2 * Copyright (C) 2007-2011 Paul Davis <paul@linuxaudiosystems.com>
3 * Copyright (C) 2009-2014 David Robillard <d@drobilla.net>
4 * Copyright (C) 2013-2015 Robin Gareus <robin@gareus.org>
6 * This program is free software; you can redistribute it and/or modify
7 * it under the terms of the GNU General Public License as published by
8 * the Free Software Foundation; either version 2 of the License, or
9 * (at your option) any later version.
11 * This program is distributed in the hope that it will be useful,
12 * but WITHOUT ANY WARRANTY; without even the implied warranty of
13 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
14 * GNU General Public License for more details.
16 * You should have received a copy of the GNU General Public License along
17 * with this program; if not, write to the Free Software Foundation, Inc.,
18 * 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
21 #ifndef __ardour_dB_h__
22 #define __ardour_dB_h__
25 #include "pbd/fastlog.h"
27 #define GAIN_COEFF_ZERO 0.f
28 #define GAIN_COEFF_SMALL 0.0000001f //-140dB
29 #define GAIN_COEFF_UNITY 1.f
31 static inline float dB_to_coefficient (float dB) {
32 return dB > -318.8f ? pow (10.0f, dB * 0.05f) : 0.0f;
35 static inline float fast_coefficient_to_dB (float coeff) {
36 return 20.0f * fast_log10 (coeff);
39 static inline float accurate_coefficient_to_dB (float coeff) {
40 if (coeff < 1e-15) return -std::numeric_limits<float>::infinity();
41 return 20.0f * log10f (coeff);
44 static inline double dB_coeff_step(double max_coeff) {
45 const double max_db = lrint(accurate_coefficient_to_dB(max_coeff));
46 return 0.1 * (max_coeff / max_db);
49 extern double zero_db_as_fraction;
51 #endif /* __ardour_dB_h__ */