apps/codecs/libpcm/ima_adpcm_common.c

   1 /***************************************************************************
   2  *             __________               __   ___.
   3  *   Open      \______   \ ____   ____ |  | _\_ |__   _______  ___
   4  *   Source     |       _//  _ \_/ ___\|  |/ /| __ \ /  _ \  \/  /
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   7  *                     \/            \/     \/    \/            \/
   8  * $Id$
   9  *
  10  * Copyright (C) 2010 Yoshihisa Uchida
  11  *
  12  * This program is free software; you can redistribute it and/or
  13  * modify it under the terms of the GNU General Public License
  14  * as published by the Free Software Foundation; either version 2
  15  * of the License, or (at your option) any later version.
  16  *
  17  * This software is distributed on an "AS IS" basis, WITHOUT WARRANTY OF ANY
  18  * KIND, either express or implied.
  19  *
  20  ****************************************************************************/
  21 #include "codeclib.h"
  22 #include "pcm_common.h"
  23 #include "ima_adpcm_common.h"
  24
  25 /*
  26  * Functions for IMA ADPCM and IMA ADPCM series format
  27  *
  28  * References
  29  * [1] The IMA Digital Audio Focus and Technical Working Groups,
  30  *     Recommended Practices for Enhancing Digital Audio Compatibility
  31  *     in Multimedia Systems Revision 3.00, 1992
  32  * [2] Microsoft Corporation, New Multimedia Data Types and Data Techniques,
  33  *     Revision:3.0, 1994
  34  * [3] ffmpeg source code, libavcodec/adpcm.c
  35  */
  36
  37 /* step table */
  38 static const uint16_t step_table[89] ICONST_ATTR = {
  39     7, 8, 9, 10, 11, 12, 13, 14,
  40     16, 17, 19, 21, 23, 25, 28, 31,
  41     34, 37, 41, 45, 50, 55, 60, 66,
  42     73, 80, 88, 97, 107, 118, 130, 143,
  43     157, 173, 190, 209, 230, 253, 279, 307,
  44     337, 371, 408, 449, 494, 544, 598, 658,
  45     724, 796, 876, 963, 1060, 1166, 1282, 1411,
  46     1552, 1707, 1878, 2066, 2272, 2499, 2749, 3024,
  47     3327, 3660, 4026, 4428, 4871, 5358, 5894, 6484,
  48     7132, 7845, 8630, 9493, 10442, 11487, 12635, 13899,
  49     15289, 16818, 18500, 20350, 22385, 24623, 27086, 29794,
  50     32767
  51 };
  52
  53 /* step index tables */
  54 static const int index_tables[4][16] ICONST_ATTR = {
  55     /* adpcm data size is 2 */
  56     { -1, 2 },
  57     /* adpcm data size is 3 */
  58     { -1, -1, 1, 2 },
  59     /* adpcm data size is 4 */
  60     { -1, -1, -1, -1, 2, 4, 6, 8 },
  61     /* adpcm data size is 5 */
  62     { -1, -1, -1, -1, -1, -1, -1, -1, 1, 2, 4, 6, 8, 10, 13, 16 },
  63 };
  64
  65 static int32_t pcmdata[2];
  66 static int8_t index[2];
  67
  68 static int adpcm_data_size;
  69 static uint8_t step_mask;
  70 static uint8_t step_sign_mask;
  71 static int8_t step_shift;
  72 static const int *use_index_table;
  73
  74 /*
  75  * Before first decoding, this function must be executed.
  76  *
  77  * params
  78  *     bit: adpcm data size (2 <= bit <= 5).
  79  *     index_table: step index table
  80  *                  if index_table is null, then step index table
  81  *                  is used index_tables[bit-2].
  82  */
  83 void init_ima_adpcm_decoder(int bit, const int *index_table)
  84 {
  85     adpcm_data_size = bit;
  86     step_sign_mask = 1 << (adpcm_data_size - 1);
  87     step_mask = step_sign_mask - 1;
  88     step_shift = adpcm_data_size - 2;
  89     if (index_table)
  90         use_index_table = index_table;
  91     else
  92         use_index_table = index_tables[adpcm_data_size - 2];
  93 }
  94
  95 /*
  96  * When starting decoding for each block, this function must be executed.
  97  *
  98  * params
  99  *     channels: channel count
 100  *     init_pcmdata: array of init pcmdata
 101  *     init_index:   array of init step indexes
 102  */
 103 void set_decode_parameters(int channels, int32_t *init_pcmdata, int8_t *init_index)
 104 {
 105     int ch;
 106
 107     for (ch = 0; ch < channels; ch++)
 108     {
 109         pcmdata[ch] = init_pcmdata[ch];
 110         index[ch] = init_index[ch];
 111     }
 112 }
 113
 114 /*
 115  * convert ADPCM to PCM for any adpcm data size.
 116  *
 117  * If adpcm_data_size is 4, then you use create_pcmdata_size4()
 118  * in place of this functon.
 119  */
 120 int16_t create_pcmdata(int ch, uint8_t nibble)
 121 {
 122     int check_bit = 1 << step_shift;
 123     int32_t delta = 0;
 124     int16_t step = step_table[index[ch]];
 125
 126     do {
 127         if (nibble & check_bit)
 128             delta += step;
 129         step >>= 1;
 130         check_bit >>= 1;
 131     } while (check_bit);
 132     delta += step;
 133
 134     if (nibble & step_sign_mask)
 135         pcmdata[ch] -= delta;
 136     else
 137         pcmdata[ch] += delta;
 138
 139     index[ch] += use_index_table[nibble & step_mask];
 140     CLIP(index[ch], 0, 88);
 141
 142     CLIP(pcmdata[ch], -32768, 32767);
 143
 144     return (int16_t)pcmdata[ch];
 145 }
 146
 147 /*
 148  * convert ADPCM to PCM when adpcm data size is 4.
 149  */
 150 int16_t create_pcmdata_size4(int ch, uint8_t nibble)
 151 {
 152     int32_t delta;
 153     int16_t step = step_table[index[ch]];
 154
 155     delta = (step >> 3);
 156     if (nibble & 4) delta += step;
 157     if (nibble & 2) delta += (step >> 1);
 158     if (nibble & 1) delta += (step >> 2);
 159
 160     if (nibble & 0x08)
 161         pcmdata[ch] -= delta;
 162     else
 163         pcmdata[ch] += delta;
 164
 165     index[ch] += use_index_table[nibble & 0x07];
 166     CLIP(index[ch], 0, 88);
 167
 168     CLIP(pcmdata[ch], -32768, 32767);
 169
 170     return (int16_t)pcmdata[ch];
 171 }