blob: d0814ac27e149c5236afa0b14f53def63913b2f9
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 | } |
71 |