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aacadtsdec.c
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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 "aacadtsdec.h"
26 #include "get_bits.h"
27 #include "mpeg4audio.h"
28 
30 {
31  int size, rdb, ch, sr;
32  int aot, crc_abs;
33 
34  if (get_bits(gbc, 12) != 0xfff)
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 */
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)
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;
66  hdr->samples = (rdb + 1) * 1024;
67  hdr->bit_rate = size * 8 * hdr->sample_rate / hdr->samples;
68 
69  return size;
70 }