146 lines
3.4 KiB
C
146 lines
3.4 KiB
C
/*
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Copyright (C) 2000-2007 Paul Davis
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This program is free software; you can redistribute it and/or modify
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it under the terms of the GNU General Public License as published by
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the Free Software Foundation; either version 2 of the License, or
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(at your option) any later version.
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This program is distributed in the hope that it will be useful,
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but WITHOUT ANY WARRANTY; without even the implied warranty of
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MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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GNU General Public License for more details.
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You should have received a copy of the GNU General Public License
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along with this program; if not, write to the Free Software
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Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
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*/
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#ifndef __ardour_gtk_log_meter_h__
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#define __ardour_gtk_log_meter_h__
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#if 1
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static inline float
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_log_meter (float power, double lower_db, double upper_db, double non_linearity)
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{
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return (power < lower_db ? 0.0 : pow((power-lower_db)/(upper_db-lower_db), non_linearity));
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}
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static inline float
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alt_log_meter (float power)
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{
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return _log_meter (power, -192.0, 0.0, 8.0);
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}
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#endif
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/* prototypes - avoid compiler warning */
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static inline float log_meter (float db);
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static inline float meter_deflect_ppm (float);
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static inline float meter_deflect_din (float);
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static inline float meter_deflect_nordic (float);
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static inline float meter_deflect_vu (float);
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static inline float meter_deflect_k (float, float);
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static inline float
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log_meter (float db)
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{
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gfloat def = 0.0f; /* Meter deflection %age */
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if (db < -70.0f) {
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def = 0.0f;
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} else if (db < -60.0f) {
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def = (db + 70.0f) * 0.25f;
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} else if (db < -50.0f) {
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def = (db + 60.0f) * 0.5f + 2.5f;
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} else if (db < -40.0f) {
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def = (db + 50.0f) * 0.75f + 7.5f;
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} else if (db < -30.0f) {
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def = (db + 40.0f) * 1.5f + 15.0f;
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} else if (db < -20.0f) {
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def = (db + 30.0f) * 2.0f + 30.0f;
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} else if (db < 6.0f) {
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def = (db + 20.0f) * 2.5f + 50.0f;
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} else {
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def = 115.0f;
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}
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/* 115 is the deflection %age that would be
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when db=6.0. this is an arbitrary
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endpoint for our scaling.
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*/
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return def/115.0f;
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}
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static inline float
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meter_deflect_ppm (float db)
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{
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if (db < -30) {
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// 2.258 == ((-30 + 32.0)/ 28.0) / 10^(-30 / 20);
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return (dB_to_coefficient(db) * 2.258769757f);
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} else {
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const float rv = (db + 32.0f) / 28.0f;
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if (rv < 1.0) {
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return rv;
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} else {
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return 1.0;
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}
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}
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}
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static inline float
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meter_deflect_din (float db)
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{
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float rv = dB_to_coefficient(db);
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rv = sqrtf (sqrtf (2.3676f * rv)) - 0.1803f;
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if (rv >= 1.0) {
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return 1.0;
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} else {
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return (rv > 0 ? rv : 0.0);
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}
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}
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static inline float
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meter_deflect_nordic (float db)
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{
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if (db < -60) {
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return 0.0;
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} else {
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const float rv = (db + 60.0f) / 54.0f;
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if (rv < 1.0) {
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return rv;
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} else {
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return 1.0;
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}
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}
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}
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static inline float
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meter_deflect_vu (float db)
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{
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const float rv = 6.77165f * dB_to_coefficient(db);
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if (rv > 1.0) return 1.0;
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return rv;
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}
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static inline float
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meter_deflect_k (float db, float krange)
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{
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db+=krange;
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if (db < -40.0f) {
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return (dB_to_coefficient(db) * 500.0f / (krange + 45.0f));
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} else {
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const float rv = (db + 45.0f) / (krange + 45.0f);
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if (rv < 1.0) {
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return rv;
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} else {
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return 1.0;
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}
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}
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}
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#endif /* __ardour_gtk_log_meter_h__ */
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