acelp_pitch_delay.c
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1 /*
2  * gain code, gain pitch and pitch delay decoding
3  *
4  * Copyright (c) 2008 Vladimir Voroshilov
5  *
6  * This file is part of Libav.
7  *
8  * Libav 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  * Libav 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 Libav; 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/mathematics.h"
24 #include "avcodec.h"
25 #include "dsputil.h"
26 #include "acelp_pitch_delay.h"
27 #include "celp_math.h"
28 
30 {
31  ac_index += 58;
32  if(ac_index > 254)
33  ac_index = 3 * ac_index - 510;
34  return ac_index;
35 }
36 
38  int ac_index,
39  int pitch_delay_min)
40 {
41  if(ac_index < 4)
42  return 3 * (ac_index + pitch_delay_min);
43  else if(ac_index < 12)
44  return 3 * pitch_delay_min + ac_index + 6;
45  else
46  return 3 * (ac_index + pitch_delay_min) - 18;
47 }
48 
50  int ac_index,
51  int pitch_delay_min)
52 {
53  return 3 * pitch_delay_min + ac_index - 2;
54 }
55 
57 {
58  if(ac_index < 463)
59  return ac_index + 105;
60  else
61  return 6 * (ac_index - 368);
62 }
64  int ac_index,
65  int pitch_delay_min)
66 {
67  return 6 * pitch_delay_min + ac_index - 3;
68 }
69 
71  int16_t* quant_energy,
72  int gain_corr_factor,
73  int log2_ma_pred_order,
74  int erasure)
75 {
76  int i;
77  int avg_gain=quant_energy[(1 << log2_ma_pred_order) - 1]; // (5.10)
78 
79  for(i=(1 << log2_ma_pred_order) - 1; i>0; i--)
80  {
81  avg_gain += quant_energy[i-1];
82  quant_energy[i] = quant_energy[i-1];
83  }
84 
85  if(erasure)
86  quant_energy[0] = FFMAX(avg_gain >> log2_ma_pred_order, -10240) - 4096; // -10 and -4 in (5.10)
87  else
88  quant_energy[0] = (6165 * ((ff_log2(gain_corr_factor) >> 2) - (13 << 13))) >> 13;
89 }
90 
92  DSPContext *dsp,
93  int gain_corr_factor,
94  const int16_t* fc_v,
95  int mr_energy,
96  const int16_t* quant_energy,
97  const int16_t* ma_prediction_coeff,
98  int subframe_size,
99  int ma_pred_order)
100 {
101  int i;
102 
103  mr_energy <<= 10;
104 
105  for(i=0; i<ma_pred_order; i++)
106  mr_energy += quant_energy[i] * ma_prediction_coeff[i];
107 
108  mr_energy = gain_corr_factor * exp(M_LN10 / (20 << 23) * mr_energy) /
109  sqrt(dsp->scalarproduct_int16(fc_v, fc_v, subframe_size, 0));
110  return mr_energy >> 12;
111 }
112 
113 float ff_amr_set_fixed_gain(float fixed_gain_factor, float fixed_mean_energy,
114  float *prediction_error, float energy_mean,
115  const float *pred_table)
116 {
117  // Equations 66-69:
118  // ^g_c = ^gamma_gc * 100.05 (predicted dB + mean dB - dB of fixed vector)
119  // Note 10^(0.05 * -10log(average x2)) = 1/sqrt((average x2)).
120  float val = fixed_gain_factor *
121  exp2f(M_LOG2_10 * 0.05 *
122  (ff_dot_productf(pred_table, prediction_error, 4) +
123  energy_mean)) /
124  sqrtf(fixed_mean_energy);
125 
126  // update quantified prediction error energy history
127  memmove(&prediction_error[0], &prediction_error[1],
128  3 * sizeof(prediction_error[0]));
129  prediction_error[3] = 20.0 * log10f(fixed_gain_factor);
130 
131  return val;
132 }
133 
134 void ff_decode_pitch_lag(int *lag_int, int *lag_frac, int pitch_index,
135  const int prev_lag_int, const int subframe,
136  int third_as_first, int resolution)
137 {
138  /* Note n * 10923 >> 15 is floor(x/3) for 0 <= n <= 32767 */
139  if (subframe == 0 || (subframe == 2 && third_as_first)) {
140 
141  if (pitch_index < 197)
142  pitch_index += 59;
143  else
144  pitch_index = 3 * pitch_index - 335;
145 
146  } else {
147  if (resolution == 4) {
148  int search_range_min = av_clip(prev_lag_int - 5, PITCH_DELAY_MIN,
149  PITCH_DELAY_MAX - 9);
150 
151  // decoding with 4-bit resolution
152  if (pitch_index < 4) {
153  // integer only precision for [search_range_min, search_range_min+3]
154  pitch_index = 3 * (pitch_index + search_range_min) + 1;
155  } else if (pitch_index < 12) {
156  // 1/3 fractional precision for [search_range_min+3 1/3, search_range_min+5 2/3]
157  pitch_index += 3 * search_range_min + 7;
158  } else {
159  // integer only precision for [search_range_min+6, search_range_min+9]
160  pitch_index = 3 * (pitch_index + search_range_min - 6) + 1;
161  }
162  } else {
163  // decoding with 5 or 6 bit resolution, 1/3 fractional precision
164  pitch_index--;
165 
166  if (resolution == 5) {
167  pitch_index += 3 * av_clip(prev_lag_int - 10, PITCH_DELAY_MIN,
168  PITCH_DELAY_MAX - 19);
169  } else
170  pitch_index += 3 * av_clip(prev_lag_int - 5, PITCH_DELAY_MIN,
171  PITCH_DELAY_MAX - 9);
172  }
173  }
174  *lag_int = pitch_index * 10923 >> 15;
175  *lag_frac = pitch_index - 3 * *lag_int - 1;
176 }