vx32

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scales.h (2722B)

      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 1994-2002             *
      9  * by the XIPHOPHORUS Company http://www.xiph.org/                  *
     10  *                                                                  *
     11  ********************************************************************
     12 
     13  function: linear scale -> dB, Bark and Mel scales
     14  last mod: $Id: scales.h 1919 2005-07-24 14:18:04Z baford $
     15 
     16  ********************************************************************/
     17 
     18 #ifndef _V_SCALES_H_
     19 #define _V_SCALES_H_
     20 
     21 #include <math.h>
     22 #include "os.h"
     23 
     24 /* 20log10(x) */
     25 #define VORBIS_IEEE_FLOAT32 1
     26 #ifdef VORBIS_IEEE_FLOAT32
     27 
     28 static float unitnorm(float x){
     29   ogg_uint32_t *ix=(ogg_uint32_t *)&x;
     30   *ix=(*ix&0x80000000UL)|(0x3f800000UL);
     31   return(x);
     32 }
     33 
     34 static float FABS(float *x){
     35   ogg_uint32_t *ix=(ogg_uint32_t *)x;
     36   *ix&=0x7fffffffUL;
     37   return(*x);
     38 }
     39 
     40 static float todB(const float *x){
     41   float calc;
     42   ogg_int32_t *i=(ogg_int32_t *)x;
     43   calc = ((*i) & 0x7fffffff);
     44   calc *= 7.1771144e-7f;
     45   calc += -764.27118f;
     46   return calc;
     47 }
     48 
     49 #define todB_nn(x) todB(x)
     50 
     51 #else
     52 
     53 static float unitnorm(float x){
     54   if(x<0)return(-1.f);
     55   return(1.f);
     56 }
     57 
     58 #define FABS(x) fabs(*(x))
     59 
     60 #define todB(x)   (*(x)==0?-400.f:log(*(x)**(x))*4.34294480f)
     61 #define todB_nn(x)   (*(x)==0.f?-400.f:log(*(x))*8.6858896f)
     62 
     63 #endif 
     64 
     65 #define fromdB(x) (exp((x)*.11512925f))  
     66 
     67 /* The bark scale equations are approximations, since the original
     68    table was somewhat hand rolled.  The below are chosen to have the
     69    best possible fit to the rolled tables, thus their somewhat odd
     70    appearance (these are more accurate and over a longer range than
     71    the oft-quoted bark equations found in the texts I have).  The
     72    approximations are valid from 0 - 30kHz (nyquist) or so.
     73 
     74    all f in Hz, z in Bark */
     75 
     76 #define toBARK(n)   (13.1f*atan(.00074f*(n))+2.24f*atan((n)*(n)*1.85e-8f)+1e-4f*(n))
     77 #define fromBARK(z) (102.f*(z)-2.f*pow(z,2.f)+.4f*pow(z,3.f)+pow(1.46f,z)-1.f)
     78 #define toMEL(n)    (log(1.f+(n)*.001f)*1442.695f)
     79 #define fromMEL(m)  (1000.f*exp((m)/1442.695f)-1000.f)
     80 
     81 /* Frequency to octave.  We arbitrarily declare 63.5 Hz to be octave
     82    0.0 */
     83 
     84 #define toOC(n)     (log(n)*1.442695f-5.965784f)
     85 #define fromOC(o)   (exp(((o)+5.965784f)*.693147f))
     86 
     87 #endif
     88