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#include "stdafx.h"
/* C O N S T A N T S */
// bits per sample for chosen quantizer
const unsigned int Res_bit [18] = {
0, 0, 0, 0, 0, 0, 0, 0, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16
};
// coefficients for requantization
// 65536/step bzw. 65536/(2*D+1)
#define _(X) MAKE_MPC_SAMPLE_EX(X,14)
const MPC_SAMPLE_FORMAT __Cc [1 + 18] = {
_(111.285962475327f), // 32768/2/255*sqrt(3)
_(65536.000000000000f), _(21845.333333333332f), _(13107.200000000001f), _(9362.285714285713f),
_(7281.777777777777f), _(4369.066666666666f), _(2114.064516129032f), _(1040.253968253968f),
_(516.031496062992f), _(257.003921568627f), _(128.250489236790f), _(64.062561094819f),
_(32.015632633121f), _(16.003907203907f), _(8.000976681723f), _(4.000244155527f),
_(2.000061037018f), _(1.000015259021f)
};
#undef _
// offset for requantization
// 2*D+1 = steps of quantizer
const int __Dc [1 + 18] = {
2,
0, 1, 2, 3, 4, 7, 15, 31, 63,
127, 255, 511, 1023, 2047, 4095, 8191, 16383, 32767
};
static unsigned find_shift(double fval)
{
MPC_INT64 val = (MPC_INT64)fval;
if (val<0) val = -val;
unsigned ptr = 0;
while(val) {val>>=1;ptr++;}
return ptr > 31 ? 0 : 31 - ptr;
}
/* F U N C T I O N S */
#define SET_SCF(N,X) SCF[N] = MAKE_MPC_SAMPLE_EX(X,SCF_shift[N] = find_shift(X));
void
MPC_decoder::ScaleOutput ( double factor )
{
#ifndef MPC_FIXED_POINT
factor *= 1.0 / (double)(1<<(MPC_FIXED_POINT_SHIFT-1));
#else
factor *= 1.0 / (double)(1<<(16 - MPC_FIXED_POINT_SHIFT));
#endif
int n;
double f1 = factor;
double f2 = factor;
// handles +1.58...-98.41 dB, where's scf[n] / scf[n-1] = 1.20050805774840750476
SET_SCF(1,factor);
f1 *= 0.83298066476582673961;
f2 *= 1/0.83298066476582673961;
for ( n = 1; n <= 128; n++ ) {
SET_SCF((unsigned char)(1+n),f1);
SET_SCF((unsigned char)(1-n),f2);
f1 *= 0.83298066476582673961;
f2 *= 1/0.83298066476582673961;
}
}
void
MPC_decoder::Quantisierungsmodes ( void ) // conversion: index -> quantizer (bitstream reading)
{ // conversion: quantizer -> index (bitstream writing)
int Band = 0;
int i;
do {
Q_bit [Band] = 4;
for ( i = 0; i < 16-1; i++ )
Q_res [Band] [i] = i;
Q_res [Band][i] = 17;
Band++;
} while ( Band < 11 );
do {
Q_bit [Band] = 3;
for ( i = 0; i < 8-1; i++ )
Q_res [Band] [i] = i;
Q_res [Band] [i] = 17;
Band++;
} while ( Band < 23 );
do {
Q_bit [Band] = 2;
for ( i = 0; i < 4-1; i++ )
Q_res [Band] [i] = i;
Q_res [Band] [i] = 17;
Band++;
} while ( Band < 32 );
}
void
MPC_decoder::initialisiere_Quantisierungstabellen ( double scale_factor )
{
Quantisierungsmodes ();
ScaleOutput ( scale_factor );
}
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