livetrax/libs/fluidsynth/src/fluid_conv.c

/* FluidSynth - A Software Synthesizer
 *
 * Copyright (C) 2003  Peter Hanappe and others.
 *
 * This library is free software; you can redistribute it and/or
 * modify it under the terms of the GNU Library General Public License
 * as published by the Free Software Foundation; either version 2 of
 * the License, or (at your option) any later version.
 *
 * This library 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
 * Library General Public License for more details.
 *
 * You should have received a copy of the GNU Library General Public
 * License along with this library; if not, write to the Free
 * Software Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA
 * 02110-1301, USA
 */

#include "fluid_conv.h"


/* conversion tables */
fluid_real_t fluid_ct2hz_tab[FLUID_CENTS_HZ_SIZE];
fluid_real_t fluid_cb2amp_tab[FLUID_CB_AMP_SIZE];
fluid_real_t fluid_atten2amp_tab[FLUID_ATTEN_AMP_SIZE];
fluid_real_t fluid_posbp_tab[128];
fluid_real_t fluid_concave_tab[128];
fluid_real_t fluid_convex_tab[128];
fluid_real_t fluid_pan_tab[FLUID_PAN_SIZE];

/*
 * void fluid_synth_init
 *
 * Does all the initialization for this module.
 */
void
fluid_conversion_config(void)
{
  int i;
  double x;

  for (i = 0; i < FLUID_CENTS_HZ_SIZE; i++) {
    fluid_ct2hz_tab[i] = (fluid_real_t) pow(2.0, (double) i / 1200.0);
  }

  /* centibels to amplitude conversion
   * Note: SF2.01 section 8.1.3: Initial attenuation range is
   * between 0 and 144 dB. Therefore a negative attenuation is
   * not allowed.
   */
  for (i = 0; i < FLUID_CB_AMP_SIZE; i++) {
    fluid_cb2amp_tab[i] = (fluid_real_t) pow(10.0, (double) i / -200.0);
  }

  /* NOTE: EMU8k and EMU10k devices don't conform to the SoundFont
   * specification in regards to volume attenuation.  The below calculation
   * is an approx. equation for generating a table equivelant to the
   * cb_to_amp_table[] in tables.c of the TiMidity++ source, which I'm told
   * was generated from device testing.  By the spec this should be centibels.
   */
  for (i = 0; i < FLUID_ATTEN_AMP_SIZE; i++) {
    fluid_atten2amp_tab[i] = (fluid_real_t) pow(10.0, (double) i / FLUID_ATTEN_POWER_FACTOR);
  }

  /* initialize the conversion tables (see fluid_mod.c
     fluid_mod_get_value cases 4 and 8) */

  /* concave unipolar positive transform curve */
  fluid_concave_tab[0] = 0.0;
  fluid_concave_tab[127] = 1.0;

  /* convex unipolar positive transform curve */
  fluid_convex_tab[0] = 0;
  fluid_convex_tab[127] = 1.0;
  x = log10(128.0 / 127.0);

  /* There seems to be an error in the specs. The equations are
     implemented according to the pictures on SF2.01 page 73. */

  for (i = 1; i < 127; i++) {
    x = -20.0 / 96.0 * log((i * i) / (127.0 * 127.0)) / log(10.0);
    fluid_convex_tab[i] = (fluid_real_t) (1.0 - x);
    fluid_concave_tab[127 - i] = (fluid_real_t) x;
  }

  /* initialize the pan conversion table */
  x = PI / 2.0 / (FLUID_PAN_SIZE - 1.0);
  for (i = 0; i < FLUID_PAN_SIZE; i++) {
    fluid_pan_tab[i] = (fluid_real_t) sin(i * x);
  }
}

/*
 * fluid_ct2hz
 */
fluid_real_t
fluid_ct2hz_real(fluid_real_t cents)
{
  if (cents < 0)
    return (fluid_real_t) 1.0;
  else if (cents < 900) {
    return (fluid_real_t) 6.875 * fluid_ct2hz_tab[(int) (cents + 300)];
  } else if (cents < 2100) {
    return (fluid_real_t) 13.75 * fluid_ct2hz_tab[(int) (cents - 900)];
  } else if (cents < 3300) {
    return (fluid_real_t) 27.5 * fluid_ct2hz_tab[(int) (cents - 2100)];
  } else if (cents < 4500) {
    return (fluid_real_t) 55.0 * fluid_ct2hz_tab[(int) (cents - 3300)];
  } else if (cents < 5700) {
    return (fluid_real_t) 110.0 * fluid_ct2hz_tab[(int) (cents - 4500)];
  } else if (cents < 6900) {
    return (fluid_real_t) 220.0 * fluid_ct2hz_tab[(int) (cents - 5700)];
  } else if (cents < 8100) {
    return (fluid_real_t) 440.0 * fluid_ct2hz_tab[(int) (cents - 6900)];
  } else if (cents < 9300) {
    return (fluid_real_t) 880.0 * fluid_ct2hz_tab[(int) (cents - 8100)];
  } else if (cents < 10500) {
    return (fluid_real_t) 1760.0 * fluid_ct2hz_tab[(int) (cents - 9300)];
  } else if (cents < 11700) {
    return (fluid_real_t) 3520.0 * fluid_ct2hz_tab[(int) (cents - 10500)];
  } else if (cents < 12900) {
    return (fluid_real_t) 7040.0 * fluid_ct2hz_tab[(int) (cents - 11700)];
  } else if (cents < 14100) {
    return (fluid_real_t) 14080.0 * fluid_ct2hz_tab[(int) (cents - 12900)];
  } else {
    return (fluid_real_t) 1.0; /* some loony trying to make you deaf */
  }
}

