FFmpeg
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subtitles.c
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1 /*
2  * Copyright (c) 2012-2013 Clément Bœsch <u pkh me>
3  *
4  * This file is part of FFmpeg.
5  *
6  * FFmpeg is free software; you can redistribute it and/or
7  * modify it under the terms of the GNU Lesser General Public
8  * License as published by the Free Software Foundation; either
9  * version 2.1 of the License, or (at your option) any later version.
10  *
11  * FFmpeg is distributed in the hope that it will be useful,
12  * but WITHOUT ANY WARRANTY; without even the implied warranty of
13  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
14  * Lesser General Public License for more details.
15  *
16  * You should have received a copy of the GNU Lesser General Public
17  * License along with FFmpeg; if not, write to the Free Software
18  * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
19  */
20 
21 #include "avformat.h"
22 #include "subtitles.h"
23 #include "libavutil/avassert.h"
24 #include "libavutil/avstring.h"
25 
27  const uint8_t *event, int len, int merge)
28 {
29  AVPacket *subs, *sub;
30 
31  if (merge && q->nb_subs > 0) {
32  /* merge with previous event */
33 
34  int old_len;
35  sub = &q->subs[q->nb_subs - 1];
36  old_len = sub->size;
37  if (av_grow_packet(sub, len) < 0)
38  return NULL;
39  memcpy(sub->data + old_len, event, len);
40  } else {
41  /* new event */
42 
43  if (q->nb_subs >= INT_MAX/sizeof(*q->subs) - 1)
44  return NULL;
45  subs = av_fast_realloc(q->subs, &q->allocated_size,
46  (q->nb_subs + 1) * sizeof(*q->subs));
47  if (!subs)
48  return NULL;
49  q->subs = subs;
50  sub = &subs[q->nb_subs++];
51  if (av_new_packet(sub, len) < 0)
52  return NULL;
53  sub->flags |= AV_PKT_FLAG_KEY;
54  sub->pts = sub->dts = 0;
55  memcpy(sub->data, event, len);
56  }
57  return sub;
58 }
59 
60 static int cmp_pkt_sub_ts_pos(const void *a, const void *b)
61 {
62  const AVPacket *s1 = a;
63  const AVPacket *s2 = b;
64  if (s1->pts == s2->pts) {
65  if (s1->pos == s2->pos)
66  return 0;
67  return s1->pos > s2->pos ? 1 : -1;
68  }
69  return s1->pts > s2->pts ? 1 : -1;
70 }
71 
72 static int cmp_pkt_sub_pos_ts(const void *a, const void *b)
73 {
74  const AVPacket *s1 = a;
75  const AVPacket *s2 = b;
76  if (s1->pos == s2->pos) {
77  if (s1->pts == s2->pts)
78  return 0;
79  return s1->pts > s2->pts ? 1 : -1;
80  }
81  return s1->pos > s2->pos ? 1 : -1;
82 }
83 
85 {
86  int i;
87 
88  qsort(q->subs, q->nb_subs, sizeof(*q->subs),
91  for (i = 0; i < q->nb_subs; i++)
92  if (q->subs[i].duration == -1 && i < q->nb_subs - 1)
93  q->subs[i].duration = q->subs[i + 1].pts - q->subs[i].pts;
94 }
95 
97 {
98  AVPacket *sub = q->subs + q->current_sub_idx;
99 
100  if (q->current_sub_idx == q->nb_subs)
101  return AVERROR_EOF;
102  if (av_copy_packet(pkt, sub) < 0) {
103  return AVERROR(ENOMEM);
104  }
105 
106  pkt->dts = pkt->pts;
107  q->current_sub_idx++;
108  return 0;
109 }
110 
111 static int search_sub_ts(const FFDemuxSubtitlesQueue *q, int64_t ts)
112 {
113  int s1 = 0, s2 = q->nb_subs - 1;
114 
115  if (s2 < s1)
116  return AVERROR(ERANGE);
117 
118  for (;;) {
119  int mid;
120 
121  if (s1 == s2)
122  return s1;
123  if (s1 == s2 - 1)
124  return q->subs[s1].pts <= q->subs[s2].pts ? s1 : s2;
125  mid = (s1 + s2) / 2;
126  if (q->subs[mid].pts <= ts)
127  s1 = mid;
128  else
129  s2 = mid;
130  }
131 }
132 
134  int64_t min_ts, int64_t ts, int64_t max_ts, int flags)
135 {
136  if (flags & AVSEEK_FLAG_BYTE) {
137  return AVERROR(ENOSYS);
