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<h2>
<span class="refentrytitle">hrtfstat</span>
</h2>
<p>hrtfstat —
Generates static 3d binaural audio for headphones using a
Woodworth based spherical head model with improved low frequency
phase accuracy.
</p>
</div>
<div class="refsect1">
<a id="idm281472925371416"></a>
<h2>Description</h2>
<p>
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. It produces a static output (azimuth and elevation parameters are i-rate), because a static source allows much more efficient processing than <a class="link" href="hrtfmove.html" title="hrtfmove"><em class="citetitle">hrtfmove</em></a> and <a class="link" href="hrtfmove2.html" title="hrtfmove2"><em class="citetitle">hrtfmove2</em></a>,.
</p>
</div>
<div class="refsect1">
<a id="idm281472925325576"></a>
<h2>Syntax</h2>
<pre class="synopsis">
aleft, aright <span class="command"><strong>hrtfstat</strong></span> asrc, iAz, iElev, ifilel, ifiler [,iradius, isr]
</pre>
</div>
<div class="refsect1">
<a id="idm281472925323336"></a>
<h2>Initialization</h2>
<p>
<span class="emphasis"><em>iAz</em></span> -- azimuth value in degrees. Positive
values represent position on the right, negative values are
positions on the left.
</p>
<p>
<span class="emphasis"><em>iElev</em></span> -- elevation value in
degrees. Positive values represent position above horizontal,
negative values are positions below horizontal (min -40).
</p>
<p>
<span class="emphasis"><em>ifilel </em></span> -- left HRTF spectral data file
</p>
<p>
<span class="emphasis"><em>ifiler </em></span> -- right HRTF spectral data file
</p>
<div class="note" style="margin-left: 0.5in; margin-right: 0.5in;">
<table border="0" summary="Note">
<tr>
<td rowspan="2" align="center" valign="top" width="25">
<img alt="[Note]" src="images/note.png" />
</td>
<th align="left">Note</th>
</tr>
<tr>
<td align="left" valign="top">
<p>
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 sr should match datafile sr. Files should be in the
current directory or the SADIR (see <a class="link" href="CommandEnvironment.html" title="Csound Environment Variables"><em class="citetitle">Environment Variables</em></a>).
</p>
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<table border="0" summary="Note">
<tr>
<td rowspan="2" align="center" valign="top" width="25">
<img alt="[Note]" src="images/note.png" />
</td>
<th align="left">Note</th>
</tr>
<tr>
<td align="left" valign="top">
<p>
HRTF Data files for use with
<a class="link" href="hrtfmove.html" title="hrtfmove"><em class="citetitle">hrtfmove</em></a>,
<a class="link" href="hrtfmove2.html" title="hrtfmove2"><em class="citetitle">hrtfmove2</em></a>,
<a class="link" href="hrtfstat.html" title="hrtfstat"><em class="citetitle">hrtfstat</em></a>,
<a class="link" href="hrtfearly.html" title="hrtfearly"><em class="citetitle">hrtfearly</em></a>,
<a class="link" href="hrtfreverb.html" title="hrtfreverb"><em class="citetitle">hrtfreverb</em></a>
were updated for Csound 5.15 and later (the code was updated and is more efficient). Old datafiles are now deprecated.
</p>
</td>
</tr>
</table>
</div>
<p>
<span class="emphasis"><em>iradius</em></span> -- optional, head radius used for
phase spectra calculation in centimeters (default 9.0)
</p>
<p>
<span class="emphasis"><em>isr</em></span> - optional (default 44.1kHz). Legal
values are 44100, 48000 and 96000.
</p>
</div>
<div class="refsect1">
<a id="idm281472925309416"></a>
<h2>Performance</h2>
<p>
Artifact-free user-defined static spatialisation is made
possible using an interpolation algorithm based on spectral
magnitude interpolation and a derived phase 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 static source version of the opcode uses overlap add
convolution (it does not need STFT processing, see <a class="link" href="hrtfmove2.html" title="hrtfmove2"><em class="citetitle">hrtfmove2</em></a>),
and is thus considerably more efficient than <a class="link" href="hrtfmove2.html" title="hrtfmove2"><em class="citetitle">hrtfmove2</em></a> or
<a class="link" href="hrtfmove.html" title="hrtfmove"><em class="citetitle">hrtfmove</em></a>, but cannot generate moving sources.
</p>
</div>
<div class="refsect1">
<a id="idm281472925305288"></a>
<h2>Examples</h2>
<p>
Here is an example of the hrtfstat opcode. It uses the file <a class="ulink" href="examples/hrtfstat.csd" target="_top"><em class="citetitle">hrtfstat.csd</em></a>.
