FFmpeg
g722.c
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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 * 2, 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 * 2, 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] * 128) + (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) * 2);
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 {
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 }
static void do_adaptive_prediction(struct G722Band *band, const int cur_diff)
adaptive predictor
Definition: g722.c:110
static int shift(int a, int b)
Definition: sonic.c:82
const int16_t ff_g722_low_inv_quant4[16]
Definition: g722.c:59
static const int16_t low_log_factor_step[16]
low_log_factor_step[index] == wl[rl42[index]]
Definition: g722.c:55
#define ACCUM(k, x, d)
static int linear_scale_factor(const int log_factor)
Definition: g722.c:136
static const int8_t sign_lookup[2]
Definition: g722.c:42
const int16_t ff_g722_low_inv_quant6[64]
Definition: g722.c:63
static const int16_t high_log_factor_step[2]
Definition: g722.c:50
void ff_g722_update_low_predictor(struct G722Band *band, const int ilow)
Definition: g722.c:143
static const int16_t inv_log2_table[32]
Definition: g722.c:44
const int16_t ff_g722_high_inv_quant[4]
Definition: g722.c:51
static void s_zero(int cur_diff, struct G722Band *band)
Definition: g722.c:74
void ff_g722_update_high_predictor(struct G722Band *band, const int dhigh, const int ihigh)
Definition: g722.c:154