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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 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/avstring.h"
23 #include "libavutil/common.h"
24 #include "libavutil/intreadwrite.h"
25 #include "libavutil/parseutils.h"
26 #include "avcodec.h"
27 #include "ass.h"
28 
29 static int html_color_parse(AVCodecContext *avctx, const char *str)
30 {
31  uint8_t rgba[4];
32  if (av_parse_color(rgba, str, strcspn(str, "\" >"), avctx) < 0)
33  return -1;
34  return rgba[0] | rgba[1] << 8 | rgba[2] << 16;
35 }
36 
37 enum {
43 };
44 
45 typedef struct {
46  char tag[128];
47  char param[PARAM_NUMBER][128];
48 } SrtStack;
49 
50 static const char *srt_to_ass(AVCodecContext *avctx, char *out, char *out_end,
51  const char *in, int x1, int y1, int x2, int y2)
52 {
53  char *param, buffer[128], tmp[128];
54  int len, tag_close, sptr = 1, line_start = 1, an = 0, end = 0;
55  SrtStack stack[16];
56 
57  stack[0].tag[0] = 0;
58  strcpy(stack[0].param[PARAM_SIZE], "{\\fs}");
59  strcpy(stack[0].param[PARAM_COLOR], "{\\c}");
60  strcpy(stack[0].param[PARAM_FACE], "{\\fn}");
61 
62  if (x1 >= 0 && y1 >= 0) {
63  if (x2 >= 0 && y2 >= 0 && (x2 != x1 || y2 != y1))
64  snprintf(out, out_end-out,
65  "{\\an1}{\\move(%d,%d,%d,%d)}", x1, y1, x2, y2);
66  else
67  snprintf(out, out_end-out, "{\\an1}{\\pos(%d,%d)}", x1, y1);
68  out += strlen(out);
69  }
70 
71  for (; out < out_end && !end && *in; in++) {
72  switch (*in) {
73  case '\r':
74  break;
75  case '\n':
76  if (line_start) {
77  end = 1;
78  break;
79  }
80  while (out[-1] == ' ')
81  out--;
82  snprintf(out, out_end-out, "\\N");
83  if(out<out_end) out += strlen(out);
84  line_start = 1;
85  break;
86  case ' ':
87  if (!line_start)
88  *out++ = *in;
89  break;
90  case '{': /* skip all {\xxx} substrings except for {\an%d}
91  and all microdvd like styles such as {Y:xxx} */
92  len = 0;
93  an += sscanf(in, "{\\an%*1u}%n", &len) >= 0 && len > 0;
94  if ((an != 1 && (len = 0, sscanf(in, "{\\%*[^}]}%n", &len) >= 0 && len > 0)) ||
95  (len = 0, sscanf(in, "{%*1[CcFfoPSsYy]:%*[^}]}%n", &len) >= 0 && len > 0)) {
96  in += len - 1;
97  } else
98  *out++ = *in;
99  break;
100  case '<':
101  tag_close = in[1] == '/';
102  len = 0;
103  if (sscanf(in+tag_close+1, "%127[^>]>%n", buffer, &len) >= 1 && len > 0) {
104  if ((param = strchr(buffer, ' ')))
105  *param++ = 0;
106  if ((!tag_close && sptr < FF_ARRAY_ELEMS(stack)) ||
107  ( tag_close && sptr > 0 && !strcmp(stack[sptr-1].tag, buffer))) {
108  int i, j, unknown = 0;
109  in += len + tag_close;
110  if (!tag_close)
111  memset(stack+sptr, 0, sizeof(*stack));
112  if (!strcmp(buffer, "font")) {
113  if (tag_close) {
114  for (i=PARAM_NUMBER-1; i>=0; i--)
115  if (stack[sptr-1].param[i][0])
116  for (j=sptr-2; j>=0; j--)
117  if (stack[j].param[i][0]) {
118  snprintf(out, out_end-out,
119  "%s", stack[j].param[i]);
120  if(out<out_end) out += strlen(out);
121  break;
122  }
123  } else {
124  while (param) {
125  if (!strncmp(param, "size=", 5)) {
126  unsigned font_size;
127  param += 5 + (param[5] == '"');
128  if (sscanf(param, "%u", &font_size) == 1) {
129  snprintf(stack[sptr].param[PARAM_SIZE],
130  sizeof(stack[0].param[PARAM_SIZE]),
131  "{\\fs%u}", font_size);
132  }
133  } else if (!strncmp(param, "color=", 6)) {
134  param += 6 + (param[6] == '"');
135  snprintf(stack[sptr].param[PARAM_COLOR],
136  sizeof(stack[0].param[PARAM_COLOR]),
137  "{\\c&H%X&}",
138  html_color_parse(avctx, param));
139  } else if (!strncmp(param, "face=", 5)) {
140  param += 5 + (param[5] == '"');
141  len = strcspn(param,
142  param[-1] == '"' ? "\"" :" ");
143  av_strlcpy(tmp, param,
