blob: ee3b85f845e5d6a66e6e18c77afd84064f189a7c
1 | /* |
2 | * G.722 ADPCM audio encoder/decoder |
3 | * |
4 | * Copyright (c) CMU 1993 Computer Science, Speech Group |
5 | * Chengxiang Lu and Alex Hauptmann |
6 | * Copyright (c) 2005 Steve Underwood <steveu at coppice.org> |
7 | * Copyright (c) 2009 Kenan Gillet |
8 | * Copyright (c) 2010 Martin Storsjo |
9 | * |
10 | * This file is part of FFmpeg. |
11 | * |
12 | * FFmpeg is free software; you can redistribute it and/or |
13 | * modify it under the terms of the GNU Lesser General Public |
14 | * License as published by the Free Software Foundation; either |
15 | * version 2.1 of the License, or (at your option) any later version. |
16 | * |
17 | * FFmpeg is distributed in the hope that it will be useful, |
18 | * but WITHOUT ANY WARRANTY; without even the implied warranty of |
19 | * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU |
20 | * Lesser General Public License for more details. |
21 | * |
22 | * You should have received a copy of the GNU Lesser General Public |
23 | * License along with FFmpeg; if not, write to the Free Software |
24 | * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA |
25 | */ |
26 | |
27 | /** |
28 | * @file |
29 | * G.722 ADPCM audio codec |
30 | * |
31 | * This G.722 decoder is a bit-exact implementation of the ITU G.722 |
32 | * specification for all three specified bitrates - 64000bps, 56000bps |
33 | * and 48000bps. It passes the ITU tests. |
34 | * |
35 | * @note For the 56000bps and 48000bps bitrates, the lowest 1 or 2 bits |
36 | * respectively of each byte are ignored. |
37 | */ |
38 | |
39 | #include "mathops.h" |
40 | #include "g722.h" |
41 | |
42 | static const int8_t sign_lookup[2] = { -1, 1 }; |
43 | |
44 | static const int16_t inv_log2_table[32] = { |
45 | 2048, 2093, 2139, 2186, 2233, 2282, 2332, 2383, |
46 | 2435, 2489, 2543, 2599, 2656, 2714, 2774, 2834, |
47 | 2896, 2960, 3025, 3091, 3158, 3228, 3298, 3371, |
48 | 3444, 3520, 3597, 3676, 3756, 3838, 3922, 4008 |
49 | }; |
50 | static const int16_t high_log_factor_step[2] = { 798, -214 }; |
51 | const int16_t ff_g722_high_inv_quant[4] = { -926, -202, 926, 202 }; |
52 | /** |
53 | * low_log_factor_step[index] == wl[rl42[index]] |
54 | */ |
55 | static const int16_t low_log_factor_step[16] = { |
56 | -60, 3042, 1198, 538, 334, 172, 58, -30, |
57 | 3042, 1198, 538, 334, 172, 58, -30, -60 |
58 | }; |
59 | const int16_t ff_g722_low_inv_quant4[16] = { |
60 | 0, -2557, -1612, -1121, -786, -530, -323, -150, |
61 | 2557, 1612, 1121, 786, 530, 323, 150, 0 |
62 | }; |
63 | const int16_t ff_g722_low_inv_quant6[64] = { |
64 | -17, -17, -17, -17, -3101, -2738, -2376, -2088, |
65 | -1873, -1689, -1535, -1399, -1279, -1170, -1072, -982, |
66 | -899, -822, -750, -682, -618, -558, -501, -447, |
67 | -396, -347, -300, -254, -211, -170, -130, -91, |
68 | 3101, 2738, 2376, 2088, 1873, 1689, 1535, 1399, |
69 | 1279, 1170, 1072, 982, 899, 822, 750, 682, |
70 | 618, 558, 501, 447, 396, 347, 300, 254, |
71 | 211, 170, 130, 91, 54, 17, -54, -17 |
72 | }; |
73 | |
74 | static inline void s_zero(int cur_diff, struct G722Band *band) |
75 | { |
76 | int s_zero = 0; |
77 | |
78 | #define ACCUM(k, x, d) do { \ |
79 | int tmp = x; \ |
