ac3.h
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1 /*
2  * Common code between the AC-3 encoder and decoder
3  * Copyright (c) 2000, 2001, 2002 Fabrice Bellard
4  *
5  * This file is part of Libav.
6  *
7  * Libav is free software; you can redistribute it and/or
8  * modify it under the terms of the GNU Lesser General Public
9  * License as published by the Free Software Foundation; either
10  * version 2.1 of the License, or (at your option) any later version.
11  *
12  * Libav is distributed in the hope that it will be useful,
13  * but WITHOUT ANY WARRANTY; without even the implied warranty of
14  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
15  * Lesser General Public License for more details.
16  *
17  * You should have received a copy of the GNU Lesser General Public
18  * License along with Libav; if not, write to the Free Software
19  * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
20  */
21 
27 #ifndef AVCODEC_AC3_H
28 #define AVCODEC_AC3_H
29 
30 #define AC3_MAX_CODED_FRAME_SIZE 3840 /* in bytes */
31 #define AC3_MAX_CHANNELS 7
32 #define CPL_CH 0
34 #define AC3_MAX_COEFS 256
35 #define AC3_BLOCK_SIZE 256
36 #define AC3_MAX_BLOCKS 6
37 #define AC3_FRAME_SIZE (AC3_MAX_BLOCKS * 256)
38 #define AC3_WINDOW_SIZE (AC3_BLOCK_SIZE * 2)
39 #define AC3_CRITICAL_BANDS 50
40 #define AC3_MAX_CPL_BANDS 18
41 
42 #include "ac3tab.h"
43 
44 /* exponent encoding strategy */
45 #define EXP_REUSE 0
46 #define EXP_NEW 1
47 
48 #define EXP_D15 1
49 #define EXP_D25 2
50 #define EXP_D45 3
51 
52 /* pre-defined gain values */
53 #define LEVEL_PLUS_3DB 1.4142135623730950
54 #define LEVEL_PLUS_1POINT5DB 1.1892071150027209
55 #define LEVEL_MINUS_1POINT5DB 0.8408964152537145
56 #define LEVEL_MINUS_3DB 0.7071067811865476
57 #define LEVEL_MINUS_4POINT5DB 0.5946035575013605
58 #define LEVEL_MINUS_6DB 0.5000000000000000
59 #define LEVEL_MINUS_9DB 0.3535533905932738
60 #define LEVEL_ZERO 0.0000000000000000
61 #define LEVEL_ONE 1.0000000000000000
62 
64 typedef enum {
65  DBA_REUSE = 0,
70 
72 typedef enum {
82 
83 typedef struct AC3BitAllocParameters {
84  int sr_code;
85  int sr_shift;
89 
94 typedef struct {
98  uint16_t sync_word;
99  uint16_t crc1;
100  uint8_t sr_code;
101  uint8_t bitstream_id;
102  uint8_t bitstream_mode;
103  uint8_t channel_mode;
104  uint8_t lfe_on;
105  uint8_t frame_type;
109  uint16_t channel_map;
111 
116  uint8_t sr_shift;
117  uint16_t sample_rate;
118  uint32_t bit_rate;
119  uint8_t channels;
120  uint16_t frame_size;
121  uint64_t channel_layout;
123 } AC3HeaderInfo;
124 
125 typedef enum {
130 } EAC3FrameType;
131 
132 void ff_ac3_common_init(void);
133 
148 void ff_ac3_bit_alloc_calc_psd(int8_t *exp, int start, int end, int16_t *psd,
149  int16_t *band_psd);
150 
173 int ff_ac3_bit_alloc_calc_mask(AC3BitAllocParameters *s, int16_t *band_psd,
174  int start, int end, int fast_gain, int is_lfe,
175  int dba_mode, int dba_nsegs, uint8_t *dba_offsets,
176  uint8_t *dba_lengths, uint8_t *dba_values,
177  int16_t *mask);
178 
179 #endif /* AVCODEC_AC3_H */