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5
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1 /*
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2 * SpanDSP - a series of DSP components for telephony
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3 *
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4 * gsm0610_short_term.c - GSM 06.10 full rate speech codec.
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5 *
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6 * Written by Steve Underwood <steveu@coppice.org>
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7 *
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8 * Copyright (C) 2006 Steve Underwood
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9 *
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10 * All rights reserved.
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11 *
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12 * This program is free software; you can redistribute it and/or modify
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13 * it under the terms of the GNU General Public License version 2, as
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14 * published by the Free Software Foundation.
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15 *
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16 * This program is distributed in the hope that it will be useful,
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17 * but WITHOUT ANY WARRANTY; without even the implied warranty of
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18 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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19 * GNU General Public License for more details.
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20 *
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21 * You should have received a copy of the GNU General Public License
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22 * along with this program; if not, write to the Free Software
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23 * Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
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24 *
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25 * This code is based on the widely used GSM 06.10 code available from
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26 * http://kbs.cs.tu-berlin.de/~jutta/toast.html
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27 *
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28 * $Id: gsm0610_short_term.c,v 1.9 2006/11/30 15:41:47 steveu Exp $
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29 */
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30
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31 /*! \file */
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32
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33 #ifdef HAVE_CONFIG_H
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34 #include <config.h>
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35 #endif
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36
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37 #include <assert.h>
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38 #include <inttypes.h>
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39 #if defined(HAVE_TGMATH_H)
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40 #include <tgmath.h>
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41 #endif
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42 #if defined(HAVE_MATH_H)
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43 #include <math.h>
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44 #endif
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45 #include <stdlib.h>
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46
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47 #include "spandsp/telephony.h"
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48 #include "spandsp/dc_restore.h"
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49 #include "spandsp/gsm0610.h"
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50
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51 #include "gsm0610_local.h"
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52
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53 /* SHORT TERM ANALYSIS FILTERING SECTION */
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54
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55 /* 4.2.8 */
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56 static void decode_log_area_ratios(int16_t LARc[8], int16_t *LARpp)
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57 {
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58 int16_t temp1;
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59
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60 /* This procedure requires for efficient implementation
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61 two tables.
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62 INVA[1..8] = integer((32768*8)/real_A[1..8])
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63 MIC[1..8] = minimum value of the LARc[1..8]
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64 */
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65
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66 /* Compute the LARpp[1..8] */
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67
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68 #undef STEP
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69 #define STEP(B,MIC,INVA) \
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70 temp1 = gsm_add(*LARc++, MIC) << 10; \
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71 temp1 = gsm_sub(temp1, B << 1); \
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72 temp1 = gsm_mult_r (INVA, temp1); \
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73 *LARpp++ = gsm_add(temp1, temp1);
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74
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75 STEP( 0, -32, 13107);
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76 STEP( 0, -32, 13107);
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77 STEP( 2048, -16, 13107);
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78 STEP(-2560, -16, 13107);
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79
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80 STEP( 94, -8, 19223);
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81 STEP(-1792, -8, 17476);
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82 STEP( -341, -4, 31454);
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83 STEP(-1144, -4, 29708);
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84
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85 /* NOTE: the addition of *MIC is used to restore the sign of *LARc. */
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86 }
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87 /*- End of function --------------------------------------------------------*/
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88
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89 /* 4.2.9 */
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90
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91 /* Computation of the quantized reflection coefficients */
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92
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93 /* 4.2.9.1 Interpolation of the LARpp[1..8] to get the LARp[1..8] */
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94
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95 /* Within each frame of 160 analyzed speech samples the short term
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96 analysis and synthesis filters operate with four different sets of
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97 coefficients, derived from the previous set of decoded LARs(LARpp(j - 1))
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98 and the actual set of decoded LARs (LARpp(j))
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99
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100 (Initial value: LARpp(j - 1)[1..8] = 0.)
