1 /*
2  * AC-3 parser internal code
3  *
4  * This file is part of FFmpeg.
5  *
6  * FFmpeg is free software; you can redistribute it and/or
7  * modify it under the terms of the GNU Lesser General Public
8  * License as published by the Free Software Foundation; either
9  * version 2.1 of the License, or (at your option) any later version.
10  *
11  * FFmpeg is distributed in the hope that it will be useful,
12  * but WITHOUT ANY WARRANTY; without even the implied warranty of
13  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
14  * Lesser General Public License for more details.
15  *
16  * You should have received a copy of the GNU Lesser General Public
17  * License along with FFmpeg; if not, write to the Free Software
18  * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
19  */
20 
21 #ifndef AVCODEC_AC3_PARSER_INTERNAL_H
22 #define AVCODEC_AC3_PARSER_INTERNAL_H
23 
24 #include <stddef.h>
25 #include <stdint.h>
26 
27 #include "ac3defs.h"
28 #include "get_bits.h"
29 
30 /**
31  * @struct AC3HeaderInfo
32  * Coded AC-3 header values up to the lfeon element, plus derived values.
33  */
34 typedef struct AC3HeaderInfo {
35     /** @name Coded elements
36      * @{
37      */
38     uint16_t sync_word;
39     uint16_t crc1;
40     uint8_t sr_code;
41     uint8_t bitstream_id;
42     uint8_t bitstream_mode;
43     uint8_t channel_mode;
44     uint8_t lfe_on;
45     uint8_t frame_type;
46     int substreamid;                        ///< substream identification
47     int center_mix_level;                   ///< Center mix level index
48     int surround_mix_level;                 ///< Surround mix level index
49     uint16_t channel_map;
50     int num_blocks;                         ///< number of audio blocks
51     int dolby_surround_mode;
52     /** @} */
53 
54     /** @name Derived values
55      * @{
56      */
57     uint8_t sr_shift;
58     uint16_t sample_rate;
59     uint32_t bit_rate;
60     uint8_t channels;
61     uint16_t frame_size;
62     uint64_t channel_layout;
63     int8_t ac3_bit_rate_code;
64     /** @} */
65 } AC3HeaderInfo;
66 
67 /**
68  * Parse AC-3 frame header.
69  * Parse the header up to the lfeon element, which is the first 52 or 54 bits
70  * depending on the audio coding mode.
71  * @param[in]  gbc BitContext containing the first 54 bits of the frame.
72  * @param[out] hdr Pointer to struct where header info is written.
73  * @return Returns 0 on success, -1 if there is a sync word mismatch,
74  * -2 if the bsid (version) element is invalid, -3 if the fscod (sample rate)
75  * element is invalid, or -4 if the frmsizecod (bit rate) element is invalid.
76  */
77 int ff_ac3_parse_header(GetBitContext *gbc, AC3HeaderInfo *hdr);
78 
79 int avpriv_ac3_parse_header(AC3HeaderInfo **hdr, const uint8_t *buf,
80                             size_t size);
81 
82 #endif /* AVCODEC_AC3_PARSER_INTERNAL_H */
83