| 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 | #include "libavutil/common.h" |
| 24 | #include "libavutil/float_dsp.h" |
| 25 | #include "libavutil/libm.h" |
| 26 | #include "libavutil/mathematics.h" |
| 27 | #include "avcodec.h" |
| 28 | #include "acelp_pitch_delay.h" |
| 29 | #include "celp_math.h" |
| 30 | #include "audiodsp.h" |
| 31 | |
| 32 | int ff_acelp_decode_8bit_to_1st_delay3(int ac_index) |
| 33 | { |
| 34 | ac_index += 58; |
| 35 | if(ac_index > 254) |
| 36 | ac_index = 3 * ac_index - 510; |
| 37 | return ac_index; |
| 38 | } |
| 39 | |
| 40 | int ff_acelp_decode_4bit_to_2nd_delay3( |
| 41 | int ac_index, |
| 42 | int pitch_delay_min) |
| 43 | { |
| 44 | if(ac_index < 4) |
| 45 | return 3 * (ac_index + pitch_delay_min); |
| 46 | else if(ac_index < 12) |
| 47 | return 3 * pitch_delay_min + ac_index + 6; |
| 48 | else |
| 49 | return 3 * (ac_index + pitch_delay_min) - 18; |
| 50 | } |
| 51 | |
| 52 | int ff_acelp_decode_5_6_bit_to_2nd_delay3( |
| 53 | int ac_index, |
| 54 | int pitch_delay_min) |
| 55 | { |
| 56 | return 3 * pitch_delay_min + ac_index - 2; |
| 57 | } |
| 58 | |
| 59 | int ff_acelp_decode_9bit_to_1st_delay6(int ac_index) |
| 60 | { |
| 61 | if(ac_index < 463) |
| 62 | return ac_index + 105; |
| 63 | else |
| 64 | return 6 * (ac_index - 368); |
| 65 | } |
| 66 | int ff_acelp_decode_6bit_to_2nd_delay6( |
| 67 | int ac_index, |
| 68 | int pitch_delay_min) |
| 69 | { |
| 70 | return 6 * pitch_delay_min + ac_index - 3; |
| 71 | } |
| 72 | |
| 73 | void ff_acelp_update_past_gain( |
| 74 | int16_t* quant_energy, |
| 75 | int gain_corr_factor, |
| 76 | int log2_ma_pred_order, |
| 77 | int erasure) |
| 78 | { |
| 79 | int i; |
| 80 | int avg_gain=quant_energy[(1 << log2_ma_pred_order) - 1]; // (5.10) |
| 81 | |
| 82 | for(i=(1 << log2_ma_pred_order) - 1; i>0; i--) |
| 83 | { |
| 84 | avg_gain += quant_energy[i-1]; |
| 85 | quant_energy[i] = quant_energy[i-1]; |
| 86 | } |
| 87 | |
| 88 | if(erasure) |
| 89 | quant_energy[0] = FFMAX(avg_gain >> log2_ma_pred_order, -10240) - 4096; // -10 and -4 in (5.10) |
| 90 | else |
| 91 | quant_energy[0] = (6165 * ((ff_log2_q15(gain_corr_factor) >> 2) - (13 << 13))) >> 13; |
| 92 | } |
| 93 | |
| 94 | int16_t ff_acelp_decode_gain_code( |
| 95 | AudioDSPContext *adsp, |
| 96 | int gain_corr_factor, |
| 97 | const int16_t* fc_v, |
| 98 | int mr_energy, |
| 99 | const int16_t* quant_energy, |
| 100 | const int16_t* ma_prediction_coeff, |
| 101 | int subframe_size, |
| 102 | int ma_pred_order) |
| 103 | { |
| 104 | int i; |
| 105 | |
| 106 | mr_energy <<= 10; |
| 107 | |
| 108 | for(i=0; i<ma_pred_order; i++) |
| 109 | mr_energy += quant_energy[i] * ma_prediction_coeff[i]; |
| 110 | |
| 111 | #ifdef G729_BITEXACT |
| 112 | mr_energy += (((-6165LL * ff_log2(dsp->scalarproduct_int16(fc_v, fc_v, subframe_size, 0))) >> 3) & ~0x3ff); |
| 113 | |
| 114 | mr_energy = (5439 * (mr_energy >> 15)) >> 8; // (0.15) = (0.15) * (7.23) |
| 115 | |
| 116 | return bidir_sal( |
