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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/float_dsp.h" | |
25 | #include "libavutil/libm.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 | ||
32 | int ff_acelp_decode_8bit_to_1st_delay3(int ac_index) | |
33 | { | |
34 | ac_index += 58; | |
35 | if(ac_index > 254) | |
36 | ac_index = 3 * ac_index - 510; | |
37 | return ac_index; | |
38 | } | |
39 | ||
40 | int ff_acelp_decode_4bit_to_2nd_delay3( | |
41 | int ac_index, | |
42 | int pitch_delay_min) | |
43 | { | |
44 | if(ac_index < 4) | |
45 | return 3 * (ac_index + pitch_delay_min); | |
46 | else if(ac_index < 12) | |
47 | return 3 * pitch_delay_min + ac_index + 6; | |
48 | else | |
49 | return 3 * (ac_index + pitch_delay_min) - 18; | |
50 | } | |
51 | ||
52 | int ff_acelp_decode_5_6_bit_to_2nd_delay3( | |
53 | int ac_index, | |
54 | int pitch_delay_min) | |
55 | { | |
56 | return 3 * pitch_delay_min + ac_index - 2; | |
57 | } | |
58 | ||
59 | int ff_acelp_decode_9bit_to_1st_delay6(int ac_index) | |
60 | { | |
61 | if(ac_index < 463) | |
62 | return ac_index + 105; | |
63 | else | |
64 | return 6 * (ac_index - 368); | |
65 | } | |
66 | int ff_acelp_decode_6bit_to_2nd_delay6( | |
67 | int ac_index, | |
68 | int pitch_delay_min) | |
69 | { | |
70 | return 6 * pitch_delay_min + ac_index - 3; | |
71 | } | |
72 | ||
73 | void ff_acelp_update_past_gain( | |
74 | int16_t* quant_energy, | |
75 | int gain_corr_factor, | |
76 | int log2_ma_pred_order, | |
77 | int erasure) | |
78 | { | |
79 | int i; | |
80 | int avg_gain=quant_energy[(1 << log2_ma_pred_order) - 1]; // (5.10) | |
81 | ||
82 | for(i=(1 << log2_ma_pred_order) - 1; i>0; i--) | |
83 | { | |
84 | avg_gain += quant_energy[i-1]; | |
85 | quant_energy[i] = quant_energy[i-1]; | |
86 | } | |
87 | ||
88 | if(erasure) | |
89 | quant_energy[0] = FFMAX(avg_gain >> log2_ma_pred_order, -10240) - 4096; // -10 and -4 in (5.10) | |
90 | else | |
91 | quant_energy[0] = (6165 * ((ff_log2_q15(gain_corr_factor) >> 2) - (13 << 13))) >> 13; | |
92 | } | |
93 | ||
94 | int16_t ff_acelp_decode_gain_code( | |
95 | AudioDSPContext *adsp, | |
96 | int gain_corr_factor, | |
97 | const int16_t* fc_v, | |
98 | int mr_energy, | |
99 | const int16_t* quant_energy, | |
100 | const int16_t* ma_prediction_coeff, | |
101 | int subframe_size, | |
102 | int ma_pred_order) | |
103 | { | |
104 | int i; | |
105 | ||
106 | mr_energy <<= 10; | |
107 | ||
108 | for(i=0; i<ma_pred_order; i++) | |
109 | mr_energy += quant_energy[i] * ma_prediction_coeff[i]; | |
110 | ||
111 | #ifdef G729_BITEXACT | |
112 | mr_energy += (((-6165LL * ff_log2(dsp->scalarproduct_int16(fc_v, fc_v, subframe_size, 0))) >> 3) & ~0x3ff); | |
113 | ||
114 | mr_energy = (5439 * (mr_energy >> 15)) >> 8; // (0.15) = (0.15) * (7.23) | |
115 | ||
116 | return bidir_sal( | |
117 | ((ff_exp2(mr_energy & 0x7fff) + 16) >> 5) * (gain_corr_factor >> 1), | |
