2 Copyright (C) 2001 Paul Davis
4 This program is free software; you can redistribute it and/or modify
5 it under the terms of the GNU General Public License as published by
6 the Free Software Foundation; either version 2 of the License, or
7 (at your option) any later version.
9 This program is distributed in the hope that it will be useful,
10 but WITHOUT ANY WARRANTY; without even the implied warranty of
11 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
12 GNU General Public License for more details.
14 You should have received a copy of the GNU General Public License
15 along with this program; if not, write to the Free Software
16 Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
20 #ifndef __ardour_dB_h__
21 #define __ardour_dB_h__
24 #include "pbd/fastlog.h"
26 #define GAIN_COEFF_ZERO 0.f
27 #define GAIN_COEFF_SMALL 0.0000001f //-140dB
28 #define GAIN_COEFF_UNITY 1.f
30 static inline float dB_to_coefficient (float dB) {
31 return dB > -318.8f ? pow (10.0f, dB * 0.05f) : 0.0f;
34 static inline float fast_coefficient_to_dB (float coeff) {
35 return 20.0f * fast_log10 (coeff);
38 static inline float accurate_coefficient_to_dB (float coeff) {
39 if (coeff < 1e-15) return -std::numeric_limits<float>::infinity();
40 return 20.0f * log10f (coeff);
43 static inline double dB_coeff_step(double max_coeff) {
44 const double max_db = lrint(accurate_coefficient_to_dB(max_coeff));
45 return 0.1 * (max_coeff / max_db);
48 extern double zero_db_as_fraction;
50 #endif /* __ardour_dB_h__ */