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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 "libavutil/crc.h"
23 
24 #include "libavcodec/bytestream.h"
25 #include "libavcodec/dca.h"
27 #include "libavcodec/get_bits.h"
28 
29 #include "avformat.h"
30 #include "rawdec.h"
31 
32 static int dts_probe(AVProbeData *p)
33 {
34  const uint8_t *buf, *bufp;
35  uint32_t state = -1;
36  int markers[4*16] = {0};
37  int exss_markers = 0, exss_nextpos = 0;
38  int sum, max, pos, i;
39  int64_t diff = 0;
40  uint8_t hdr[12 + AV_INPUT_BUFFER_PADDING_SIZE] = { 0 };
41 
42  for (pos = FFMIN(4096, p->buf_size); pos < p->buf_size - 2; pos += 2) {
43  int marker, sample_blocks, sample_rate, sr_code, framesize;
44  int lfe, wide_hdr, hdr_size;
45  GetBitContext gb;
46 
47  bufp = buf = p->buf + pos;
48  state = (state << 16) | bytestream_get_be16(&bufp);
49 
50  if (pos >= 4)
51  diff += FFABS(((int16_t)AV_RL16(buf)) - (int16_t)AV_RL16(buf-4));
52 
53  /* extension substream (EXSS) */
54  if (state == DCA_SYNCWORD_SUBSTREAM) {
55  if (pos < exss_nextpos)
56  continue;
57 
58  init_get_bits(&gb, buf - 2, 96);
59  skip_bits_long(&gb, 42);
60 
61  wide_hdr = get_bits1(&gb);
62  hdr_size = get_bits(&gb, 8 + 4 * wide_hdr) + 1;
63  framesize = get_bits(&gb, 16 + 4 * wide_hdr) + 1;
64  if (hdr_size & 3 || framesize & 3)
65  continue;
66  if (hdr_size < 16 || framesize < hdr_size)
67  continue;
68  if (pos - 2 + hdr_size > p->buf_size)
69  continue;
70  if (av_crc(av_crc_get_table(AV_CRC_16_CCITT), 0xffff, buf + 3, hdr_size - 5))
71  continue;
72 
73  if (pos == exss_nextpos)
74  exss_markers++;
75  else
76  exss_markers = FFMAX(1, exss_markers - 1);
77  exss_nextpos = pos + framesize;
78  continue;
79  }
80 
81  /* regular bitstream */
82  if (state == DCA_SYNCWORD_CORE_BE &&
83  (bytestream_get_be16(&bufp) & 0xFC00) == 0xFC00)
84  marker = 0;
85  else if (state == DCA_SYNCWORD_CORE_LE &&
86  (bytestream_get_be16(&bufp) & 0x00FC) == 0x00FC)
87  marker = 1;
88 
89  /* 14 bits big-endian bitstream */
90  else if (state == DCA_SYNCWORD_CORE_14B_BE &&
91  (bytestream_get_be16(&bufp) & 0xFFF0) == 0x07F0)
92  marker = 2;
93 
94  /* 14 bits little-endian bitstream */
95  else if (state == DCA_SYNCWORD_CORE_14B_LE &&
96  (bytestream_get_be16(&bufp) & 0xF0FF) == 0xF007)
97  marker = 3;
98  else
99  continue;
100 
101  if (avpriv_dca_convert_bitstream(buf-2, 12, hdr, 12) < 0)
102  continue;
103 
104  init_get_bits(&gb, hdr, 96);
105  skip_bits_long(&gb, 39);
106 
107  sample_blocks = get_bits(&gb, 7) + 1;
108  if (sample_blocks < 8)
109  continue;
110 
111  framesize = get_bits(&gb, 14) + 1;
112  if (framesize < 95)
113  continue;
114 
115  skip_bits(&gb, 6);
116  sr_code = get_bits(&gb, 4);
117  sample_rate = avpriv_dca_sample_rates[sr_code];
118  if (sample_rate == 0)
119  continue;
120 
121  get_bits(&gb, 5);
122  if (get_bits(&gb, 1))
123  continue;
124 
125  skip_bits_long(&gb, 9);
126  lfe = get_bits(&gb, 2);
127  if (lfe > 2)
128  continue;
129 
130  marker += 4* sr_code;
131 
132  markers[marker] ++;
133  }
134 
135  if (exss_markers > 3)
136  return AVPROBE_SCORE_EXTENSION + 1;
137 
138  sum = max = 0;
139  for (i=0; i<FF_ARRAY_ELEMS(markers); i++) {
140  sum += markers[i];
141  if (markers[max] < markers[i])
142  max = i;
143  }
144 
145  if (markers[max] > 3 && p->buf_size / markers[max] < 32*1024 &&
146  markers[max] * 4 > sum * 3 &&
147  diff / p->buf_size > 200)
148  return AVPROBE_SCORE_EXTENSION + 1;
149 
150  return 0;
151 }
152 
154  .name = "dts",
155  .long_name = NULL_IF_CONFIG_SMALL("raw DTS"),
156  .read_probe = dts_probe,
157  .read_header = ff_raw_audio_read_header,
158  .read_packet = ff_raw_read_partial_packet,
159  .flags = AVFMT_GENERIC_INDEX,
160  .extensions = "dts",
161  .raw_codec_id = AV_CODEC_ID_DTS,
162 };
static unsigned int get_bits(GetBitContext *s, int n)
Read 1-25 bits.
