1 /********************************************************************
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. *
8 * THE OggVorbis SOURCE CODE IS (C) COPYRIGHT 1994-2001 *
9 * by the XIPHOPHORUS Company http://www.xiph.org/ *
11 ********************************************************************
13 function: linear scale -> dB, Bark and Mel scales
14 last mod: $Id: scales.h,v 1.23 2002/03/29 07:10:39 xiphmont Exp $
16 ********************************************************************/
25 #ifdef VORBIS_IEEE_FLOAT32
27 static float unitnorm(float x){
28 ogg_uint32_t *ix=(ogg_uint32_t *)&x;
29 *ix=(*ix&0x80000000UL)|(0x3f800000UL);
33 static float FABS(float *x){
34 ogg_uint32_t *ix=(ogg_uint32_t *)&x;
39 static float todB(const float *x){
41 ogg_int32_t *i=(ogg_int32_t *)x;
42 calc = ((*i) & 0x7fffffff);
43 calc *= 7.1771144e-7f;
48 #define todB_nn(x) todB(x)
52 static float unitnorm(float x){
57 #define FABS(x) fabs(*(x))
59 #define todB(x) (*(x)==0?-400.f:log(*(x)**(x))*4.34294480f)
60 #define todB_nn(x) (*(x)==0.f?-400.f:log(*(x))*8.6858896f)
64 #define fromdB(x) (exp((x)*.11512925f))
66 /* The bark scale equations are approximations, since the original
67 table was somewhat hand rolled. The below are chosen to have the
68 best possible fit to the rolled tables, thus their somewhat odd
69 appearance (these are more accurate and over a longer range than
70 the oft-quoted bark equations found in the texts I have). The
71 approximations are valid from 0 - 30kHz (nyquist) or so.
73 all f in Hz, z in Bark */
75 #define toBARK(n) (13.1f*atan(.00074f*(n))+2.24f*atan((n)*(n)*1.85e-8f)+1e-4f*(n))
76 #define fromBARK(z) (102.f*(z)-2.f*pow(z,2.f)+.4f*pow(z,3.f)+pow(1.46f,z)-1.f)
77 #define toMEL(n) (log(1.f+(n)*.001f)*1442.695f)
78 #define fromMEL(m) (1000.f*exp((m)/1442.695f)-1000.f)
80 /* Frequency to octave. We arbitrarily declare 63.5 Hz to be octave
83 #define toOC(n) (log(n)*1.442695f-5.965784f)
84 #define fromOC(o) (exp(((o)+5.965784f)*.693147f))