srtdec.c
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1 /*
2  * SubRip subtitle decoder
3  * Copyright (c) 2010 Aurelien Jacobs <aurel@gnuage.org>
4  *
5  * This file is part of Libav.
6  *
7  * Libav 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  * Libav 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 Libav; 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/avstring.h"
23 #include "libavutil/parseutils.h"
24 #include "avcodec.h"
25 #include "ass.h"
26 
27 static int html_color_parse(AVCodecContext *avctx, const char *str)
28 {
29  uint8_t rgba[4];
30  if (av_parse_color(rgba, str, strcspn(str, "\" >"), avctx) < 0)
31  return -1;
32  return rgba[0] | rgba[1] << 8 | rgba[2] << 16;
33 }
34 
35 enum {
41 };
42 
43 typedef struct {
44  char tag[128];
45  char param[PARAM_NUMBER][128];
46 } SrtStack;
47 
48 static const char *srt_to_ass(AVCodecContext *avctx, char *out, char *out_end,
49  const char *in, int x1, int y1, int x2, int y2)
50 {
51  char c, *param, buffer[128], tmp[128];
52  int len, tag_close, sptr = 1, line_start = 1, an = 0, end = 0;
53  SrtStack stack[16];
54 
55  stack[0].tag[0] = 0;
56  strcpy(stack[0].param[PARAM_SIZE], "{\\fs}");
57  strcpy(stack[0].param[PARAM_COLOR], "{\\c}");
58  strcpy(stack[0].param[PARAM_FACE], "{\\fn}");
59 
60  if (x1 >= 0 && y1 >= 0) {
61  if (x2 >= 0 && y2 >= 0 && (x2 != x1 || y2 != y1))
62  out += snprintf(out, out_end-out,
63  "{\\an1}{\\move(%d,%d,%d,%d)}", x1, y1, x2, y2);
64  else
65  out += snprintf(out, out_end-out, "{\\an1}{\\pos(%d,%d)}", x1, y1);
66  }
67 
68  for (; out < out_end && !end && *in; in++) {
69  switch (*in) {
70  case '\r':
71  break;
72  case '\n':
73  if (line_start) {
74  end = 1;
75  break;
76  }
77  while (out[-1] == ' ')
78  out--;
79  out += snprintf(out, out_end-out, "\\N");
80  line_start = 1;
81  break;
82  case ' ':
83  if (!line_start)
84  *out++ = *in;
85  break;
86  case '{': /* skip all {\xxx} substrings except for {\an%d}
87  and all microdvd like styles such as {Y:xxx} */
88  an += sscanf(in, "{\\an%*1u}%c", &c) == 1;
89  if ((an != 1 && sscanf(in, "{\\%*[^}]}%n%c", &len, &c) > 0) ||
90  sscanf(in, "{%*1[CcFfoPSsYy]:%*[^}]}%n%c", &len, &c) > 0) {
91  in += len - 1;
92  } else
93  *out++ = *in;
94  break;
95  case '<':
96  tag_close = in[1] == '/';
97  if (sscanf(in+tag_close+1, "%127[^>]>%n%c", buffer, &len,&c) >= 2) {
98  if ((param = strchr(buffer, ' ')))
99  *param++ = 0;
100  if ((!tag_close && sptr < FF_ARRAY_ELEMS(stack)) ||
101  ( tag_close && sptr > 0 && !strcmp(stack[sptr-1].tag, buffer))) {
102  int i, j, unknown = 0;
103  in += len + tag_close;
104  if (!tag_close)
105  memset(stack+sptr, 0, sizeof(*stack));
106  if (!strcmp(buffer, "font")) {
107  if (tag_close) {
108  for (i=PARAM_NUMBER-1; i>=0; i--)
109  if (stack[sptr-1].param[i][0])
110  for (j=sptr-2; j>=0; j--)
111  if (stack[j].param[i][0]) {
112  out += snprintf(out, out_end-out,
113  "%s", stack[j].param[i]);
114  break;
115  }
116  } else {
117  while (param) {
118  if (!strncmp(param, "size=", 5)) {
119  unsigned font_size;
120  param += 5 + (param[5] == '"');
121  if (sscanf(param, "%u", &font_size) == 1) {
122  snprintf(stack[sptr].param[PARAM_SIZE],
