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dca_parser.c
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1 /*
2  * DCA parser
3  * Copyright (C) 2004 Gildas Bazin
4  * Copyright (C) 2004 Benjamin Zores
5  * Copyright (C) 2006 Benjamin Larsson
6  * Copyright (C) 2007 Konstantin Shishkov
7  *
8  * This file is part of FFmpeg.
9  *
10  * FFmpeg is free software; you can redistribute it and/or
11  * modify it under the terms of the GNU Lesser General Public
12  * License as published by the Free Software Foundation; either
13  * version 2.1 of the License, or (at your option) any later version.
14  *
15  * FFmpeg is distributed in the hope that it will be useful,
16  * but WITHOUT ANY WARRANTY; without even the implied warranty of
17  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
18  * Lesser General Public License for more details.
19  *
20  * You should have received a copy of the GNU Lesser General Public
21  * License along with FFmpeg; if not, write to the Free Software
22  * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
23  */
24 
25 #include "dca.h"
26 #include "dca_syncwords.h"
27 #include "get_bits.h"
28 #include "parser.h"
29 
30 typedef struct DCAParseContext {
32  uint32_t lastmarker;
33  int size;
34  int framesize;
36 
37 #define IS_CORE_MARKER(state) \
38  (((state & 0xFFFFFFFFF0FF) == (((uint64_t)DCA_SYNCWORD_CORE_14B_LE << 16) | 0xF007)) || \
39  ((state & 0xFFFFFFFFFFF0) == (((uint64_t)DCA_SYNCWORD_CORE_14B_BE << 16) | 0x07F0)) || \
40  ((state & 0xFFFFFFFF00FC) == (((uint64_t)DCA_SYNCWORD_CORE_LE << 16) | 0x00FC)) || \
41  ((state & 0xFFFFFFFFFC00) == (((uint64_t)DCA_SYNCWORD_CORE_BE << 16) | 0xFC00)))
42 
43 #define IS_EXSS_MARKER(state) ((state & 0xFFFFFFFF) == DCA_SYNCWORD_SUBSTREAM)
44 
45 #define IS_MARKER(state) (IS_CORE_MARKER(state) || IS_EXSS_MARKER(state))
46 
47 #define CORE_MARKER(state) ((state >> 16) & 0xFFFFFFFF)
48 #define EXSS_MARKER(state) (state & 0xFFFFFFFF)
49 
50 /**
51  * Find the end of the current frame in the bitstream.
52  * @return the position of the first byte of the next frame, or -1
53  */
55  int buf_size)
56 {
57  int start_found, i;
58  uint64_t state;
59  ParseContext *pc = &pc1->pc;
60 
61  start_found = pc->frame_start_found;
62  state = pc->state64;
63 
64  i = 0;
65  if (!start_found) {
66  for (i = 0; i < buf_size; i++) {
67  state = (state << 8) | buf[i];
68  if (IS_MARKER(state)) {
69  if (!pc1->lastmarker ||
70  pc1->lastmarker == CORE_MARKER(state) ||
72  start_found = 1;
73  if (IS_EXSS_MARKER(state))
74  pc1->lastmarker = EXSS_MARKER(state);
75  else
76  pc1->lastmarker = CORE_MARKER(state);
77  i++;
78  break;
79  }
80  }
81  }
82  }
83  if (start_found) {
84  for (; i < buf_size; i++) {
85  pc1->size++;
86  state = (state << 8) | buf[i];
87  if (IS_MARKER(state) &&
88  (pc1->lastmarker == CORE_MARKER(state) ||
90  if (pc1->framesize > pc1->size)
91  continue;
92  pc->frame_start_found = 0;
93  pc->state64 = -1;
94  pc1->size = 0;
95  return IS_EXSS_MARKER(state) ? i - 3 : i - 5;
96  }
97  }
98  }
99  pc->frame_start_found = start_found;
100  pc->state64 = state;
101  return END_NOT_FOUND;
102 }
103 
105 {
106  DCAParseContext *pc1 = s->priv_data;
107 
108  pc1->lastmarker = 0;
109  return 0;
110 }
111 
112 static int dca_parse_params(const uint8_t *buf, int buf_size, int *duration,
113  int *sample_rate, int *framesize)
114 {
115  GetBitContext gb;
116  uint8_t hdr[12 + FF_INPUT_BUFFER_PADDING_SIZE] = { 0 };
117  int ret, sample_blocks, sr_code;
118 
119  if (buf_size < 12)
120  return AVERROR_INVALIDDATA;
121 
122  if ((ret = avpriv_dca_convert_bitstream(buf, 12, hdr, 12)) < 0)
123  return ret;
124 
125  init_get_bits(&gb, hdr, 96);
126 
127  skip_bits_long(&gb, 39);
128  sample_blocks = get_bits(&gb, 7) + 1;
129  if (sample_blocks < 8)
130  return AVERROR_INVALIDDATA;
131  *duration = 256 * (sample_blocks / 8);
132 
133  *framesize = get_bits(&gb, 14) + 1;
134  if (*framesize < 95)
135  return AVERROR_INVALIDDATA;
136 
137  skip_bits(&gb, 6);
138  sr_code = get_bits(&gb, 4);
139  *sample_rate = avpriv_dca_sample_rates[sr_code];
140  if (*sample_rate == 0)
141  return AVERROR_INVALIDDATA;
142 
143  return 0;
144 }
145 
147  const uint8_t **poutbuf, int *poutbuf_size,
148  const uint8_t *buf, int buf_size)
149 {
150  DCAParseContext *pc1 = s->priv_data;
151  ParseContext *pc = &pc1->pc;
152  int next, duration, sample_rate;
153 
155  next = buf_size;
156  } else {
157  next = dca_find_frame_end(pc1, buf, buf_size);
158 
159  if (ff_combine_frame(pc, next, &buf, &buf_size) < 0) {
160  *poutbuf = NULL;
161  *poutbuf_size = 0;
162  return buf_size;
163  }
164  }
165 
166  /* read the duration and sample rate from the frame header */
167  if (!dca_parse_params(buf, buf_size, &duration, &sample_rate, &pc1->framesize)) {
168  s->duration = duration;
169  avctx->sample_rate = sample_rate;
170  } else
171  s->duration = 0;
172 
173  *poutbuf = buf;
174  *poutbuf_size = buf_size;
175  return next;
176 }
177 
179  .codec_ids = { AV_CODEC_ID_DTS },
180  .priv_data_size = sizeof(DCAParseContext),
181  .parser_init = dca_parse_init,
182  .parser_parse = dca_parse,
183  .parser_close = ff_parse_close,
184 };