mirror of https://github.com/FFmpeg/FFmpeg.git
The AAC decoder and ADTS-to-ASC BSF both require the header decoder but not full parsing capabilities. Originally committed as revision 24217 to svn://svn.ffmpeg.org/ffmpeg/trunkoldabi
Alex Converse
15 years ago
parent
65415bb93a
commit
3cac899af9
8 changed files with 84 additions and 59 deletions
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/*
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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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* Copyright (c) 2009 Alex Converse |
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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 "aac_ac3_parser.h" |
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#include "aacadtsdec.h" |
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#include "get_bits.h" |
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#include "mpeg4audio.h" |
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int ff_aac_parse_header(GetBitContext *gbc, AACADTSHeaderInfo *hdr) |
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{ |
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int size, rdb, ch, sr; |
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int aot, crc_abs; |
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if(get_bits(gbc, 12) != 0xfff) |
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return AAC_AC3_PARSE_ERROR_SYNC; |
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skip_bits1(gbc); /* id */ |
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skip_bits(gbc, 2); /* layer */ |
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crc_abs = get_bits1(gbc); /* protection_absent */ |
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aot = get_bits(gbc, 2); /* profile_objecttype */ |
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sr = get_bits(gbc, 4); /* sample_frequency_index */ |
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if(!ff_mpeg4audio_sample_rates[sr]) |
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return AAC_AC3_PARSE_ERROR_SAMPLE_RATE; |
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skip_bits1(gbc); /* private_bit */ |
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ch = get_bits(gbc, 3); /* channel_configuration */ |
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skip_bits1(gbc); /* original/copy */ |
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skip_bits1(gbc); /* home */ |
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/* adts_variable_header */ |
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skip_bits1(gbc); /* copyright_identification_bit */ |
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skip_bits1(gbc); /* copyright_identification_start */ |
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size = get_bits(gbc, 13); /* aac_frame_length */ |
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if(size < AAC_ADTS_HEADER_SIZE) |
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return AAC_AC3_PARSE_ERROR_FRAME_SIZE; |
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skip_bits(gbc, 11); /* adts_buffer_fullness */ |
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rdb = get_bits(gbc, 2); /* number_of_raw_data_blocks_in_frame */ |
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hdr->object_type = aot + 1; |
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hdr->chan_config = ch; |
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hdr->crc_absent = crc_abs; |
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hdr->num_aac_frames = rdb + 1; |
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hdr->sampling_index = sr; |
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hdr->sample_rate = ff_mpeg4audio_sample_rates[sr]; |
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hdr->samples = (rdb + 1) * 1024; |
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hdr->bit_rate = size * 8 * hdr->sample_rate / hdr->samples; |
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return size; |
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} |
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