release/src/router/libvorbis/lib/scales.h

   1 /********************************************************************
   2  *                                                                  *
   3  * THIS FILE IS PART OF THE OggVorbis SOFTWARE CODEC SOURCE CODE.   *
   4  * USE, DISTRIBUTION AND REPRODUCTION OF THIS LIBRARY SOURCE IS     *
   5  * GOVERNED BY A BSD-STYLE SOURCE LICENSE INCLUDED WITH THIS SOURCE *
   6  * IN 'COPYING'. PLEASE READ THESE TERMS BEFORE DISTRIBUTING.       *
   7  *                                                                  *
   8  * THE OggVorbis SOURCE CODE IS (C) COPYRIGHT 1994-2009             *
   9  * by the Xiph.Org Foundation http://www.xiph.org/                  *
  10  *                                                                  *
  11  ********************************************************************
  12
  13  function: linear scale -> dB, Bark and Mel scales
  14  last mod: $Id: scales.h 16227 2009-07-08 06:58:46Z xiphmont $
  15
  16  ********************************************************************/
  17
  18 #ifndef _V_SCALES_H_
  19 #define _V_SCALES_H_
  20
  21 #include <math.h>
  22 #include "os.h"
  23
  24 #ifdef _MSC_VER
  25 /* MS Visual Studio doesn't have C99 inline keyword. */
  26 #define inline __inline
  27 #endif
  28
  29 /* 20log10(x) */
  30 #define VORBIS_IEEE_FLOAT32 1
  31 #ifdef VORBIS_IEEE_FLOAT32
  32
  33 static inline float unitnorm(float x){
  34   union {
  35     ogg_uint32_t i;
  36     float f;
  37   } ix;
  38   ix.f = x;
  39   ix.i = (ix.i & 0x80000000U) | (0x3f800000U);
  40   return ix.f;
  41 }
  42
  43 /* Segher was off (too high) by ~ .3 decibel.  Center the conversion correctly. */
  44 static inline float todB(const float *x){
  45   union {
  46     ogg_uint32_t i;
  47     float f;
  48   } ix;
  49   ix.f = *x;
  50   ix.i = ix.i&0x7fffffff;
  51   return (float)(ix.i * 7.17711438e-7f -764.6161886f);
  52 }
  53
  54 #define todB_nn(x) todB(x)
  55
  56 #else
  57
  58 static float unitnorm(float x){
  59   if(x<0)return(-1.f);
  60   return(1.f);
  61 }
  62
  63 #define todB(x)   (*(x)==0?-400.f:log(*(x)**(x))*4.34294480f)
  64 #define todB_nn(x)   (*(x)==0.f?-400.f:log(*(x))*8.6858896f)
  65
  66 #endif
  67
  68 #define fromdB(x) (exp((x)*.11512925f))
  69
  70 /* The bark scale equations are approximations, since the original
  71    table was somewhat hand rolled.  The below are chosen to have the
  72    best possible fit to the rolled tables, thus their somewhat odd
  73    appearance (these are more accurate and over a longer range than
  74    the oft-quoted bark equations found in the texts I have).  The
  75    approximations are valid from 0 - 30kHz (nyquist) or so.
  76
  77    all f in Hz, z in Bark */
  78
  79 #define toBARK(n)   (13.1f*atan(.00074f*(n))+2.24f*atan((n)*(n)*1.85e-8f)+1e-4f*(n))
  80 #define fromBARK(z) (102.f*(z)-2.f*pow(z,2.f)+.4f*pow(z,3.f)+pow(1.46f,z)-1.f)
  81 #define toMEL(n)    (log(1.f+(n)*.001f)*1442.695f)
  82 #define fromMEL(m)  (1000.f*exp((m)/1442.695f)-1000.f)
  83
  84 /* Frequency to octave.  We arbitrarily declare 63.5 Hz to be octave
  85    0.0 */
  86
  87 #define toOC(n)     (log(n)*1.442695f-5.965784f)
  88 #define fromOC(o)   (exp(((o)+5.965784f)*.693147f))
  89
  90 #endif