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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 * lpc10.h - LPC10 low bit 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 * $Id: lpc10.h,v 1.10 2006/11/21 13:57:40 steveu Exp $
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26 */
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27
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28 #if !defined(_LPC10_H_)
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29 #define _LPC10_H_
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30
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31 /*! \page lpc10_page LPC10 encoding and decoding
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32 \section lpc10_page_sec_1 What does it do?
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33 The LPC10 module implements the US Department of Defense LPC10
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34 codec. This codec produces compressed data at 2400bps. At such
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35 a low rate high fidelity cannot be expected. However, the speech
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36 clarity is quite good, and this codec is unencumbered by patent
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37 or other restrictions.
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38
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39 \section lpc10_page_sec_2 How does it work?
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40 ???.
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41 */
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42
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43 #define LPC10_SAMPLES_PER_FRAME 180
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44 #define LPC10_BITS_IN_COMPRESSED_FRAME 54
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45
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46 /*!
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47 LPC10 codec unpacked frame.
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48 */
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49 typedef struct
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50 {
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51 int32_t ipitch;
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52 int32_t irms;
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53 int32_t irc[10];
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54 } lpc10_frame_t;
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55
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56 /*!
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57 LPC10 codec encoder state descriptor. This defines the state of
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58 a single working instance of the LPC10 encoder.
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59 */
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60 typedef struct
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61 {
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62 int error_correction;
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63
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64 /* State used only by function high_pass_100hz */
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65 float z11;
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66 float z21;
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67 float z12;
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68 float z22;
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69
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70 /* State used by function lpc10_analyse */
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71 float inbuf[LPC10_SAMPLES_PER_FRAME*3];
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72 float pebuf[LPC10_SAMPLES_PER_FRAME*3];
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73 float lpbuf[696];
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74 float ivbuf[312];
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75 float bias;
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76 int32_t osbuf[10]; /* No initial value necessary */
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77 int32_t osptr; /* Initial value 1 */
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78 int32_t obound[3];
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79 int32_t vwin[3][2]; /* Initial value vwin[2][0] = 307; vwin[2][1] = 462; */
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80 int32_t awin[3][2]; /* Initial value awin[2][0] = 307; awin[2][1] = 462; */
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81 int32_t voibuf[4][2];
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82 float rmsbuf[3];
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83 float rcbuf[3][10];
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84 float zpre;
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85
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86 /* State used by function onset */
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87 float n;
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88 float d__; /* Initial value 1.0f */
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89 float fpc; /* No initial value necessary */
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90 float l2buf[16];
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91 float l2sum1;
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92 int32_t l2ptr1; /* Initial value 1 */
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93 int32_t l2ptr2; /* Initial value 9 */
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94 int32_t lasti; /* No initial value necessary */
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95 int hyst; /* Initial value FALSE */
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96
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97 /* State used by function lpc10_voicing */
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98 float dither; /* Initial value 20.0f */
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99 float snr;
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100 float maxmin;
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101 float voice[3][2]; /* Initial value is probably unnecessary */
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102 int32_t lbve;
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103 int32_t lbue;
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104 int32_t fbve;
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105 int32_t fbue;
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106 int32_t ofbue;
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107 int32_t sfbue;
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108 int32_t olbue;
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109 int32_t slbue;
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110
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111 /* State used by function dynamic_pitch_tracking */
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112 float s[60];
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113 int32_t p[2][60];
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114 int32_t ipoint;
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115 float alphax;
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116
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117 /* State used by function lpc10_pack */
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118 int32_t isync;
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119 } lpc10_encode_state_t;
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120
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121 /*!
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122 LPC10 codec decoder state descriptor. This defines the state of
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123 a single working instance of the LPC10 decoder.
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124 */
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125 typedef struct
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126 {
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127 int error_correction;
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128
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129 /* State used by function decode */
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130 int32_t iptold; /* Initial value 60 */
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131 int first; /* Initial value TRUE */
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132 int32_t ivp2h;
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133 int32_t iovoic;
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134 int32_t iavgp; /* Initial value 60 */
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135 int32_t erate;
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136 int32_t drc[10][3];
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137 int32_t dpit[3];
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138 int32_t drms[3];
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139
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140 /* State used by function synths */
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141 float buf[LPC10_SAMPLES_PER_FRAME*2];
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142 int32_t buflen; /* Initial value LPC10_SAMPLES_PER_FRAME */
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143
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144 /* State used by function pitsyn */
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145 int32_t ivoico; /* No initial value necessary as long as first_pitsyn is initially TRUE_ */
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146 int32_t ipito; /* No initial value necessary as long as first_pitsyn is initially TRUE_ */
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147 float rmso; /* Initial value 1.0f */
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148 float rco[10]; /* No initial value necessary as long as first_pitsyn is initially TRUE_ */
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149 int32_t jsamp; /* Nno initial value necessary as long as first_pitsyn is initially TRUE_ */
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150 int first_pitsyn; /* Initial value TRUE */
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151
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152 /* State used by function bsynz */
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153 int32_t ipo;
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154 float exc[166];
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155 float exc2[166];
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156 float lpi[3];
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157 float hpi[3];
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158 float rmso_bsynz;
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159
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160 /* State used by function random */
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161 int32_t j;
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162 int32_t k;
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163 int16_t y[5];
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164
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165 /* State used by function deemp */
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166 float dei[2];
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167 float deo[3];
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168 } lpc10_decode_state_t;
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169
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170 #ifdef __cplusplus
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171 extern "C" {
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172 #endif
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173
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174 /*! Initialise an LPC10e encode context.
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175 \param s The LPC10e context
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176 \param error_correction ???
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177 \return A pointer to the LPC10e context, or NULL for error. */
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178 lpc10_encode_state_t *lpc10_encode_init(lpc10_encode_state_t *s, int error_correction);
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179
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180 int lpc10_encode_release(lpc10_encode_state_t *s);
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181
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182 /*! Encode a buffer of linear PCM data to LPC10e.
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183 \param s The LPC10e context.
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184 \param ima_data The LPC10e data produced.
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185 \param amp The audio sample buffer.
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186 \param len The number of samples in the buffer.
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187 \return The number of bytes of LPC10e data produced. */
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188 int lpc10_encode(lpc10_encode_state_t *s, uint8_t code[], const int16_t amp[], int quant);
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189
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190 /*! Initialise an LPC10e decode context.
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191 \param s The LPC10e context
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192 \param error_correction ???
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193 \return A pointer to the LPC10e context, or NULL for error. */
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194 lpc10_decode_state_t *lpc10_decode_init(lpc10_decode_state_t *st, int error_correction);
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195
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196 int lpc10_decode_release(lpc10_decode_state_t *s);
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197
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198 /*! Decode a buffer of LPC10e data to linear PCM.
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199 \param s The LPC10e context.
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200 \param amp The audio sample buffer.
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201 \param code The LPC10e data.
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202 \param quant The number of frames of LPC10e data to be decoded.
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203 \return The number of samples returned. */
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204 int lpc10_decode(lpc10_decode_state_t *s, int16_t amp[], const uint8_t code[], int quant);
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205
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206
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207 #ifdef __cplusplus
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208 }
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209 #endif
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210
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211 #endif
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212 /*- End of include ---------------------------------------------------------*/
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