fluid_conv.c
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上传日期:2020-08-17
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文件大小:8k
- /* 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
- * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA
- * 02111-1307, 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];
- }