1/*
2 * Audio and Video frame extraction
3 * Copyright (c) 2003 Fabrice Bellard
4 * Copyright (c) 2003 Michael Niedermayer
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 "parser.h"
24#include "aac_ac3_parser.h"
25#include "aac_parser.h"
26#include "get_bits.h"
27#include "mpeg4audio.h"
28
29int ff_aac_parse_header(GetBitContext *gbc, AACADTSHeaderInfo *hdr)
30{
31    int size, rdb, ch, sr;
32    int aot, crc_abs;
33
34    if(get_bits(gbc, 12) != 0xfff)
35        return AAC_AC3_PARSE_ERROR_SYNC;
36
37    skip_bits1(gbc);             /* id */
38    skip_bits(gbc, 2);           /* layer */
39    crc_abs = get_bits1(gbc);    /* protection_absent */
40    aot     = get_bits(gbc, 2);  /* profile_objecttype */
41    sr      = get_bits(gbc, 4);  /* sample_frequency_index */
42    if(!ff_mpeg4audio_sample_rates[sr])
43        return AAC_AC3_PARSE_ERROR_SAMPLE_RATE;
44    skip_bits1(gbc);             /* private_bit */
45    ch      = get_bits(gbc, 3);  /* channel_configuration */
46
47    skip_bits1(gbc);             /* original/copy */
48    skip_bits1(gbc);             /* home */
49
50    /* adts_variable_header */
51    skip_bits1(gbc);             /* copyright_identification_bit */
52    skip_bits1(gbc);             /* copyright_identification_start */
53    size    = get_bits(gbc, 13); /* aac_frame_length */
54    if(size < AAC_ADTS_HEADER_SIZE)
55        return AAC_AC3_PARSE_ERROR_FRAME_SIZE;
56
57    skip_bits(gbc, 11);          /* adts_buffer_fullness */
58    rdb = get_bits(gbc, 2);      /* number_of_raw_data_blocks_in_frame */
59
60    hdr->object_type    = aot + 1;
61    hdr->chan_config    = ch;
62    hdr->crc_absent     = crc_abs;
63    hdr->num_aac_frames = rdb + 1;
64    hdr->sampling_index = sr;
65    hdr->sample_rate    = ff_mpeg4audio_sample_rates[sr];
66    hdr->samples        = (rdb + 1) * 1024;
67    hdr->bit_rate       = size * 8 * hdr->sample_rate / hdr->samples;
68
69    return size;
70}
71
72static int aac_sync(uint64_t state, AACAC3ParseContext *hdr_info,
73        int *need_next_header, int *new_frame_start)
74{
75    GetBitContext bits;
76    AACADTSHeaderInfo hdr;
77    int size;
78    union {
79        uint64_t u64;
80        uint8_t  u8[8];
81    } tmp;
82
83    tmp.u64 = be2me_64(state);
84    init_get_bits(&bits, tmp.u8+8-AAC_ADTS_HEADER_SIZE, AAC_ADTS_HEADER_SIZE * 8);
85
86    if ((size = ff_aac_parse_header(&bits, &hdr)) < 0)
87        return 0;
88    *need_next_header = 0;
89    *new_frame_start  = 1;
90    hdr_info->sample_rate = hdr.sample_rate;
91    hdr_info->channels    = ff_mpeg4audio_channels[hdr.chan_config];
92    hdr_info->samples     = hdr.samples;
93    hdr_info->bit_rate    = hdr.bit_rate;
94    return size;
95}
96
97static av_cold int aac_parse_init(AVCodecParserContext *s1)
98{
99    AACAC3ParseContext *s = s1->priv_data;
100    s->header_size = AAC_ADTS_HEADER_SIZE;
101    s->sync = aac_sync;
102    return 0;
103}
104
105
106AVCodecParser aac_parser = {
107    { CODEC_ID_AAC },
108    sizeof(AACAC3ParseContext),
109    aac_parse_init,
110    ff_aac_ac3_parse,
111    ff_parse_close,
112};
113