80 | band->zero_mem[k] = ((band->zero_mem[k] * 255) >> 8) + \ |
81 | d*((band->diff_mem[k]^cur_diff) < 0 ? -128 : 128); \ |
82 | band->diff_mem[k] = tmp; \ |
83 | s_zero += (tmp * band->zero_mem[k]) >> 15; \ |
84 | } while (0) |
85 | if (cur_diff) { |
86 | ACCUM(5, band->diff_mem[4], 1); |
87 | ACCUM(4, band->diff_mem[3], 1); |
88 | ACCUM(3, band->diff_mem[2], 1); |
89 | ACCUM(2, band->diff_mem[1], 1); |
90 | ACCUM(1, band->diff_mem[0], 1); |
91 | ACCUM(0, cur_diff << 1, 1); |
92 | } else { |
93 | ACCUM(5, band->diff_mem[4], 0); |
94 | ACCUM(4, band->diff_mem[3], 0); |
95 | ACCUM(3, band->diff_mem[2], 0); |
96 | ACCUM(2, band->diff_mem[1], 0); |
97 | ACCUM(1, band->diff_mem[0], 0); |
98 | ACCUM(0, cur_diff << 1, 0); |
99 | } |
100 | #undef ACCUM |
101 | band->s_zero = s_zero; |
102 | } |
103 | |
104 | /** |
105 | * adaptive predictor |
106 | * |
107 | * @param cur_diff the dequantized and scaled delta calculated from the |
108 | * current codeword |
109 | */ |
110 | static void do_adaptive_prediction(struct G722Band *band, const int cur_diff) |
111 | { |
112 | int sg[2], limit, cur_qtzd_reconst; |
113 | |
114 | const int cur_part_reconst = band->s_zero + cur_diff < 0; |
115 | |
116 | sg[0] = sign_lookup[cur_part_reconst != band->part_reconst_mem[0]]; |
117 | sg[1] = sign_lookup[cur_part_reconst == band->part_reconst_mem[1]]; |
118 | band->part_reconst_mem[1] = band->part_reconst_mem[0]; |
119 | band->part_reconst_mem[0] = cur_part_reconst; |
120 | |
121 | band->pole_mem[1] = av_clip((sg[0] * av_clip(band->pole_mem[0], -8191, 8191) >> 5) + |
122 | (sg[1] << 7) + (band->pole_mem[1] * 127 >> 7), -12288, 12288); |
123 | |
124 | limit = 15360 - band->pole_mem[1]; |
125 | band->pole_mem[0] = av_clip(-192 * sg[0] + (band->pole_mem[0] * 255 >> 8), -limit, limit); |
126 | |
127 | s_zero(cur_diff, band); |
128 | |
129 | cur_qtzd_reconst = av_clip_int16((band->s_predictor + cur_diff) << 1); |
130 | band->s_predictor = av_clip_int16(band->s_zero + |
131 | (band->pole_mem[0] * cur_qtzd_reconst >> 15) + |
132 | (band->pole_mem[1] * band->prev_qtzd_reconst >> 15)); |
133 | band->prev_qtzd_reconst = cur_qtzd_reconst; |
134 | } |
135 | |
136 | static inline int linear_scale_factor(const int log_factor) |
137 | { |
138 | const int wd1 = inv_log2_table[(log_factor >> 6) & 31]; |
139 | const int shift = log_factor >> 11; |
140 | return shift < 0 ? wd1 >> -shift : wd1 << shift; |
141 | } |
142 | |
143 | void ff_g722_update_low_predictor(struct G722Band *band, const int ilow) |
144 | { |
145 | do_adaptive_prediction(band, |
146 | band->scale_factor * ff_g722_low_inv_quant4[ilow] >> 10); |
147 | |
148 | // quantizer adaptation |
149 | band->log_factor = av_clip((band->log_factor * 127 >> 7) + |
150 | low_log_factor_step[ilow], 0, 18432); |
151 | band->scale_factor = linear_scale_factor(band->log_factor - (8 << 11)); |
152 | } |
153 | |
154 | void ff_g722_update_high_predictor(struct G722Band *band, const int dhigh, |
155 | const int ihigh) |
156 | { |
157 | do_adaptive_prediction(band, dhigh); |
158 | |
159 | // quantizer adaptation |
160 | band->log_factor = av_clip((band->log_factor * 127 >> 7) + |
161 | high_log_factor_step[ihigh&1], 0, 22528); |
162 | band->scale_factor = linear_scale_factor(band->log_factor - (10 << 11)); |
163 | } |
164 |