2 Copyright (C) 2000-2007 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_gtk_log_meter_h__
21 #define __ardour_gtk_log_meter_h__
25 _log_meter (float power, double lower_db, double upper_db, double non_linearity)
27 return (power < lower_db ? 0.0 : pow((power-lower_db)/(upper_db-lower_db), non_linearity));
31 alt_log_meter (float power)
33 return _log_meter (power, -192.0, 0.0, 8.0);
37 /* prototypes - avoid compiler warning */
38 static inline float log_meter (float db);
39 static inline float meter_deflect_ppm (float);
40 static inline float meter_deflect_din (float);
41 static inline float meter_deflect_nordic (float);
42 static inline float meter_deflect_vu (float);
43 static inline float meter_deflect_k (float, float);
50 gfloat def = 0.0f; /* Meter deflection %age */
54 } else if (db < -60.0f) {
55 def = (db + 70.0f) * 0.25f;
56 } else if (db < -50.0f) {
57 def = (db + 60.0f) * 0.5f + 2.5f;
58 } else if (db < -40.0f) {
59 def = (db + 50.0f) * 0.75f + 7.5f;
60 } else if (db < -30.0f) {
61 def = (db + 40.0f) * 1.5f + 15.0f;
62 } else if (db < -20.0f) {
63 def = (db + 30.0f) * 2.0f + 30.0f;
64 } else if (db < 6.0f) {
65 def = (db + 20.0f) * 2.5f + 50.0f;
70 /* 115 is the deflection %age that would be
71 when db=6.0. this is an arbitrary
72 endpoint for our scaling.
79 meter_deflect_ppm (float db)
82 // 2.258 == ((-30 + 32.0)/ 28.0) / 10^(-30 / 20);
83 return (dB_to_coefficient(db) * 2.258769757f);
85 const float rv = (db + 32.0f) / 28.0f;
95 meter_deflect_din (float db)
97 float rv = dB_to_coefficient(db);
98 rv = sqrtf (sqrtf (2.3676f * rv)) - 0.1803f;
102 return (rv > 0 ? rv : 0.0);
107 meter_deflect_nordic (float db)
112 const float rv = (db + 60.0f) / 54.0f;
122 meter_deflect_vu (float db)
124 const float rv = 6.77165f * dB_to_coefficient(db);
125 if (rv > 1.0) return 1.0;
130 meter_deflect_k (float db, float krange)
134 return (dB_to_coefficient(db) * 500.0f / (krange + 45.0f));
136 const float rv = (db + 45.0f) / (krange + 45.0f);
145 #endif /* __ardour_gtk_log_meter_h__ */