| /* | |
| * Audio and Video frame extraction | |
| * Copyright (c) 2003 Fabrice Bellard | |
| * Copyright (c) 2003 Michael Niedermayer | |
| * Copyright (c) 2009 Alex Converse | |
| * | |
| * 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 | |
| */ | |
| int ff_adts_header_parse(GetBitContext *gbc, AACADTSHeaderInfo *hdr) | |
| { | |
| int size, rdb, ch, sr; | |
| int aot, crc_abs; | |
| memset(hdr, 0, sizeof(*hdr)); | |
| if (get_bits(gbc, 12) != 0xfff) | |
| return AAC_AC3_PARSE_ERROR_SYNC; | |
| skip_bits1(gbc); /* id */ | |
| skip_bits(gbc, 2); /* layer */ | |
| crc_abs = get_bits1(gbc); /* protection_absent */ | |
| aot = get_bits(gbc, 2); /* profile_objecttype */ | |
| sr = get_bits(gbc, 4); /* sample_frequency_index */ | |
| if (!ff_mpeg4audio_sample_rates[sr]) | |
| return AAC_AC3_PARSE_ERROR_SAMPLE_RATE; | |
| skip_bits1(gbc); /* private_bit */ | |
| ch = get_bits(gbc, 3); /* channel_configuration */ | |
| skip_bits1(gbc); /* original/copy */ | |
| skip_bits1(gbc); /* home */ | |
| /* adts_variable_header */ | |
| skip_bits1(gbc); /* copyright_identification_bit */ | |
| skip_bits1(gbc); /* copyright_identification_start */ | |
| size = get_bits(gbc, 13); /* aac_frame_length */ | |
| if (size < AV_AAC_ADTS_HEADER_SIZE) | |
| return AAC_AC3_PARSE_ERROR_FRAME_SIZE; | |
| skip_bits(gbc, 11); /* adts_buffer_fullness */ | |
| rdb = get_bits(gbc, 2); /* number_of_raw_data_blocks_in_frame */ | |
| hdr->object_type = aot + 1; | |
| hdr->chan_config = ch; | |
| hdr->crc_absent = crc_abs; | |
| hdr->num_aac_frames = rdb + 1; | |
| hdr->sampling_index = sr; | |
| hdr->sample_rate = ff_mpeg4audio_sample_rates[sr]; | |
| hdr->samples = (rdb + 1) * 1024; | |
| hdr->bit_rate = size * 8 * hdr->sample_rate / hdr->samples; | |
| hdr->frame_length = size; | |
| return size; | |
| } | |