/*
  * RAW DTS demuxer
  * Copyright (c) 2008 Benjamin Larsson
  *
  * 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/bytestream.h"

 #include "libavcodec/dca.h"

 #include "libavcodec/dca_syncwords.h"

 #include "libavcodec/get_bits.h"

 #include "avformat.h"

 #include "rawdec.h"

 
 static int dts_probe(AVProbeData *p)
 {
     const uint8_t *buf, *bufp;
     uint32_t state = -1;

     int markers[4*16] = {0};

     int exss_markers = 0, exss_nextpos = 0;
     int sum, max, pos, i;

     int64_t diff = 0;

     uint8_t hdr[12 + AV_INPUT_BUFFER_PADDING_SIZE] = { 0 };

     for (pos = FFMIN(4096, p->buf_size); pos < p->buf_size - 2; pos += 2) {

         int marker, sample_blocks, sample_rate, sr_code, framesize;

         int lfe, wide_hdr, hdr_size;

         GetBitContext gb;
 

         bufp = buf = p->buf + pos;

         state = (state << 16) | bytestream_get_be16(&bufp);
 

         if (pos >= 4)

             diff += FFABS(((int16_t)AV_RL16(buf)) - (int16_t)AV_RL16(buf-4));
 

         /* extension substream (EXSS) */
         if (state == DCA_SYNCWORD_SUBSTREAM) {
             if (pos < exss_nextpos)
                 continue;
 
             init_get_bits(&gb, buf - 2, 96);
             skip_bits_long(&gb, 42);
 
             wide_hdr  = get_bits1(&gb);
             hdr_size  = get_bits(&gb,  8 + 4 * wide_hdr) + 1;
             framesize = get_bits(&gb, 16 + 4 * wide_hdr) + 1;
             if (hdr_size & 3 || framesize & 3)
                 continue;
             if (hdr_size < 16 || framesize < hdr_size)
                 continue;
             if (pos - 2 + hdr_size > p->buf_size)
                 continue;

             if (av_crc(av_crc_get_table(AV_CRC_16_CCITT), 0xffff, buf + 3, hdr_size - 5))

                 continue;
 
             if (pos == exss_nextpos)
                 exss_markers++;
             else
                 exss_markers = FFMAX(1, exss_markers - 1);
             exss_nextpos = pos + framesize;
             continue;
         }
 

         /* regular bitstream */

         if (state == DCA_SYNCWORD_CORE_BE &&
             (bytestream_get_be16(&bufp) & 0xFC00) == 0xFC00)

             marker = 0;

         else if (state == DCA_SYNCWORD_CORE_LE &&
                  (bytestream_get_be16(&bufp) & 0x00FC) == 0x00FC)

             marker = 1;

 
         /* 14 bits big-endian bitstream */

         else if (state == DCA_SYNCWORD_CORE_14B_BE &&

                  (bytestream_get_be16(&bufp) & 0xFFF0) == 0x07F0)
             marker = 2;

 
         /* 14 bits little-endian bitstream */

         else if (state == DCA_SYNCWORD_CORE_14B_LE &&

                  (bytestream_get_be16(&bufp) & 0xF0FF) == 0xF007)
             marker = 3;
         else
             continue;

         if (avpriv_dca_convert_bitstream(buf-2, 12, hdr, 12) < 0)
             continue;
 
         init_get_bits(&gb, hdr, 96);
         skip_bits_long(&gb, 39);
 
         sample_blocks = get_bits(&gb, 7) + 1;
         if (sample_blocks < 8)
             continue;
 
         framesize = get_bits(&gb, 14) + 1;
         if (framesize < 95)
             continue;
 
         skip_bits(&gb, 6);
         sr_code = get_bits(&gb, 4);
         sample_rate = avpriv_dca_sample_rates[sr_code];
         if (sample_rate == 0)
             continue;
 

         get_bits(&gb, 5);
         if (get_bits(&gb, 1))
             continue;
 
         skip_bits_long(&gb, 9);
         lfe = get_bits(&gb, 2);
         if (lfe > 2)
             continue;
 
         marker += 4* sr_code;
 

         markers[marker] ++;

     }

     if (exss_markers > 3)
         return AVPROBE_SCORE_EXTENSION + 1;
 

     sum = max = 0;
     for (i=0; i<FF_ARRAY_ELEMS(markers); i++) {
         sum += markers[i];

         if (markers[max] < markers[i])
             max = i;

     }
 

     if (markers[max] > 3 && p->buf_size / markers[max] < 32*1024 &&

         markers[max] * 4 > sum * 3 &&
         diff / p->buf_size > 200)

         return AVPROBE_SCORE_EXTENSION + 1;

 
     return 0;
 }
 

 AVInputFormat ff_dts_demuxer = {

     .name           = "dts",
     .long_name      = NULL_IF_CONFIG_SMALL("raw DTS"),
     .read_probe     = dts_probe,
     .read_header    = ff_raw_audio_read_header,
     .read_packet    = ff_raw_read_partial_packet,

     .flags          = AVFMT_GENERIC_INDEX,
     .extensions     = "dts",

     .raw_codec_id   = AV_CODEC_ID_DTS,

 };