1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
|
/*
* gain code, gain pitch and pitch delay decoding
*
* Copyright (c) 2008 Vladimir Voroshilov
*
* This file is part of Libav.
*
* Libav is free software; you can redistribute it and/or
* modify it under the terms of the GNU Lesser General Public
* License as published by the Free Software Foundation; either
* version 2.1 of the License, or (at your option) any later version.
*
* Libav is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
* Lesser General Public License for more details.
*
* You should have received a copy of the GNU Lesser General Public
* License along with Libav; if not, write to the Free Software
* Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
*/
#ifndef AVCODEC_ACELP_PITCH_DELAY_H
#define AVCODEC_ACELP_PITCH_DELAY_H
#include <stdint.h>
#include "dsputil.h"
#define PITCH_DELAY_MIN 20
#define PITCH_DELAY_MAX 143
/**
* \brief Decode pitch delay of the first subframe encoded by 8 bits with 1/3
* resolution.
* \param ac_index adaptive codebook index (8 bits)
*
* \return pitch delay in 1/3 units
*
* Pitch delay is coded:
* with 1/3 resolution, 19 < pitch_delay < 85
* integers only, 85 <= pitch_delay <= 143
*/
int ff_acelp_decode_8bit_to_1st_delay3(int ac_index);
/**
* \brief Decode pitch delay of the second subframe encoded by 5 or 6 bits
* with 1/3 precision.
* \param ac_index adaptive codebook index (5 or 6 bits)
* \param pitch_delay_min lower bound (integer) of pitch delay interval
* for second subframe
*
* \return pitch delay in 1/3 units
*
* Pitch delay is coded:
* with 1/3 resolution, -6 < pitch_delay - int(prev_pitch_delay) < 5
*
* \remark The routine is used in G.729 @@8k, AMR @@10.2k, AMR @@7.95k,
* AMR @@7.4k for the second subframe.
*/
int ff_acelp_decode_5_6_bit_to_2nd_delay3(
int ac_index,
int pitch_delay_min);
/**
* \brief Decode pitch delay with 1/3 precision.
* \param ac_index adaptive codebook index (4 bits)
* \param pitch_delay_min lower bound (integer) of pitch delay interval for
* second subframe
*
* \return pitch delay in 1/3 units
*
* Pitch delay is coded:
* integers only, -6 < pitch_delay - int(prev_pitch_delay) <= -2
* with 1/3 resolution, -2 < pitch_delay - int(prev_pitch_delay) < 1
* integers only, 1 <= pitch_delay - int(prev_pitch_delay) < 5
*
* \remark The routine is used in G.729 @@6.4k, AMR @@6.7k, AMR @@5.9k,
* AMR @@5.15k, AMR @@4.75k for the second subframe.
*/
int ff_acelp_decode_4bit_to_2nd_delay3(
int ac_index,
int pitch_delay_min);
/**
* \brief Decode pitch delay of the first subframe encoded by 9 bits
* with 1/6 precision.
* \param ac_index adaptive codebook index (9 bits)
*
* \return pitch delay in 1/6 units
*
* Pitch delay is coded:
* with 1/6 resolution, 17 < pitch_delay < 95
* integers only, 95 <= pitch_delay <= 143
*
* \remark The routine is used in AMR @@12.2k for the first and third subframes.
*/
int ff_acelp_decode_9bit_to_1st_delay6(int ac_index);
/**
* \brief Decode pitch delay of the second subframe encoded by 6 bits
* with 1/6 precision.
* \param ac_index adaptive codebook index (6 bits)
* \param pitch_delay_min lower bound (integer) of pitch delay interval for
* second subframe
*
* \return pitch delay in 1/6 units
*
* Pitch delay is coded:
* with 1/6 resolution, -6 < pitch_delay - int(prev_pitch_delay) < 5
*
* \remark The routine is used in AMR @@12.2k for the second and fourth subframes.
*/
int ff_acelp_decode_6bit_to_2nd_delay6(
int ac_index,
int pitch_delay_min);
/**
* \brief Update past quantized energies
* \param[in,out] quant_energy past quantized energies (5.10)
* \param gain_corr_factor gain correction factor
* \param log2_ma_pred_order log2() of MA prediction order
* \param erasure frame erasure flag
*
* If frame erasure flag is not equal to zero, memory is updated with
* averaged energy, attenuated by 4dB:
* max(avg(quant_energy[i])-4, -14), i=0,ma_pred_order
*
* In normal mode memory is updated with
* Er - Ep = 20 * log10(gain_corr_factor)
*
* \remark The routine is used in G.729 and AMR (all modes).
