8715ce6b753f19da391544e899ddced0afa8bb89
[libav.git] / libavcodec / aac_parser.c
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 "bitstream.h"
26 #include "mpeg4audio.h"
27
28 #define AAC_HEADER_SIZE 7
29
30 static int aac_sync(AACAC3ParseContext *hdr_info)
31 {
32 GetBitContext bits;
33 int size, rdb, ch, sr;
34
35 init_get_bits(&bits, hdr_info->inbuf, AAC_HEADER_SIZE * 8);
36
37 if(get_bits(&bits, 12) != 0xfff)
38 return 0;
39
40 skip_bits1(&bits); /* id */
41 skip_bits(&bits, 2); /* layer */
42 skip_bits1(&bits); /* protection_absent */
43 skip_bits(&bits, 2); /* profile_objecttype */
44 sr = get_bits(&bits, 4); /* sample_frequency_index */
45 if(!ff_mpeg4audio_sample_rates[sr])
46 return 0;
47 skip_bits1(&bits); /* private_bit */
48 ch = get_bits(&bits, 3); /* channel_configuration */
49 if(!ff_mpeg4audio_channels[ch])
50 return 0;
51 skip_bits1(&bits); /* original/copy */
52 skip_bits1(&bits); /* home */
53
54 /* adts_variable_header */
55 skip_bits1(&bits); /* copyright_identification_bit */
56 skip_bits1(&bits); /* copyright_identification_start */
57 size = get_bits(&bits, 13); /* aac_frame_length */
58 if(size < AAC_HEADER_SIZE)
59 return 0;
60
61 skip_bits(&bits, 11); /* adts_buffer_fullness */
62 rdb = get_bits(&bits, 2); /* number_of_raw_data_blocks_in_frame */
63
64 hdr_info->channels = ff_mpeg4audio_channels[ch];
65 hdr_info->sample_rate = ff_mpeg4audio_sample_rates[sr];
66 hdr_info->samples = (rdb + 1) * 1024;
67 hdr_info->bit_rate = size * 8 * hdr_info->sample_rate / hdr_info->samples;
68
69 return size;
70 }
71
72 static av_cold int aac_parse_init(AVCodecParserContext *s1)
73 {
74 AACAC3ParseContext *s = s1->priv_data;
75 s->inbuf_ptr = s->inbuf;
76 s->header_size = AAC_HEADER_SIZE;
77 s->sync = aac_sync;
78 return 0;
79 }
80
81
82 AVCodecParser aac_parser = {
83 { CODEC_ID_AAC },
84 sizeof(AACAC3ParseContext),
85 aac_parse_init,
86 ff_aac_ac3_parse,
87 NULL,
88 };