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<refentry id="vbap4">
<indexterm id="IndexVbap4"><primary>vbap4</primary></indexterm>
<refentryinfo><title>Signal Modifiers:Panning and Spatialization</title></refentryinfo>
<refmeta>
<refentrytitle>vbap4</refentrytitle>
</refmeta>
<refnamediv>
<refname>vbap4</refname>
<refpurpose>
Distributes an audio signal among 4 channels.
</refpurpose>
</refnamediv>
<refsect1>
<title>Description</title>
<para>
Distributes an audio signal among 4 channels.
</para>
</refsect1>
<refsect1>
<title>Syntax</title>
<synopsis>ar1, ar2, ar3, ar4 <command>vbap4</command> asig, kazim [, kelev] [, kspread]</synopsis>
</refsect1>
<!-- <refsect1>
<title>Initialization</title>
</refsect1>-->
<refsect1>
<title>Performance</title>
<para>
<emphasis>asig</emphasis> -- audio signal to be panned
</para>
<para>
<emphasis>kazim</emphasis> -- azimuth angle of the virtual source
</para>
<para>
<emphasis>kelev</emphasis> (optional) -- elevation angle of the virtual source
</para>
<para>
<emphasis>kspread</emphasis> (optional) -- spreading of the virtual source (range 0 - 100). If value is zero, conventional amplitude panning is used. When <emphasis>kspread</emphasis> is increased, the number of loudspeakers used in panning increases. If value is 100, the sound is applied to all loudspeakers.
</para>
<para>
<emphasis>vbap4</emphasis> takes an input signal, <emphasis>asig</emphasis> and distributes it among 4 outputs, according to the controls <emphasis>kazim</emphasis> and <emphasis>kelev</emphasis>, and the configured loudspeaker placement. If <emphasis>idim</emphasis> = 2, <emphasis>kelev</emphasis> is set to zero. The distribution is performed using Vector Base Amplitude Panning (VBAP - See reference). VBAP distributes the signal using loudspeaker data configured with <emphasis>vbaplsinit</emphasis>. The signal is applied to, at most, two loudspeakers in 2-D loudspeaker configurations, and three loudspeakers in 3-D loudspeaker configurations. If the virtual source is panned outside the region spanned by loudspeakers, the nearest loudspeakers are used in panning.
</para>
<warning>
<para>Please note that all <emphasis>vbap</emphasis> panning opcodes require the <emphasis>vbap</emphasis> system to be initialized using <link linkend="vbaplsinit"><citetitle>vbaplsinit</citetitle></link>.</para>
</warning>
</refsect1>
<refsect1>
<title>Examples</title>
<para>
See the entry for <link linkend="vbap8"><citetitle>vbap8</citetitle></link> for an example of usage of the <emphasis>vbap</emphasis> opcodes.
</para>
</refsect1>
<refsect1>
<title>Reference</title>
<para>
Ville Pulkki: <quote>Virtual Sound Source Positioning Using Vector Base Amplitude Panning</quote> <emphasis>Journal of the Audio Engineering Society</emphasis>, 1997 June, Vol. 45/6, p. 456.
</para>
</refsect1>
<refsect1>
<title>See Also</title>
<para>
<link linkend="vbap16"><citetitle>vbap16</citetitle></link>,
<link linkend="vbap16move"><citetitle>vbap16move</citetitle></link>,
<link linkend="vbap4move"><citetitle>vbap4move</citetitle></link>,
<link linkend="vbap8"><citetitle>vbap8</citetitle></link>,
<link linkend="vbap8move"><citetitle>vbap8move</citetitle></link>,
<link linkend="vbaplsinit"><citetitle>vbaplsinit</citetitle></link>,
<link linkend="vbapz"><citetitle>vbapz</citetitle></link>,
<link linkend="vbapzmove"><citetitle>vbapzmove</citetitle></link>
</para>
</refsect1>
<refsect1>
<title>Credits</title>
<para>
<simplelist>
<member>Author: Ville Pulkki</member>
<member>Sibelius Academy Computer Music Studio</member>
<member>Laboratory of Acoustics and Audio Signal Processing</member>
<member>Helsinki University of Technology</member>
<member>Helsinki, Finland</member>
<member>May 2000</member>
</simplelist>
</para>
<para>New in Csound Version 4.06. Input parameters accept k-rate since Csund 5.09.</para>
</refsect1>
</refentry>
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