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