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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 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/float_dsp.h"
25 #include "libavutil/libm.h"
26 #include "libavutil/mathematics.h"
27 #include "avcodec.h"
28 #include "acelp_pitch_delay.h"
29 #include "celp_math.h"
30 
32 {
33  ac_index += 58;
34  if(ac_index > 254)
35  ac_index = 3 * ac_index - 510;
36  return ac_index;
37 }
38 
40  int ac_index,
41  int pitch_delay_min)
42 {
43  if(ac_index < 4)
44  return 3 * (ac_index + pitch_delay_min);
45  else if(ac_index < 12)
46  return 3 * pitch_delay_min + ac_index + 6;
47  else
48  return 3 * (ac_index + pitch_delay_min) - 18;
49 }
50 
52  int ac_index,
53  int pitch_delay_min)
54 {
55  return 3 * pitch_delay_min + ac_index - 2;
56 }
57 
59 {
60  if(ac_index < 463)
61  return ac_index + 105;
62  else
63  return 6 * (ac_index - 368);
64 }
66  int ac_index,
67  int pitch_delay_min)
68 {
69  return 6 * pitch_delay_min + ac_index - 3;
70 }
71 
73  int16_t* quant_energy,
74  int gain_corr_factor,
75  int log2_ma_pred_order,
76  int erasure)
77 {
78  int i;
79  int avg_gain=quant_energy[(1 << log2_ma_pred_order) - 1]; // (5.10)
80 
81  for(i=(1 << log2_ma_pred_order) - 1; i>0; i--)
82  {
83  avg_gain += quant_energy[i-1];
84  quant_energy[i] = quant_energy[i-1];
85  }
86 
87  if(erasure)
88  quant_energy[0] = FFMAX(avg_gain >> log2_ma_pred_order, -10240) - 4096; // -10 and -4 in (5.10)
89  else
90  quant_energy[0] = (6165 * ((ff_log2_q15(gain_corr_factor) >> 2) - (13 << 13))) >> 13;
91 }
92 
94  DSPContext *dsp,
95  int gain_corr_factor,
96  const int16_t* fc_v,
97  int mr_energy,
98  const int16_t* quant_energy,
99  const int16_t* ma_prediction_coeff,
100  int subframe_size,
101  int ma_pred_order)
102 {
103  int i;
104 
105  mr_energy <<= 10;
106 
107  for(i=0; i<ma_pred_order; i++)
108  mr_energy += quant_energy[i] * ma_prediction_coeff[i];
109 
110 #ifdef G729_BITEXACT
111  mr_energy += (((-6165LL * ff_log2(dsp->scalarproduct_int16(fc_v, fc_v, subframe_size, 0))) >> 3) & ~0x3ff);
112 
113  mr_energy = (5439 * (mr_energy >> 15)) >> 8; // (0.15) = (0.15) * (7.23)
114 
115  return bidir_sal(
116  ((ff_exp2(mr_energy & 0x7fff) + 16) >> 5) * (gain_corr_factor >> 1),
117  (mr_energy >> 15) - 25
118  );
119 #else
120  mr_energy = gain_corr_factor * exp(M_LN10 / (20 << 23) * mr_energy) /
121  sqrt(dsp->scalarproduct_int16(fc_v, fc_v, subframe_size));
122  return mr_energy >> 12;
123 #endif
124 }
125 
126 float ff_amr_set_fixed_gain(float fixed_gain_factor, float fixed_mean_energy,
127  float *prediction_error, float energy_mean,
128  const float *pred_table)
129 {
130  // Equations 66-69:
131  // ^g_c = ^gamma_gc * 100.05 (predicted dB + mean dB - dB of fixed vector)
132  // Note 10^(0.05 * -10log(average x2)) = 1/sqrt((average x2)).
133  float val = fixed_gain_factor *
134  exp2f(M_LOG2_10 * 0.05 *
135  (avpriv_scalarproduct_float_c(pred_table, prediction_error, 4) +
136  energy_mean)) /
137  sqrtf(fixed_mean_energy);
138 
139  // update quantified prediction error energy history
140  memmove(&prediction_error[0], &prediction_error[1],
141  3 * sizeof(prediction_error[0]));
142  prediction_error[3] = 20.0 * log10f(fixed_gain_factor);
143 
144  return val;
145 }
146 
147 void ff_decode_pitch_lag(int *lag_int, int *lag_frac, int pitch_index,
148  const int prev_lag_int, const int subframe,
149  int third_as_first, int resolution)
150 {
151  /* Note n * 10923 >> 15 is floor(x/3) for 0 <= n <= 32767 */
152  if (subframe == 0 || (subframe == 2 && third_as_first)) {
153 
154  if (pitch_index < 197)
155  pitch_index += 59;
156  else
157  pitch_index = 3 * pitch_index - 335;
158 
159  } else {
160  if (resolution == 4) {
161  int search_range_min = av_clip(prev_lag_int - 5, PITCH_DELAY_MIN,
162  PITCH_DELAY_MAX - 9);
163 
164  // decoding with 4-bit resolution
165  if (pitch_index < 4) {
166  // integer only precision for [search_range_min, search_range_min+3]
167  pitch_index = 3 * (pitch_index + search_range_min) + 1;
168  } else if (pitch_index < 12) {
169  // 1/3 fractional precision for [search_range_min+3 1/3, search_range_min+5 2/3]
170  pitch_index += 3 * search_range_min + 7;
171  } else {
172  // integer only precision for [search_range_min+6, search_range_min+9]
173  pitch_index = 3 * (pitch_index + search_range_min - 6) + 1;
174  }
175  } else {
176  // decoding with 5 or 6 bit resolution, 1/3 fractional precision
177  pitch_index--;
178 
179  if (resolution == 5) {
180  pitch_index += 3 * av_clip(prev_lag_int - 10, PITCH_DELAY_MIN,
181  PITCH_DELAY_MAX - 19);
182  } else
183  pitch_index += 3 * av_clip(prev_lag_int - 5, PITCH_DELAY_MIN,
184  PITCH_DELAY_MAX - 9);
185  }
186  }
187  *lag_int = pitch_index * 10923 >> 15;
188  *lag_frac = pitch_index - 3 * *lag_int - 1;
189 }