adts_header.c (2999B)
1 /* 2 * Audio and Video frame extraction 3 * Copyright (c) 2003 Fabrice Bellard 4 * Copyright (c) 2003 Michael Niedermayer 5 * Copyright (c) 2009 Alex Converse 6 * 7 * This file is part of FFmpeg. 8 * 9 * FFmpeg is free software; you can redistribute it and/or 10 * modify it under the terms of the GNU Lesser General Public 11 * License as published by the Free Software Foundation; either 12 * version 2.1 of the License, or (at your option) any later version. 13 * 14 * FFmpeg is distributed in the hope that it will be useful, 15 * but WITHOUT ANY WARRANTY; without even the implied warranty of 16 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU 17 * Lesser General Public License for more details. 18 * 19 * You should have received a copy of the GNU Lesser General Public 20 * License along with FFmpeg; if not, write to the Free Software 21 * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA 22 */ 23 24 #include "adts_header.h" 25 #include "adts_parser.h" 26 #include "get_bits.h" 27 #include "mpeg4audio.h" 28 #include "libavutil/avassert.h" 29 30 int ff_adts_header_parse(GetBitContext *gbc, AACADTSHeaderInfo *hdr) 31 { 32 int size, rdb, ch, sr; 33 int aot, crc_abs; 34 35 memset(hdr, 0, sizeof(*hdr)); 36 37 if (get_bits(gbc, 12) != 0xfff) 38 return AAC_PARSE_ERROR_SYNC; 39 40 skip_bits1(gbc); /* id */ 41 skip_bits(gbc, 2); /* layer */ 42 crc_abs = get_bits1(gbc); /* protection_absent */ 43 aot = get_bits(gbc, 2); /* profile_objecttype */ 44 sr = get_bits(gbc, 4); /* sample_frequency_index */ 45 if (!ff_mpeg4audio_sample_rates[sr]) 46 return AAC_PARSE_ERROR_SAMPLE_RATE; 47 skip_bits1(gbc); /* private_bit */ 48 ch = get_bits(gbc, 3); /* channel_configuration */ 49 50 skip_bits1(gbc); /* original/copy */ 51 skip_bits1(gbc); /* home */ 52 53 /* adts_variable_header */ 54 skip_bits1(gbc); /* copyright_identification_bit */ 55 skip_bits1(gbc); /* copyright_identification_start */ 56 size = get_bits(gbc, 13); /* aac_frame_length */ 57 if (size < AV_AAC_ADTS_HEADER_SIZE) 58 return AAC_PARSE_ERROR_FRAME_SIZE; 59 60 skip_bits(gbc, 11); /* adts_buffer_fullness */ 61 rdb = get_bits(gbc, 2); /* number_of_raw_data_blocks_in_frame */ 62 63 hdr->object_type = aot + 1; 64 hdr->chan_config = ch; 65 hdr->crc_absent = crc_abs; 66 hdr->num_aac_frames = rdb + 1; 67 hdr->sampling_index = sr; 68 hdr->sample_rate = ff_mpeg4audio_sample_rates[sr]; 69 hdr->samples = (rdb + 1) * 1024; 70 hdr->bit_rate = size * 8 * hdr->sample_rate / hdr->samples; 71 hdr->frame_length = size; 72 73 return size; 74 } 75 76 int ff_adts_header_parse_buf(const uint8_t buf[AV_AAC_ADTS_HEADER_SIZE + AV_INPUT_BUFFER_PADDING_SIZE], 77 AACADTSHeaderInfo *hdr) 78 { 79 GetBitContext gb; 80 av_unused int ret = init_get_bits8(&gb, buf, AV_AAC_ADTS_HEADER_SIZE); 81 av_assert1(ret >= 0); 82 return ff_adts_header_parse(&gb, hdr); 83 }