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<refentry id="vbap4move">
<indexterm id="IndexVbap4move"><primary>vbap4move</primary></indexterm>
<refentryinfo><title>Signal Modifiers:Panning and Spatialization</title></refentryinfo>
<refmeta>
<refentrytitle>vbap4move</refentrytitle>
</refmeta>
<refnamediv>
<refname>vbap4move</refname>
<refpurpose>
Distributes an audio signal among 4 channels with moving virtual sources.
</refpurpose>
</refnamediv>
<refsect1>
<title>Description</title>
<para>
Distributes an audio signal among 4 channels with moving virtual sources.
</para>
</refsect1>
<refsect1>
<title>Syntax</title>
<synopsis>ar1, ar2, ar3, ar4 <command>vbap4move</command> asig, idur, ispread, ifldnum, ifld1 \
[, ifld2] [...]</synopsis>
</refsect1>
<refsect1>
<title>Initialization</title>
<para>
<emphasis>idur</emphasis> -- the duration over which the
movement takes place.
</para>
<para>
<emphasis>ispread</emphasis> -- spreading of the virtual source
(range 0 - 100). If value is zero, conventional amplitude panning
is used. When <emphasis>ispread</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>ifldnum</emphasis> -- number of fields (absolute value must be 2 or larger). If <emphasis>ifldnum</emphasis> is positive, the virtual source movement is a polyline specified by given directions. Each transition is performed in an equal time interval. If <emphasis>ifldnum</emphasis> is negative, specified angular velocities are applied to the virtual source during specified relative time intervals (see below).
</para>
<para>
<emphasis>ifld1, ifld2, ...</emphasis> -- azimuth angles or angular velocities, and relative durations of movement phases (see below).
</para>
</refsect1>
<refsect1>
<title>Performance</title>
<para>
<emphasis>asig</emphasis> -- audio signal to be panned
</para>
<para>
<emphasis>vbap4move</emphasis> allows the use of moving virtual sources. If <emphasis>ifldnum</emphasis> is positive, the fields represent directions of virtual sources and equal times, <emphasis>iazi1</emphasis>, [<emphasis>iele1</emphasis>,] <emphasis>iazi2</emphasis>, [<emphasis>iele2</emphasis>,], etc. The position of the virtual source is interpolated between directions starting from the first direction and ending at the last. Each interval is interpolated in time that is fraction total_time / number_of_intervals of the duration of the sound event.
</para>
<para>
If <emphasis>ifldnum</emphasis> is negative, the fields represent angular velocities and equal times. The first field is, however, the starting direction, <emphasis>iazi1</emphasis>, [<emphasis>iele1</emphasis>,] <emphasis>iazi_vel1</emphasis>, [<emphasis>iele_vel1</emphasis>,] <emphasis>iazi_vel2</emphasis>, [<emphasis>iele_vel2</emphasis>,] .... Each velocity is applied to the note that is fraction total_time / number_of_velocities of the duration of the sound event. If the elevation of the virtual source becomes greater than 90 degrees or less than 0 degrees, the polarity of angular velocity is changed. Thus the elevational angular velocity produces a virtual source that moves up and down between 0 and 90 degrees.
</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="vbap8move"><citetitle>vbap8move</citetitle></link> for an example of usage of the <emphasis>vbapXmove</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="vbap4"><citetitle>vbap4</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 4.07</para>
</refsect1>
</refentry>
|