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101 */
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102
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103 static void coefficients_0_12(int16_t *LARpp_j_1,
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104 int16_t *LARpp_j,
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105 int16_t *LARp)
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106 {
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107 int i;
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108
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109 for (i = 1; i <= 8; i++, LARp++, LARpp_j_1++, LARpp_j++)
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110 {
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111 *LARp = gsm_add(*LARpp_j_1 >> 2, *LARpp_j >> 2);
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112 *LARp = gsm_add(*LARp, *LARpp_j_1 >> 1);
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113 }
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114 /*endfor*/
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115 }
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116 /*- End of function --------------------------------------------------------*/
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117
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118 static void coefficients_13_26(int16_t *LARpp_j_1,
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119 int16_t *LARpp_j,
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120 int16_t *LARp)
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121 {
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122 int i;
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123
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124 for (i = 1; i <= 8; i++, LARpp_j_1++, LARpp_j++, LARp++)
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125 *LARp = gsm_add(*LARpp_j_1 >> 1, *LARpp_j >> 1);
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126 /*endfor*/
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127 }
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128 /*- End of function --------------------------------------------------------*/
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129
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130 static void coefficients_27_39(int16_t *LARpp_j_1,
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131 int16_t *LARpp_j,
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132 int16_t *LARp)
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133 {
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134 int i;
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135
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136 for (i = 1; i <= 8; i++, LARpp_j_1++, LARpp_j++, LARp++)
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137 {
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138 *LARp = gsm_add(*LARpp_j_1 >> 2, *LARpp_j >> 2);
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139 *LARp = gsm_add(*LARp, *LARpp_j >> 1);
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140 }
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141 /*endfor*/
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142 }
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143 /*- End of function --------------------------------------------------------*/
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144
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145 static void coefficients_40_159(int16_t *LARpp_j, int16_t *LARp)
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146 {
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147 int i;
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148
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149 for (i = 1; i <= 8; i++)
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150 *LARp++ = *LARpp_j++;
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151 /*endfor*/
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152 }
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153 /*- End of function --------------------------------------------------------*/
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154
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155 /* 4.2.9.2 */
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156 static void larp_to_rp(int16_t LARp[8])
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157 {
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158 int i;
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159 int16_t *LARpx;
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160 int16_t temp;
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161
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162 /* The input to this procedure is the interpolated LARp[0..7] array.
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163 The reflection coefficients, rp[i], are used in the analysis
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164 filter and in the synthesis filter.
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165 */
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166
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167 LARpx = LARp;
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168 for (i = 1; i <= 8; i++, LARpx++)
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169 {
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170 temp = *LARpx;
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171 if (temp < 0)
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172 {
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173 if (temp == INT16_MIN)
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174 temp = INT16_MAX;
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175 else
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176 temp = -temp;
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177 /*endif*/
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178 if (temp < 11059)
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179 temp <<= 1;
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180 else if (temp < 20070)
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181 temp += 11059;
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182 else
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183 temp = gsm_add(temp >> 2, 26112);
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184 /*endif*/
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185 *LARpx = -temp;
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186 }
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187 else
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188 {
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189 if (temp < 11059)
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190 temp <<= 1;
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191 else if (temp < 20070)
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192 temp += 11059;
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193 else
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194 temp = gsm_add(temp >> 2, 26112);
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195 /*endif*/
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196 *LARpx = temp;
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197 }
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198 /*endif*/
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199 }
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200 /*endfor*/
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201 }
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202 /*- End of function --------------------------------------------------------*/
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203
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204 /* 4.2.10 */
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205 static void short_term_analysis_filtering(gsm0610_state_t *s,
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206 int16_t rp[8],
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207 int k_n, // k_end - k_start
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208 int16_t amp[]) // [0..n-1] IN/OUT
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209 {
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210 /* This procedure computes the short term residual signal d[..] to be fed
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211 to the RPE-LTP loop from the s[..] signal and from the local rp[..]
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212 array (quantized reflection coefficients). As the call of this
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213 procedure can be done in many ways (see the interpolation of the LAR
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214 coefficient), it is assumed that the computation begins with index
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215 k_start (for arrays d[..] and s[..]) and stops with index k_end
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216 (k_start and k_end are defined in 4.2.9.1). This procedure also
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217 needs to keep the array u[0..7] in memory for each call.
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218 */
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219 int16_t *u0;
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220 int16_t *u_top;
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221 int i;
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222 int16_t *u;
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223 int16_t *rpx;
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224 int32_t di;
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225 int32_t u_out;
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226
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227 u0 = s->u;
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228 u_top = u0 + 8;
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229
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230 for (i = 0; i < k_n; i++)
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231 {
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232 di =
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233 u_out = amp[i];
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234 for (rpx = rp, u = u0; u < u_top; )
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235 {
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236 int32_t ui;
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237 int32_t rpi;
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238
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239 ui = *u;
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240 *u++ = (int16_t) u_out;
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241 rpi = *rpx++;
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242 u_out = ui + (((rpi*di) + 0x4000) >> 15);
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243 di = di + (((rpi*ui) + 0x4000) >> 15);
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244 u_out = saturate(u_out);
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245 di = saturate(di);
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246 }
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247 /*endfor*/
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248 amp[i] = (int16_t) di;
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249 }
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250 /*endfor*/
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251 }
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252 /*- End of function --------------------------------------------------------*/
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253
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254 static void short_term_synthesis_filtering(gsm0610_state_t *s,
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255 int16_t rrp[8],
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256 int k, // k_end - k_start
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257 int16_t *wt, // [0..k - 1]
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258 int16_t *sr) // [0..k - 1]
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259 {
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260 int16_t *v;
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261 int i;
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262 int16_t sri;
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263 int16_t tmp1;
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264 int16_t tmp2;
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265
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266 v = s->v;
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267 while (k--)
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268 {
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269 sri = *wt++;
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270 for (i = 8; i--; )
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271 {
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272 tmp1 = rrp[i];
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273 tmp2 = v[i];
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274 tmp2 = ((tmp1 == INT16_MIN && tmp2 == INT16_MIN)
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275 ?
