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