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comparison: media/libvorbis/lib/scales.h
media/libvorbis/lib/scales.h
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| 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 |
