mirror of https://github.com/FFmpeg/FFmpeg.git
You can not select more than 25 topics
Topics must start with a letter or number, can include dashes ('-') and can be up to 35 characters long.
100 lines
2.9 KiB
100 lines
2.9 KiB
/* |
|
* Audio and Video frame extraction |
|
* Copyright (c) 2003 Fabrice Bellard. |
|
* Copyright (c) 2003 Michael Niedermayer. |
|
* |
|
* This file is part of FFmpeg. |
|
* |
|
* FFmpeg is free software; you can redistribute it and/or |
|
* modify it under the terms of the GNU Lesser General Public |
|
* License as published by the Free Software Foundation; either |
|
* version 2.1 of the License, or (at your option) any later version. |
|
* |
|
* FFmpeg is distributed in the hope that it will be useful, |
|
* but WITHOUT ANY WARRANTY; without even the implied warranty of |
|
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU |
|
* Lesser General Public License for more details. |
|
* |
|
* You should have received a copy of the GNU Lesser General Public |
|
* License along with FFmpeg; if not, write to the Free Software |
|
* Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA |
|
*/ |
|
|
|
#include "parser.h" |
|
#include "aac_ac3_parser.h" |
|
#include "bitstream.h" |
|
|
|
|
|
#define AAC_HEADER_SIZE 7 |
|
|
|
|
|
static const int aac_sample_rates[16] = { |
|
96000, 88200, 64000, 48000, 44100, 32000, |
|
24000, 22050, 16000, 12000, 11025, 8000, 7350 |
|
}; |
|
|
|
static const int aac_channels[8] = { |
|
0, 1, 2, 3, 4, 5, 6, 8 |
|
}; |
|
|
|
|
|
static int aac_sync(const uint8_t *buf, int *channels, int *sample_rate, |
|
int *bit_rate, int *samples) |
|
{ |
|
GetBitContext bits; |
|
int size, rdb, ch, sr; |
|
|
|
init_get_bits(&bits, buf, AAC_HEADER_SIZE * 8); |
|
|
|
if(get_bits(&bits, 12) != 0xfff) |
|
return 0; |
|
|
|
skip_bits1(&bits); /* id */ |
|
skip_bits(&bits, 2); /* layer */ |
|
skip_bits1(&bits); /* protection_absent */ |
|
skip_bits(&bits, 2); /* profile_objecttype */ |
|
sr = get_bits(&bits, 4); /* sample_frequency_index */ |
|
if(!aac_sample_rates[sr]) |
|
return 0; |
|
skip_bits1(&bits); /* private_bit */ |
|
ch = get_bits(&bits, 3); /* channel_configuration */ |
|
if(!aac_channels[ch]) |
|
return 0; |
|
skip_bits1(&bits); /* original/copy */ |
|
skip_bits1(&bits); /* home */ |
|
|
|
/* adts_variable_header */ |
|
skip_bits1(&bits); /* copyright_identification_bit */ |
|
skip_bits1(&bits); /* copyright_identification_start */ |
|
size = get_bits(&bits, 13); /* aac_frame_length */ |
|
if(size < AAC_HEADER_SIZE) |
|
return 0; |
|
|
|
skip_bits(&bits, 11); /* adts_buffer_fullness */ |
|
rdb = get_bits(&bits, 2); /* number_of_raw_data_blocks_in_frame */ |
|
|
|
*channels = aac_channels[ch]; |
|
*sample_rate = aac_sample_rates[sr]; |
|
*samples = (rdb + 1) * 1024; |
|
*bit_rate = size * 8 * *sample_rate / *samples; |
|
|
|
return size; |
|
} |
|
|
|
static int aac_parse_init(AVCodecParserContext *s1) |
|
{ |
|
AACAC3ParseContext *s = s1->priv_data; |
|
s->inbuf_ptr = s->inbuf; |
|
s->header_size = AAC_HEADER_SIZE; |
|
s->sync = aac_sync; |
|
return 0; |
|
} |
|
|
|
|
|
AVCodecParser aac_parser = { |
|
{ CODEC_ID_AAC }, |
|
sizeof(AACAC3ParseContext), |
|
aac_parse_init, |
|
ff_aac_ac3_parse, |
|
NULL, |
|
};
|
|
|