/*
  * RAW AC-3 and E-AC-3 demuxer
  * Copyright (c) 2007 Justin Ruggles <justin.ruggles@gmail.com>
  *
  * 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 "libavutil/crc.h"
 #include "libavcodec/ac3_parser.h"
 #include "avformat.h"

 #include "rawdec.h"

 
 static int ac3_eac3_probe(AVProbeData *p, enum CodecID expected_codec_id)
 {
     int max_frames, first_frames = 0, frames;
     uint8_t *buf, *buf2, *end;
     AC3HeaderInfo hdr;
     GetBitContext gbc;
     enum CodecID codec_id = CODEC_ID_AC3;
 
     max_frames = 0;
     buf = p->buf;
     end = buf + p->buf_size;
 
     for(; buf < end; buf++) {
         buf2 = buf;
 
         for(frames = 0; buf2 < end; frames++) {

             if(!memcmp(buf2, "\x1\x10\0\0\0\0\0\0", 8))
                 buf2+=16;

             init_get_bits(&gbc, buf2, 54);

             if(avpriv_ac3_parse_header(&gbc, &hdr) < 0)

                 break;
             if(buf2 + hdr.frame_size > end ||
                av_crc(av_crc_get_table(AV_CRC_16_ANSI), 0, buf2 + 2, hdr.frame_size - 2))
                 break;
             if (hdr.bitstream_id > 10)
                 codec_id = CODEC_ID_EAC3;
             buf2 += hdr.frame_size;
         }
         max_frames = FFMAX(max_frames, frames);
         if(buf == p->buf)
             first_frames = frames;
     }
     if(codec_id != expected_codec_id) return 0;
     // keep this in sync with mp3 probe, both need to avoid
     // issues with MPEG-files!
     if   (first_frames>=4) return AVPROBE_SCORE_MAX/2+1;

     else if(max_frames>200)return AVPROBE_SCORE_MAX/2;

     else if(max_frames>=4) return AVPROBE_SCORE_MAX/4;
     else if(max_frames>=1) return 1;
     else                   return 0;
 }
 
 #if CONFIG_AC3_DEMUXER
 static int ac3_probe(AVProbeData *p)
 {
     return ac3_eac3_probe(p, CODEC_ID_AC3);
 }
 

 AVInputFormat ff_ac3_demuxer = {

     .name           = "ac3",
     .long_name      = NULL_IF_CONFIG_SMALL("raw AC-3"),
     .read_probe     = ac3_probe,
     .read_header    = ff_raw_audio_read_header,
     .read_packet    = ff_raw_read_partial_packet,

     .flags= AVFMT_GENERIC_INDEX,
     .extensions = "ac3",
     .value = CODEC_ID_AC3,
 };
 #endif
 
 #if CONFIG_EAC3_DEMUXER
 static int eac3_probe(AVProbeData *p)
 {
     return ac3_eac3_probe(p, CODEC_ID_EAC3);
 }
 

 AVInputFormat ff_eac3_demuxer = {

     .name           = "eac3",
     .long_name      = NULL_IF_CONFIG_SMALL("raw E-AC-3"),
     .read_probe     = eac3_probe,
     .read_header    = ff_raw_audio_read_header,
     .read_packet    = ff_raw_read_partial_packet,

     .flags= AVFMT_GENERIC_INDEX,
     .extensions = "eac3",
     .value = CODEC_ID_EAC3,
 };
 #endif