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HRTF.cc

/*
      HRTF.cc
      
      Copyright 2002-5 Tim Goetze <tim@quitte.de>
      
      http://quitte.de/dsp/

      high-order IIR filtering modeled after HRTF impulse responses

*/
/*
      This program is free software; you can redistribute it and/or
      modify it under the terms of the GNU General Public License
      as published by the Free Software Foundation; either version 2
      of the License, or (at your option) any later version.

      This program is distributed in the hope that it will be useful,
      but WITHOUT ANY WARRANTY; without even the implied warranty of
      MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
      GNU General Public License for more details.

      You should have received a copy of the GNU General Public License
      along with this program; if not, write to the Free Software
      Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA
      02111-1307, USA or point your web browser to http://www.gnu.org.
*/

#include "basics.h"

#include "HRTF.h"
#include "Descriptor.h"

#include "elev0.h"

/* //////////////////////////////////////////////////////////////////////// */

void
HRTF::init (double fs)
{
      normal = NOISE_FLOOR;
      h = 0;
}

void
HRTF::set_pan (int p)
{
      n = 31;

      pan = p;

      if (p >= 0)
      {
            left.a = elev0[p].left.a;
            left.b = elev0[p].left.b;
            right.a = elev0[p].right.a;
            right.b = elev0[p].right.b;
      }
      else
      {
            p = -p;
            left.a = elev0[p].right.a;
            left.b = elev0[p].right.b;
            right.a = elev0[p].left.a;
            right.b = elev0[p].left.b;
      }     

      memset (left.y, 0, sizeof (left.y));
      memset (right.y, 0, sizeof (right.y));
}

template <sample_func_t F>
void
HRTF::one_cycle (int frames)
{
      d_sample * s = ports[0];

      int p = (int) *ports[1];
      if (p != pan) set_pan (p);

      d_sample * dl = ports[2];
      d_sample * dr = ports[3];

      double l, r;

      for (int i = 0; i < frames; ++i)
      {
            x[h] = l = r = s[i] + normal;
            
            l *= left.a[0];
            r *= right.a[0];

            for (int j = 1, z = h - 1; j < n; --z, ++j)
            {
                  z &= 31;
                  l += left.a[j] * x[z];
                  l += left.b[j] * left.y[z];
                  r += right.a[j] * x[z];
                  r += right.b[j] * right.y[z];
            }

            left.y[h] = l;
            right.y[h] = r;

            h = (h + 1) & 31;
            
            F (dl, i, l, adding_gain);
            F (dr, i, r, adding_gain);
      }

      normal = -normal;
}

/* //////////////////////////////////////////////////////////////////////// */

PortInfo
HRTF::port_info [] =
{
      {
            "in",
            INPUT | AUDIO,
            {BOUNDED, -1, 1}
      }, {
            "pan",
            INPUT | CONTROL,
            {BOUNDED | INTEGER | DEFAULT_0, -36, 36}
      }, {
            "out:l",
            OUTPUT | AUDIO,
            {0}
      }, {
            "out:r",
            OUTPUT | AUDIO,
            {0}
      }
};

template <> void
Descriptor<HRTF>::setup()
{
      UniqueID = 1787;
      Label = "HRTF";
      Properties = HARD_RT;

      Name = "CAPS: HRTF - Head-related transfer function at elevation 0";
      Maker = "Tim Goetze <tim@quitte.de>";
      Copyright = "GPL, 2004-5";

      /* fill port info and vtable */
      autogen();
}


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