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 "dsputil.h"
  25 #include "acelp_pitch_delay.h"
  26 #include "celp_math.h"
  27
  28 int ff_acelp_decode_8bit_to_1st_delay3(int ac_index)
  29 {
  30     ac_index += 58;
  31     if(ac_index > 254)
  32         ac_index = 3 * ac_index - 510;
  33     return ac_index;
  34 }
  35
  36 int ff_acelp_decode_4bit_to_2nd_delay3(
  37         int ac_index,
  38         int pitch_delay_min)
  39 {
  40     if(ac_index < 4)
  41         return 3 * (ac_index + pitch_delay_min);
  42     else if(ac_index < 12)
  43         return 3 * pitch_delay_min + ac_index + 6;
  44     else
  45         return 3 * (ac_index + pitch_delay_min) - 18;
  46 }
  47
  48 int ff_acelp_decode_5_6_bit_to_2nd_delay3(
  49         int ac_index,
  50         int pitch_delay_min)
  51 {
  52         return 3 * pitch_delay_min + ac_index - 2;
  53 }
  54
  55 int ff_acelp_decode_9bit_to_1st_delay6(int ac_index)
  56 {
  57     if(ac_index < 463)
  58         return ac_index + 105;
  59     else
  60         return 6 * (ac_index - 368);
  61 }
  62 int ff_acelp_decode_6bit_to_2nd_delay6(
  63         int ac_index,
  64         int pitch_delay_min)
  65 {
  66     return 6 * pitch_delay_min + ac_index - 3;
  67 }
  68
  69 void ff_acelp_update_past_gain(
  70     int16_t* quant_energy,
  71     int gain_corr_factor,
  72     int log2_ma_pred_order,
  73     int erasure)
  74 {
  75     int i;
  76     int avg_gain=quant_energy[(1 << log2_ma_pred_order) - 1]; // (5.10)
  77
  78     for(i=(1 << log2_ma_pred_order) - 1; i>0; i--)
  79     {
  80         avg_gain       += quant_energy[i-1];
  81         quant_energy[i] = quant_energy[i-1];
  82     }
  83
  84     if(erasure)
  85         quant_energy[0] = FFMAX(avg_gain >> log2_ma_pred_order, -10240) - 4096; // -10 and -4 in (5.10)
  86     else
  87         quant_energy[0] = (6165 * ((ff_log2(gain_corr_factor) >> 2) - (13 << 13))) >> 13;
  88 }
  89
  90 int16_t ff_acelp_decode_gain_code(
  91     DSPContext *dsp,
  92     int gain_corr_factor,
  93     const int16_t* fc_v,
  94     int mr_energy,
  95     const int16_t* quant_energy,
  96     const int16_t* ma_prediction_coeff,
  97     int subframe_size,
  98     int ma_pred_order)
  99 {
 100     int i;
 101
 102     mr_energy <<= 10;
 103
 104     for(i=0; i<ma_pred_order; i++)
 105         mr_energy += quant_energy[i] * ma_prediction_coeff[i];
 106
 107 #ifdef G729_BITEXACT
 108     mr_energy += (((-6165LL * ff_log2(dsp->scalarproduct_int16(fc_v, fc_v, subframe_size, 0))) >> 3) & ~0x3ff);
 109
 110     mr_energy = (5439 * (mr_energy >> 15)) >> 8;           // (0.15) = (0.15) * (7.23)
 111
 112     return bidir_sal(
 113                ((ff_exp2(mr_energy & 0x7fff) + 16) >> 5) * (gain_corr_factor >> 1),
 114                (mr_energy >> 15) - 25
 115            );
 116 #else
 117     mr_energy = gain_corr_factor * exp(M_LN10 / (20 << 23) * mr_energy) /
 118                 sqrt(dsp->scalarproduct_int16(fc_v, fc_v, subframe_size, 0));
 119     return mr_energy >> 12;
 120 #endif
 121 }