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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 * g722.h - The ITU G.722 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) 2005 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 * Based on a single channel G.722 codec which is:
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26 *
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27 ***** Copyright (c) CMU 1993 *****
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28 * Computer Science, Speech Group
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29 * Chengxiang Lu and Alex Hauptmann
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30 *
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31 * $Id: g722.h,v 1.13 2006/10/24 13:45:28 steveu Exp $
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32 */
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33
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34
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35 /*! \file */
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36
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37 #if !defined(_G722_H_)
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38 #define _G722_H_
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39
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40 /*! \page g722_page G.722 encoding and decoding
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41 \section g722_page_sec_1 What does it do?
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42 The G.722 module is a bit exact implementation of the ITU G.722 specification for all three
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43 specified bit rates - 64000bps, 56000bps and 48000bps. It passes the ITU tests.
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44
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45 To allow fast and flexible interworking with narrow band telephony, the encoder and decoder
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46 support an option for the linear audio to be an 8k samples/second stream. In this mode the
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47 codec is considerably faster, and still fully compatible with wideband terminals using G.722.
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48
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49 \section g722_page_sec_2 How does it work?
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50 ???.
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51 */
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52
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53 enum
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54 {
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55 G722_SAMPLE_RATE_8000 = 0x0001,
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56 G722_PACKED = 0x0002
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57 };
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58
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59 typedef struct
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60 {
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61 /*! TRUE if the operating in the special ITU test mode, with the band split filters
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62 disabled. */
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63 int itu_test_mode;
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64 /*! TRUE if the G.722 data is packed */
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65 int packed;
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66 /*! TRUE if encode from 8k samples/second */
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67 int eight_k;
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68 /*! 6 for 48000kbps, 7 for 56000kbps, or 8 for 64000kbps. */
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69 int bits_per_sample;
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70
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71 /*! Signal history for the QMF */
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72 int x[24];
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73
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74 struct
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75 {
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76 int s;
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77 int sp;
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78 int sz;
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79 int r[3];
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80 int a[3];
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81 int ap[3];
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82 int p[3];
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83 int d[7];
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84 int b[7];
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85 int bp[7];
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86 int sg[7];
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87 int nb;
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88 int det;
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89 } band[2];
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90
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91 unsigned int in_buffer;
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92 int in_bits;
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93 unsigned int out_buffer;
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94 int out_bits;
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95 } g722_encode_state_t;
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96
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97 typedef struct
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98 {
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99 /*! TRUE if the operating in the special ITU test mode, with the band split filters
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100 disabled. */
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101 int itu_test_mode;
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102 /*! TRUE if the G.722 data is packed */
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103 int packed;
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104 /*! TRUE if decode to 8k samples/second */
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105 int eight_k;
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106 /*! 6 for 48000kbps, 7 for 56000kbps, or 8 for 64000kbps. */
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107 int bits_per_sample;
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108
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109 /*! Signal history for the QMF */
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110 int x[24];
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111
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112 struct
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113 {
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114 int s;
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115 int sp;
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116 int sz;
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117 int r[3];
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118 int a[3];
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119 int ap[3];
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120 int p[3];
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121 int d[7];
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122 int b[7];
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123 int bp[7];
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124 int sg[7];
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125 int nb;
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126 int det;
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127 } band[2];
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128
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129 unsigned int in_buffer;
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130 int in_bits;
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131 unsigned int out_buffer;
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132 int out_bits;
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133 } g722_decode_state_t;
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134
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135 #ifdef __cplusplus
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136 extern "C" {
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137 #endif
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138
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139 /*! Initialise an G.722 encode context.
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140 \param s The G.722 encode context.
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141 \param rate The required bit rate for the G.722 data.
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142 The valid rates are 64000, 56000 and 48000.
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143 \param options
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144 \return A pointer to the G.722 encode context, or NULL for error. */
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145 g722_encode_state_t *g722_encode_init(g722_encode_state_t *s, int rate, int options);
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146
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147 int g722_encode_release(g722_encode_state_t *s);
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148
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149 /*! Encode a buffer of linear PCM data to G.722
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150 \param s The G.722 context.
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151 \param g722_data The G.722 data produced.
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152 \param amp The audio sample buffer.
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153 \param len The number of samples in the buffer.
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154 \return The number of bytes of G.722 data produced. */
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155 int g722_encode(g722_encode_state_t *s, uint8_t g722_data[], const int16_t amp[], int len);
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156
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157 /*! Initialise an G.722 decode context.
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158 \param s The G.722 decode context.
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159 \param rate The bit rate of the G.722 data.
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160 The valid rates are 64000, 56000 and 48000.
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161 \param options
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162 \return A pointer to the G.722 decode context, or NULL for error. */
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163 g722_decode_state_t *g722_decode_init(g722_decode_state_t *s, int rate, int options);
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164
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165 int g722_decode_release(g722_decode_state_t *s);
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166
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167 /*! Decode a buffer of G.722 data to linear PCM.
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168 \param s The G.722 context.
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169 \param amp The audio sample buffer.
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170 \param g722_data
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171 \param len
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172 \return The number of samples returned. */
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173 int g722_decode(g722_decode_state_t *s, int16_t amp[], const uint8_t g722_data[], int len);
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174
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175 #ifdef __cplusplus
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176 }
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177 #endif
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178
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179 #endif
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