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 "avcodec.h"
  24 #include "acelp_pitch_delay.h"
  25 #include "acelp_math.h"
  26
  27 int ff_acelp_decode_8bit_to_1st_delay3(int ac_index)
  28 {
  29     ac_index += 58;
  30     if(ac_index > 254)
  31         ac_index = 3 * ac_index - 510;
  32     return ac_index;
  33 }
  34
  35 int ff_acelp_decode_4bit_to_2nd_delay3(
  36         int ac_index,
  37         int pitch_delay_min)
  38 {
  39     if(ac_index < 4)
  40         return 3 * (ac_index + pitch_delay_min);
  41     else if(ac_index < 12)
  42         return 3 * pitch_delay_min + ac_index + 6;
  43     else
  44         return 3 * (ac_index + pitch_delay_min) - 18;
  45 }
  46
  47 int ff_acelp_decode_5_6_bit_to_2nd_delay3(
  48         int ac_index,
  49         int pitch_delay_min)
  50 {
  51         return 3 * pitch_delay_min + ac_index - 2;
  52 }
  53
  54 int ff_acelp_decode_9bit_to_1st_delay6(int ac_index)
  55 {
  56     if(ac_index < 463)
  57         return ac_index + 105;
  58     else
  59         return 6 * (ac_index - 368);
  60 }
  61 int ff_acelp_decode_6bit_to_2nd_delay6(
  62         int ac_index,
  63         int pitch_delay_min)
  64 {
  65     return 6 * pitch_delay_min + ac_index - 3;
  66 }
  67
  68 void ff_acelp_update_past_gain(
  69     int16_t* quant_energy,
  70     int gain_corr_factor,
  71     int log2_ma_pred_order,
  72     int erasure)
  73 {
  74     int i;
  75     int avg_gain=quant_energy[(1 << log2_ma_pred_order) - 1]; // (5.10)
  76
  77     for(i=(1 << log2_ma_pred_order) - 1; i>0; i--)
  78     {
  79         avg_gain       += quant_energy[i-1];
  80         quant_energy[i] = quant_energy[i-1];
  81     }
  82
  83     if(erasure)
  84         quant_energy[0] = FFMAX(avg_gain >> log2_ma_pred_order, -10240) - 4096; // -10 and -4 in (5.10)
  85     else
  86         quant_energy[0] = (6165 * ((ff_log2(gain_corr_factor) >> 2) - (13 << 13))) >> 13;
  87 }
  88
  89 int16_t ff_acelp_decode_gain_code(
  90     int gain_corr_factor,
  91     const int16_t* fc_v,
  92     int mr_energy,
  93     const int16_t* quant_energy,
  94     const int16_t* ma_prediction_coeff,
  95     int subframe_size,
  96     int ma_pred_order)
  97 {
  98     int i;
  99
 100     mr_energy <<= 10;
 101
 102     for(i=0; i<ma_pred_order; i++)
 103         mr_energy += quant_energy[i] * ma_prediction_coeff[i];
 104
 105 #ifdef G729_BITEXACT
 106     mr_energy += (((-6165LL * ff_log2(dot_product(fc_v, fc_v, subframe_size, 0))) >> 3) & ~0x3ff);
 107
 108     mr_energy = (5439 * (mr_energy >> 15)) >> 8;           // (0.15) = (0.15) * (7.23)
 109
 110     return bidir_sal(
 111                ((ff_exp2(mr_energy & 0x7fff) + 16) >> 5) * (gain_corr_factor >> 1),
 112                (mr_energy >> 15) - 25
 113            );
 114 #else
 115     mr_energy = gain_corr_factor * exp(M_LN10 / (20 << 23) * mr_energy) /
 116                 sqrt(dot_product(fc_v, fc_v, subframe_size, 0));
 117     return mr_energy >> 12;
 118 #endif
 119 }