FFmpeg
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subtitles.c
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1 /*
2  * Copyright (c) 2012 Clément Bœsch
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/avstring.h"
24 
26  const uint8_t *event, int len, int merge)
27 {
28  AVPacket *subs, *sub;
29 
30  if (merge && q->nb_subs > 0) {
31  /* merge with previous event */
32 
33  int old_len;
34  sub = &q->subs[q->nb_subs - 1];
35  old_len = sub->size;
36  if (av_grow_packet(sub, len) < 0)
37  return NULL;
38  memcpy(sub->data + old_len, event, len);
39  } else {
40  /* new event */
41 
42  if (q->nb_subs >= INT_MAX/sizeof(*q->subs) - 1)
43  return NULL;
44  subs = av_fast_realloc(q->subs, &q->allocated_size,
45  (q->nb_subs + 1) * sizeof(*q->subs));
46  if (!subs)
47  return NULL;
48  q->subs = subs;
49  sub = &subs[q->nb_subs++];
50  if (av_new_packet(sub, len) < 0)
51  return NULL;
52  sub->destruct = 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(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 
73 {
74  int i;
75 
76  qsort(q->subs, q->nb_subs, sizeof(*q->subs), cmp_pkt_sub);
77  for (i = 0; i < q->nb_subs; i++)
78  if (q->subs[i].duration == -1 && i < q->nb_subs - 1)
79  q->subs[i].duration = q->subs[i + 1].pts - q->subs[i].pts;
80 }
81 
83 {
84  AVPacket *sub = q->subs + q->current_sub_idx;
85 
86  if (q->current_sub_idx == q->nb_subs)
87  return AVERROR_EOF;
88  *pkt = *sub;
89  pkt->dts = pkt->pts;
90  q->current_sub_idx++;
91  return 0;
92 }
93 
95  int64_t min_ts, int64_t ts, int64_t max_ts, int flags)
96 {
97  if (flags & AVSEEK_FLAG_BYTE) {
98  return AVERROR(ENOSYS);
99  } else if (flags & AVSEEK_FLAG_FRAME) {
100  if (ts < 0 || ts >= q->nb_subs)
101  return AVERROR(ERANGE);
102  q->current_sub_idx = ts;
103  } else {
104  int i, idx = -1;
105  int64_t min_ts_diff = INT64_MAX;
106  int64_t ts_selected;
107  /* TODO: q->subs[] is sorted by pts so we could do a binary search */
108  for (i = 0; i < q->nb_subs; i++) {
109  int64_t pts = q->subs[i].pts;
110  uint64_t ts_diff = FFABS(pts - ts);
111  if (pts >= min_ts && pts <= max_ts && ts_diff < min_ts_diff) {
112  min_ts_diff = ts_diff;
113  idx = i;
114  }
115  }
116  if (idx < 0)
117  return AVERROR(ERANGE);
118  /* look back in the latest subtitles for overlapping subtitles */
119  ts_selected = q->subs[idx].pts;
120  for (i = idx - 1; i >= 0; i--) {
121  if (q->subs[i].duration <= 0)
122  continue;
123  if (q->subs[i].pts > ts_selected - q->subs[i].duration)
124  idx = i;
125  else
126  break;
127  }
128  q->current_sub_idx = idx;
129  }
130  return 0;
131 }
132 
134 {
135  int i;
136 
137  for (i = 0; i < q->nb_subs; i++)
138  av_destruct_packet(&q->subs[i]);
139  av_freep(&q->subs);
140  q->nb_subs = q->allocated_size = q->current_sub_idx = 0;
141 }
142 
144 {
145  int i = 0;
146  char end_chr;
147 
148  if (!*c) // cached char?
149  *c = avio_r8(pb);
150  if (!*c)
151  return 0;
152 
153  end_chr = *c == '<' ? '>' : '<';
154  do {
155  av_bprint_chars(buf, *c, 1);
156  *c = avio_r8(pb);
157  i++;
158  } while (*c != end_chr && *c);
159  if (end_chr == '>') {
160  av_bprint_chars(buf, '>', 1);
161  *c = 0;
162  }
163  return i;
164 }
165 
166 const char *ff_smil_get_attr_ptr(const char *s, const char *attr)
167 {
168  int in_quotes = 0;
169  const int len = strlen(attr);
170 
171  while (*s) {
172  while (*s) {
173  if (!in_quotes && isspace(*s))
174  break;
175  in_quotes ^= *s == '"'; // XXX: support escaping?
176  s++;
177  }
178  while (isspace(*s))
179  s++;
180  if (!av_strncasecmp(s, attr, len) && s[len] == '=')
181  return s + len + 1 + (s[len + 1] == '"');
182  }
183  return NULL;
184 }
185 
186 static inline int is_eol(char c)
187 {
188  return c == '\r' || c == '\n';
189 }
190 
192 {
193  char eol_buf[5];
194  int n = 0, i = 0, nb_eol = 0;
195 
196  av_bprint_clear(buf);
197 
198  for (;;) {
199  char c = avio_r8(pb);
200 
201  if (!c)
202  break;
203 
204  /* ignore all initial line breaks */
205  if (n == 0 && is_eol(c))
206  continue;
207 
208  /* line break buffering: we don't want to add the trailing \r\n */
209  if (is_eol(c)) {
210  nb_eol += c == '\n';
211  if (nb_eol == 2)
212  break;
213  eol_buf[i++] = c;
214  if (i == sizeof(eol_buf) - 1)
215  break;
216  continue;
217  }
218 
219  /* only one line break followed by data: we flush the line breaks
220  * buffer */
221  if (i) {
222  eol_buf[i] = 0;
223  av_bprintf(buf, "%s", eol_buf);
224  i = nb_eol = 0;
225  }
226 
227  av_bprint_chars(buf, c, 1);
228  n++;
229  }
230 }