yading@10: /*
yading@10:  * Audio and Video frame extraction
yading@10:  * Copyright (c) 2003 Fabrice Bellard
yading@10:  * Copyright (c) 2003 Michael Niedermayer
yading@10:  * Copyright (c) 2009 Alex Converse
yading@10:  *
yading@10:  * This file is part of FFmpeg.
yading@10:  *
yading@10:  * FFmpeg is free software; you can redistribute it and/or
yading@10:  * modify it under the terms of the GNU Lesser General Public
yading@10:  * License as published by the Free Software Foundation; either
yading@10:  * version 2.1 of the License, or (at your option) any later version.
yading@10:  *
yading@10:  * FFmpeg is distributed in the hope that it will be useful,
yading@10:  * but WITHOUT ANY WARRANTY; without even the implied warranty of
yading@10:  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
yading@10:  * Lesser General Public License for more details.
yading@10:  *
yading@10:  * You should have received a copy of the GNU Lesser General Public
yading@10:  * License along with FFmpeg; if not, write to the Free Software
yading@10:  * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
yading@10:  */
yading@10: 
yading@10: #include "aac_ac3_parser.h"
yading@10: #include "aacadtsdec.h"
yading@10: #include "get_bits.h"
yading@10: #include "mpeg4audio.h"
yading@10: 
yading@10: int avpriv_aac_parse_header(GetBitContext *gbc, AACADTSHeaderInfo *hdr)
yading@10: {
yading@10:     int size, rdb, ch, sr;
yading@10:     int aot, crc_abs;
yading@10: 
yading@10:     if(get_bits(gbc, 12) != 0xfff)
yading@10:         return AAC_AC3_PARSE_ERROR_SYNC;
yading@10: 
yading@10:     skip_bits1(gbc);             /* id */
yading@10:     skip_bits(gbc, 2);           /* layer */
yading@10:     crc_abs = get_bits1(gbc);    /* protection_absent */
yading@10:     aot     = get_bits(gbc, 2);  /* profile_objecttype */
yading@10:     sr      = get_bits(gbc, 4);  /* sample_frequency_index */
yading@10:     if(!avpriv_mpeg4audio_sample_rates[sr])
yading@10:         return AAC_AC3_PARSE_ERROR_SAMPLE_RATE;
yading@10:     skip_bits1(gbc);             /* private_bit */
yading@10:     ch      = get_bits(gbc, 3);  /* channel_configuration */
yading@10: 
yading@10:     skip_bits1(gbc);             /* original/copy */
yading@10:     skip_bits1(gbc);             /* home */
yading@10: 
yading@10:     /* adts_variable_header */
yading@10:     skip_bits1(gbc);             /* copyright_identification_bit */
yading@10:     skip_bits1(gbc);             /* copyright_identification_start */
yading@10:     size    = get_bits(gbc, 13); /* aac_frame_length */
yading@10:     if(size < AAC_ADTS_HEADER_SIZE)
yading@10:         return AAC_AC3_PARSE_ERROR_FRAME_SIZE;
yading@10: 
yading@10:     skip_bits(gbc, 11);          /* adts_buffer_fullness */
yading@10:     rdb = get_bits(gbc, 2);      /* number_of_raw_data_blocks_in_frame */
yading@10: 
yading@10:     hdr->object_type    = aot + 1;
yading@10:     hdr->chan_config    = ch;
yading@10:     hdr->crc_absent     = crc_abs;
yading@10:     hdr->num_aac_frames = rdb + 1;
yading@10:     hdr->sampling_index = sr;
yading@10:     hdr->sample_rate    = avpriv_mpeg4audio_sample_rates[sr];
yading@10:     hdr->samples        = (rdb + 1) * 1024;
yading@10:     hdr->bit_rate       = size * 8 * hdr->sample_rate / hdr->samples;
yading@10: 
yading@10:     return size;
yading@10: }