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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/dca.h"
25 #include "libavcodec/get_bits.h"
26 
27 #include "avformat.h"
28 #include "rawdec.h"
29 
30 static int dts_probe(AVProbeData *p)
31 {
32  const uint8_t *buf, *bufp;
33  uint32_t state = -1;
34  int markers[4*16] = {0};
35  int sum, max, i;
36  int64_t diff = 0;
37  uint8_t hdr[12 + AV_INPUT_BUFFER_PADDING_SIZE] = { 0 };
38 
39  buf = p->buf + FFMIN(4096, p->buf_size);
40 
41  for(; buf < (p->buf+p->buf_size)-2; buf+=2) {
42  int marker, sample_blocks, sample_rate, sr_code, framesize;
43  int lfe;
44  GetBitContext gb;
45 
46  bufp = buf;
47  state = (state << 16) | bytestream_get_be16(&bufp);
48 
49  if (buf - p->buf >= 4)
50  diff += FFABS(((int16_t)AV_RL16(buf)) - (int16_t)AV_RL16(buf-4));
51 
52  /* regular bitstream */
53  if (state == DCA_SYNCWORD_CORE_BE &&
54  (bytestream_get_be16(&bufp) & 0xFC00) == 0xFC00)
55  marker = 0;
56  else if (state == DCA_SYNCWORD_CORE_LE &&
57  (bytestream_get_be16(&bufp) & 0x00FC) == 0x00FC)
58  marker = 1;
59 
60  /* 14 bits big-endian bitstream */
61  else if (state == DCA_SYNCWORD_CORE_14B_BE &&
62  (bytestream_get_be16(&bufp) & 0xFFF0) == 0x07F0)
63  marker = 2;
64 
65  /* 14 bits little-endian bitstream */
66  else if (state == DCA_SYNCWORD_CORE_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  get_bits(&gb, 5);
93  if (get_bits(&gb, 1))
94  continue;
95 
96  skip_bits_long(&gb, 9);
97  lfe = get_bits(&gb, 2);
98  if (lfe > 2)
99  continue;
100 
101  marker += 4* sr_code;
102 
103  markers[marker] ++;
104  }
105 
106  sum = max = 0;
107  for (i=0; i<FF_ARRAY_ELEMS(markers); i++) {
108  sum += markers[i];
109  if (markers[max] < markers[i])
110  max = i;
111  }
112 
113  if (markers[max] > 3 && p->buf_size / markers[max] < 32*1024 &&
114  markers[max] * 4 > sum * 3 &&
115  diff / p->buf_size > 200)
116  return AVPROBE_SCORE_EXTENSION + 1;
117 
118  return 0;
119 }
120 
122  .name = "dts",
123  .long_name = NULL_IF_CONFIG_SMALL("raw DTS"),
124  .read_probe = dts_probe,
125  .read_header = ff_raw_audio_read_header,
126  .read_packet = ff_raw_read_partial_packet,
127  .flags = AVFMT_GENERIC_INDEX,
128  .extensions = "dts",
129  .raw_codec_id = AV_CODEC_ID_DTS,
130 };
static unsigned int get_bits(GetBitContext *s, int n)
Read 1-25 bits.
Definition: get_bits.h:260
static void skip_bits_long(GetBitContext *s, int n)
Definition: get_bits.h:217
static int dts_probe(AVProbeData *p)
Definition: dtsdec.c:30
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
bitstream reader API header.
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:175
int buf_size
Size of buf except extra allocated bytes.
Definition: avformat.h:451
unsigned char * buf
Buffer must have AVPROBE_PADDING_SIZE of extra allocated bytes filled with zero.
Definition: avformat.h:450
#define FFMIN(a, b)
Definition: common.h:81
int ff_raw_audio_read_header(AVFormatContext *s)
Definition: rawdec.c:55
static struct @197 state
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:39
#define FFABS(a)
Absolute value, Note, INT_MIN / INT64_MIN result in undefined behavior as they are not representable ...
Definition: common.h:68
const uint32_t avpriv_dca_sample_rates[16]
Definition: dca.c:34
#define FF_ARRAY_ELEMS(a)
sample_rate
AVInputFormat ff_dts_demuxer
Definition: dtsdec.c:121
void * buf
Definition: avisynth_c.h:553
static void skip_bits(GetBitContext *s, int n)
Definition: get_bits.h:297
#define AVFMT_GENERIC_INDEX
Use generic index building code.
Definition: avformat.h:473
static int init_get_bits(GetBitContext *s, const uint8_t *buffer, int bit_size)
Initialize GetBitContext.
Definition: get_bits.h:410
#define AVPROBE_SCORE_EXTENSION
score for file extension
Definition: avformat.h:458
This structure contains the data a format has to probe a file.
Definition: avformat.h:448
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:636
static av_always_inline int diff(const uint32_t a, const uint32_t b)
const char * name
A comma separated list of short names for the format.
Definition: avformat.h:628