tal-reverb-2-juce/src/Engine/AudioUtils.h

   1 /*
   2 ==============================================================================
   3 This file is part of Tal-Dub-III by Patrick Kunz.
   4
   5 Copyright(c) 2005-2009 Patrick Kunz, TAL
   6 Togu Audio Line, Inc.
   7 http://kunz.corrupt.ch
   8
   9 This file may be licensed under the terms of of the
  10 GNU General Public License Version 2 (the ``GPL'').
  11
  12 Software distributed under the License is distributed
  13 on an ``AS IS'' basis, WITHOUT WARRANTY OF ANY KIND, either
  14 express or implied. See the GPL for the specific language
  15 governing rights and limitations.
  16
  17 You should have received a copy of the GPL along with this
  18 program. If not, go to http://www.gnu.org/licenses/gpl.html
  19 or write to the Free Software Foundation, Inc.,
  20 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA.
  21 ==============================================================================
  22 */
  23
  24
  25 #if !defined(__AudioUtils_h)
  26 #define __AudioUtils_h
  27
  28 #include "Math.h"
  29
  30 class AudioUtils
  31 {
  32 private:
  33
  34 public:
  35         AudioUtils()
  36         {
  37         }
  38
  39         ~AudioUtils()
  40         {
  41         }
  42
  43         float getLogScaledValueInDecibel(float inputValue, float maxValue)
  44         {
  45                 float logScaled = getLogScaledVolume(inputValue, maxValue);
  46                 return getValueInDecibel(logScaled);
  47         }
  48
  49         float getLogScaledValueInDecibelFilter(float inputValue, float maxValue)
  50         {
  51                 float logScaled = getLogScaledVolume(inputValue, maxValue);
  52                 return getValueInDecibelFilter(logScaled);
  53         }
  54
  55         // max value unscalled
  56         float getLogScaledVolume(float inputValue, float maxValue)
  57         {
  58                 return (expf(inputValue * maxValue * logf(20.0f)) - 1.0f) / 19.0f;
  59         }
  60
  61         // max value unscalled
  62         float getLogScaledValue(float inputValue)
  63         {
  64                 // have to return a value between 0..1
  65                 return (expf(inputValue * logf(20.0f)) - 1.0f) / 19.0f;
  66         }
  67
  68         float getLogScaledFrequency(float inputValue)
  69         {
  70                 return 100.0f + getLogScaledValue(inputValue) * 9900.0f;
  71         }
  72
  73         float getLogScaledValueInverted(float inputValue)
  74         {
  75                 // have to return a value between 0..1
  76                 inputValue = 1.0f - inputValue;
  77                 inputValue = (expf(inputValue * logf(20.0f)) - 1.0f) / 19.0f;
  78                 return 1.0f - inputValue;
  79         }
  80
  81         // input value >= 0
  82         float getValueInDecibel(float inputValue)
  83         {
  84                 if (inputValue <= 0)
  85                 {
  86                         return -96.0f;
  87                 }
  88                 else
  89                 {
  90                         // 1.0 --> 0dB
  91                         return 20.0f * log10f(inputValue / 1.0f);
  92                 }
  93         }
  94
  95         float getValueInDecibelFilter(float inputValue)
  96         {
  97                 if (inputValue <= 0)
  98                 {
  99                         return -18.0f;
 100                 }
 101                 else
 102                 {
 103                         // 1.0 --> 0dB
 104                         return 5.0f * log10f(inputValue / 1.0f);
 105                 }
 106         }
 107
 108         inline float tanhApp(float x)
 109         {
 110                 // Original
 111                 //return tanh(x);
 112
 113                 // Approx
 114                 x*= 2.0f;
 115                 float a= fabs(x);
 116                 float b= 6.0f + a*(3.0f + a); // 6, 3
 117                 return (x * b)/(a * b + 12.0f);
 118         }
 119
 120         inline int getNextNearPrime(int value)
 121         {
 122                 while (!isPrime(value)) value++;
 123                 return value;
 124         }
 125
 126         inline bool isPrime(int value)
 127         {
 128                 bool answer = true;
 129                 if (value == 0) value = 1;
 130                 for (int i = 2; i <= sqrtf((float)value) ; i++)
 131                 {
 132                         if (value % i == 0)
 133                         {
 134                                 answer = false;
 135                                 break;
 136                         }
 137                 }
 138                 return answer;
 139         }
 140 };
 141 #endif
 142