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/*
Copyright (c) 2005, The Musepack Development Team
All rights reserved.
Redistribution and use in source and binary forms, with or without
modification, are permitted provided that the following conditions are
met:
* Redistributions of source code must retain the above copyright
notice, this list of conditions and the following disclaimer.
* Redistributions in binary form must reproduce the above
copyright notice, this list of conditions and the following
disclaimer in the documentation and/or other materials provided
with the distribution.
* Neither the name of the The Musepack Development Team nor the
names of its contributors may be used to endorse or promote
products derived from this software without specific prior
written permission.
THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
"AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
(INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
*/
/// \file requant.c
/// Requantization function implementations.
/// \todo document me
#include "musepack.h"
#include "internal.h"
/* C O N S T A N T S */
// bits per sample for chosen quantizer
const mpc_uint32_t Res_bit [18] ICONST_ATTR = {
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] ICONST_ATTR = {
_(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 mpc_int32_t __Dc [1 + 18] ICONST_ATTR = {
2,
0, 1, 2, 3, 4, 7, 15, 31, 63,
127, 255, 511, 1023, 2047, 4095, 8191, 16383, 32767
};
#ifdef MPC_FIXED_POINT
static mpc_uint32_t find_shift(double fval)
{
mpc_int64_t val = (mpc_int64_t)fval;
mpc_uint32_t ptr = 0;
if (val<0) val = -val;
while(val) {val>>=1;ptr++;}
return ptr > 31 ? 0 : 31 - ptr;
}
#endif
/* F U N C T I O N S */
#define SET_SCF(N,X) d->SCF[N] = MAKE_MPC_SAMPLE_EX(X,d->SCF_shift[N] = (unsigned char)find_shift(X));
void
mpc_decoder_scale_output(mpc_decoder *d, double factor)
{
mpc_int32_t n;
double f1;
double f2;
#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
f1 = 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_initialisiere_quantisierungstabellen(mpc_decoder *d, double scale_factor)
{
mpc_decoder_scale_output(d, scale_factor);
}
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