FFmpeg  4.4
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/ffmath.h"
25 #include "libavutil/float_dsp.h"
26 #include "libavutil/mathematics.h"
27 #include "avcodec.h"
28 #include "acelp_pitch_delay.h"
29 #include "celp_math.h"
30 #include "audiodsp.h"
31 
33  int16_t* quant_energy,
34  int gain_corr_factor,
35  int log2_ma_pred_order,
36  int erasure)
37 {
38  int i;
39  int avg_gain=quant_energy[(1 << log2_ma_pred_order) - 1]; // (5.10)
40 
41  for(i=(1 << log2_ma_pred_order) - 1; i>0; i--)
42  {
43  avg_gain += quant_energy[i-1];
44  quant_energy[i] = quant_energy[i-1];
45  }
46 
47  if(erasure)
48  quant_energy[0] = FFMAX(avg_gain >> log2_ma_pred_order, -10240) - 4096; // -10 and -4 in (5.10)
49  else
50  quant_energy[0] = (6165 * ((ff_log2_q15(gain_corr_factor) >> 2) - (13 << 13))) >> 13;
51 }
52 
54  AudioDSPContext *adsp,
55  int gain_corr_factor,
56  const int16_t* fc_v,
57  int mr_energy,
58  const int16_t* quant_energy,
59  const int16_t* ma_prediction_coeff,
60  int subframe_size,
61  int ma_pred_order)
62 {
63  int i;
64 
65  mr_energy <<= 10;
66 
67  for(i=0; i<ma_pred_order; i++)
68  mr_energy += quant_energy[i] * ma_prediction_coeff[i];
69 
70 #ifdef G729_BITEXACT
71  mr_energy += (((-6165LL * ff_log2(dsp->scalarproduct_int16(fc_v, fc_v, subframe_size, 0))) >> 3) & ~0x3ff);
72 
73  mr_energy = (5439 * (mr_energy >> 15)) >> 8; // (0.15) = (0.15) * (7.23)
74 
75  return bidir_sal(
76  ((ff_exp2(mr_energy & 0x7fff) + 16) >> 5) * (gain_corr_factor >> 1),
77  (mr_energy >> 15) - 25
78  );
79 #else
80  mr_energy = gain_corr_factor * ff_exp10((double)mr_energy / (20 << 23)) /
81  sqrt(adsp->scalarproduct_int16(fc_v, fc_v, subframe_size));
82  return mr_energy >> 12;
83 #endif
84 }
85 
86 float ff_amr_set_fixed_gain(float fixed_gain_factor, float fixed_mean_energy,
87  float *prediction_error, float energy_mean,
88  const float *pred_table)
89 {
90  // Equations 66-69:
91  // ^g_c = ^gamma_gc * 100.05 (predicted dB + mean dB - dB of fixed vector)
92  // Note 10^(0.05 * -10log(average x2)) = 1/sqrt((average x2)).
93  float val = fixed_gain_factor *
94  ff_exp10(0.05 *
95  (avpriv_scalarproduct_float_c(pred_table, prediction_error, 4) +
96  energy_mean)) /
97  sqrtf(fixed_mean_energy ? fixed_mean_energy : 1.0);
98 
99  // update quantified prediction error energy history
100  memmove(&prediction_error[0], &prediction_error[1],
101  3 * sizeof(prediction_error[0]));
102  prediction_error[3] = 20.0 * log10f(fixed_gain_factor);
103 
104  return val;
105 }
106 
107 void ff_decode_pitch_lag(int *lag_int, int *lag_frac, int pitch_index,
108  const int prev_lag_int, const int subframe,
109  int third_as_first, int resolution)
110 {
111  /* Note n * 10923 >> 15 is floor(x/3) for 0 <= n <= 32767 */
112  if (subframe == 0 || (subframe == 2 && third_as_first)) {
113 
114  if (pitch_index < 197)
115  pitch_index += 59;
116  else
117  pitch_index = 3 * pitch_index - 335;
118 
119  } else {
120  if (resolution == 4) {
121  int search_range_min = av_clip(prev_lag_int - 5, PITCH_DELAY_MIN,
122  PITCH_DELAY_MAX - 9);
123 
124  // decoding with 4-bit resolution
125  if (pitch_index < 4) {
126  // integer only precision for [search_range_min, search_range_min+3]
127  pitch_index = 3 * (pitch_index + search_range_min) + 1;
128  } else if (pitch_index < 12) {
129  // 1/3 fractional precision for [search_range_min+3 1/3, search_range_min+5 2/3]
130  pitch_index += 3 * search_range_min + 7;
131  } else {
132  // integer only precision for [search_range_min+6, search_range_min+9]
133  pitch_index = 3 * (pitch_index + search_range_min - 6) + 1;
134  }
135  } else {
136  // decoding with 5 or 6 bit resolution, 1/3 fractional precision
137  pitch_index--;
138 
139  if (resolution == 5) {
140  pitch_index += 3 * av_clip(prev_lag_int - 10, PITCH_DELAY_MIN,
141  PITCH_DELAY_MAX - 19);
142  } else
143  pitch_index += 3 * av_clip(prev_lag_int - 5, PITCH_DELAY_MIN,
144  PITCH_DELAY_MAX - 9);
145  }
146  }
147  *lag_int = pitch_index * 10923 >> 15;
148  *lag_frac = pitch_index - 3 * *lag_int - 1;
149 }
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)
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...
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(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).
#define PITCH_DELAY_MIN
#define PITCH_DELAY_MAX
static double val(void *priv, double ch)
Definition: aeval.c:76
static const float energy_mean[8]
desired mean innovation energy, indexed by active mode
Definition: amrnbdata.h:1453
Libavcodec external API header.
int ff_log2_q15(uint32_t value)
Calculate log2(x).
Definition: celp_math.c:80
int ff_exp2(uint16_t power)
fixed-point implementation of exp2(x) in [0; 1] domain.
static int bidir_sal(int value, int offset)
Shift value left or right depending on sign of offset parameter.
Definition: celp_math.h:81
common internal and external API header
#define av_clip
Definition: common.h:122
#define FFMAX(a, b)
Definition: common.h:103
internal math functions header
static av_always_inline double ff_exp10(double x)
Compute 10^x for floating point values.
Definition: ffmath.h:42
static const uint16_t ma_prediction_coeff[4]
MA prediction coefficients (3.9.1 of G.729, near Equation 69)
Definition: g729data.h:343
int i
Definition: input.c:407
#define ff_log2
Definition: intmath.h:50
float avpriv_scalarproduct_float_c(const float *v1, const float *v2, int len)
Return the scalar product of two vectors.
Definition: float_dsp.c:124
#define log10f(x)
Definition: libm.h:414
int32_t(* scalarproduct_int16)(const int16_t *v1, const int16_t *v2, int len)
Calculate scalar product of two vectors.
Definition: audiodsp.h:29