1
by Sérgio Benjamim
FFmpeg 2.7.1 source for ppsspp. |
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 */ |