1 files changed, 89 insertions, 0 deletions
diff --git a/vorbis/lib/scales.h b/vorbis/lib/scales.h
new file mode 100644
index 0000000..18bc4e7
--- /dev/null
+++ b/vorbis/lib/scales.h
@@ -0,0 +1,89 @@
+/********************************************************************
+ *                                                                  *
+ * THIS FILE IS PART OF THE OggVorbis SOFTWARE CODEC SOURCE CODE.   *
+ * USE, DISTRIBUTION AND REPRODUCTION OF THIS LIBRARY SOURCE IS     *
+ * GOVERNED BY A BSD-STYLE SOURCE LICENSE INCLUDED WITH THIS SOURCE *
+ * IN 'COPYING'. PLEASE READ THESE TERMS BEFORE DISTRIBUTING.       *
+ *                                                                  *
+ * THE OggVorbis SOURCE CODE IS (C) COPYRIGHT 1994-2009             *
+ * by the Xiph.Org Foundation http://www.xiph.org/                  *
+ *                                                                  *
+ ********************************************************************
+
+ function: linear scale -> dB, Bark and Mel scales
+
+ ********************************************************************/
+
+#ifndef _V_SCALES_H_
+#define _V_SCALES_H_
+
+#include <math.h>
+#include "os.h"
+
+#ifdef _MSC_VER
+/* MS Visual Studio doesn't have C99 inline keyword. */
+#define inline __inline
+#endif
+
+/* 20log10(x) */
+#define VORBIS_IEEE_FLOAT32 1
+#ifdef VORBIS_IEEE_FLOAT32
+
+static inline float unitnorm(float x){
+  union {
+    ogg_uint32_t i;
+    float f;
+  } ix;
+  ix.f = x;
+  ix.i = (ix.i & 0x80000000U) | (0x3f800000U);
+  return ix.f;
+}
+
+/* Segher was off (too high) by ~ .3 decibel.  Center the conversion correctly. */
+static inline float todB(const float *x){
+  union {
+    ogg_uint32_t i;
+    float f;
+  } ix;
+  ix.f = *x;
+  ix.i = ix.i&0x7fffffff;
+  return (float)(ix.i * 7.17711438e-7f -764.6161886f);
+}
+
+#define todB_nn(x) todB(x)
+
+#else
+
+static float unitnorm(float x){
+  if(x<0)return(-1.f);
+  return(1.f);
+}
+
+#define todB(x)   (*(x)==0?-400.f:log(*(x)**(x))*4.34294480f)
+#define todB_nn(x)   (*(x)==0.f?-400.f:log(*(x))*8.6858896f)
+
+#endif
+
+#define fromdB(x) (exp((x)*.11512925f))
+
+/* The bark scale equations are approximations, since the original
+   table was somewhat hand rolled.  The below are chosen to have the
+   best possible fit to the rolled tables, thus their somewhat odd
+   appearance (these are more accurate and over a longer range than
+   the oft-quoted bark equations found in the texts I have).  The
+   approximations are valid from 0 - 30kHz (nyquist) or so.
+
+   all f in Hz, z in Bark */
+
+#define toBARK(n)   (13.1f*atan(.00074f*(n))+2.24f*atan((n)*(n)*1.85e-8f)+1e-4f*(n))
+#define fromBARK(z) (102.f*(z)-2.f*pow(z,2.f)+.4f*pow(z,3.f)+pow(1.46f,z)-1.f)
+#define toMEL(n)    (log(1.f+(n)*.001f)*1442.695f)
+#define fromMEL(m)  (1000.f*exp((m)/1442.695f)-1000.f)
+
+/* Frequency to octave.  We arbitrarily declare 63.5 Hz to be octave
+   0.0 */
+
+#define toOC(n)     (log(n)*1.442695f-5.965784f)
+#define fromOC(o)   (exp(((o)+5.965784f)*.693147f))
+
+#endif