138  } else if (flags & AVSEEK_FLAG_FRAME) {
139  if (ts < 0 || ts >= q->nb_subs)
140  return AVERROR(ERANGE);
141  q->current_sub_idx = ts;
142  } else {
143  int i, idx = search_sub_ts(q, ts);
144  int64_t ts_selected;
145 
146  if (idx < 0)
147  return idx;
148  for (i = idx; i < q->nb_subs && q->subs[i].pts < min_ts; i++)
149  if (stream_index == -1 || q->subs[i].stream_index == stream_index)
150  idx = i;
151  for (i = idx; i > 0 && q->subs[i].pts > max_ts; i--)
152  if (stream_index == -1 || q->subs[i].stream_index == stream_index)
153  idx = i;
154 
155  ts_selected = q->subs[idx].pts;
156  if (ts_selected < min_ts || ts_selected > max_ts)
157  return AVERROR(ERANGE);
158 
159  /* look back in the latest subtitles for overlapping subtitles */
160  for (i = idx - 1; i >= 0; i--) {
161  int64_t pts = q->subs[i].pts;
162  if (q->subs[i].duration <= 0 ||
163  (stream_index != -1 && q->subs[i].stream_index != stream_index))
164  continue;
165  if (pts >= min_ts && pts > ts_selected - q->subs[i].duration)
166  idx = i;
167  else
168  break;
169  }
170 
171  /* If the queue is used to store multiple subtitles streams (like with
172  * VobSub) and the stream index is not specified, we need to make sure
173  * to focus on the smallest file position offset for a same timestamp;
174  * queue is ordered by pts and then filepos, so we can take the first
175  * entry for a given timestamp. */
176  if (stream_index == -1)
177  while (idx > 0 && q->subs[idx - 1].pts == q->subs[idx].pts)
178  idx--;
179 
180  q->current_sub_idx = idx;
181  }
182  return 0;
183 }
184 
186 {
187  int i;
188 
189  for (i = 0; i < q->nb_subs; i++)
190  av_free_packet(&q->subs[i]);
191  av_freep(&q->subs);
192  q->nb_subs = q->allocated_size = q->current_sub_idx = 0;
193 }
194 
196 {
197  int i = 0;
198  char end_chr;
199 
200  if (!*c) // cached char?
201  *c = avio_r8(pb);
202  if (!*c)
203  return 0;
204 
205  end_chr = *c == '<' ? '>' : '<';
206  do {
207  av_bprint_chars(buf, *c, 1);
208  *c = avio_r8(pb);
209  i++;
210  } while (*c != end_chr && *c);
211  if (end_chr == '>') {
212  av_bprint_chars(buf, '>', 1);
213  *c = 0;
214  }
215  return i;
216 }
217 
218 const char *ff_smil_get_attr_ptr(const char *s, const char *attr)
219 {
220  int in_quotes = 0;
221  const int len = strlen(attr);
222 
223  while (*s) {
224  while (*s) {
225  if (!in_quotes && av_isspace(*s))
226  break;
227  in_quotes ^= *s == '"'; // XXX: support escaping?
228  s++;
229  }
230  while (av_isspace(*s))
231  s++;
232  if (!av_strncasecmp(s, attr, len) && s[len] == '=')
233  return s + len + 1 + (s[len + 1] == '"');
234  }
235  return NULL;
236 }
237 
238 static inline int is_eol(char c)
239 {
240  return c == '\r' || c == '\n';
241 }
242 
244 {
245  char eol_buf[5], last_was_cr = 0;
246  int n = 0, i = 0, nb_eol = 0;
247 
248  av_bprint_clear(buf);
249 
250  for (;;) {
251  char c = avio_r8(pb);
252 
253  if (!c)
254  break;
255 
256  /* ignore all initial line breaks */
257  if (n == 0 && is_eol(c))
258  continue;
259 
260  /* line break buffering: we don't want to add the trailing \r\n */
261  if (is_eol(c)) {
262  nb_eol += c == '\n' || last_was_cr;
263  if (nb_eol == 2)
264  break;
265  eol_buf[i++] = c;
266  if (i == sizeof(eol_buf) - 1)
267  break;
268  last_was_cr = c == '\r';
269  continue;
270  }
271 
272  /* only one line break followed by data: we flush the line breaks
273  * buffer */
274  if (i) {
275  eol_buf[i] = 0;
276  av_bprintf(buf, "%s", eol_buf);
277  i = nb_eol = 0;
278  }
279 
280  av_bprint_chars(buf, c, 1);
281  n++;
282  }
283 }