118 | (mr_energy >> 15) - 25 | |
119 | ); | |
120 | #else | |
121 | mr_energy = gain_corr_factor * exp(M_LN10 / (20 << 23) * mr_energy) / | |
122 | sqrt(adsp->scalarproduct_int16(fc_v, fc_v, subframe_size)); | |
123 | return mr_energy >> 12; | |
124 | #endif | |
125 | } | |
126 | ||
127 | float ff_amr_set_fixed_gain(float fixed_gain_factor, float fixed_mean_energy, | |
128 | float *prediction_error, float energy_mean, | |
129 | const float *pred_table) | |
130 | { | |
131 | // Equations 66-69: | |
132 | // ^g_c = ^gamma_gc * 100.05 (predicted dB + mean dB - dB of fixed vector) | |
133 | // Note 10^(0.05 * -10log(average x2)) = 1/sqrt((average x2)). | |
134 | float val = fixed_gain_factor * | |
135 | exp2f(M_LOG2_10 * 0.05 * | |
136 | (avpriv_scalarproduct_float_c(pred_table, prediction_error, 4) + | |
137 | energy_mean)) / | |
138 | sqrtf(fixed_mean_energy); | |
139 | ||
140 | // update quantified prediction error energy history | |
141 | memmove(&prediction_error[0], &prediction_error[1], | |
142 | 3 * sizeof(prediction_error[0])); | |
143 | prediction_error[3] = 20.0 * log10f(fixed_gain_factor); | |
144 | ||
145 | return val; | |
146 | } | |
147 | ||
148 | void ff_decode_pitch_lag(int *lag_int, int *lag_frac, int pitch_index, | |
149 | const int prev_lag_int, const int subframe, | |
150 | int third_as_first, int resolution) | |
151 | { | |
152 | /* Note n * 10923 >> 15 is floor(x/3) for 0 <= n <= 32767 */ | |
153 | if (subframe == 0 || (subframe == 2 && third_as_first)) { | |
154 | ||
155 | if (pitch_index < 197) | |
156 | pitch_index += 59; | |
157 | else | |
158 | pitch_index = 3 * pitch_index - 335; | |
159 | ||
160 | } else { | |
161 | if (resolution == 4) { | |
162 | int search_range_min = av_clip(prev_lag_int - 5, PITCH_DELAY_MIN, | |
163 | PITCH_DELAY_MAX - 9); | |
164 | ||
165 | // decoding with 4-bit resolution | |
166 | if (pitch_index < 4) { | |
167 | // integer only precision for [search_range_min, search_range_min+3] | |
168 | pitch_index = 3 * (pitch_index + search_range_min) + 1; | |
169 | } else if (pitch_index < 12) { | |
170 | // 1/3 fractional precision for [search_range_min+3 1/3, search_range_min+5 2/3] | |
171 | pitch_index += 3 * search_range_min + 7; | |
172 | } else { | |
173 | // integer only precision for [search_range_min+6, search_range_min+9] | |
174 | pitch_index = 3 * (pitch_index + search_range_min - 6) + 1; | |
175 | } | |
176 | } else { | |
177 | // decoding with 5 or 6 bit resolution, 1/3 fractional precision | |
178 | pitch_index--; | |
179 | ||
180 | if (resolution == 5) { | |
181 | pitch_index += 3 * av_clip(prev_lag_int - 10, PITCH_DELAY_MIN, | |
182 | PITCH_DELAY_MAX - 19); | |
183 | } else | |
184 | pitch_index += 3 * av_clip(prev_lag_int - 5, PITCH_DELAY_MIN, | |
185 | PITCH_DELAY_MAX - 9); | |
186 | } | |
187 | } | |
188 | *lag_int = pitch_index * 10923 >> 15; | |
189 | *lag_frac = pitch_index - 3 * *lag_int - 1; | |
190 | } |