apps/codecs/libmusepack/requant.c

   1 /*
   2   Copyright (c) 2005-2009, 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 /// \file requant.c
  35 /// Requantization function implementations.
  36 /// \todo document me
  37 #include "mpcdec.h"
  38 #include "requant.h"
  39 #include "mpcdec_math.h"
  40 #include "decoder.h"
  41 #include "internal.h"
  42
  43 /* C O N S T A N T S */
  44 // Bits per sample for chosen quantizer
  45 const mpc_uint8_t  Res_bit [18] ICONST_ATTR = {
  46     0,  0,  0,  0,  0,  0,  0,  0,  7,  8,  9, 10, 11, 12, 13, 14, 15, 16
  47 };
  48
  49 // Requantization coefficients
  50 // 65536/step bzw. 65536/(2*D+1)
  51
  52 #define _(X) MAKE_MPC_SAMPLE_EX(X,14)
  53
  54 const MPC_SAMPLE_FORMAT  __Cc [1 + 18] ICONST_ATTR = {
  55     _(111.285962475327f),   // 32768/2/255*sqrt(3)
  56     _(65536.000000000000f), _(21845.333333333332f), _(13107.200000000001f), _(9362.285714285713f),
  57     _(7281.777777777777f),  _(4369.066666666666f),  _(2114.064516129032f),  _(1040.253968253968f),
  58     _(516.031496062992f),   _(257.003921568627f),   _(128.250489236790f),   _(64.062561094819f),
  59     _(32.015632633121f),    _(16.003907203907f),    _(8.000976681723f),     _(4.000244155527f),
  60     _(2.000061037018f),     _(1.000015259021f)
  61 };
  62
  63 #undef _
  64
  65 // Requantization offset
  66 // 2*D+1 = steps of quantizer
  67 const mpc_int16_t  __Dc [1 + 18] ICONST_ATTR = {
  68       2,
  69       0,     1,     2,     3,     4,     7,    15,    31,    63,
  70     127,   255,   511,  1023,  2047,  4095,  8191, 16383, 32767
  71 };
  72
  73 #ifdef MPC_FIXED_POINT
  74 static mpc_uint32_t find_shift(double fval)
  75 {
  76     mpc_int64_t  val = (mpc_int64_t) fval;
  77     mpc_uint32_t ptr = 0;
  78     if(val<0)
  79         val = -val;
  80     while(val)
  81     {
  82         val >>= 1;
  83         ptr++;
  84     }
  85     return ptr > 31 ? 0 : 31 - ptr;
  86 }
  87 #endif
  88
  89 /* F U N C T I O N S */
  90
  91 #define SET_SCF(N,X) d->SCF[N] = MAKE_MPC_SAMPLE_EX(X,d->SCF_shift[N] = (mpc_uint8_t) find_shift(X));
  92
  93 void
  94 mpc_decoder_scale_output(mpc_decoder *d, double factor)
  95 {
  96     mpc_int32_t n; double f1, f2;
  97
  98 #ifndef MPC_FIXED_POINT
  99     factor *= 1.0 / (double) (1<<(MPC_FIXED_POINT_SHIFT-1));
 100 #else
 101     factor *= 1.0 / (double) (1<<(16-MPC_FIXED_POINT_SHIFT));
 102 #endif
 103     f1 = f2 = factor;
 104
 105     // handles +1.58...-98.41 dB, where's scf[n] / scf[n-1] = 1.20050805774840750476
 106
 107     SET_SCF(1,factor);
 108
 109     f1 *=   0.83298066476582673961;
 110     f2 *= 1/0.83298066476582673961;
 111
 112     for ( n = 1; n <= 128; n++ ) {
 113         SET_SCF((mpc_uint8_t)(1+n),f1);
 114         SET_SCF((mpc_uint8_t)(1-n),f2);
 115         f1 *=   0.83298066476582673961;
 116         f2 *= 1/0.83298066476582673961;
 117     }
 118 }
 119
 120 void
 121 mpc_decoder_init_quant(mpc_decoder *d, double scale_factor)
 122 {
 123     mpc_decoder_scale_output(d, scale_factor);
 124 }