</p>
<p>
In most cases, this opcode is called from the orchestra header. Using <span class="emphasis"><em>vco2init</em></span> in instruments is possible but not recommended. This is because replacing tables during performance can result in a Csound crash if other opcodes are accessing the tables at the same time.
</p>
<p>
Note that <span class="emphasis"><em>vco2init</em></span> is not required for <span class="emphasis"><em>vco2</em></span> to work (tables are automatically allocated by the first <span class="emphasis"><em>vco2</em></span> call, if not done yet), however it can be useful in some cases:
</p>
<div class="itemizedlist">
<ul class="itemizedlist" type="disc">
<li class="listitem">
<p>Pre-calculate tables at orchestra load time. This is useful to avoid generating the tables during performance, which could interrupt real-time processing.</p>
</li>
<li class="listitem">
<p>Share the tables as Csound ftables. By default, the tables can be accessed only by <a class="link" href="vco2.html" title="vco2"><em class="citetitle">vco2</em></a>.</p>
</li>
<li class="listitem">
<p>Change the default parameters of tables (e.g. size) or use an user-defined waveform specified in a function table.</p>
</li>
</ul>
</div>
<p>
</p>
</div>
<div class="refsect1" title="Syntax">
<a id="idp51085448"></a>
<h2>Syntax</h2>
<pre class="synopsis">ifn <span class="command"><strong>vco2init</strong></span> iwave [, ibasfn] [, ipmul] [, iminsiz] [, imaxsiz] [, isrcft]</pre>
</div>
<div class="refsect1" title="Initialization">
<a id="idp51086616"></a>
<h2>Initialization</h2>
<p>
<span class="emphasis"><em>ifn</em></span> -- the first free ftable number after the allocated tables. If <span class="emphasis"><em>ibasfn</em></span> was not specified, -1 is returned.
</p>
<p>
<span class="emphasis"><em>iwave</em></span> -- sum of the following values selecting which waveforms are to be calculated:
</p>
<div class="itemizedlist">
<ul class="itemizedlist" type="disc">
<li class="listitem">
<p>16: triangle</p>
</li>
<li class="listitem">
<p>8: square wave</p>
</li>
<li class="listitem">
<p>4: pulse (not normalized)</p>
</li>
<li class="listitem">
<p>2: 4 * x * (1 - x) (integrated sawtooth)</p>
</li>
<li class="listitem">
<p>1: sawtooth</p>
</li>
</ul>
</div>
<p>
</p>
<p>
Alternatively, <span class="emphasis"><em>iwave</em></span> can be set to a negative integer that selects an user-defined waveform. This also requires the <span class="emphasis"><em>isrcft</em></span> parameter to be specified. <a class="link" href="vco2.html" title="vco2"><em class="citetitle">vco2</em></a> can access waveform number -1. However, other user-defined waveforms are usable only with <a class="link" href="vco2ft.html" title="vco2ft"><em class="citetitle">vco2ft</em></a> or <a class="link" href="vco2ift.html" title="vco2ift"><em class="citetitle">vco2ift</em></a>.
</p>
<p>
<span class="emphasis"><em>ibasfn</em></span> (optional, default=-1) -- ftable number from which the table set(s) can be accessed by opcodes other than <span class="emphasis"><em>vco2</em></span>. This is required by user defined waveforms, with the exception of -1. If this value is less than 1, it is not possible to access the tables calculated by <span class="emphasis"><em>vco2init</em></span> as Csound function tables.
</p>
<p>
<span class="emphasis"><em>ipmul</em></span> (optional, default=1.05) -- multiplier value for number of harmonic partials. If one table has n partials, the next one will have n * <span class="emphasis"><em>ipmul</em></span> (at least n + 1). The allowed range for <span class="emphasis"><em>ipmul</em></span> is 1.01 to 2. Zero or negative values select the default (1.05).
</p>
<p>
<span class="emphasis"><em>iminsiz</em></span> (optional, default=-1) -- minimum table size.
</p>
<p>
<span class="emphasis"><em>imaxsiz</em></span> (optional, default=-1) -- maximum table size.
</p>
<p>
The actual table size is calculated by multiplying the square root of the number of harmonic partials by <span class="emphasis"><em>iminsiz</em></span>, rounding up the result to the next power of two, and limiting this not to be greater than <span class="emphasis"><em>imaxsiz</em></span>.
</p>
<p>
Both parameters, <span class="emphasis"><em>iminsiz</em></span> and <span class="emphasis"><em>imaxsiz</em></span>, must be power of two, and in the allowed range. The allowed range is 16 to 262144 for <span class="emphasis"><em>iminsiz</em></span> to up to 16777216 for <span class="emphasis"><em>imaxsiz</em></span>. Zero or negative values select the default settings:
</p>
<div class="itemizedlist">
<ul class="itemizedlist" type="disc">
<li class="listitem">
<p>The minimum size is 128 for all waveforms except pulse (<span class="emphasis"><em>iwave</em></span>=4). Its minimum size is 256.</p>
</li>
<li class="listitem">
<p>The default maximum size is usually the minimum size multiplied by 64, but not more than 16384 if possible. It is always at least the minimum size.</p>
</li>
</ul>
</div>
<p>
</p>
<p>
<span class="emphasis"><em>isrcft</em></span> (optional, default=-1) -- source ftable number for user-defined waveforms (if <span class="emphasis"><em>iwave</em></span> < 0). <span class="emphasis"><em>isrcft</em></span> should point to a function table containing the waveform to be used for generating the table array. The table size is recommended to be at least <span class="emphasis"><em>imaxsiz</em></span> points. If <span class="emphasis"><em>iwave</em></span> is not negative (built-in waveforms are used), <span class="emphasis"><em>isrcft</em></span> is ignored.
