blob: 2aade2f226177fc480050193c6ee8e8877a320f4
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 | #ifndef AVCODEC_ACELP_PITCH_DELAY_H |
24 | #define AVCODEC_ACELP_PITCH_DELAY_H |
25 | |
26 | #include <stdint.h> |
27 | |
28 | #include "audiodsp.h" |
29 | |
30 | #define PITCH_DELAY_MIN 20 |
31 | #define PITCH_DELAY_MAX 143 |
32 | |
33 | /** |
34 | * @brief Decode pitch delay of the first subframe encoded by 8 bits with 1/3 |
35 | * resolution. |
36 | * @param ac_index adaptive codebook index (8 bits) |
37 | * |
38 | * @return pitch delay in 1/3 units |
39 | * |
40 | * Pitch delay is coded: |
41 | * with 1/3 resolution, 19 < pitch_delay < 85 |
42 | * integers only, 85 <= pitch_delay <= 143 |
43 | */ |
44 | int ff_acelp_decode_8bit_to_1st_delay3(int ac_index); |
45 | |
46 | /** |
47 | * @brief Decode pitch delay of the second subframe encoded by 5 or 6 bits |
48 | * with 1/3 precision. |
49 | * @param ac_index adaptive codebook index (5 or 6 bits) |
50 | * @param pitch_delay_min lower bound (integer) of pitch delay interval |
51 | * for second subframe |
52 | * |
53 | * @return pitch delay in 1/3 units |
54 | * |
55 | * Pitch delay is coded: |
56 | * with 1/3 resolution, -6 < pitch_delay - int(prev_pitch_delay) < 5 |
57 | * |
58 | * @remark The routine is used in G.729 @@8k, AMR @@10.2k, AMR @@7.95k, |
59 | * AMR @@7.4k for the second subframe. |
60 | */ |
61 | int ff_acelp_decode_5_6_bit_to_2nd_delay3( |
62 | int ac_index, |
63 | int pitch_delay_min); |
64 | |
65 | /** |
66 | * @brief Decode pitch delay with 1/3 precision. |
67 | * @param ac_index adaptive codebook index (4 bits) |
68 | * @param pitch_delay_min lower bound (integer) of pitch delay interval for |
69 | * second subframe |
70 | * |
71 | * @return pitch delay in 1/3 units |
72 | * |
73 | * Pitch delay is coded: |
74 | * integers only, -6 < pitch_delay - int(prev_pitch_delay) <= -2 |
75 | * with 1/3 resolution, -2 < pitch_delay - int(prev_pitch_delay) < 1 |
76 | * integers only, 1 <= pitch_delay - int(prev_pitch_delay) < 5 |
77 | * |
78 | * @remark The routine is used in G.729 @@6.4k, AMR @@6.7k, AMR @@5.9k, |
79 | * AMR @@5.15k, AMR @@4.75k for the second subframe. |
80 | */ |
81 | int ff_acelp_decode_4bit_to_2nd_delay3( |
82 | int ac_index, |
83 | int pitch_delay_min); |
84 | |
85 | /** |
86 | * @brief Decode pitch delay of the first subframe encoded by 9 bits |
87 | * with 1/6 precision. |
88 | * @param ac_index adaptive codebook index (9 bits) |
89 | * |
90 | * @return pitch delay in 1/6 units |
91 | * |
92 | * Pitch delay is coded: |
93 | * with 1/6 resolution, 17 < pitch_delay < 95 |
94 | * integers only, 95 <= pitch_delay <= 143 |
95 | * |
96 | * @remark The routine is used in AMR @@12.2k for the first and third subframes. |
97 | */ |
98 | int ff_acelp_decode_9bit_to_1st_delay6(int ac_index); |
99 | |
100 | /** |
101 | * @brief Decode pitch delay of the second subframe encoded by 6 bits |
102 | * with 1/6 precision. |
103 | * @param ac_index adaptive codebook index (6 bits) |
104 | * @param pitch_delay_min lower bound (integer) of pitch delay interval for |
105 | * second subframe |
106 | * |
107 | * @return pitch delay in 1/6 units |
108 | * |
109 | * Pitch delay is coded: |
110 | * with 1/6 resolution, -6 < pitch_delay - int(prev_pitch_delay) < 5 |
111 | * |
112 | * @remark The routine is used in AMR @@12.2k for the second and fourth subframes. |
113 | */ |
114 | int ff_acelp_decode_6bit_to_2nd_delay6( |
115 | int ac_index, |
116 | int pitch_delay_min); |
117 | |
118 | /** |
119 | * @brief Update past quantized energies |
120 | * @param[in,out] quant_energy past quantized energies (5.10) |
121 | * @param gain_corr_factor gain correction factor |
122 | * @param log2_ma_pred_order log2() of MA prediction order |
123 | * @param erasure frame erasure flag |
124 | * |
125 | * If frame erasure flag is not equal to zero, memory is updated with |
126 | * averaged energy, attenuated by 4dB: |
127 | * max(avg(quant_energy[i])-4, -14), i=0,ma_pred_order |
128 | * |
129 | * In normal mode memory is updated with |
130 | * Er - Ep = 20 * log10(gain_corr_factor) |
131 | * |
132 | * @remark The routine is used in G.729 and AMR (all modes). |
133 | */ |
134 | void ff_acelp_update_past_gain( |
135 | int16_t* quant_energy, |
136 | int gain_corr_factor, |
137 | int log2_ma_pred_order, |
138 | int erasure); |
139 | |
140 | /** |
141 | * @brief Decode the adaptive codebook gain and add |
142 | * correction (4.1.5 and 3.9.1 of G.729). |
143 | * @param adsp initialized audio DSP context |
144 | * @param gain_corr_factor gain correction factor (2.13) |
