1/* 2 * Audio and Video frame extraction 3 * Copyright (c) 2003 Fabrice Bellard 4 * Copyright (c) 2003 Michael Niedermayer 5 * 6 * This file is part of FFmpeg. 7 * 8 * FFmpeg is free software; you can redistribute it and/or 9 * modify it under the terms of the GNU Lesser General Public 10 * License as published by the Free Software Foundation; either 11 * version 2.1 of the License, or (at your option) any later version. 12 * 13 * FFmpeg is distributed in the hope that it will be useful, 14 * but WITHOUT ANY WARRANTY; without even the implied warranty of 15 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU 16 * Lesser General Public License for more details. 17 * 18 * You should have received a copy of the GNU Lesser General Public 19 * License along with FFmpeg; if not, write to the Free Software 20 * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA 21 */ 22 23#include "parser.h" 24#include "aac_ac3_parser.h" 25#include "aac_parser.h" 26#include "bitstream.h" 27#include "mpeg4audio.h" 28 29#define AAC_HEADER_SIZE 7 30 31int ff_aac_parse_header(GetBitContext *gbc, AACADTSHeaderInfo *hdr) 32{ 33 int size, rdb, ch, sr; 34 int aot, crc_abs; 35 36 if(get_bits(gbc, 12) != 0xfff) 37 return AAC_AC3_PARSE_ERROR_SYNC; 38 39 skip_bits1(gbc); /* id */ 40 skip_bits(gbc, 2); /* layer */ 41 crc_abs = get_bits1(gbc); /* protection_absent */ 42 aot = get_bits(gbc, 2); /* profile_objecttype */ 43 sr = get_bits(gbc, 4); /* sample_frequency_index */ 44 if(!ff_mpeg4audio_sample_rates[sr]) 45 return AAC_AC3_PARSE_ERROR_SAMPLE_RATE; 46 skip_bits1(gbc); /* private_bit */ 47 ch = get_bits(gbc, 3); /* channel_configuration */ 48 49 if(!ff_mpeg4audio_channels[ch]) 50 return AAC_AC3_PARSE_ERROR_CHANNEL_CFG; 51 52 skip_bits1(gbc); /* original/copy */ 53 skip_bits1(gbc); /* home */ 54 55 /* adts_variable_header */ 56 skip_bits1(gbc); /* copyright_identification_bit */ 57 skip_bits1(gbc); /* copyright_identification_start */ 58 size = get_bits(gbc, 13); /* aac_frame_length */ 59 if(size < AAC_HEADER_SIZE) 60 return AAC_AC3_PARSE_ERROR_FRAME_SIZE; 61 62 skip_bits(gbc, 11); /* adts_buffer_fullness */ 63 rdb = get_bits(gbc, 2); /* number_of_raw_data_blocks_in_frame */ 64 65 hdr->object_type = aot + 1; 66 hdr->chan_config = ch; 67 hdr->crc_absent = crc_abs; 68 hdr->num_aac_frames = rdb + 1; 69 hdr->sampling_index = sr; 70 hdr->sample_rate = ff_mpeg4audio_sample_rates[sr]; 71 hdr->samples = (rdb + 1) * 1024; 72 hdr->bit_rate = size * 8 * hdr->sample_rate / hdr->samples; 73 74 return size; 75} 76 77static int aac_sync(uint64_t state, AACAC3ParseContext *hdr_info, 78 int *need_next_header, int *new_frame_start) 79{ 80 GetBitContext bits; 81 AACADTSHeaderInfo hdr; 82 int size; 83 union { 84 uint64_t u64; 85 uint8_t u8[8]; 86 } tmp; 87 88 tmp.u64 = be2me_64(state); 89 init_get_bits(&bits, tmp.u8+8-AAC_HEADER_SIZE, AAC_HEADER_SIZE * 8); 90 91 if ((size = ff_aac_parse_header(&bits, &hdr)) < 0) 92 return 0; 93 *need_next_header = 0; 94 *new_frame_start = 1; 95 hdr_info->sample_rate = hdr.sample_rate; 96 hdr_info->channels = ff_mpeg4audio_channels[hdr.chan_config]; 97 hdr_info->samples = hdr.samples; 98 hdr_info->bit_rate = hdr.bit_rate; 99 return size; 100} 101 102static av_cold int aac_parse_init(AVCodecParserContext *s1) 103{ 104 AACAC3ParseContext *s = s1->priv_data; 105 s->header_size = AAC_HEADER_SIZE; 106 s->sync = aac_sync; 107 return 0; 108} 109 110 111AVCodecParser aac_parser = { 112 { CODEC_ID_AAC }, 113 sizeof(AACAC3ParseContext), 114 aac_parse_init, 115 ff_aac_ac3_parse, 116 ff_parse_close, 117}; 118