The Tor Browser: media/libvorbis/lib/scales.h@6474c204b198

Cloned upstream origin tor-browser at tor-browser-31.3.0esr-4.5-1-build1
revision ID fc1c9ff7c1b2defdbc039f12214767608f46423f for hacking purpose.

     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  ********************************************************************

    13  function: linear scale -> dB, Bark and Mel scales

    14  last mod: $Id: scales.h 16227 2009-07-08 06:58:46Z xiphmont $

    16  ********************************************************************/

    18 #ifndef _V_SCALES_H_

    19 #define _V_SCALES_H_

    21 #include <math.h>

    22 #include "os.h"

    24 #ifdef _MSC_VER

    25 /* MS Visual Studio doesn't have C99 inline keyword. */

    26 #define inline __inline

    27 #endif

    29 /* 20log10(x) */

    30 #define VORBIS_IEEE_FLOAT32 1

    31 #ifdef VORBIS_IEEE_FLOAT32

    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 }

    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 }

    54 #define todB_nn(x) todB(x)

    56 #else

    58 static float unitnorm(float x){

    59   if(x<0)return(-1.f);

    60   return(1.f);

    61 }

    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)

    66 #endif

    68 #define fromdB(x) (exp((x)*.11512925f))

    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.

    77    all f in Hz, z in Bark */

    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)

    84 /* Frequency to octave.  We arbitrarily declare 63.5 Hz to be octave

    85    0.0 */

    87 #define toOC(n)     (log(n)*1.442695f-5.965784f)

    88 #define fromOC(o)   (exp(((o)+5.965784f)*.693147f))

    90 #endif

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