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/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 
31 {
32  ac_index += 58;
33  if(ac_index > 254)
34  ac_index = 3 * ac_index - 510;
35  return ac_index;
36 }
37 
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 
51  int ac_index,
52  int pitch_delay_min)
53 {
54  return 3 * pitch_delay_min + ac_index - 2;
55 }
56 
58 {
59  if(ac_index < 463)
60  return ac_index + 105;
61  else
62  return 6 * (ac_index - 368);
63 }
65  int ac_index,
66  int pitch_delay_min)
67 {
68  return 6 * pitch_delay_min + ac_index - 3;
69 }
70 
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_q15(gain_corr_factor) >> 2) - (13 << 13))) >> 13;
90 }
91 
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  mr_energy = gain_corr_factor * exp(M_LN10 / (20 << 23) * mr_energy) /
110  sqrt(dsp->scalarproduct_int16(fc_v, fc_v, subframe_size));
111  return mr_energy >> 12;
112 }
113 
114 float ff_amr_set_fixed_gain(float fixed_gain_factor, float fixed_mean_energy,
115  float *prediction_error, float energy_mean,
116  const float *pred_table)
117 {
118  // Equations 66-69:
119  // ^g_c = ^gamma_gc * 100.05 (predicted dB + mean dB - dB of fixed vector)
120  // Note 10^(0.05 * -10log(average x2)) = 1/sqrt((average x2)).
121  float val = fixed_gain_factor *
122  exp2f(M_LOG2_10 * 0.05 *
123  (ff_scalarproduct_float_c(pred_table, prediction_error, 4) +
124  energy_mean)) /
125  sqrtf(fixed_mean_energy);
126 
127  // update quantified prediction error energy history
128  memmove(&prediction_error[0], &prediction_error[1],
129  3 * sizeof(prediction_error[0]));
130  prediction_error[3] = 20.0 * log10f(fixed_gain_factor);
131 
132  return val;
133 }
134 
135 void ff_decode_pitch_lag(int *lag_int, int *lag_frac, int pitch_index,
136  const int prev_lag_int, const int subframe,
137  int third_as_first, int resolution)
138 {
139  /* Note n * 10923 >> 15 is floor(x/3) for 0 <= n <= 32767 */
140  if (subframe == 0 || (subframe == 2 && third_as_first)) {
141 
142  if (pitch_index < 197)
143  pitch_index += 59;
144  else
145  pitch_index = 3 * pitch_index - 335;
146 
147  } else {
148  if (resolution == 4) {
149  int search_range_min = av_clip(prev_lag_int - 5, PITCH_DELAY_MIN,
150  PITCH_DELAY_MAX - 9);
151 
152  // decoding with 4-bit resolution
153  if (pitch_index < 4) {
154  // integer only precision for [search_range_min, search_range_min+3]
155  pitch_index = 3 * (pitch_index + search_range_min) + 1;
156  } else if (pitch_index < 12) {
157  // 1/3 fractional precision for [search_range_min+3 1/3, search_range_min+5 2/3]
158  pitch_index += 3 * search_range_min + 7;
159  } else {
160  // integer only precision for [search_range_min+6, search_range_min+9]
161  pitch_index = 3 * (pitch_index + search_range_min - 6) + 1;
162  }
163  } else {
164  // decoding with 5 or 6 bit resolution, 1/3 fractional precision
165  pitch_index--;
166 
167  if (resolution == 5) {
168  pitch_index += 3 * av_clip(prev_lag_int - 10, PITCH_DELAY_MIN,
169  PITCH_DELAY_MAX - 19);
170  } else
171  pitch_index += 3 * av_clip(prev_lag_int - 5, PITCH_DELAY_MIN,
172  PITCH_DELAY_MAX - 9);
173  }
174  }
175  *lag_int = pitch_index * 10923 >> 15;
176  *lag_frac = pitch_index - 3 * *lag_int - 1;
177 }
void ff_decode_pitch_lag(int *lag_int, int *lag_frac, int pitch_index, const int prev_lag_int, const int subframe, int third_as_first, int resolution)
Decode the adaptive codebook index to the integer and fractional parts of the pitch lag for one subfr...
int ff_acelp_decode_6bit_to_2nd_delay6(int ac_index, int pitch_delay_min)
Decode pitch delay of the second subframe encoded by 6 bits with 1/6 precision.
int ff_acelp_decode_4bit_to_2nd_delay3(int ac_index, int pitch_delay_min)
Decode pitch delay with 1/3 precision.
int ff_acelp_decode_8bit_to_1st_delay3(int ac_index)
Decode pitch delay of the first subframe encoded by 8 bits with 1/3 resolution.
int ff_acelp_decode_9bit_to_1st_delay6(int ac_index)
Decode pitch delay of the first subframe encoded by 9 bits with 1/6 precision.
DSPContext dsp
Definition: ac3enc.h:162
#define PITCH_DELAY_MAX
int ff_acelp_decode_5_6_bit_to_2nd_delay3(int ac_index, int pitch_delay_min)
Decode pitch delay of the second subframe encoded by 5 or 6 bits with 1/3 precision.
int32_t(* scalarproduct_int16)(const int16_t *v1, const int16_t *v2, int len)
Calculate scalar product of two vectors.
Definition: dsputil.h:450
float ff_scalarproduct_float_c(const float *v1, const float *v2, int len)
Return the scalar product of two vectors.
Definition: dsputil.c:2418
int ff_log2_q15(uint32_t value)
Calculate log2(x).
Definition: celp_math.c:70
#define M_LOG2_10
Definition: mathematics.h:31
void ff_acelp_update_past_gain(int16_t *quant_energy, int gain_corr_factor, int log2_ma_pred_order, int erasure)
Update past quantized energies.
int16_t ff_acelp_decode_gain_code(DSPContext *dsp, int gain_corr_factor, const int16_t *fc_v, int mr_energy, const int16_t *quant_energy, const int16_t *ma_prediction_coeff, int subframe_size, int ma_pred_order)
Decode the adaptive codebook gain and add correction (4.1.5 and 3.9.1 of G.729).
#define exp2f(x)
Definition: libm.h:71
external API header
common internal and external API header
DSP utils.
static const float energy_mean[8]
desired mean innovation energy, indexed by active mode
Definition: amrnbdata.h:1458
#define PITCH_DELAY_MIN
#define log10f(x)
Definition: libm.h:121
float ff_amr_set_fixed_gain(float fixed_gain_factor, float fixed_mean_energy, float *prediction_error, float energy_mean, const float *pred_table)
Calculate fixed gain (part of section 6.1.3 of AMR spec)
DSPContext.
Definition: dsputil.h:194