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276 INT16_MAX
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277 :
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278 (int16_t) (((int32_t) tmp1*(int32_t) tmp2 + 16384) >> 15) & 0xFFFF);
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279
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280 sri = gsm_sub(sri, tmp2);
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281
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282 tmp1 = ((tmp1 == INT16_MIN && sri == INT16_MIN)
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283 ?
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284 INT16_MAX
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285 :
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286 (int16_t) (((int32_t) tmp1*(int32_t) sri + 16384) >> 15) & 0xFFFF);
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287
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288 v[i + 1] = gsm_add(v[i], tmp1);
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289 }
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290 /*endfor*/
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291 *sr++ =
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292 v[0] = sri;
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293 }
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294 /*endwhile*/
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295 }
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296 /*- End of function --------------------------------------------------------*/
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297
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298 void gsm0610_short_term_analysis_filter(gsm0610_state_t *s,
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299 int16_t LARc[8],
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300 int16_t amp[GSM0610_FRAME_LEN])
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301 {
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302 int16_t *LARpp_j;
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303 int16_t *LARpp_j_1;
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304 int16_t LARp[8];
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305
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306 LARpp_j = s->LARpp[s->j];
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307 LARpp_j_1 = s->LARpp[s->j ^= 1];
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308
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309 decode_log_area_ratios(LARc, LARpp_j);
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310
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311 coefficients_0_12(LARpp_j_1, LARpp_j, LARp);
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312 larp_to_rp(LARp);
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313 short_term_analysis_filtering(s, LARp, 13, amp);
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314
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315 coefficients_13_26(LARpp_j_1, LARpp_j, LARp);
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316 larp_to_rp(LARp);
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317 short_term_analysis_filtering(s, LARp, 14, amp + 13);
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318
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319 coefficients_27_39(LARpp_j_1, LARpp_j, LARp);
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320 larp_to_rp(LARp);
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321 short_term_analysis_filtering(s, LARp, 13, amp + 27);
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322
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323 coefficients_40_159(LARpp_j, LARp);
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324 larp_to_rp(LARp);
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325 short_term_analysis_filtering(s, LARp, 120, amp + 40);
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326 }
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327 /*- End of function --------------------------------------------------------*/
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328
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329 void gsm0610_short_term_synthesis_filter(gsm0610_state_t *s,
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330 int16_t LARcr[8],
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331 int16_t wt[GSM0610_FRAME_LEN],
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332 int16_t amp[GSM0610_FRAME_LEN])
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333 {
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334 int16_t *LARpp_j;
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335 int16_t *LARpp_j_1;
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336 int16_t LARp[8];
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337
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338 LARpp_j = s->LARpp[s->j];
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339 LARpp_j_1 = s->LARpp[s->j ^= 1];
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340
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341 decode_log_area_ratios(LARcr, LARpp_j);
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342
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343 coefficients_0_12(LARpp_j_1, LARpp_j, LARp);
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344 larp_to_rp(LARp);
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345 short_term_synthesis_filtering(s, LARp, 13, wt, amp);
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346
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347 coefficients_13_26(LARpp_j_1, LARpp_j, LARp);
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348 larp_to_rp(LARp);
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349 short_term_synthesis_filtering(s, LARp, 14, wt + 13, amp + 13);
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350
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351 coefficients_27_39(LARpp_j_1, LARpp_j, LARp);
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352 larp_to_rp(LARp);
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353 short_term_synthesis_filtering(s, LARp, 13, wt + 27, amp + 27);
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354
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355 coefficients_40_159(LARpp_j, LARp);
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356 larp_to_rp(LARp);
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357 short_term_synthesis_filtering(s, LARp, 120, wt + 40, amp + 40);
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358 }
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359 /*- End of function --------------------------------------------------------*/
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360 /*- End of file ------------------------------------------------------------*/
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