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dtsdec.c
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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 
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 
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 };