git.sesse.net Git - ffmpeg/blob - libavcodec/acelp_pitch_delay.c

   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/ffmath.h"
  25 #include "libavutil/float_dsp.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         ff_exp10(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 }