FFmpeg
dtsdec.c
Go to the documentation of this file.
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(const 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, ret, i;
39  int64_t diff = 0;
40  int diffcount = 1;
42 
43  for (pos = FFMIN(4096, p->buf_size); pos < p->buf_size - 2; pos += 2) {
44  int marker, wide_hdr, hdr_size, framesize;
46  GetBitContext gb;
47 
48  bufp = buf = p->buf + pos;
49  state = (state << 16) | bytestream_get_be16(&bufp);
50 
51  if (pos >= 4) {
52  if (AV_RL16(buf) || AV_RL16(buf-4)) {
53  diff += FFABS(((int16_t)AV_RL16(buf)) - (int16_t)AV_RL16(buf-4));
54  diffcount ++;
55  }
56  }
57 
58  /* extension substream (EXSS) */
60  if (pos < exss_nextpos)
61  continue;
62 
63  init_get_bits(&gb, buf - 2, 96);
64  skip_bits_long(&gb, 42);
65 
66  wide_hdr = get_bits1(&gb);
67  hdr_size = get_bits(&gb, 8 + 4 * wide_hdr) + 1;
68  framesize = get_bits(&gb, 16 + 4 * wide_hdr) + 1;
69  if (hdr_size & 3 || framesize & 3)
70  continue;
71  if (hdr_size < 16 || framesize < hdr_size)
72  continue;
73  if (pos - 2 + hdr_size > p->buf_size)
74  continue;
75  if (av_crc(av_crc_get_table(AV_CRC_16_CCITT), 0xffff, buf + 3, hdr_size - 5))
76  continue;
77 
78  if (pos == exss_nextpos)
79  exss_markers++;
80  else
81  exss_markers = FFMAX(1, exss_markers - 1);
82  exss_nextpos = pos + framesize;
83  continue;
84  }
85 
86  /* regular bitstream */
87  if (state == DCA_SYNCWORD_CORE_BE &&
88  (bytestream_get_be16(&bufp) & 0xFC00) == 0xFC00)
89  marker = 0;
90  else if (state == DCA_SYNCWORD_CORE_LE &&
91  (bytestream_get_be16(&bufp) & 0x00FC) == 0x00FC)
92  marker = 1;
93 
94  /* 14 bits big-endian bitstream */
95  else if (state == DCA_SYNCWORD_CORE_14B_BE &&
96  (bytestream_get_be16(&bufp) & 0xFFF0) == 0x07F0)
97  marker = 2;
98 
99  /* 14 bits little-endian bitstream */
100  else if (state == DCA_SYNCWORD_CORE_14B_LE &&
101  (bytestream_get_be16(&bufp) & 0xF0FF) == 0xF007)
102  marker = 3;
103  else
104  continue;
105 
107  hdr, DCA_CORE_FRAME_HEADER_SIZE)) < 0)
108  continue;
109  if (avpriv_dca_parse_core_frame_header(&h, hdr, ret) < 0)
110  continue;
111 
112  marker += 4 * h.sr_code;
113 
114  markers[marker] ++;
115  }
116 
117  if (exss_markers > 3)
118  return AVPROBE_SCORE_EXTENSION + 1;
119 
120  sum = max = 0;
121  for (i=0; i<FF_ARRAY_ELEMS(markers); i++) {
122  sum += markers[i];
123  if (markers[max] < markers[i])
124  max = i;
125  }
126 
127  if (markers[max] > 3 && p->buf_size / markers[max] < 32*1024 &&
128  markers[max] * 4 > sum * 3 &&
129  diff / diffcount > 600)
130  return AVPROBE_SCORE_EXTENSION + 1;
131 
132  return 0;
133 }
134 
137  .name = "dts",
138  .long_name = NULL_IF_CONFIG_SMALL("raw DTS"),
139  .read_probe = dts_probe,
140  .read_header = ff_raw_audio_read_header,
141  .read_packet = ff_raw_read_partial_packet,
142  .flags = AVFMT_GENERIC_INDEX,
143  .extensions = "dts",
144  .raw_codec_id = AV_CODEC_ID_DTS,
145  .priv_data_size = sizeof(FFRawDemuxerContext),
146  .priv_class = &dts_demuxer_class,};
skip_bits_long
static void skip_bits_long(GetBitContext *s, int n)
Skips the specified number of bits.
Definition: get_bits.h:292
dca.h
state
static struct @321 state
DCA_SYNCWORD_CORE_14B_BE
#define DCA_SYNCWORD_CORE_14B_BE
Definition: dca_syncwords.h:24
dts_probe
static int dts_probe(const AVProbeData *p)
Definition: dtsdec.c:32
max
#define max(a, b)
Definition: cuda_runtime.h:33
AVProbeData::buf_size
int buf_size
Size of buf except extra allocated bytes.
