apps/codecs/libmusepack/requant.c

   1 /*
   2   Copyright (c) 2005, The Musepack Development Team
   3   All rights reserved.
   4
   5   Redistribution and use in source and binary forms, with or without
   6   modification, are permitted provided that the following conditions are
   7   met:
   8
   9   * Redistributions of source code must retain the above copyright
  10   notice, this list of conditions and the following disclaimer.
  11
  12   * Redistributions in binary form must reproduce the above
  13   copyright notice, this list of conditions and the following
  14   disclaimer in the documentation and/or other materials provided
  15   with the distribution.
  16
  17   * Neither the name of the The Musepack Development Team nor the
  18   names of its contributors may be used to endorse or promote
  19   products derived from this software without specific prior
  20   written permission.
  21
  22   THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
  23   "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
  24   LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
  25   A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
  26   OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
  27   SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
  28   LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
  29   DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
  30   THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
  31   (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
  32   OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
  33 */
  34
  35 /// \file requant.c
  36 /// Requantization function implementations.
  37 /// \todo document me
  38
  39 #include "musepack.h"
  40 #include "internal.h"
  41
  42 /* C O N S T A N T S */
  43 // bits per sample for chosen quantizer
  44 const mpc_uint32_t  Res_bit [18] ICONST_ATTR = {
  45     0,  0,  0,  0,  0,  0,  0,  0,  7,  8,  9, 10, 11, 12, 13, 14, 15, 16
  46 };
  47
  48 // coefficients for requantization
  49 // 65536/step bzw. 65536/(2*D+1)
  50
  51 #define _(X) MAKE_MPC_SAMPLE_EX(X,14)
  52
  53 const MPC_SAMPLE_FORMAT  __Cc [1 + 18] ICONST_ATTR = {
  54       _(111.285962475327f),                                        // 32768/2/255*sqrt(3)
  55     _(65536.000000000000f), _(21845.333333333332f), _(13107.200000000001f), _(9362.285714285713f),
  56      _(7281.777777777777f),  _(4369.066666666666f),  _(2114.064516129032f), _(1040.253968253968f),
  57       _(516.031496062992f),   _(257.003921568627f),   _(128.250489236790f),   _(64.062561094819f),
  58        _(32.015632633121f),    _(16.003907203907f),     _(8.000976681723f),    _(4.000244155527f),
  59         _(2.000061037018f),     _(1.000015259021f)
  60 };
  61
  62 #undef _
  63
  64 // offset for requantization
  65 // 2*D+1 = steps of quantizer
  66 const mpc_int32_t  __Dc [1 + 18] ICONST_ATTR = {
  67       2,
  68       0,     1,     2,     3,     4,     7,    15,    31,    63,
  69     127,   255,   511,  1023,  2047,  4095,  8191, 16383, 32767
  70 };
  71
  72 #ifdef MPC_FIXED_POINT
  73 static mpc_uint32_t find_shift(double fval)
  74 {
  75     mpc_int64_t  val = (mpc_int64_t)fval;
  76     mpc_uint32_t ptr = 0;
  77     if (val<0) val = -val;
  78     while(val) {val>>=1;ptr++;}
  79
  80     return ptr > 31 ? 0 : 31 - ptr;
  81 }
  82 #endif
  83
  84 /* F U N C T I O N S */
  85
  86 #define SET_SCF(N,X) d->SCF[N] = MAKE_MPC_SAMPLE_EX(X,d->SCF_shift[N] = (unsigned char)find_shift(X));
  87
  88 void
  89 mpc_decoder_scale_output(mpc_decoder *d, double factor)
  90 {
  91     mpc_int32_t     n;
  92     double  f1;
  93     double  f2;
  94 #ifndef MPC_FIXED_POINT
  95     factor *= 1.0 / (double)(1<<(MPC_FIXED_POINT_SHIFT-1));
  96 #else
  97     factor *= 1.0 / (double)(1<<(16 - MPC_FIXED_POINT_SHIFT));
  98 #endif
  99     f1 = f2 = factor;
 100
 101     // handles +1.58...-98.41 dB, where's scf[n] / scf[n-1] = 1.20050805774840750476
 102
 103     SET_SCF(1,factor);
 104
 105     f1 *=   0.83298066476582673961;
 106     f2 *= 1/0.83298066476582673961;
 107
 108     for ( n = 1; n <= 128; n++ ) {
 109         SET_SCF((unsigned char)(1+n),f1);
 110         SET_SCF((unsigned char)(1-n),f2);
 111         f1 *=   0.83298066476582673961;
 112         f2 *= 1/0.83298066476582673961;
 113     }
 114 }
 115
 116 void
 117 mpc_decoder_initialisiere_quantisierungstabellen(mpc_decoder *d, double scale_factor)
 118 {
 119     mpc_decoder_scale_output(d, scale_factor);
 120 }