144  FFMIN(sizeof(tmp), len+1));
145  param += len;
146  snprintf(stack[sptr].param[PARAM_FACE],
147  sizeof(stack[0].param[PARAM_FACE]),
148  "{\\fn%s}", tmp);
149  }
150  if ((param = strchr(param, ' ')))
151  param++;
152  }
153  for (i=0; i<PARAM_NUMBER; i++)
154  if (stack[sptr].param[i][0]) {
155  snprintf(out, out_end-out,
156  "%s", stack[sptr].param[i]);
157  if(out<out_end) out += strlen(out);
158  }
159  }
160  } else if (!buffer[1] && strspn(buffer, "bisu") == 1) {
161  snprintf(out, out_end-out,
162  "{\\%c%d}", buffer[0], !tag_close);
163  if(out<out_end) out += strlen(out);
164  } else {
165  unknown = 1;
166  snprintf(tmp, sizeof(tmp), "</%s>", buffer);
167  }
168  if (tag_close) {
169  sptr--;
170  } else if (unknown && !strstr(in, tmp)) {
171  in -= len + tag_close;
172  *out++ = *in;
173  } else
174  av_strlcpy(stack[sptr++].tag, buffer,
175  sizeof(stack[0].tag));
176  break;
177  }
178  }
179  default:
180  *out++ = *in;
181  break;
182  }
183  if (*in != ' ' && *in != '\r' && *in != '\n')
184  line_start = 0;
185  }
186 
187  out = FFMIN(out, out_end-3);
188  while (!strncmp(out-2, "\\N", 2))
189  out -= 2;
190  while (out[-1] == ' ')
191  out--;
192  snprintf(out, out_end-out, "\r\n");
193  return in;
194 }
195 
196 static const char *read_ts(const char *buf, int *ts_start, int *ts_end,
197  int *x1, int *y1, int *x2, int *y2)
198 {
199  int i, hs, ms, ss, he, me, se;
200 
201  for (i=0; i<2; i++) {
202  /* try to read timestamps in either the first or second line */
203  int c = sscanf(buf, "%d:%2d:%2d%*1[,.]%3d --> %d:%2d:%2d%*1[,.]%3d"
204  "%*[ ]X1:%u X2:%u Y1:%u Y2:%u",
205  &hs, &ms, &ss, ts_start, &he, &me, &se, ts_end,
206  x1, x2, y1, y2);
207  buf += strcspn(buf, "\n");
208  buf += !!*buf;
209  if (c >= 8) {
210  *ts_start = 100*(ss + 60*(ms + 60*hs)) + *ts_start/10;
211  *ts_end = 100*(se + 60*(me + 60*he)) + *ts_end /10;
212  return buf;
213  }
214  }
215  return NULL;
216 }
217 
219  void *data, int *got_sub_ptr, AVPacket *avpkt)
220 {
221  AVSubtitle *sub = data;
222  int ts_start, ts_end, x1 = -1, y1 = -1, x2 = -1, y2 = -1;
223  char buffer[2048];
224  const char *ptr = avpkt->data;
225  const char *end = avpkt->data + avpkt->size;
226  int size;
228 
229  if (p && size == 16) {
230  x1 = AV_RL32(p );
231  y1 = AV_RL32(p + 4);
232  x2 = AV_RL32(p + 8);
233  y2 = AV_RL32(p + 12);
234  }
235 
236  if (avpkt->size <= 0)
237  return avpkt->size;
238 
239  while (ptr < end && *ptr) {
240  if (avctx->codec->id == AV_CODEC_ID_SRT) {
241  ptr = read_ts(ptr, &ts_start, &ts_end, &x1, &y1, &x2, &y2);
242  if (!ptr)
243  break;
244  } else {
245  // Do final divide-by-10 outside rescale to force rounding down.
246  ts_start = av_rescale_q(avpkt->pts,
247  avctx->time_base,
248  (AVRational){1,100});
249  ts_end = av_rescale_q(avpkt->pts + avpkt->duration,
250  avctx->time_base,
251  (AVRational){1,100});
252  }
253  ptr = srt_to_ass(avctx, buffer, buffer+sizeof(buffer), ptr,
254  x1, y1, x2, y2);
255  ff_ass_add_rect(sub, buffer, ts_start, ts_end-ts_start, 0);
256  }
257 
258  *got_sub_ptr = sub->num_rects > 0;
259  return avpkt->size;
260 }
261 
262 #if CONFIG_SRT_DECODER
263 /* deprecated decoder */
264 AVCodec ff_srt_decoder = {
265  .name = "srt",
266  .long_name = NULL_IF_CONFIG_SMALL("SubRip subtitle with embedded timing"),
267  .type = AVMEDIA_TYPE_SUBTITLE,
268  .id = AV_CODEC_ID_SRT,
270  .decode = srt_decode_frame,
271 };
272 #endif
273 
274 #if CONFIG_SUBRIP_DECODER
275 AVCodec ff_subrip_decoder = {
276  .name = "subrip",
277  .long_name = NULL_IF_CONFIG_SMALL("SubRip subtitle"),
278  .type = AVMEDIA_TYPE_SUBTITLE,
279  .id = AV_CODEC_ID_SUBRIP,
281  .decode = srt_decode_frame,
282 };
283 #endif