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
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,
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 #ifdef G729_BITEXACT
112
113 mr_energy = (5439 * (mr_energy >> 15)) >> 8; // (0.15) = (0.15) * (7.23)
114
116 ((
ff_exp2(mr_energy & 0x7fff) + 16) >> 5) * (gain_corr_factor >> 1),
117 (mr_energy >> 15) - 25
118 );
119 #else
120 mr_energy = gain_corr_factor * exp(
M_LN10 / (20 << 23) * mr_energy) /
122 return mr_energy >> 12;
123 #endif
124 }
125
128 const float *pred_table)
129 {
130 // Equations 66-69:
131 // ^g_c = ^gamma_gc * 100.05 (predicted dB + mean dB - dB of fixed vector)
132 // Note 10^(0.05 * -10log(average x2)) = 1/sqrt((average x2)).
133 float val = fixed_gain_factor *
136 energy_mean)) /
137 sqrtf(fixed_mean_energy);
138
139 // update quantified prediction error energy history
140 memmove(&prediction_error[0], &prediction_error[1],
141 3 * sizeof(prediction_error[0]));
142 prediction_error[3] = 20.0 *
log10f(fixed_gain_factor);
143
145 }
146
148 const int prev_lag_int, const int subframe,
149 int third_as_first, int resolution)
150 {
151 /* Note n * 10923 >> 15 is floor(x/3) for 0 <= n <= 32767 */
152 if (subframe == 0 || (subframe == 2 && third_as_first)) {
153
154 if (pitch_index < 197)
155 pitch_index += 59;
156 else
157 pitch_index = 3 * pitch_index - 335;
158
159 } else {
160 if (resolution == 4) {
163
164 // decoding with 4-bit resolution
165 if (pitch_index < 4) {
166 // integer only precision for [search_range_min, search_range_min+3]
167 pitch_index = 3 * (pitch_index + search_range_min) + 1;
168 } else if (pitch_index < 12) {
169 // 1/3 fractional precision for [search_range_min+3 1/3, search_range_min+5 2/3]
170 pitch_index += 3 * search_range_min + 7;
171 } else {
172 // integer only precision for [search_range_min+6, search_range_min+9]
173 pitch_index = 3 * (pitch_index + search_range_min - 6) + 1;
174 }
175 } else {
176 // decoding with 5 or 6 bit resolution, 1/3 fractional precision
177 pitch_index--;
178
179 if (resolution == 5) {
182 } else
185 }
186 }
187 *lag_int = pitch_index * 10923 >> 15;
188 *lag_frac = pitch_index - 3 * *lag_int - 1;
189 }