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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 {
38  PARAM_UNKNOWN = -1,
39  PARAM_SIZE,
40  PARAM_COLOR,
41  PARAM_FACE,
42  PARAM_NUMBER
43 };
44 
45 typedef struct SrtStack {
46  char tag[128];
47  char param[PARAM_NUMBER][128];
48 } SrtStack;
49 
50 static void rstrip_spaces_buf(AVBPrint *buf)
51 {
52  while (buf->len > 0 && buf->str[buf->len - 1] == ' ')
53  buf->str[--buf->len] = 0;
54 }
55 
56 static void srt_to_ass(AVCodecContext *avctx, AVBPrint *dst,
57  const char *in, int x1, int y1, int x2, int y2)
58 {
59  char *param, buffer[128], tmp[128];
60  int len, tag_close, sptr = 1, line_start = 1, an = 0, end = 0;
61  SrtStack stack[16];
62 
63  stack[0].tag[0] = 0;
64  strcpy(stack[0].param[PARAM_SIZE], "{\\fs}");
65  strcpy(stack[0].param[PARAM_COLOR], "{\\c}");
66  strcpy(stack[0].param[PARAM_FACE], "{\\fn}");
67 
68  if (x1 >= 0 && y1 >= 0) {
69  if (x2 >= 0 && y2 >= 0 && (x2 != x1 || y2 != y1))
70  av_bprintf(dst, "{\\an1}{\\move(%d,%d,%d,%d)}", x1, y1, x2, y2);
71  else
72  av_bprintf(dst, "{\\an1}{\\pos(%d,%d)}", x1, y1);
73  }
74 
75  for (; !end && *in; in++) {
76  switch (*in) {
77  case '\r':
78  break;
79  case '\n':
80  if (line_start) {
81  end = 1;
82  break;
83  }
84  rstrip_spaces_buf(dst);
85  av_bprintf(dst, "\\N");
86  line_start = 1;
87  break;
88  case ' ':
89  if (!line_start)
90  av_bprint_chars(dst, *in, 1);
91  break;
92  case '{': /* skip all {\xxx} substrings except for {\an%d}
93  and all microdvd like styles such as {Y:xxx} */
94  len = 0;
95  an += sscanf(in, "{\\an%*1u}%n", &len) >= 0 && len > 0;
96  if ((an != 1 && (len = 0, sscanf(in, "{\\%*[^}]}%n", &len) >= 0 && len > 0)) ||
97  (len = 0, sscanf(in, "{%*1[CcFfoPSsYy]:%*[^}]}%n", &len) >= 0 && len > 0)) {
98  in += len - 1;
99  } else
100  av_bprint_chars(dst, *in, 1);
101  break;
102  case '<':
103  tag_close = in[1] == '/';
104  len = 0;
105  if (sscanf(in+tag_close+1, "%127[^>]>%n", buffer, &len) >= 1 && len > 0) {
106  if ((param = strchr(buffer, ' ')))
107  *param++ = 0;
108  if ((!tag_close && sptr < FF_ARRAY_ELEMS(stack)) ||
109  ( tag_close && sptr > 0 && !strcmp(stack[sptr-1].tag, buffer))) {
110  int i, j, unknown = 0;
111  in += len + tag_close;
112  if (!tag_close)
113  memset(stack+sptr, 0, sizeof(*stack));
114  if (!strcmp(buffer, "font")) {
115  if (tag_close) {
116  for (i=PARAM_NUMBER-1; i>=0; i--)
117  if (stack[sptr-1].param[i][0])
118  for (j=sptr-2; j>=0; j--)
119  if (stack[j].param[i][0]) {
120  av_bprintf(dst, "%s", stack[j].param[i]);
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  av_bprintf(dst, "%s", stack[sptr].param[i]);
156  }
157  } else if (!buffer[1] && strspn(buffer, "bisu") == 1) {
158  av_bprintf(dst, "{\\%c%d}", buffer[0], !tag_close);
159  } else {
160  unknown = 1;
161  snprintf(tmp, sizeof(tmp), "</%s>", buffer);
162  }
163  if (tag_close) {
164  sptr--;
165  } else if (unknown && !strstr(in, tmp)) {
166  in -= len + tag_close;
167  av_bprint_chars(dst, *in, 1);
168  } else
169  av_strlcpy(stack[sptr++].tag, buffer,
170  sizeof(stack[0].tag));
171  break;
172  }
173  }
174  default:
175  av_bprint_chars(dst, *in, 1);
176  break;
177  }
178  if (*in != ' ' && *in != '\r' && *in != '\n')
179  line_start = 0;
180  }
181 
182  while (dst->len >= 2 && !strncmp(&dst->str[dst->len - 2], "\\N", 2))
183  dst->len -= 2;
184  dst->str[dst->len] = 0;
185  rstrip_spaces_buf(dst);
186 }
187 
188 static int srt_decode_frame(AVCodecContext *avctx,
189  void *data, int *got_sub_ptr, AVPacket *avpkt)
190 {
191  AVSubtitle *sub = data;
192  AVBPrint buffer;
193  int ts_start, ts_end, x1 = -1, y1 = -1, x2 = -1, y2 = -1;
194  int size, ret;
195  const uint8_t *p = av_packet_get_side_data(avpkt, AV_PKT_DATA_SUBTITLE_POSITION, &size);
196 
197  if (p && size == 16) {
198  x1 = AV_RL32(p );
199  y1 = AV_RL32(p + 4);
200  x2 = AV_RL32(p + 8);
201  y2 = AV_RL32(p + 12);
202  }
203 
204  if (avpkt->size <= 0)
205  return avpkt->size;
206 
207  av_bprint_init(&buffer, 0, AV_BPRINT_SIZE_UNLIMITED);
208 
209  // TODO: reindent
210  // Do final divide-by-10 outside rescale to force rounding down.
211  ts_start = av_rescale_q(avpkt->pts,
212  avctx->time_base,
213  (AVRational){1,100});
214  ts_end = av_rescale_q(avpkt->pts + avpkt->duration,
215  avctx->time_base,
216  (AVRational){1,100});
217 
218  srt_to_ass(avctx, &buffer, avpkt->data, x1, y1, x2, y2);
219  ret = ff_ass_add_rect_bprint(sub, &buffer, ts_start, ts_end-ts_start);
220  av_bprint_finalize(&buffer, NULL);
221  if (ret < 0)
222  return ret;
223 
224  *got_sub_ptr = sub->num_rects > 0;
225  return avpkt->size;
226 }
227 
228 #if CONFIG_SRT_DECODER
229 /* deprecated decoder */
230 AVCodec ff_srt_decoder = {
231  .name = "srt",
232  .long_name = NULL_IF_CONFIG_SMALL("SubRip subtitle"),
233  .type = AVMEDIA_TYPE_SUBTITLE,
234  .id = AV_CODEC_ID_SUBRIP,
235  .init = ff_ass_subtitle_header_default,
236  .decode = srt_decode_frame,
237 };
238 #endif
239 
240 #if CONFIG_SUBRIP_DECODER
241 AVCodec ff_subrip_decoder = {
242  .name = "subrip",
243  .long_name = NULL_IF_CONFIG_SMALL("SubRip subtitle"),
244  .type = AVMEDIA_TYPE_SUBTITLE,
245  .id = AV_CODEC_ID_SUBRIP,
246  .init = ff_ass_subtitle_header_default,
247  .decode = srt_decode_frame,
248 };
249 #endif
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