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<refentry id="hrtfmove2">
<indexterm id="IndexHrtfmove2"><primary>hrtfmove2</primary></indexterm>
<refentryinfo><title>Signal Modifiers:Panning and Spatialization</title></refentryinfo>
<refmeta>
<refentrytitle>hrtfmove2</refentrytitle>
</refmeta>
<refnamediv>
<refname>hrtfmove2</refname>
<refpurpose>
Generates dynamic 3d binaural audio for headphones using a Woodworth based spherical head model
with improved low frequency phase accuracy.
</refpurpose>
</refnamediv>
<refsect1>
<title>Description</title>
<para>
This opcode takes a source signal and spatialises it in the 3 dimensional space around a listener
using head related transfer function (HRTF) based filters.
</para>
</refsect1>
<refsect1>
<title>Syntax</title>
<synopsis>aleft, aright <command>hrtfmove2</command> asrc, kAz, kElev, ifilel, ifiler [,ioverlap, iradius, isr]</synopsis>
</refsect1>
<refsect1>
<title>Initialization</title>
<para>
<emphasis>ifilel</emphasis> -- left HRTF spectral data file
</para>
<para>
<emphasis>ifiler</emphasis> -- right HRTF spectral data file
</para>
<note>
<para>
Spectral datafiles (based on the MIT HRTF database) are available in 3 different sampling rates: 44.1, 48 and 96 khz and are labelled accordingly. Input and processing <emphasis>sr</emphasis> should match datafile <emphasis>sr</emphasis>. Files should be in the current directory or the SADIR (see <link linkend="CommandEnvironment"><citetitle>Environment Variables</citetitle></link>).
</para>
</note>
<para>
<emphasis>ioverlap</emphasis> -- optional, number of overlaps for STFT processing (default 4). See STFT section of manual.
</para>
<para>
<emphasis>iradius</emphasis> -- optional, head radius used for phase spectra calculation in centimeters (default 9.0)
</para>
<para>
<emphasis>isr</emphasis> - optional, default 44.1kHz, legal values: 44100, 48000 and 96000.
</para>
</refsect1>
<refsect1>
<title>Performance</title>
<para>
<emphasis>asrc</emphasis> -- Input/source signal.
</para>
<para>
<emphasis>kAz</emphasis> -- azimuth value in degrees. Positive values represent position on the right, negative values are positions on the left.
</para>
<para>
<emphasis>kElev</emphasis> -- elevation value in degrees. Positive values represent position above horizontal, negative values are positions below horizontal (min -40).
</para>
<para>
Artifact-free user-defined trajectories are made possible using an interpolation algorithm based on spectral
magnitude interpolation and a derived phase spectrum based on the Woodworth spherical head model.
Accuracy is increased for the data set provided by extracting and applying a frequency dependent scaling factor
to the phase spectra, leading to a more precise low frequency interaural time difference.
Users can control head radius for the phase derivation, allowing a crude level of individualisation.
The dynamic source version of the opcode uses a Short Time Fourier Transform algorithm to avoid artefacts
caused by derived phase spectra changes. STFT processing means this opcode is more computationally intensive
than <link linkend="hrtfmove"><citetitle>hrtfmove</citetitle></link> using phase truncation, but phase is constantly updated by <emphasis>hrtfmove2</emphasis>.
</para>
</refsect1>
<refsect1>
<title>Examples</title>
<para>
Here is an example of the hrtfmove2 opcode. It uses the file <ulink url="examples/hrtfmove2.csd"><citetitle>hrtfmove2.csd</citetitle></ulink>.
</para>
<example>
<title>Example of the htrfmove2 opcode.</title>
<xi:include href="examples-xml/hrtfmove2.csd.xml" xmlns:xi="http://www.w3.org/2001/XInclude"/>
</example>
</refsect1>
<refsect1>
<title>See Also</title>
<para>
<link linkend="hrtfmove"><citetitle>hrtfmove</citetitle></link>,
<link linkend="hrtfstat"><citetitle>hrtfstat</citetitle></link>,
<link linkend="hrtfer"><citetitle>hrtfer</citetitle></link>.
</para>
</refsect1>
<refsect1>
<title>Credits</title>
<para>
<simplelist>
<member>Author: Brian Carty</member>
<member>Maynooth</member>
<member>2008</member>
</simplelist>
</para>
</refsect1>
</refentry>
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