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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 "libavcodec/get_bits.h"
24 #include "libavcodec/dca.h"
25 #include "avformat.h"
26 #include "rawdec.h"
27 
28 #define DCA_MARKER_14B_BE 0x1FFFE800
29 #define DCA_MARKER_14B_LE 0xFF1F00E8
30 #define DCA_MARKER_RAW_BE 0x7FFE8001
31 #define DCA_MARKER_RAW_LE 0xFE7F0180
32 
33 static int dts_probe(AVProbeData *p)
34 {
35  const uint8_t *buf, *bufp;
36  uint32_t state = -1;
37  int markers[4] = {0};
38  int sum, max, i;
39  int64_t diff = 0;
40  uint8_t hdr[12 + FF_INPUT_BUFFER_PADDING_SIZE] = { 0 };
41 
42  buf = p->buf + FFMIN(4096, p->buf_size);
43 
44  for(; buf < (p->buf+p->buf_size)-2; buf+=2) {
45  int marker, sample_blocks, sample_rate, sr_code, framesize;
46  GetBitContext gb;
47 
48  bufp = buf;
49  state = (state << 16) | bytestream_get_be16(&bufp);
50 
51  if (buf - p->buf >= 4)
52  diff += FFABS(((int16_t)AV_RL16(buf)) - (int16_t)AV_RL16(buf-4));
53 
54  /* regular bitstream */
55  if (state == DCA_MARKER_RAW_BE)
56  marker = 0;
57  else if (state == DCA_MARKER_RAW_LE)
58  marker = 1;
59 
60  /* 14 bits big-endian bitstream */
61  else if (state == DCA_MARKER_14B_BE &&
62  (bytestream_get_be16(&bufp) & 0xFFF0) == 0x07F0)
63  marker = 2;
64 
65  /* 14 bits little-endian bitstream */
66  else if (state == DCA_MARKER_14B_LE &&
67  (bytestream_get_be16(&bufp) & 0xF0FF) == 0xF007)
68  marker = 3;
69  else
70  continue;
71 
72  if (avpriv_dca_convert_bitstream(buf-2, 12, hdr, 12) < 0)
73  continue;
74 
75  init_get_bits(&gb, hdr, 96);
76  skip_bits_long(&gb, 39);
77 
78  sample_blocks = get_bits(&gb, 7) + 1;
79  if (sample_blocks < 8)
80  continue;
81 
82  framesize = get_bits(&gb, 14) + 1;
83  if (framesize < 95)
84  continue;
85 
86  skip_bits(&gb, 6);
87  sr_code = get_bits(&gb, 4);
88  sample_rate = avpriv_dca_sample_rates[sr_code];
89  if (sample_rate == 0)
90  continue;
91 
92  markers[marker] ++;
93  }
94  sum = markers[0] + markers[1] + markers[2] + markers[3];
95  max = 0;
96  for (i=1; i<4; i++)
97  if (markers[max] < markers[i])
98  max = i;
99  if (markers[max] > 3 && p->buf_size / markers[max] < 32*1024 &&
100  markers[max] * 4 > sum * 3 &&
101  diff / p->buf_size > 200)
102  return AVPROBE_SCORE_EXTENSION + 1;
103 
104  return 0;
105 }
106 
108  .name = "dts",
109  .long_name = NULL_IF_CONFIG_SMALL("raw DTS"),
110  .read_probe = dts_probe,
111  .read_header = ff_raw_audio_read_header,
112  .read_packet = ff_raw_read_partial_packet,
113  .flags = AVFMT_GENERIC_INDEX,
114  .extensions = "dts",
115  .raw_codec_id = AV_CODEC_ID_DTS,
116 };