Definition: avformat.h:449
init_get_bits
static int init_get_bits(GetBitContext *s, const uint8_t *buffer, int bit_size)
Initialize GetBitContext.
Definition: get_bits.h:660
crc.h
get_bits
static unsigned int get_bits(GetBitContext *s, int n)
Read 1-25 bits.
Definition: get_bits.h:380
avpriv_dca_convert_bitstream
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:54
GetBitContext
Definition: get_bits.h:62
FFRawDemuxerContext
Definition: rawdec.h:37
AVFMT_GENERIC_INDEX
#define AVFMT_GENERIC_INDEX
Use generic index building code.
Definition: avformat.h:468
AVInputFormat
Definition: avformat.h:621
FF_ARRAY_ELEMS
#define FF_ARRAY_ELEMS(a)
Definition: sinewin_tablegen.c:29
ff_raw_read_partial_packet
int ff_raw_read_partial_packet(AVFormatContext *s, AVPacket *pkt)
Definition: rawdec.c:35
AVInputFormat::name
const char * name
A comma separated list of short names for the format.
Definition: avformat.h:626
AVProbeData::buf
unsigned char * buf
Buffer must have AVPROBE_PADDING_SIZE of extra allocated bytes filled with zero.
Definition: avformat.h:448
get_bits.h
AV_RL16
uint64_t_TMPL AV_WL64 unsigned int_TMPL AV_WL32 unsigned int_TMPL AV_WL24 unsigned int_TMPL AV_RL16
Definition: bytestream.h:94
dca_syncwords.h
FFABS
#define FFABS(a)
Absolute value, Note, INT_MIN / INT64_MIN result in undefined behavior as they are not representable ...
Definition: common.h:72
rawdec.h
get_bits1
static unsigned int get_bits1(GetBitContext *s)
Definition: get_bits.h:499
ff_raw_audio_read_header
int ff_raw_audio_read_header(AVFormatContext *s)
Definition: rawdec.c:56
AVProbeData
This structure contains the data a format has to probe a file.
Definition: avformat.h:446
AVPROBE_SCORE_EXTENSION
#define AVPROBE_SCORE_EXTENSION
score for file extension
Definition: avformat.h:456
DCA_SYNCWORD_CORE_BE
#define DCA_SYNCWORD_CORE_BE
Definition: dca_syncwords.h:22
DCACoreFrameHeader
Definition: dca.h:51
NULL_IF_CONFIG_SMALL
#define NULL_IF_CONFIG_SMALL(x)
Return NULL if CONFIG_SMALL is true, otherwise the argument without modification.
Definition: internal.h:117
FFMAX
#define FFMAX(a, b)
Definition: common.h:103
AV_CODEC_ID_DTS
@ AV_CODEC_ID_DTS
Definition: codec_id.h:426
DCA_SYNCWORD_CORE_14B_LE
#define DCA_SYNCWORD_CORE_14B_LE
Definition: dca_syncwords.h:25
FFMIN
#define FFMIN(a, b)
Definition: common.h:105
av_crc_get_table
const AVCRC * av_crc_get_table(AVCRCId crc_id)
Get an initialized standard CRC table.
Definition: crc.c:374
i
int i
Definition: input.c:407
AV_CRC_16_CCITT
@ AV_CRC_16_CCITT
Definition: crc.h:52
DCA_SYNCWORD_SUBSTREAM
#define DCA_SYNCWORD_SUBSTREAM
Definition: dca_syncwords.h:32
ret
ret
Definition: filter_design.txt:187
DCA_CORE_FRAME_HEADER_SIZE
#define DCA_CORE_FRAME_HEADER_SIZE
Definition: dca.h:37
pos
unsigned int pos
Definition: spdifenc.c:412
avformat.h
AV_INPUT_BUFFER_PADDING_SIZE
#define AV_INPUT_BUFFER_PADDING_SIZE
Definition: defs.h:40
av_crc
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:392
DCA_SYNCWORD_CORE_LE
#define DCA_SYNCWORD_CORE_LE
Definition: dca_syncwords.h:23
avpriv_dca_parse_core_frame_header
int avpriv_dca_parse_core_frame_header(DCACoreFrameHeader *h, const uint8_t *buf, int size)
Parse and validate core frame header.
Definition: dca.c:149
diff
static av_always_inline int diff(const uint32_t a, const uint32_t b)
Definition: vf_palettegen.c:136
ff_dts_demuxer
const AVInputFormat ff_dts_demuxer
Definition: dtsdec.c:136
bytestream.h
h
h
Definition: vp9dsp_template.c:2038
FF_RAW_DEMUXER_CLASS
#define FF_RAW_DEMUXER_CLASS(name)
Definition: rawdec.h:55