2 * Audio and Video frame extraction
3 * Copyright (c) 2003 Fabrice Bellard.
4 * Copyright (c) 2003 Michael Niedermayer.
6 * This file is part of FFmpeg.
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.
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.
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
24 #include "aac_ac3_parser.h"
25 #include "bitstream.h"
28 #define AAC_HEADER_SIZE 7
31 static const int aac_sample_rates[16] = {
32 96000, 88200, 64000, 48000, 44100, 32000,
33 24000, 22050, 16000, 12000, 11025, 8000, 7350
36 static const int aac_channels[8] = {
37 0, 1, 2, 3, 4, 5, 6, 8
41 static int aac_sync(const uint8_t *buf, int *channels, int *sample_rate,
42 int *bit_rate, int *samples)
45 int size, rdb, ch, sr;
47 init_get_bits(&bits, buf, AAC_HEADER_SIZE * 8);
49 if(get_bits(&bits, 12) != 0xfff)
52 skip_bits1(&bits); /* id */
53 skip_bits(&bits, 2); /* layer */
54 skip_bits1(&bits); /* protection_absent */
55 skip_bits(&bits, 2); /* profile_objecttype */
56 sr = get_bits(&bits, 4); /* sample_frequency_index */
57 if(!aac_sample_rates[sr])
59 skip_bits1(&bits); /* private_bit */
60 ch = get_bits(&bits, 3); /* channel_configuration */
63 skip_bits1(&bits); /* original/copy */
64 skip_bits1(&bits); /* home */
66 /* adts_variable_header */
67 skip_bits1(&bits); /* copyright_identification_bit */
68 skip_bits1(&bits); /* copyright_identification_start */
69 size = get_bits(&bits, 13); /* aac_frame_length */
70 skip_bits(&bits, 11); /* adts_buffer_fullness */
71 rdb = get_bits(&bits, 2); /* number_of_raw_data_blocks_in_frame */
73 *channels = aac_channels[ch];
74 *sample_rate = aac_sample_rates[sr];
75 *samples = (rdb + 1) * 1024;
76 *bit_rate = size * 8 * *sample_rate / *samples;
81 static int aac_parse_init(AVCodecParserContext *s1)
83 AACAC3ParseContext *s = s1->priv_data;
84 s->inbuf_ptr = s->inbuf;
85 s->header_size = AAC_HEADER_SIZE;
91 AVCodecParser aac_parser = {
93 sizeof(AACAC3ParseContext),