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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  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 
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 };