</p>
<div class="example">
<a id="idm281472925303384"></a>
<p class="title">
<strong>Example 406. Example of the hrtfstat 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="idm281472754337704"></a>
<pre class="programlisting">
<span class="nt"><CsoundSynthesizer></span>
<span class="nt"><CsOptions></span>
<span class="c1">; Select audio/midi flags here according to platform</span>
-odac <span class="c1">;;;realtime audio out</span>
<span class="c1">;-iadc ;;;uncomment -iadc if realtime audio input is needed too</span>
<span class="c1">; For Non-realtime ouput leave only the line below:</span>
<span class="c1">; -o hrtfstat.wav -W ;;; for file output any platform</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">ksmps</span> <span class="o">=</span> <span class="mi">32</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>
ga<span class="n">src</span> <span class="nb">init</span> <span class="mi">0</span>
<span class="kd">instr</span> <span class="nf">1</span> <span class="c1">;a plucked string</span>
k<span class="n">amp</span> <span class="o">=</span> <span class="nb">p4</span>
k<span class="n">cps</span> <span class="o">=</span> <span class="nb">cpspch</span><span class="p">(</span><span class="nb">p5</span><span class="p">)</span>
i<span class="n">cps</span> <span class="o">=</span> <span class="nb">cpspch</span><span class="p">(</span><span class="nb">p5</span><span class="p">)</span>
a<span class="n">1</span> <span class="nb">pluck</span> k<span class="n">amp</span><span class="p">,</span> k<span class="n">cps</span><span class="p">,</span> i<span class="n">cps</span><span class="p">,</span> <span class="mi">0</span><span class="p">,</span> <span class="mi">1</span>
ga<span class="n">src</span> <span class="o">=</span> a<span class="n">1</span>
<span class="kd">endin</span>
<span class="kd">instr</span> <span class="nf">10</span><span class="c1">;uses output from instr1 as source</span>
a<span class="n">left</span><span class="p">,</span>a<span class="n">right</span> <span class="nb">hrtfstat</span> ga<span class="n">src</span><span class="p">,</span> <span class="mi">90</span><span class="p">,</span><span class="mi">0</span><span class="p">,</span> <span class="s">"hrtf-44100-left.dat"</span><span class="p">,</span><span class="s">"hrtf-44100-right.dat"</span>
<span class="nb">outs</span> a<span class="n">left</span><span class="p">,</span> a<span class="n">right</span>
<span class="nb">clear</span> ga<span class="n">src</span>
<span class="kd">endin</span>
<span class="nt"></CsInstruments></span>
<span class="nt"><CsScore></span>
<span class="nb">i</span><span class="mi">1</span> <span class="mi">0</span> <span class="mi">2</span> <span class="mf">.7</span> <span class="mf">8.00</span> <span class="c1">; Play Instrument 1: a plucked string</span>
<span class="nb">i</span><span class="mi">1</span> <span class="mf">.5</span> <span class="mi">2</span> <span class="mf">.7</span> <span class="mf">8.00</span>
<span class="nb">i</span><span class="mi">1</span> <span class="mi">1</span> <span class="mi">2</span> <span class="mf">.7</span> <span class="mf">8.00</span>
<span class="nb">i</span><span class="mi">1</span> <span class="mi">2</span> <span class="mi">2</span> <span class="mf">.7</span> <span class="mf">7.00</span>
<span class="nb">i</span><span class="mi">10</span> <span class="mi">0</span> <span class="mi">12</span> <span class="c1">; Play Instrument 10 for 2 seconds.</span>
<span class="nt"></CsScore></span>
<span class="nt"></CsoundSynthesizer></span>
</pre>
</div>
</div>
</div>
<br class="example-break" />
<p>
Here is another example of the hrtfstat opcode. It uses the file <a class="ulink" href="examples/hrtfstat-2.csd" target="_top"><em class="citetitle">htrfstat-2.csd</em></a>, and <a class="ulink" href="examples/Church.wav" target="_top"><em class="citetitle">Church.wav</em></a>, which is a looped sample.