*/
void ff_acelp_update_past_gain(
int16_t* quant_energy,
int gain_corr_factor,
int log2_ma_pred_order,
int erasure);
/**
* \brief Decode the adaptive codebook gain and add
* correction (4.1.5 and 3.9.1 of G.729).
* \param dsp initialized dsputil context
* \param gain_corr_factor gain correction factor (2.13)
* \param fc_v fixed-codebook vector (2.13)
* \param mr_energy mean innovation energy and fixed-point correction (7.13)
* \param[in,out] quant_energy past quantized energies (5.10)
* \param subframe_size length of subframe
*
* \return quantized fixed-codebook gain (14.1)
*
* The routine implements equations 69, 66 and 71 of the G.729 specification (3.9.1)
*
* Em - mean innovation energy (dB, constant, depends on decoding algorithm)
* Ep - mean-removed predicted energy (dB)
* Er - mean-removed innovation energy (dB)
* Ei - mean energy of the fixed-codebook contribution (dB)
* N - subframe_size
* M - MA (Moving Average) prediction order
* gc - fixed-codebook gain
* gc_p - predicted fixed-codebook gain
*
* Fixed codebook gain is computed using predicted gain gc_p and
* correction factor gain_corr_factor as shown below:
*
* gc = gc_p * gain_corr_factor
*
* The predicted fixed codebook gain gc_p is found by predicting
* the energy of the fixed-codebook contribution from the energy
* of previous fixed-codebook contributions.
*
* mean = 1/N * sum(i,0,N){ fc_v[i] * fc_v[i] }
*
* Ei = 10log(mean)
*
* Er = 10log(1/N * gc^2 * mean) - Em = 20log(gc) + Ei - Em
*
* Replacing Er with Ep and gc with gc_p we will receive:
*
* Ep = 10log(1/N * gc_p^2 * mean) - Em = 20log(gc_p) + Ei - Em
*
* and from above:
*
* gc_p = 10^((Ep - Ei + Em) / 20)
*
* Ep is predicted using past energies and prediction coefficients:
*
* Ep = sum(i,0,M){ ma_prediction_coeff[i] * quant_energy[i] }
*
* gc_p in fixed-point arithmetic is calculated as following:
*
* mean = 1/N * sum(i,0,N){ (fc_v[i] / 2^13) * (fc_v[i] / 2^13) } =
* = 1/N * sum(i,0,N) { fc_v[i] * fc_v[i] } / 2^26
*
* Ei = 10log(mean) = -10log(N) - 10log(2^26) +
* + 10log(sum(i,0,N) { fc_v[i] * fc_v[i] })
*
* Ep - Ei + Em = Ep + Em + 10log(N) + 10log(2^26) -
* - 10log(sum(i,0,N) { fc_v[i] * fc_v[i] }) =
* = Ep + mr_energy - 10log(sum(i,0,N) { fc_v[i] * fc_v[i] })
*
* gc_p = 10 ^ ((Ep - Ei + Em) / 20) =
* = 2 ^ (3.3219 * (Ep - Ei + Em) / 20) = 2 ^ (0.166 * (Ep - Ei + Em))
*
* where
*
* mr_energy = Em + 10log(N) + 10log(2^26)
*
* \remark The routine is used in G.729 and AMR (all modes).
*/
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 max_pred_order);
/**
* Calculate fixed gain (part of section 6.1.3 of AMR spec)
*
* @param fixed_gain_factor gain correction factor
* @param fixed_mean_energy mean decoded algebraic codebook vector energy
* @param prediction_error vector of the quantified predictor errors of
* the four previous subframes. It is updated by this function.
* @param energy_mean desired mean innovation energy
* @param pred_table table of four moving average coefficients
*/
float ff_amr_set_fixed_gain(float fixed_gain_factor, float fixed_mean_energy,
float *prediction_error, float energy_mean,
const float *pred_table);
/**
* Decode the adaptive codebook index to the integer and fractional parts
* of the pitch lag for one subframe at 1/3 fractional precision.
*
* The choice of pitch lag is described in 3GPP TS 26.090 section 5.6.1.
*
* @param lag_int integer part of pitch lag of the current subframe
* @param lag_frac fractional part of pitch lag of the current subframe
* @param pitch_index parsed adaptive codebook (pitch) index
* @param prev_lag_int integer part of pitch lag for the previous subframe
* @param subframe current subframe number
* @param third_as_first treat the third frame the same way as the first
*/
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);
#endif /* AVCODEC_ACELP_PITCH_DELAY_H */
|