145 | * @param fc_v fixed-codebook vector (2.13) |
146 | * @param mr_energy mean innovation energy and fixed-point correction (7.13) |
147 | * @param[in,out] quant_energy past quantized energies (5.10) |
148 | * @param subframe_size length of subframe |
149 | * |
150 | * @return quantized fixed-codebook gain (14.1) |
151 | * |
152 | * The routine implements equations 69, 66 and 71 of the G.729 specification (3.9.1) |
153 | * |
154 | * Em - mean innovation energy (dB, constant, depends on decoding algorithm) |
155 | * Ep - mean-removed predicted energy (dB) |
156 | * Er - mean-removed innovation energy (dB) |
157 | * Ei - mean energy of the fixed-codebook contribution (dB) |
158 | * N - subframe_size |
159 | * M - MA (Moving Average) prediction order |
160 | * gc - fixed-codebook gain |
161 | * gc_p - predicted fixed-codebook gain |
162 | * |
163 | * Fixed codebook gain is computed using predicted gain gc_p and |
164 | * correction factor gain_corr_factor as shown below: |
165 | * |
166 | * gc = gc_p * gain_corr_factor |
167 | * |
168 | * The predicted fixed codebook gain gc_p is found by predicting |
169 | * the energy of the fixed-codebook contribution from the energy |
170 | * of previous fixed-codebook contributions. |
171 | * |
172 | * mean = 1/N * sum(i,0,N){ fc_v[i] * fc_v[i] } |
173 | * |
174 | * Ei = 10log(mean) |
175 | * |
176 | * Er = 10log(1/N * gc^2 * mean) - Em = 20log(gc) + Ei - Em |
177 | * |
178 | * Replacing Er with Ep and gc with gc_p we will receive: |
179 | * |
180 | * Ep = 10log(1/N * gc_p^2 * mean) - Em = 20log(gc_p) + Ei - Em |
181 | * |
182 | * and from above: |
183 | * |
184 | * gc_p = 10^((Ep - Ei + Em) / 20) |
185 | * |
186 | * Ep is predicted using past energies and prediction coefficients: |
187 | * |
188 | * Ep = sum(i,0,M){ ma_prediction_coeff[i] * quant_energy[i] } |
189 | * |
190 | * gc_p in fixed-point arithmetic is calculated as following: |
191 | * |
192 | * mean = 1/N * sum(i,0,N){ (fc_v[i] / 2^13) * (fc_v[i] / 2^13) } = |
193 | * = 1/N * sum(i,0,N) { fc_v[i] * fc_v[i] } / 2^26 |
194 | * |
195 | * Ei = 10log(mean) = -10log(N) - 10log(2^26) + |
196 | * + 10log(sum(i,0,N) { fc_v[i] * fc_v[i] }) |
197 | * |
198 | * Ep - Ei + Em = Ep + Em + 10log(N) + 10log(2^26) - |
199 | * - 10log(sum(i,0,N) { fc_v[i] * fc_v[i] }) = |
200 | * = Ep + mr_energy - 10log(sum(i,0,N) { fc_v[i] * fc_v[i] }) |
201 | * |
202 | * gc_p = 10 ^ ((Ep - Ei + Em) / 20) = |
203 | * = 2 ^ (3.3219 * (Ep - Ei + Em) / 20) = 2 ^ (0.166 * (Ep - Ei + Em)) |
204 | * |
205 | * where |
206 | * |
207 | * mr_energy = Em + 10log(N) + 10log(2^26) |
208 | * |
209 | * @remark The routine is used in G.729 and AMR (all modes). |
210 | */ |
211 | int16_t ff_acelp_decode_gain_code( |
212 | AudioDSPContext *adsp, |
213 | int gain_corr_factor, |
214 | const int16_t* fc_v, |
215 | int mr_energy, |
216 | const int16_t* quant_energy, |
217 | const int16_t* ma_prediction_coeff, |
218 | int subframe_size, |
219 | int max_pred_order); |
220 | |
221 | /** |
222 | * Calculate fixed gain (part of section 6.1.3 of AMR spec) |
223 | * |
224 | * @param fixed_gain_factor gain correction factor |
225 | * @param fixed_mean_energy mean decoded algebraic codebook vector energy |
226 | * @param prediction_error vector of the quantified predictor errors of |
227 | * the four previous subframes. It is updated by this function. |
228 | * @param energy_mean desired mean innovation energy |
229 | * @param pred_table table of four moving average coefficients |
230 | */ |
231 | float ff_amr_set_fixed_gain(float fixed_gain_factor, float fixed_mean_energy, |
232 | float *prediction_error, float energy_mean, |
233 | const float *pred_table); |
234 | |
235 | |
236 | /** |
237 | * Decode the adaptive codebook index to the integer and fractional parts |
238 | * of the pitch lag for one subframe at 1/3 fractional precision. |
239 | * |
240 | * The choice of pitch lag is described in 3GPP TS 26.090 section 5.6.1. |
241 | * |
242 | * @param lag_int integer part of pitch lag of the current subframe |
243 | * @param lag_frac fractional part of pitch lag of the current subframe |
244 | * @param pitch_index parsed adaptive codebook (pitch) index |
245 | * @param prev_lag_int integer part of pitch lag for the previous subframe |
246 | * @param subframe current subframe number |
247 | * @param third_as_first treat the third frame the same way as the first |
248 | */ |
249 | void ff_decode_pitch_lag(int *lag_int, int *lag_frac, int pitch_index, |
250 | const int prev_lag_int, const int subframe, |
251 | int third_as_first, int resolution); |
252 | |
253 | #endif /* AVCODEC_ACELP_PITCH_DELAY_H */ |
254 |