Libav
acelp_pitch_delay.c
Go to the documentation of this file.
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/float_dsp.h"
25 #include "libavutil/mathematics.h"
26 #include "avcodec.h"
27 #include "acelp_pitch_delay.h"
28 #include "celp_math.h"
29 #include "audiodsp.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 
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  mr_energy = gain_corr_factor * exp(M_LN10 / (20 << 23) * mr_energy) /
111  sqrt(adsp->scalarproduct_int16(fc_v, fc_v, subframe_size));
112  return mr_energy >> 12;
113 }
114 
115 float ff_amr_set_fixed_gain(float fixed_gain_factor, float fixed_mean_energy,
116  float *prediction_error, float energy_mean,
117  const float *pred_table)
118 {
119  // Equations 66-69:
120  // ^g_c = ^gamma_gc * 100.05 (predicted dB + mean dB - dB of fixed vector)
121  // Note 10^(0.05 * -10log(average x2)) = 1/sqrt((average x2)).
122  float val = fixed_gain_factor *
123  exp2f(M_LOG2_10 * 0.05 *
124  (avpriv_scalarproduct_float_c(pred_table, prediction_error, 4) +
125  energy_mean)) /
126  sqrtf(fixed_mean_energy);
127 
128  // update quantified prediction error energy history
129  memmove(&prediction_error[0], &prediction_error[1],
130  3 * sizeof(prediction_error[0]));
131  prediction_error[3] = 20.0 * log10f(fixed_gain_factor);
132 
133  return val;
134 }
135 
136 void ff_decode_pitch_lag(int *lag_int, int *lag_frac, int pitch_index,
137  const int prev_lag_int, const int subframe,
138  int third_as_first, int resolution)
139 {
140  /* Note n * 10923 >> 15 is floor(x/3) for 0 <= n <= 32767 */
141  if (subframe == 0 || (subframe == 2 && third_as_first)) {
142 
143  if (pitch_index < 197)
144  pitch_index += 59;
145  else
146  pitch_index = 3 * pitch_index - 335;
147 
148  } else {
149  if (resolution == 4) {
150  int search_range_min = av_clip(prev_lag_int - 5, PITCH_DELAY_MIN,
151  PITCH_DELAY_MAX - 9);
152 
153  // decoding with 4-bit resolution
154  if (pitch_index < 4) {
155  // integer only precision for [search_range_min, search_range_min+3]
156  pitch_index = 3 * (pitch_index + search_range_min) + 1;
157  } else if (pitch_index < 12) {
158  // 1/3 fractional precision for [search_range_min+3 1/3, search_range_min+5 2/3]
159  pitch_index += 3 * search_range_min + 7;
160  } else {
161  // integer only precision for [search_range_min+6, search_range_min+9]
162  pitch_index = 3 * (pitch_index + search_range_min - 6) + 1;
163  }
164  } else {
165  // decoding with 5 or 6 bit resolution, 1/3 fractional precision
166  pitch_index--;
167 
168  if (resolution == 5) {
169  pitch_index += 3 * av_clip(prev_lag_int - 10, PITCH_DELAY_MIN,
170  PITCH_DELAY_MAX - 19);
171  } else
172  pitch_index += 3 * av_clip(prev_lag_int - 5, PITCH_DELAY_MIN,
173  PITCH_DELAY_MAX - 9);
174  }
175  }
176  *lag_int = pitch_index * 10923 >> 15;
177  *lag_frac = pitch_index - 3 * *lag_int - 1;
178 }
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.
float avpriv_scalarproduct_float_c(const float *v1, const float *v2, int len)
Return the scalar product of two vectors.
Definition: float_dsp.c:104
#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.
int ff_log2_q15(uint32_t value)
Calculate log2(x).
Definition: celp_math.c:70
#define FFMAX(a, b)
Definition: common.h:55
AudioDSPContext adsp
Definition: ac3enc.h:165
#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.
#define exp2f(x)
Definition: libm.h:71
Libavcodec external API header.
int32_t(* scalarproduct_int16)(const int16_t *v1, const int16_t *v2, int len)
Calculate scalar product of two vectors.
Definition: audiodsp.h:29
common internal and external API header
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
int16_t ff_acelp_decode_gain_code(AudioDSPContext *adsp, 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).
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)