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97 lines
2.9 KiB
97 lines
2.9 KiB
/* |
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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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