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/*
* 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,
};
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