Definition: get_bits.h:247
static void skip_bits_long(GetBitContext *s, int n)
Definition: get_bits.h:204
static int dts_probe(AVProbeData *p)
Definition: dtsdec.c:32
uint64_t_TMPL AV_WL64 unsigned int_TMPL AV_WL32 unsigned int_TMPL AV_WL24 unsigned int_TMPL AV_RL16
Definition: bytestream.h:87
uint8_t
#define DCA_SYNCWORD_CORE_14B_BE
Definition: dca_syncwords.h:24
Public header for CRC hash function implementation.
bitstream reader API header.
#define DCA_SYNCWORD_CORE_BE
Definition: dca_syncwords.h:22
int ff_raw_read_partial_packet(AVFormatContext *s, AVPacket *pkt)
Definition: rawdec.c:35
#define NULL_IF_CONFIG_SMALL(x)
Return NULL if CONFIG_SMALL is true, otherwise the argument without modification. ...
Definition: internal.h:176
#define DCA_SYNCWORD_CORE_14B_LE
Definition: dca_syncwords.h:25
#define FFMAX(a, b)
Definition: common.h:94
int buf_size
Size of buf except extra allocated bytes.
Definition: avformat.h:464
unsigned char * buf
Buffer must have AVPROBE_PADDING_SIZE of extra allocated bytes filled with zero.
Definition: avformat.h:463
#define FFMIN(a, b)
Definition: common.h:96
int ff_raw_audio_read_header(AVFormatContext *s)
Definition: rawdec.c:55
int avpriv_dca_convert_bitstream(const uint8_t *src, int src_size, uint8_t *dst, int max_size)
Convert bitstream to one representation based on sync marker.
Definition: dca.c:48
uint32_t av_crc(const AVCRC *ctx, uint32_t crc, const uint8_t *buffer, size_t length)
Calculate the CRC of a block.
Definition: crc.c:357
#define FFABS(a)
Absolute value, Note, INT_MIN / INT64_MIN result in undefined behavior as they are not representable ...
Definition: common.h:72
const uint32_t avpriv_dca_sample_rates[16]
Definition: dca.c:34
#define FF_ARRAY_ELEMS(a)
sample_rate
#define DCA_SYNCWORD_CORE_LE
Definition: dca_syncwords.h:23
AVInputFormat ff_dts_demuxer
Definition: dtsdec.c:153
void * buf
Definition: avisynth_c.h:690
static unsigned int get_bits1(GetBitContext *s)
Definition: get_bits.h:299
static void skip_bits(GetBitContext *s, int n)
Definition: get_bits.h:292
#define AVFMT_GENERIC_INDEX
Use generic index building code.
Definition: avformat.h:487
static int init_get_bits(GetBitContext *s, const uint8_t *buffer, int bit_size)
Initialize GetBitContext.
Definition: get_bits.h:406
#define AVPROBE_SCORE_EXTENSION
score for file extension
Definition: avformat.h:471
This structure contains the data a format has to probe a file.
Definition: avformat.h:461
static struct @244 state
const AVCRC * av_crc_get_table(AVCRCId crc_id)
Get an initialized standard CRC table.
Definition: crc.c:343
Main libavformat public API header.
#define AV_INPUT_BUFFER_PADDING_SIZE
Required number of additionally allocated bytes at the end of the input bitstream for decoding...
Definition: avcodec.h:733
static av_always_inline int diff(const uint32_t a, const uint32_t b)
#define DCA_SYNCWORD_SUBSTREAM
Definition: dca_syncwords.h:32
const char * name
A comma separated list of short names for the format.
Definition: avformat.h:662