1/* 2 * gain code, gain pitch and pitch delay decoding 3 * 4 * Copyright (c) 2008 Vladimir Voroshilov 5 * 6 * This file is part of FFmpeg. 7 * 8 * FFmpeg is free software; you can redistribute it and/or 9 * modify it under the terms of the GNU Lesser General Public 10 * License as published by the Free Software Foundation; either 11 * version 2.1 of the License, or (at your option) any later version. 12 * 13 * FFmpeg is distributed in the hope that it will be useful, 14 * but WITHOUT ANY WARRANTY; without even the implied warranty of 15 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU 16 * Lesser General Public License for more details. 17 * 18 * You should have received a copy of the GNU Lesser General Public 19 * License along with FFmpeg; if not, write to the Free Software 20 * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA 21 */ 22 23#ifndef AVCODEC_ACELP_PITCH_DELAY_H 24#define AVCODEC_ACELP_PITCH_DELAY_H 25 26#include <stdint.h> 27#include "dsputil.h" 28 29#define PITCH_DELAY_MIN 20 30#define PITCH_DELAY_MAX 143 31 32/** 33 * \brief Decode pitch delay of the first subframe encoded by 8 bits with 1/3 34 * resolution. 35 * \param ac_index adaptive codebook index (8 bits) 36 * 37 * \return pitch delay in 1/3 units 38 * 39 * Pitch delay is coded: 40 * with 1/3 resolution, 19 < pitch_delay < 85 41 * integers only, 85 <= pitch_delay <= 143 42 */ 43int ff_acelp_decode_8bit_to_1st_delay3(int ac_index); 44 45/** 46 * \brief Decode pitch delay of the second subframe encoded by 5 or 6 bits 47 * with 1/3 precision. 48 * \param ac_index adaptive codebook index (5 or 6 bits) 49 * \param pitch_delay_min lower bound (integer) of pitch delay interval 50 * for second subframe 51 * 52 * \return pitch delay in 1/3 units 53 * 54 * Pitch delay is coded: 55 * with 1/3 resolution, -6 < pitch_delay - int(prev_pitch_delay) < 5 56 * 57 * \remark The routine is used in G.729 @8k, AMR @10.2k, AMR @7.95k, 58 * AMR @7.4k for the second subframe. 59 */ 60int ff_acelp_decode_5_6_bit_to_2nd_delay3( 61 int ac_index, 62 int pitch_delay_min); 63 64/** 65 * \brief Decode pitch delay with 1/3 precision. 66 * \param ac_index adaptive codebook index (4 bits) 67 * \param pitch_delay_min lower bound (integer) of pitch delay interval for 68 * second subframe 69 * 70 * \return pitch delay in 1/3 units 71 * 72 * Pitch delay is coded: 73 * integers only, -6 < pitch_delay - int(prev_pitch_delay) <= -2 74 * with 1/3 resolution, -2 < pitch_delay - int(prev_pitch_delay) < 1 75 * integers only, 1 <= pitch_delay - int(prev_pitch_delay) < 5 76 * 77 * \remark The routine is used in G.729 @6.4k, AMR @6.7k, AMR @5.9k, 78 * AMR @5.15k, AMR @4.75k for the second subframe. 79 */ 80int ff_acelp_decode_4bit_to_2nd_delay3( 81 int ac_index, 82 int pitch_delay_min); 83 84/** 85 * \brief Decode pitch delay of the first subframe encoded by 9 bits 86 * with 1/6 precision. 87 * \param ac_index adaptive codebook index (9 bits) 88 * \param pitch_delay_min lower bound (integer) of pitch delay interval for 89 * second subframe 90 * 91 * \return pitch delay in 1/6 units 92 * 93 * Pitch delay is coded: 94 * with 1/6 resolution, 17 < pitch_delay < 95 95 * integers only, 95 <= pitch_delay <= 143 96 * 97 * \remark The routine is used in AMR @12.2k for the first and third subframes. 98 */ 99int ff_acelp_decode_9bit_to_1st_delay6(int ac_index); 100 101/** 102 * \brief Decode pitch delay of the second subframe encoded by 6 bits 103 * with 1/6 precision. 104 * \param ac_index adaptive codebook index (6 bits) 105 * \param pitch_delay_min lower bound (integer) of pitch delay interval for 106 * second subframe 107 * 108 * \return pitch delay in 1/6 units 109 * 110 * Pitch delay is coded: 111 * with 1/6 resolution, -6 < pitch_delay - int(prev_pitch_delay) < 5 112 * 113 * \remark The routine is used in AMR @12.2k for the second and fourth subframes. 114 */ 115int ff_acelp_decode_6bit_to_2nd_delay6( 116 int ac_index, 117 int pitch_delay_min); 118 119/** 120 * \brief Update past quantized energies 121 * \param quant_energy [in/out] past quantized energies (5.10) 122 * \param gain_corr_factor gain correction factor 123 * \param log2_ma_pred_order log2() of MA prediction order 124 * \param erasure frame erasure flag 125 * 126 * If frame erasure flag is not equal to zero, memory is updated with 127 * averaged energy, attenuated by 4dB: 128 * max(avg(quant_energy[i])-4, -14), i=0,ma_pred_order 129 * 130 * In normal mode memory is updated with 131 * Er - Ep = 20 * log10(gain_corr_factor) 132 * 133 * \remark The routine is used in G.729 and AMR (all modes). 