1/*
2 * Audio and Video frame extraction
3 * Copyright (c) 2003 Fabrice Bellard
4 * Copyright (c) 2003 Michael Niedermayer
5 * Copyright (c) 2009 Alex Converse
6 *
7 * This file is part of FFmpeg.
8 *
9 * FFmpeg is free software; you can redistribute it and/or
10 * modify it under the terms of the GNU Lesser General Public
11 * License as published by the Free Software Foundation; either
12 * version 2.1 of the License, or (at your option) any later version.
13 *
14 * FFmpeg is distributed in the hope that it will be useful,
15 * but WITHOUT ANY WARRANTY; without even the implied warranty of
16 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
17 * Lesser General Public License for more details.
18 *
19 * You should have received a copy of the GNU Lesser General Public
20 * License along with FFmpeg; if not, write to the Free Software
21 * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
22 */
23
24#include "aac_ac3_parser.h"
25#include "adts_header.h"
26#include "adts_parser.h"
27#include "get_bits.h"
28#include "mpeg4audio.h"
29
30int ff_adts_header_parse(GetBitContext *gbc, AACADTSHeaderInfo *hdr)
31{
32    int size, rdb, ch, sr;
33    int aot, crc_abs;
34
35    if (get_bits(gbc, 12) != 0xfff)
36        return AAC_AC3_PARSE_ERROR_SYNC;
37
38    skip_bits1(gbc);             /* id */
39    skip_bits(gbc, 2);           /* layer */
40    crc_abs = get_bits1(gbc);    /* protection_absent */
41    aot     = get_bits(gbc, 2);  /* profile_objecttype */
42    sr      = get_bits(gbc, 4);  /* sample_frequency_index */
43    if (!ff_mpeg4audio_sample_rates[sr])
44        return AAC_AC3_PARSE_ERROR_SAMPLE_RATE;
45    skip_bits1(gbc);             /* private_bit */
46    ch = get_bits(gbc, 3);       /* channel_configuration */
47
48    skip_bits1(gbc);             /* original/copy */
49    skip_bits1(gbc);             /* home */
50
51    /* adts_variable_header */
52    skip_bits1(gbc);             /* copyright_identification_bit */
53    skip_bits1(gbc);             /* copyright_identification_start */
54    size = get_bits(gbc, 13);    /* aac_frame_length */
55    if (size < AV_AAC_ADTS_HEADER_SIZE)
56        return AAC_AC3_PARSE_ERROR_FRAME_SIZE;
57
58    skip_bits(gbc, 11);          /* adts_buffer_fullness */
59    rdb = get_bits(gbc, 2);      /* number_of_raw_data_blocks_in_frame */
60
61    hdr->object_type    = aot + 1;
62    hdr->chan_config    = ch;
63    hdr->crc_absent     = crc_abs;
64    hdr->num_aac_frames = rdb + 1;
65    hdr->sampling_index = sr;
66    hdr->sample_rate    = ff_mpeg4audio_sample_rates[sr];
67    hdr->samples        = (rdb + 1) * 1024;
68    hdr->bit_rate       = size * 8 * hdr->sample_rate / hdr->samples;
69    hdr->frame_length   = size;
70
71    return size;
72}
73