</p>
<div class="warning" title="Warning" style="margin-left: 0.5in; margin-right: 0.5in;">
<table border="0" summary="Warning: Warning">
<tr>
<td rowspan="2" align="center" valign="top" width="25">
<img alt="[Warning]" src="images/warning.png" />
</td>
<th align="left">Warning</th>
</tr>
<tr>
<td align="left" valign="top">
<p>
The number and size of tables is not fixed. Orchestras should not depend on these parameters, as they are subject to changes between releases.
</p>
<p>
If the selected table set already exists, it is replaced. If any opcode is accessing the tables at the same time, it is very likely that a crash will occur. This is why it is recommended to use <span class="emphasis"><em>vco2init</em></span> only in the orchestra header.
</p>
<p>
These tables should not be replaced/overwritten by GEN routines or the <span class="emphasis"><em>ftgen</em></span> opcode. Otherwise, unpredictable behavior or a Csound crash may occur if <a class="link" href="vco2.html" title="vco2"><em class="citetitle">vco2</em></a> is used. The first free ftable after the table array(s) is returned in <span class="emphasis"><em>ifn</em></span>.
</p>
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<div class="refsect1" title="Examples">
<a id="idp51103128"></a>
<h2>Examples</h2>
<p>
Here is an example of the vco2init opcode. It uses the file <a class="ulink" href="examples/vco2init.csd" target="_top"><em class="citetitle">vco2init.csd</em></a>.
</p>
<div class="example">
<a id="idp51104112"></a>
<p class="title">
<strong>Example 932. Example of the vco2init 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>
-odac <span class="comment">;;;realtime audio out</span>
<span class="comment">;-iadc ;;;uncomment -iadc if realtime audio input is needed too</span>
<span class="comment">; For Non-realtime ouput leave only the line below:</span>
<span class="comment">; -o vco2init.wav -W ;;; for file output any platform</span>
<span class="csdtag"></CsOptions></span>
<span class="csdtag"><CsInstruments></span>
<span class="ohdr">sr</span><span class="op">=</span>44100
<span class="ohdr">ksmps</span><span class="op">=</span>1
<span class="ohdr">nchnls</span><span class="op">=</span>2
<span class="comment">; create waveform with discontinuities, so it has a lot of high freq content</span>
gitable <span class="ohdr">ftgen</span> 0, 0, 2^16<span class="op">+</span>1, 7, <span class="op">-</span>1, 2^14, 1, 0, <span class="op">-</span>1, 2^14, 1, 0, <span class="op">-</span>1, 2^15, 1
<span class="comment">; make bandlimited tables of the waveform</span>
gi_nextfree <span class="opc">vco2init</span> <span class="op">-</span>gitable, gitable<span class="op">+</span>1, 1.05, 128, 2^16, gitable
gitable_bl <span class="op">=</span> <span class="op">-</span>gitable
<span class="oblock">instr</span> 1
kfreq <span class="opc">expon</span> 14000, p3, 500
kfn <span class="opc">vco2ft</span> kfreq, gitable_bl
asig <span class="opc">oscilikt</span> 5000, kfreq, kfn
<span class="opc">printk</span> 0.1, kfn
<span class="comment">; remove semicolon on next line to hear original waveform, demonstrating the aliasing</span>
<span class="comment">;asig oscili 5000, kfreq, gitable</span>
<span class="opc">outs</span> asig, asig
<span class="oblock">endin</span>
<span class="csdtag"></CsInstruments></span>
<span class="csdtag"><CsScore></span>
<span class="stamnt">i</span>1 0 5
<span class="stamnt">e</span>
<span class="csdtag"></CsScore></span>
<span class="csdtag"></CsoundSynthesizer></span>
</pre>
</div>
</div>
<p><br class="example-break" />
Its output should include a line like these:
</p>
<pre class="screen">
i 1 time 0.00002: 103.00000
i 1 time 0.10000: 103.00000
i 1 time 0.20000: 103.00000
i 1 time 0.30002: 103.00000
i 1 time 0.40000: 104.00000
i 1 time 0.50000: 104.00000
.......
......
i 1 time 4.80002: 135.00000
i 1 time 4.90000: 136.00000
i 1 time 5.00000: 138.00000
</pre>
<p>
</p>
<p>
See the example for the <a class="link" href="vco2.html" title="vco2"><em class="citetitle">vco2</em></a> opcode too.
</p>
</div>
<div class="refsect1" title="See Also">
<a id="idp51107832"></a>
<h2>See Also</h2>
<p>
<a class="link" href="vco2ft.html" title="vco2ft"><em class="citetitle">vco2ft</em></a>,
<a class="link" href="vco2ift.html" title="vco2ift"><em class="citetitle">vco2ift</em></a>, and
<a class="link" href="vco2.html" title="vco2"><em class="citetitle">vco2</em></a>.
</p>
</div>
<div class="refsect1" title="Credits">
<a id="idp51109872"></a>
<h2>Credits</h2>
<p>Author: Istvan Varga</p>
<p>New in version 4.22</p>
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