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2ba45a60 DM |
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 | ||
29 | int avpriv_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 (!avpriv_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 = avpriv_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 | } |