123  sizeof(stack[0].param[PARAM_SIZE]),
124  "{\\fs%u}", font_size);
125  }
126  } else if (!strncmp(param, "color=", 6)) {
127  param += 6 + (param[6] == '"');
128  snprintf(stack[sptr].param[PARAM_COLOR],
129  sizeof(stack[0].param[PARAM_COLOR]),
130  "{\\c&H%X&}",
131  html_color_parse(avctx, param));
132  } else if (!strncmp(param, "face=", 5)) {
133  param += 5 + (param[5] == '"');
134  len = strcspn(param,
135  param[-1] == '"' ? "\"" :" ");
136  av_strlcpy(tmp, param,
137  FFMIN(sizeof(tmp), len+1));
138  param += len;
139  snprintf(stack[sptr].param[PARAM_FACE],
140  sizeof(stack[0].param[PARAM_FACE]),
141  "{\\fn%s}", tmp);
142  }
143  if ((param = strchr(param, ' ')))
144  param++;
145  }
146  for (i=0; i<PARAM_NUMBER; i++)
147  if (stack[sptr].param[i][0])
148  out += snprintf(out, out_end-out,
149  "%s", stack[sptr].param[i]);
150  }
151  } else if (!buffer[1] && strspn(buffer, "bisu") == 1) {
152  out += snprintf(out, out_end-out,
153  "{\\%c%d}", buffer[0], !tag_close);
154  } else {
155  unknown = 1;
156  snprintf(tmp, sizeof(tmp), "</%s>", buffer);
157  }
158  if (tag_close) {
159  sptr--;
160  } else if (unknown && !strstr(in, tmp)) {
161  in -= len + tag_close;
162  *out++ = *in;
163  } else
164  av_strlcpy(stack[sptr++].tag, buffer,
165  sizeof(stack[0].tag));
166  break;
167  }
168  }
169  default:
170  *out++ = *in;
171  break;
172  }
173  if (*in != ' ' && *in != '\r' && *in != '\n')
174  line_start = 0;
175  }
176 
177  out = FFMIN(out, out_end-3);
178  while (!strncmp(out-2, "\\N", 2))
179  out -= 2;
180  while (out[-1] == ' ')
181  out--;
182  out += snprintf(out, out_end-out, "\r\n");
183  return in;
184 }
185 
186 static const char *read_ts(const char *buf, int *ts_start, int *ts_end,
187  int *x1, int *y1, int *x2, int *y2)
188 {
189  int i, hs, ms, ss, he, me, se;
190 
191  for (i=0; i<2; i++) {
192  /* try to read timestamps in either the first or second line */
193  int c = sscanf(buf, "%d:%2d:%2d%*1[,.]%3d --> %d:%2d:%2d%*1[,.]%3d"
194  "%*[ ]X1:%u X2:%u Y1:%u Y2:%u",
195  &hs, &ms, &ss, ts_start, &he, &me, &se, ts_end,
196  x1, x2, y1, y2);
197  buf += strcspn(buf, "\n") + 1;
198  if (c >= 8) {
199  *ts_start = 100*(ss + 60*(ms + 60*hs)) + *ts_start/10;
200  *ts_end = 100*(se + 60*(me + 60*he)) + *ts_end /10;
201  return buf;
202  }
203  }
204  return NULL;
205 }
206 
208  void *data, int *got_sub_ptr, AVPacket *avpkt)
209 {
210  AVSubtitle *sub = data;
211  int ts_start, ts_end, x1 = -1, y1 = -1, x2 = -1, y2 = -1;
212  char buffer[2048];
213  const char *ptr = avpkt->data;
214  const char *end = avpkt->data + avpkt->size;
215 
216  if (avpkt->size <= 0)
217  return avpkt->size;
218 
219  ff_ass_init(sub);
220 
221  while (ptr < end && *ptr) {
222  ptr = read_ts(ptr, &ts_start, &ts_end, &x1, &y1, &x2, &y2);
223  if (!ptr)
224  break;
225  ptr = srt_to_ass(avctx, buffer, buffer+sizeof(buffer), ptr,
226  x1, y1, x2, y2);
227  ff_ass_add_rect(sub, buffer, ts_start, ts_end, 0);
228  }
229 
230  *got_sub_ptr = sub->num_rects > 0;
231  return avpkt->size;
232 }
233 
235  .name = "srt",
236  .long_name = NULL_IF_CONFIG_SMALL("SubRip subtitle"),
237  .type = AVMEDIA_TYPE_SUBTITLE,
238  .id = CODEC_ID_SRT,
240  .decode = srt_decode_frame,
241 };