/*

  * AC-3 parser

  * Copyright (c) 2003 Fabrice Bellard
  * Copyright (c) 2003 Michael Niedermayer

  *
  * 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 "parser.h"
 #include "ac3_parser.h"
 #include "aac_ac3_parser.h"
 #include "bitstream.h"
 
 
 #define AC3_HEADER_SIZE 7
 
 
 static const uint8_t eac3_blocks[4] = {
     1, 2, 3, 6
 };
 

 
 int ff_ac3_parse_header(GetBitContext *gbc, AC3HeaderInfo *hdr)

 {

     int frame_size_code;

 
     memset(hdr, 0, sizeof(*hdr));
 

     hdr->sync_word = get_bits(gbc, 16);

     if(hdr->sync_word != 0x0B77)

         return AAC_AC3_PARSE_ERROR_SYNC;

     /* read ahead to bsid to distinguish between AC-3 and E-AC-3 */

     hdr->bitstream_id = show_bits_long(gbc, 29) & 0x1F;

     if(hdr->bitstream_id > 16)

         return AAC_AC3_PARSE_ERROR_BSID;

     hdr->num_blocks = 6;
 

     /* set default mix levels */

     hdr->center_mix_level   = 1;  // -4.5dB
     hdr->surround_mix_level = 1;  // -6.0dB

     if(hdr->bitstream_id <= 10) {

         /* Normal AC-3 */

         hdr->crc1 = get_bits(gbc, 16);
         hdr->sr_code = get_bits(gbc, 2);

         if(hdr->sr_code == 3)

             return AAC_AC3_PARSE_ERROR_SAMPLE_RATE;

         frame_size_code = get_bits(gbc, 6);

         if(frame_size_code > 37)

             return AAC_AC3_PARSE_ERROR_FRAME_SIZE;

         skip_bits(gbc, 5); // skip bsid, already got it
 
         skip_bits(gbc, 3); // skip bitstream mode
         hdr->channel_mode = get_bits(gbc, 3);
 

         if(hdr->channel_mode == AC3_CHMODE_STEREO) {

             skip_bits(gbc, 2); // skip dsurmod
         } else {
             if((hdr->channel_mode & 1) && hdr->channel_mode != AC3_CHMODE_MONO)

                 hdr->center_mix_level = get_bits(gbc, 2);

             if(hdr->channel_mode & 4)

                 hdr->surround_mix_level = get_bits(gbc, 2);

         }

         hdr->lfe_on = get_bits1(gbc);

 
         hdr->sr_shift = FFMAX(hdr->bitstream_id, 8) - 8;
         hdr->sample_rate = ff_ac3_sample_rate_tab[hdr->sr_code] >> hdr->sr_shift;
         hdr->bit_rate = (ff_ac3_bitrate_tab[frame_size_code>>1] * 1000) >> hdr->sr_shift;
         hdr->channels = ff_ac3_channels_tab[hdr->channel_mode] + hdr->lfe_on;
         hdr->frame_size = ff_ac3_frame_size_tab[frame_size_code][hdr->sr_code] * 2;

         hdr->frame_type = EAC3_FRAME_TYPE_AC3_CONVERT; //EAC3_FRAME_TYPE_INDEPENDENT;

         hdr->substreamid = 0;

     } else {
         /* Enhanced AC-3 */
         hdr->crc1 = 0;

         hdr->frame_type = get_bits(gbc, 2);

         if(hdr->frame_type == EAC3_FRAME_TYPE_RESERVED)

             return AAC_AC3_PARSE_ERROR_FRAME_TYPE;

         hdr->substreamid = get_bits(gbc, 3);

         hdr->frame_size = (get_bits(gbc, 11) + 1) << 1;

         if(hdr->frame_size < AC3_HEADER_SIZE)

             return AAC_AC3_PARSE_ERROR_FRAME_SIZE;

         hdr->sr_code = get_bits(gbc, 2);

