libavformat/dtsdec.c

   1 /*
   2  * RAW DTS demuxer
   3  * Copyright (c) 2008 Benjamin Larsson
   4  *
   5  * This file is part of Libav.
   6  *
   7  * Libav 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  * Libav 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 Libav; 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
  38     buf = p->buf;
  39
  40     for(; buf < (p->buf+p->buf_size)-2; buf+=2) {
  41         bufp = buf;
  42         state = (state << 16) | bytestream_get_be16(&bufp);
  43
  44         /* regular bitstream */
  45         if (state == DCA_MARKER_RAW_BE || state == DCA_MARKER_RAW_LE)
  46             markers[0]++;
  47
  48         /* 14 bits big-endian bitstream */
  49         if (state == DCA_MARKER_14B_BE)
  50             if ((bytestream_get_be16(&bufp) & 0xFFF0) == 0x07F0)
  51                 markers[1]++;
  52
  53         /* 14 bits little-endian bitstream */
  54         if (state == DCA_MARKER_14B_LE)
  55             if ((bytestream_get_be16(&bufp) & 0xF0FF) == 0xF007)
  56                 markers[2]++;
  57     }
  58     sum = markers[0] + markers[1] + markers[2];
  59     max = markers[1] > markers[0];
  60     max = markers[2] > markers[max] ? 2 : max;
  61     if (markers[max] > 3 && p->buf_size / markers[max] < 32*1024 &&
  62         markers[max] * 4 > sum * 3)
  63         return AVPROBE_SCORE_MAX/2+1;
  64
  65     return 0;
  66 }
  67
  68 AVInputFormat ff_dts_demuxer = {
  69     .name           = "dts",
  70     .long_name      = NULL_IF_CONFIG_SMALL("raw DTS"),
  71     .read_probe     = dts_probe,
  72     .read_header    = ff_raw_audio_read_header,
  73     .read_packet    = ff_raw_read_partial_packet,
  74     .flags          = AVFMT_GENERIC_INDEX,
  75     .extensions     = "dts",
  76     .raw_codec_id   = AV_CODEC_ID_DTS,
  77 };