FFmpeg
adts_header.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 "adts_header.h"
26 #include "adts_parser.h"
27 #include "get_bits.h"
28 #include "mpeg4audio.h"
29 
31 {
32  int size, rdb, ch, sr;
33  int aot, crc_abs;
34 
35  memset(hdr, 0, sizeof(*hdr));
36 
37  if (get_bits(gbc, 12) != 0xfff)
39 
40  skip_bits1(gbc); /* id */
41  skip_bits(gbc, 2); /* layer */
42  crc_abs = get_bits1(gbc); /* protection_absent */
43  aot = get_bits(gbc, 2); /* profile_objecttype */
44  sr = get_bits(gbc, 4); /* sample_frequency_index */
47  skip_bits1(gbc); /* private_bit */
48  ch = get_bits(gbc, 3); /* channel_configuration */
49 
50  skip_bits1(gbc); /* original/copy */
51  skip_bits1(gbc); /* home */
52 
53  /* adts_variable_header */
54  skip_bits1(gbc); /* copyright_identification_bit */
55  skip_bits1(gbc); /* copyright_identification_start */
56  size = get_bits(gbc, 13); /* aac_frame_length */
59 
60  skip_bits(gbc, 11); /* adts_buffer_fullness */
61  rdb = get_bits(gbc, 2); /* number_of_raw_data_blocks_in_frame */
62 
63  hdr->object_type = aot + 1;
64  hdr->chan_config = ch;
65  hdr->crc_absent = crc_abs;
66  hdr->num_aac_frames = rdb + 1;
67  hdr->sampling_index = sr;
69  hdr->samples = (rdb + 1) * 1024;
70  hdr->bit_rate = size * 8 * hdr->sample_rate / hdr->samples;
71  hdr->frame_length = size;
72 
73  return size;
74 }
AV_AAC_ADTS_HEADER_SIZE
#define AV_AAC_ADTS_HEADER_SIZE
Definition: adts_parser.h:25
aac_ac3_parser.h
AACADTSHeaderInfo::samples
uint32_t samples
Definition: adts_header.h:30
AACADTSHeaderInfo::bit_rate
uint32_t bit_rate
Definition: adts_header.h:31
skip_bits
static void skip_bits(GetBitContext *s, int n)
Definition: get_bits.h:467
get_bits
static unsigned int get_bits(GetBitContext *s, int n)
Read 1-25 bits.
Definition: get_bits.h:379
mpeg4audio.h
ff_adts_header_parse
int ff_adts_header_parse(GetBitContext *gbc, AACADTSHeaderInfo *hdr)
Parse the ADTS frame header to the end of the variable header, which is the first 54 bits.
Definition: adts_header.c:30
GetBitContext
Definition: get_bits.h:61
AACADTSHeaderInfo::chan_config
uint8_t chan_config
Definition: adts_header.h:35
AAC_AC3_PARSE_ERROR_SYNC
@ AAC_AC3_PARSE_ERROR_SYNC
Definition: aac_ac3_parser.h:32
get_bits.h
AACADTSHeaderInfo::num_aac_frames
uint8_t num_aac_frames
Definition: adts_header.h:36
AACADTSHeaderInfo::sampling_index
uint8_t sampling_index
Definition: adts_header.h:34
get_bits1
static unsigned int get_bits1(GetBitContext *s)
Definition: get_bits.h:498
AACADTSHeaderInfo::frame_length
uint32_t frame_length
Definition: adts_header.h:37
AAC_AC3_PARSE_ERROR_SAMPLE_RATE
@ AAC_AC3_PARSE_ERROR_SAMPLE_RATE
Definition: aac_ac3_parser.h:34
size
int size
Definition: twinvq_data.h:10344
skip_bits1
static void skip_bits1(GetBitContext *s)
Definition: get_bits.h:538
AACADTSHeaderInfo::object_type
uint8_t object_type
Definition: adts_header.h:33
AAC_AC3_PARSE_ERROR_FRAME_SIZE
@ AAC_AC3_PARSE_ERROR_FRAME_SIZE
Definition: aac_ac3_parser.h:35
AACADTSHeaderInfo::sample_rate
uint32_t sample_rate
Definition: adts_header.h:29
adts_parser.h
AACADTSHeaderInfo::crc_absent
uint8_t crc_absent
Definition: adts_header.h:32
ff_mpeg4audio_sample_rates
const int ff_mpeg4audio_sample_rates[16]
Definition: mpeg4audio_sample_rates.h:26
adts_header.h
AACADTSHeaderInfo
Definition: adts_header.h:28