134 */ 135void ff_acelp_update_past_gain( 136 int16_t* quant_energy, 137 int gain_corr_factor, 138 int log2_ma_pred_order, 139 int erasure); 140 141/** 142 * \brief Decode the adaptive codebook gain and add 143 * correction (4.1.5 and 3.9.1 of G.729). 144 * \param dsp initialized dsputil context 145 * \param gain_corr_factor gain correction factor (2.13) 146 * \param fc_v fixed-codebook vector (2.13) 147 * \param mr_energy mean innovation energy and fixed-point correction (7.13) 148 * \param quant_energy [in/out] past quantized energies (5.10) 149 * \param subframe_size length of subframe 150 * \param ma_pred_order MA prediction order 151 * 152 * \return quantized fixed-codebook gain (14.1) 153 * 154 * The routine implements equations 69, 66 and 71 of the G.729 specification (3.9.1) 155 * 156 * Em - mean innovation energy (dB, constant, depends on decoding algorithm) 157 * Ep - mean-removed predicted energy (dB) 158 * Er - mean-removed innovation energy (dB) 159 * Ei - mean energy of the fixed-codebook contribution (dB) 160 * N - subframe_size 161 * M - MA (Moving Average) prediction order 162 * gc - fixed-codebook gain 163 * gc_p - predicted fixed-codebook gain 164 * 165 * Fixed codebook gain is computed using predicted gain gc_p and 166 * correction factor gain_corr_factor as shown below: 167 * 168 * gc = gc_p * gain_corr_factor 169 * 170 * The predicted fixed codebook gain gc_p is found by predicting 171 * the energy of the fixed-codebook contribution from the energy 172 * of previous fixed-codebook contributions. 173 * 174 * mean = 1/N * sum(i,0,N){ fc_v[i] * fc_v[i] } 175 * 176 * Ei = 10log(mean) 177 * 178 * Er = 10log(1/N * gc^2 * mean) - Em = 20log(gc) + Ei - Em 179 * 180 * Replacing Er with Ep and gc with gc_p we will receive: 181 * 182 * Ep = 10log(1/N * gc_p^2 * mean) - Em = 20log(gc_p) + Ei - Em 183 * 184 * and from above: 185 * 186 * gc_p = 10^((Ep - Ei + Em) / 20) 187 * 188 * Ep is predicted using past energies and prediction coefficients: 189 * 190 * Ep = sum(i,0,M){ ma_prediction_coeff[i] * quant_energy[i] } 191 * 192 * gc_p in fixed-point arithmetic is calculated as following: 193 * 194 * mean = 1/N * sum(i,0,N){ (fc_v[i] / 2^13) * (fc_v[i] / 2^13) } = 195 * = 1/N * sum(i,0,N) { fc_v[i] * fc_v[i] } / 2^26 196 * 197 * Ei = 10log(mean) = -10log(N) - 10log(2^26) + 198 * + 10log(sum(i,0,N) { fc_v[i] * fc_v[i] }) 199 * 200 * Ep - Ei + Em = Ep + Em + 10log(N) + 10log(2^26) - 201 * - 10log(sum(i,0,N) { fc_v[i] * fc_v[i] }) = 202 * = Ep + mr_energy - 10log(sum(i,0,N) { fc_v[i] * fc_v[i] }) 203 * 204 * gc_p = 10 ^ ((Ep - Ei + Em) / 20) = 205 * = 2 ^ (3.3219 * (Ep - Ei + Em) / 20) = 2 ^ (0.166 * (Ep - Ei + Em)) 206 * 207 * where 208 * 209 * mr_energy = Em + 10log(N) + 10log(2^26) 210 * 211 * \remark The routine is used in G.729 and AMR (all modes). 212 */ 213int16_t ff_acelp_decode_gain_code( 214 DSPContext *dsp, 215 int gain_corr_factor, 216 const int16_t* fc_v, 217 int mr_energy, 218 const int16_t* quant_energy, 219 const int16_t* ma_prediction_coeff, 220 int subframe_size, 221 int max_pred_order); 222 223/** 224 * Calculate fixed gain (part of section 6.1.3 of AMR spec) 225 * 226 * @param fixed_gain_factor gain correction factor 227 * @param fixed_energy decoded algebraic codebook vector energy 228 * @param prediction_error vector of the quantified predictor errors of 229 * the four previous subframes. It is updated by this function. 230 * @param energy_mean desired mean innovation energy 231 * @param pred_table table of four moving average coefficients 232 */ 233float ff_amr_set_fixed_gain(float fixed_gain_factor, float fixed_mean_energy, 234 float *prediction_error, float energy_mean, 235 const float *pred_table); 236 237 238/** 239 * Decode the adaptive codebook index to the integer and fractional parts 240 * of the pitch lag for one subframe at 1/3 fractional precision. 241 * 242 * The choice of pitch lag is described in 3GPP TS 26.090 section 5.6.1. 243 * 244 * @param lag_int integer part of pitch lag of the current subframe 245 * @param lag_frac fractional part of pitch lag of the current subframe 246 * @param pitch_index parsed adaptive codebook (pitch) index 247 * @param prev_lag_int integer part of pitch lag for the previous subframe 248 * @param subframe current subframe number 249 * @param third_as_first treat the third frame the same way as the first 250 */ 251void ff_decode_pitch_lag(int *lag_int, int *lag_frac, int pitch_index, 252 const int prev_lag_int, const int subframe, 253 int third_as_first, int resolution); 254 255#endif /* AVCODEC_ACELP_PITCH_DELAY_H */ 256