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