| 117 | ((ff_exp2(mr_energy & 0x7fff) + 16) >> 5) * (gain_corr_factor >> 1), |
| 118 | (mr_energy >> 15) - 25 |
| 119 | ); |
| 120 | #else |
| 121 | mr_energy = gain_corr_factor * exp(M_LN10 / (20 << 23) * mr_energy) / |
| 122 | sqrt(adsp->scalarproduct_int16(fc_v, fc_v, subframe_size)); |
| 123 | return mr_energy >> 12; |
| 124 | #endif |
| 125 | } |
| 126 | |
| 127 | float ff_amr_set_fixed_gain(float fixed_gain_factor, float fixed_mean_energy, |
| 128 | float *prediction_error, float energy_mean, |
| 129 | const float *pred_table) |
| 130 | { |
| 131 | // Equations 66-69: |
| 132 | // ^g_c = ^gamma_gc * 100.05 (predicted dB + mean dB - dB of fixed vector) |
| 133 | // Note 10^(0.05 * -10log(average x2)) = 1/sqrt((average x2)). |
| 134 | float val = fixed_gain_factor * |
| 135 | exp2f(M_LOG2_10 * 0.05 * |
| 136 | (avpriv_scalarproduct_float_c(pred_table, prediction_error, 4) + |
| 137 | energy_mean)) / |
| 138 | sqrtf(fixed_mean_energy); |
| 139 | |
| 140 | // update quantified prediction error energy history |
| 141 | memmove(&prediction_error[0], &prediction_error[1], |
| 142 | 3 * sizeof(prediction_error[0])); |
| 143 | prediction_error[3] = 20.0 * log10f(fixed_gain_factor); |
| 144 | |
| 145 | return val; |
| 146 | } |
| 147 | |
| 148 | void ff_decode_pitch_lag(int *lag_int, int *lag_frac, int pitch_index, |
| 149 | const int prev_lag_int, const int subframe, |
| 150 | int third_as_first, int resolution) |
| 151 | { |
| 152 | /* Note n * 10923 >> 15 is floor(x/3) for 0 <= n <= 32767 */ |
| 153 | if (subframe == 0 || (subframe == 2 && third_as_first)) { |
| 154 | |
| 155 | if (pitch_index < 197) |
| 156 | pitch_index += 59; |
| 157 | else |
| 158 | pitch_index = 3 * pitch_index - 335; |
| 159 | |
| 160 | } else { |
| 161 | if (resolution == 4) { |
| 162 | int search_range_min = av_clip(prev_lag_int - 5, PITCH_DELAY_MIN, |
| 163 | PITCH_DELAY_MAX - 9); |
| 164 | |
| 165 | // decoding with 4-bit resolution |
| 166 | if (pitch_index < 4) { |
| 167 | // integer only precision for [search_range_min, search_range_min+3] |
| 168 | pitch_index = 3 * (pitch_index + search_range_min) + 1; |
| 169 | } else if (pitch_index < 12) { |
| 170 | // 1/3 fractional precision for [search_range_min+3 1/3, search_range_min+5 2/3] |
| 171 | pitch_index += 3 * search_range_min + 7; |
| 172 | } else { |
| 173 | // integer only precision for [search_range_min+6, search_range_min+9] |
| 174 | pitch_index = 3 * (pitch_index + search_range_min - 6) + 1; |
| 175 | } |
| 176 | } else { |
| 177 | // decoding with 5 or 6 bit resolution, 1/3 fractional precision |
| 178 | pitch_index--; |
| 179 | |
| 180 | if (resolution == 5) { |
| 181 | pitch_index += 3 * av_clip(prev_lag_int - 10, PITCH_DELAY_MIN, |
| 182 | PITCH_DELAY_MAX - 19); |
| 183 | } else |
| 184 | pitch_index += 3 * av_clip(prev_lag_int - 5, PITCH_DELAY_MIN, |
| 185 | PITCH_DELAY_MAX - 9); |
| 186 | } |
| 187 | } |
| 188 | *lag_int = pitch_index * 10923 >> 15; |
| 189 | *lag_frac = pitch_index - 3 * *lag_int - 1; |
| 190 | } |