/*
  * 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
  */
 
 #include "aac_ac3_parser.h"
 #include "aacadtsdec.h"
 #include "get_bits.h"
 #include "mpeg4audio.h"
 

 int avpriv_aac_parse_header(GetBitContext *gbc, AACADTSHeaderInfo *hdr)

 {
     int size, rdb, ch, sr;
     int aot, crc_abs;
 

     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 (!avpriv_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 < 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    = avpriv_mpeg4audio_sample_rates[sr];

     hdr->samples        = (rdb + 1) * 1024;
     hdr->bit_rate       = size * 8 * hdr->sample_rate / hdr->samples;
 
     return size;
 }