/*
 * fluid_ct2hz
 */
fluid_real_t
fluid_ct2hz(fluid_real_t cents)
{
  /* Filter fc limit: SF2.01 page 48 # 8 */
  if (cents >= 13500){
    cents = 13500;             /* 20 kHz */
  } else if (cents < 1500){
    cents = 1500;              /* 20 Hz */
  }
  return fluid_ct2hz_real(cents);
}

/*
 * fluid_cb2amp
 *
 * in: a value between 0 and 960, 0 is no attenuation
 * out: a value between 1 and 0
 */
fluid_real_t
fluid_cb2amp(fluid_real_t cb)
{
  /*
   * cb: an attenuation in 'centibels' (1/10 dB)
   * SF2.01 page 49 # 48 limits it to 144 dB.
   * 96 dB is reasonable for 16 bit systems, 144 would make sense for 24 bit.
   */

  /* minimum attenuation: 0 dB */
  if (cb < 0) {
    return 1.0;
  }
  if (cb >= FLUID_CB_AMP_SIZE) {
    return 0.0;
  }
  return fluid_cb2amp_tab[(int) cb];
}

/*
 * fluid_atten2amp
 *
 * in: a value between 0 and 1440, 0 is no attenuation
 * out: a value between 1 and 0
 *
 * Note: Volume attenuation is supposed to be centibels but EMU8k/10k don't
 * follow this.  Thats the reason for separate fluid_cb2amp and fluid_atten2amp.
 */
fluid_real_t
fluid_atten2amp(fluid_real_t atten)
{
  if (atten < 0) return 1.0;
  else if (atten >= FLUID_ATTEN_AMP_SIZE) return 0.0;
  else return fluid_atten2amp_tab[(int) atten];
}

/*
 * fluid_tc2sec_delay
 */
fluid_real_t
fluid_tc2sec_delay(fluid_real_t tc)
{
  /* SF2.01 section 8.1.2 items 21, 23, 25, 33
   * SF2.01 section 8.1.3 items 21, 23, 25, 33
   *
   * The most negative number indicates a delay of 0. Range is limited
   * from -12000 to 5000 */
  if (tc <= -32768.0f) {
	  return (fluid_real_t) 0.0f;
  };
  if (tc < -12000.) {
	  tc = (fluid_real_t) -12000.0f;
  }
  if (tc > 5000.0f) {
	  tc = (fluid_real_t) 5000.0f;
  }
  return (fluid_real_t) pow(2.0, (double) tc / 1200.0);
}

/*
 * fluid_tc2sec_attack
 */
fluid_real_t
fluid_tc2sec_attack(fluid_real_t tc)
{
  /* SF2.01 section 8.1.2 items 26, 34
   * SF2.01 section 8.1.3 items 26, 34
   * The most negative number indicates a delay of 0
   * Range is limited from -12000 to 8000 */
  if (tc<=-32768.){return (fluid_real_t) 0.0;};
  if (tc<-12000.){tc=(fluid_real_t) -12000.0;};
  if (tc>8000.){tc=(fluid_real_t) 8000.0;};
  return (fluid_real_t) pow(2.0, (double) tc / 1200.0);
}

/*
 * fluid_tc2sec
 */
fluid_real_t
fluid_tc2sec(fluid_real_t tc)
{
  /* No range checking here! */
  return (fluid_real_t) pow(2.0, (double) tc / 1200.0);
}

/*
 * fluid_tc2sec_release
 */
fluid_real_t
fluid_tc2sec_release(fluid_real_t tc)
{
  /* SF2.01 section 8.1.2 items 30, 38
   * SF2.01 section 8.1.3 items 30, 38
   * No 'most negative number' rule here!
   * Range is limited from -12000 to 8000 */
  if (tc<=-32768.){return (fluid_real_t) 0.0;};
  if (tc<-12000.){tc=(fluid_real_t) -12000.0;};
  if (tc>8000.){tc=(fluid_real_t) 8000.0;};
  return (fluid_real_t) pow(2.0, (double) tc / 1200.0);
}

/*
 * fluid_act2hz
 *
 * Convert from absolute cents to Hertz
 */
fluid_real_t
fluid_act2hz(fluid_real_t c)
{
  return (fluid_real_t) (8.176 * pow(2.0, (double) c / 1200.0));
}

/*
 * fluid_hz2ct
 *
 * Convert from Hertz to cents
 */
fluid_real_t
fluid_hz2ct(fluid_real_t f)
{
  return (fluid_real_t) (6900 + 1200 * log(f / 440.0) / log(2.0));
}

/*
 * fluid_pan
 */
fluid_real_t
fluid_pan(fluid_real_t c, int left)
{
  if (left) {
    c = -c;
  }
  if (c < -500) {
    return (fluid_real_t) 0.0;
  } else if (c > 500) {
    return (fluid_real_t) 1.0;
  } else {
    return fluid_pan_tab[(int) (c + 500)];
  }
}

/*
 * fluid_concave
 */
fluid_real_t
fluid_concave(fluid_real_t val)
{
  if (val < 0) {
    return 0;
  } else if (val > 127) {
    return 1;
  }
  return fluid_concave_tab[(int) val];
}

/*
 * fluid_convex
 */
fluid_real_t
fluid_convex(fluid_real_t val)
{
  if (val < 0) {
    return 0;
  } else if (val > 127) {
    return 1;
  }
  return fluid_convex_tab[(int) val];
}