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  1. /*
  2.  * RAW DTS demuxer
  3.  * Copyright (c) 2008 Benjamin Larsson
  4.  *
  5.  * This file is part of FFmpeg.
  6.  *
  7.  * FFmpeg is free software; you can redistribute it and/or
  8.  * modify it under the terms of the GNU Lesser General Public
  9.  * License as published by the Free Software Foundation; either
  10.  * version 2.1 of the License, or (at your option) any later version.
  11.  *
  12.  * FFmpeg is distributed in the hope that it will be useful,
  13.  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  14.  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
  15.  * Lesser General Public License for more details.
  16.  *
  17.  * You should have received a copy of the GNU Lesser General Public
  18.  * License along with FFmpeg; if not, write to the Free Software
  19.  * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
  20.  */
  21.  
  22. #include "libavcodec/bytestream.h"
  23. #include "avformat.h"
  24. #include "rawdec.h"
  25.  
  26. #define DCA_MARKER_14B_BE 0x1FFFE800
  27. #define DCA_MARKER_14B_LE 0xFF1F00E8
  28. #define DCA_MARKER_RAW_BE 0x7FFE8001
  29. #define DCA_MARKER_RAW_LE 0xFE7F0180
  30.  
  31. static int dts_probe(AVProbeData *p)
  32. {
  33.     const uint8_t *buf, *bufp;
  34.     uint32_t state = -1;
  35.     int markers[3] = {0};
  36.     int sum, max;
  37.     int64_t diff = 0;
  38.  
  39.     buf = p->buf;
  40.  
  41.     for(; buf < (p->buf+p->buf_size)-2; buf+=2) {
  42.         bufp = buf;
  43.         state = (state << 16) | bytestream_get_be16(&bufp);
  44.  
  45.         /* regular bitstream */
  46.         if (state == DCA_MARKER_RAW_BE || state == DCA_MARKER_RAW_LE)
  47.             markers[0]++;
  48.  
  49.         /* 14 bits big-endian bitstream */
  50.         if (state == DCA_MARKER_14B_BE)
  51.             if ((bytestream_get_be16(&bufp) & 0xFFF0) == 0x07F0)
  52.                 markers[1]++;
  53.  
  54.         /* 14 bits little-endian bitstream */
  55.         if (state == DCA_MARKER_14B_LE)
  56.             if ((bytestream_get_be16(&bufp) & 0xF0FF) == 0xF007)
  57.                 markers[2]++;
  58.  
  59.         if (buf - p->buf >= 4)
  60.             diff += FFABS(AV_RL16(buf) - AV_RL16(buf-4));
  61.     }
  62.     sum = markers[0] + markers[1] + markers[2];
  63.     max = markers[1] > markers[0];
  64.     max = markers[2] > markers[max] ? 2 : max;
  65.     if (markers[max] > 3 && p->buf_size / markers[max] < 32*1024 &&
  66.         markers[max] * 4 > sum * 3 &&
  67.         diff / p->buf_size > 200)
  68.         return AVPROBE_SCORE_EXTENSION + 1;
  69.  
  70.     return 0;
  71. }
  72.  
  73. AVInputFormat ff_dts_demuxer = {
  74.     .name           = "dts",
  75.     .long_name      = NULL_IF_CONFIG_SMALL("raw DTS"),
  76.     .read_probe     = dts_probe,
  77.     .read_header    = ff_raw_audio_read_header,
  78.     .read_packet    = ff_raw_read_partial_packet,
  79.     .flags          = AVFMT_GENERIC_INDEX,
  80.     .extensions     = "dts",
  81.     .raw_codec_id   = AV_CODEC_ID_DTS,
  82. };
  83.