</p>
<div class="example">
<a id="idm281472925297352"></a>
<p class="title">
<strong>Example 407. Example two of the hrtfstat opcode</strong>
</p>
<div class="example-contents">
<div class="refsect1">
<a id="idm281472754264168"></a>
<pre class="programlisting">
<span class="nt"><CsoundSynthesizer></span>
<span class="nt"><CsOptions></span>
<span class="c1">; Select audio/midi flags here according to platform</span>
-odac <span class="c1">;;;realtime audio out</span>
<span class="c1">;-iadc ;;;uncomment -iadc if realtime audio input is needed too</span>
<span class="c1">; For Non-realtime ouput leave only the line below:</span>
<span class="c1">; -o hrtfstat-2.wav -W ;;; for file output any platform</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">ksmps</span> <span class="o">=</span> <span class="mi">32</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="kd">instr</span> <span class="nf">1</span>
i<span class="n">Az</span> <span class="o">=</span> <span class="nb">p4</span>
i<span class="n">Elev</span> <span class="o">=</span> <span class="nb">p5</span>
i<span class="n">tim</span> <span class="o">=</span> <span class="nb">ftlptim</span><span class="p">(</span><span class="mi">1</span><span class="p">)</span>
<span class="c1">; transeg a dur ty b dur ty c dur ty d</span>
k<span class="n">amp</span> <span class="nb">transeg</span> <span class="mi">0</span><span class="p">,</span> <span class="nb">p3</span><span class="o">*</span><span class="mf">.1</span><span class="p">,</span> <span class="mi">0</span><span class="p">,</span> <span class="mf">.9</span><span class="p">,</span> <span class="nb">p3</span><span class="o">*</span><span class="mf">.3</span><span class="p">,</span> <span class="o">-</span><span class="mi">3</span><span class="p">,</span> <span class="mf">.5</span><span class="p">,</span> <span class="nb">p3</span><span class="o">*</span><span class="mf">.3</span><span class="p">,</span> <span class="o">-</span><span class="mi">2</span><span class="p">,</span> <span class="mi">0</span>
a<span class="n">in</span> <span class="nb">loscil3</span> k<span class="n">amp</span><span class="p">,</span> <span class="mi">50</span><span class="p">,</span> <span class="mi">1</span>
a<span class="n">left</span><span class="p">,</span>a<span class="n">right</span> <span class="nb">hrtfstat</span> a<span class="n">in</span><span class="p">,</span> i<span class="n">Az</span><span class="p">,</span> i<span class="n">Elev</span><span class="p">,</span> <span class="s">"hrtf-44100-left.dat"</span><span class="p">,</span><span class="s">"hrtf-44100-right.dat"</span>
<span class="nb">outs</span> a<span class="n">left</span><span class="p">,</span> a<span class="n">right</span>
<span class="kd">endin</span>
<span class="nt"></CsInstruments></span>
<span class="nt"><CsScore></span>
<span class="nb">f</span> <span class="mi">1</span> <span class="mi">0</span> <span class="mi">0</span> <span class="mi">1</span> <span class="s">"Church.wav"</span> <span class="mi">0</span> <span class="mi">0</span> <span class="mi">0</span> <span class="c1">;Csound computes tablesize</span>
<span class="c1">; Azim Elev</span>
<span class="nb">i</span><span class="mi">1</span> <span class="mi">0</span> <span class="mi">7</span> <span class="mi">90</span> <span class="mi">0</span> <span class="c1">;to the right</span>
<span class="nb">i</span><span class="mi">1</span> <span class="mi">3</span> <span class="mi">7</span> <span class="o">-</span><span class="mi">90</span> <span class="o">-</span><span class="mi">40</span> <span class="c1">;to the left and below</span>
<span class="nb">i</span><span class="mi">1</span> <span class="mi">6</span> <span class="mi">7</span> <span class="mi">180</span> <span class="mi">90</span> <span class="c1">;behind and up</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="idm281472925295432"></a>
<h2>See Also</h2>
<p>
<a class="link" href="hrtfmove.html" title="hrtfmove"><em class="citetitle">hrtfmove</em></a>,
<a class="link" href="hrtfmove2.html" title="hrtfmove2"><em class="citetitle">hrtfmove2</em></a>,
<a class="link" href="hrtfer.html" title="hrtfer"><em class="citetitle">hrtfer</em></a>.
</p>
<p> More information on this opcode: <a class="ulink" href="http://www.csoundjournal.com/issue9/newHRTFOpcodes.html" target="_top"><em class="citetitle">http://www.csoundjournal.com/issue9/newHRTFOpcodes.html</em></a> , written by Brian Carty </p>
</div>
<div class="refsect1">
<a id="idm281472925290072"></a>
<h2>Credits</h2>
<p>
</p>
<table border="0" summary="Simple list" class="simplelist">
<tr>
<td>Author: Brian Carty</td>
</tr>
<tr>
<td>Maynooth</td>
</tr>
<tr>
<td>2008</td>
</tr>
</table>
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</p>
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