Chris@1: /********************************************************************
Chris@1:  *                                                                  *
Chris@1:  * THIS FILE IS PART OF THE OggVorbis SOFTWARE CODEC SOURCE CODE.   *
Chris@1:  * USE, DISTRIBUTION AND REPRODUCTION OF THIS LIBRARY SOURCE IS     *
Chris@1:  * GOVERNED BY A BSD-STYLE SOURCE LICENSE INCLUDED WITH THIS SOURCE *
Chris@1:  * IN 'COPYING'. PLEASE READ THESE TERMS BEFORE DISTRIBUTING.       *
Chris@1:  *                                                                  *
Chris@1:  * THE OggVorbis SOURCE CODE IS (C) COPYRIGHT 1994-2009             *
Chris@1:  * by the Xiph.Org Foundation http://www.xiph.org/                  *
Chris@1:  *                                                                  *
Chris@1:  ********************************************************************
Chris@1: 
Chris@1:  function: linear scale -> dB, Bark and Mel scales
Chris@1:  last mod: $Id: scales.h 16227 2009-07-08 06:58:46Z xiphmont $
Chris@1: 
Chris@1:  ********************************************************************/
Chris@1: 
Chris@1: #ifndef _V_SCALES_H_
Chris@1: #define _V_SCALES_H_
Chris@1: 
Chris@1: #include <math.h>
Chris@1: #include "os.h"
Chris@1: 
Chris@1: #ifdef _MSC_VER
Chris@1: /* MS Visual Studio doesn't have C99 inline keyword. */
Chris@1: #define inline __inline
Chris@1: #endif
Chris@1: 
Chris@1: /* 20log10(x) */
Chris@1: #define VORBIS_IEEE_FLOAT32 1
Chris@1: #ifdef VORBIS_IEEE_FLOAT32
Chris@1: 
Chris@1: static inline float unitnorm(float x){
Chris@1:   union {
Chris@1:     ogg_uint32_t i;
Chris@1:     float f;
Chris@1:   } ix;
Chris@1:   ix.f = x;
Chris@1:   ix.i = (ix.i & 0x80000000U) | (0x3f800000U);
Chris@1:   return ix.f;
Chris@1: }
Chris@1: 
Chris@1: /* Segher was off (too high) by ~ .3 decibel.  Center the conversion correctly. */
Chris@1: static inline float todB(const float *x){
Chris@1:   union {
Chris@1:     ogg_uint32_t i;
Chris@1:     float f;
Chris@1:   } ix;
Chris@1:   ix.f = *x;
Chris@1:   ix.i = ix.i&0x7fffffff;
Chris@1:   return (float)(ix.i * 7.17711438e-7f -764.6161886f);
Chris@1: }
Chris@1: 
Chris@1: #define todB_nn(x) todB(x)
Chris@1: 
Chris@1: #else
Chris@1: 
Chris@1: static float unitnorm(float x){
Chris@1:   if(x<0)return(-1.f);
Chris@1:   return(1.f);
Chris@1: }
Chris@1: 
Chris@1: #define todB(x)   (*(x)==0?-400.f:log(*(x)**(x))*4.34294480f)
Chris@1: #define todB_nn(x)   (*(x)==0.f?-400.f:log(*(x))*8.6858896f)
Chris@1: 
Chris@1: #endif
Chris@1: 
Chris@1: #define fromdB(x) (exp((x)*.11512925f))
Chris@1: 
Chris@1: /* The bark scale equations are approximations, since the original
Chris@1:    table was somewhat hand rolled.  The below are chosen to have the
Chris@1:    best possible fit to the rolled tables, thus their somewhat odd
Chris@1:    appearance (these are more accurate and over a longer range than
Chris@1:    the oft-quoted bark equations found in the texts I have).  The
Chris@1:    approximations are valid from 0 - 30kHz (nyquist) or so.
Chris@1: 
Chris@1:    all f in Hz, z in Bark */
Chris@1: 
Chris@1: #define toBARK(n)   (13.1f*atan(.00074f*(n))+2.24f*atan((n)*(n)*1.85e-8f)+1e-4f*(n))
Chris@1: #define fromBARK(z) (102.f*(z)-2.f*pow(z,2.f)+.4f*pow(z,3.f)+pow(1.46f,z)-1.f)
Chris@1: #define toMEL(n)    (log(1.f+(n)*.001f)*1442.695f)
Chris@1: #define fromMEL(m)  (1000.f*exp((m)/1442.695f)-1000.f)
Chris@1: 
Chris@1: /* Frequency to octave.  We arbitrarily declare 63.5 Hz to be octave
Chris@1:    0.0 */
Chris@1: 
Chris@1: #define toOC(n)     (log(n)*1.442695f-5.965784f)
Chris@1: #define fromOC(o)   (exp(((o)+5.965784f)*.693147f))
Chris@1: 
Chris@1: #endif