         if (hdr->sr_code == 3) {

             int sr_code2 = get_bits(gbc, 2);

             if(sr_code2 == 3)

                 return AAC_AC3_PARSE_ERROR_SAMPLE_RATE;

             hdr->sample_rate = ff_ac3_sample_rate_tab[sr_code2] / 2;
             hdr->sr_shift = 1;
         } else {

             hdr->num_blocks = eac3_blocks[get_bits(gbc, 2)];

             hdr->sample_rate = ff_ac3_sample_rate_tab[hdr->sr_code];
             hdr->sr_shift = 0;
         }
 

         hdr->channel_mode = get_bits(gbc, 3);
         hdr->lfe_on = get_bits1(gbc);

 
         hdr->bit_rate = (uint32_t)(8.0 * hdr->frame_size * hdr->sample_rate /

                         (hdr->num_blocks * 256.0));

         hdr->channels = ff_ac3_channels_tab[hdr->channel_mode] + hdr->lfe_on;
     }

 
     return 0;
 }
 

 int ff_ac3_parse_header_full(GetBitContext *gbc, AC3HeaderInfo *hdr){
     int ret, i;
     ret = ff_ac3_parse_header(gbc, hdr);
     if(!ret){
         if(hdr->bitstream_id>10){
             /* Enhanced AC-3 */
             skip_bits(gbc, 5); // skip bitstream id
 
             /* skip dialog normalization and compression gain */
             for (i = 0; i < (hdr->channel_mode ? 1 : 2); i++) {
                 skip_bits(gbc, 5); // skip dialog normalization
                 if (get_bits1(gbc)) {
                     skip_bits(gbc, 8); //skip Compression gain word
                 }
             }
             /* dependent stream channel map */
             if (hdr->frame_type == EAC3_FRAME_TYPE_DEPENDENT && get_bits1(gbc)) {
                     hdr->channel_map = get_bits(gbc, 16); //custom channel map
                     return 0;
             }
         }
         //default channel map based on acmod and lfeon
         hdr->channel_map = ff_eac3_default_chmap[hdr->channel_mode];
         if(hdr->lfe_on)
             hdr->channel_map |= AC3_CHMAP_LFE;
     }
     return ret;
 }
 

 static int ac3_sync(uint64_t state, AACAC3ParseContext *hdr_info,
         int *need_next_header, int *new_frame_start)

 {
     int err;

     union {
         uint64_t u64;
         uint8_t  u8[8];
     } tmp = { be2me_64(state) };

     AC3HeaderInfo hdr;

     GetBitContext gbc;

     init_get_bits(&gbc, tmp.u8+8-AC3_HEADER_SIZE, 54);

     err = ff_ac3_parse_header(&gbc, &hdr);

     if(err < 0)

         return 0;
 

     hdr_info->sample_rate = hdr.sample_rate;
     hdr_info->bit_rate = hdr.bit_rate;
     hdr_info->channels = hdr.channels;

     hdr_info->samples = hdr.num_blocks * 256;

     if(hdr.bitstream_id>10)
         hdr_info->codec_id = CODEC_ID_EAC3;
     else
         hdr_info->codec_id = CODEC_ID_AC3;

     *need_next_header = (hdr.frame_type != EAC3_FRAME_TYPE_AC3_CONVERT);
     *new_frame_start  = (hdr.frame_type != EAC3_FRAME_TYPE_DEPENDENT);

     return hdr.frame_size;

 }
 

 static av_cold int ac3_parse_init(AVCodecParserContext *s1)

 {

     AACAC3ParseContext *s = s1->priv_data;

     s->header_size = AC3_HEADER_SIZE;
     s->sync = ac3_sync;
     return 0;
 }
 
 
 AVCodecParser ac3_parser = {

     { CODEC_ID_AC3, CODEC_ID_EAC3 },

     sizeof(AACAC3ParseContext),

     ac3_parse_init,

     ff_aac_ac3_parse,

     ff_parse_close,

 };