FFmpeg
subtitles.c
Go to the documentation of this file.
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 "avio_internal.h"
24 #include "libavutil/avassert.h"
25 #include "libavutil/avstring.h"
26 
28 {
29  int i;
30  r->pb = pb;
31  r->buf_pos = r->buf_len = 0;
32  r->type = FF_UTF_8;
33  for (i = 0; i < 2; i++)
34  r->buf[r->buf_len++] = avio_r8(r->pb);
35  if (strncmp("\xFF\xFE", r->buf, 2) == 0) {
36  r->type = FF_UTF16LE;
37  r->buf_pos += 2;
38  } else if (strncmp("\xFE\xFF", r->buf, 2) == 0) {
39  r->type = FF_UTF16BE;
40  r->buf_pos += 2;
41  } else {
42  r->buf[r->buf_len++] = avio_r8(r->pb);
43  if (strncmp("\xEF\xBB\xBF", r->buf, 3) == 0) {
44  // UTF8
45  r->buf_pos += 3;
46  }
47  }
48  if (s && (r->type == FF_UTF16LE || r->type == FF_UTF16BE))
50  "UTF16 is automatically converted to UTF8, do not specify a character encoding\n");
51 }
52 
53 void ff_text_init_buf(FFTextReader *r, void *buf, size_t size)
54 {
55  memset(&r->buf_pb, 0, sizeof(r->buf_pb));
56  ffio_init_context(&r->buf_pb, buf, size, 0, NULL, NULL, NULL, NULL);
57  ff_text_init_avio(NULL, r, &r->buf_pb);
58 }
59 
61 {
62  return avio_tell(r->pb) - r->buf_len + r->buf_pos;
63 }
64 
66 {
67  uint32_t val;
68  uint8_t tmp;
69  if (r->buf_pos < r->buf_len)
70  return r->buf[r->buf_pos++];
71  if (r->type == FF_UTF16LE) {
72  GET_UTF16(val, avio_rl16(r->pb), return 0;)
73  } else if (r->type == FF_UTF16BE) {
74  GET_UTF16(val, avio_rb16(r->pb), return 0;)
75  } else {
76  return avio_r8(r->pb);
77  }
78  if (!val)
79  return 0;
80  r->buf_pos = 0;
81  r->buf_len = 0;
82  PUT_UTF8(val, tmp, r->buf[r->buf_len++] = tmp;)
83  return r->buf[r->buf_pos++]; // buf_len is at least 1
84 }
85 
86 void ff_text_read(FFTextReader *r, char *buf, size_t size)
87 {
88  for ( ; size > 0; size--)
89  *buf++ = ff_text_r8(r);
90 }
91 
93 {
94  return r->buf_pos >= r->buf_len && avio_feof(r->pb);
95 }
96 
98 {
99  int c;
100  if (r->buf_pos < r->buf_len)
101  return r->buf[r->buf_pos];
102  c = ff_text_r8(r);
103  if (!avio_feof(r->pb)) {
104  r->buf_pos = 0;
105  r->buf_len = 1;
106  r->buf[0] = c;
107  }
108  return c;
109 }
110 
112  const uint8_t *event, size_t len, int merge)
113 {
114  AVPacket *subs, *sub;
115 
116  if (merge && q->nb_subs > 0) {
117  /* merge with previous event */
118 
119  int old_len;
120  sub = &q->subs[q->nb_subs - 1];
121  old_len = sub->size;
122  if (av_grow_packet(sub, len) < 0)
123  return NULL;
124  memcpy(sub->data + old_len, event, len);
125  } else {
126  /* new event */
127 
128  if (q->nb_subs >= INT_MAX/sizeof(*q->subs) - 1)
129  return NULL;
130  subs = av_fast_realloc(q->subs, &q->allocated_size,
131  (q->nb_subs + 1) * sizeof(*q->subs));
132  if (!subs)
133  return NULL;
134  q->subs = subs;
135  sub = &subs[q->nb_subs];
136  if (av_new_packet(sub, len) < 0)
137  return NULL;
138  q->nb_subs++;
139  sub->flags |= AV_PKT_FLAG_KEY;
140  sub->pts = sub->dts = 0;
141  memcpy(sub->data, event, len);
142  }
143  return sub;
144 }
145 
146 static int cmp_pkt_sub_ts_pos(const void *a, const void *b)
147 {
148  const AVPacket *s1 = a;
149  const AVPacket *s2 = b;
150  if (s1->pts == s2->pts)
151  return FFDIFFSIGN(s1->pos, s2->pos);
152  return FFDIFFSIGN(s1->pts , s2->pts);
153 }
154 
155 static int cmp_pkt_sub_pos_ts(const void *a, const void *b)
156 {
157  const AVPacket *s1 = a;
158  const AVPacket *s2 = b;
159  if (s1->pos == s2->pos) {
160  if (s1->pts == s2->pts)
161  return 0;
162  return s1->pts > s2->pts ? 1 : -1;
163  }
164  return s1->pos > s2->pos ? 1 : -1;
165 }
166 
167 static void drop_dups(void *log_ctx, FFDemuxSubtitlesQueue *q)
168 {
169  int i, drop = 0;
170 
171  for (i = 1; i < q->nb_subs; i++) {
172  const int last_id = i - 1 - drop;
173  const AVPacket *last = &q->subs[last_id];
174 
175  if (q->subs[i].pts == last->pts &&
176  q->subs[i].duration == last->duration &&
177  q->subs[i].stream_index == last->stream_index &&
178  !strcmp(q->subs[i].data, last->data)) {
179 
180  av_packet_unref(&q->subs[i]);
181  drop++;
182  } else if (drop) {
183  q->subs[last_id + 1] = q->subs[i];
184  memset(&q->subs[i], 0, sizeof(q->subs[i])); // for safety
185  }
186  }
187 
188  if (drop) {
189  q->nb_subs -= drop;
190  av_log(log_ctx, AV_LOG_WARNING, "Dropping %d duplicated subtitle events\n", drop);
191  }
192 }
193 
195 {
196  int i;
197 
198  if (!q->nb_subs)
199  return;
200 
201  qsort(q->subs, q->nb_subs, sizeof(*q->subs),
204  for (i = 0; i < q->nb_subs; i++)
205  if (q->subs[i].duration < 0 && i < q->nb_subs - 1)
206  q->subs[i].duration = q->subs[i + 1].pts - q->subs[i].pts;
207 
208  if (!q->keep_duplicates)
209  drop_dups(log_ctx, q);
210 }
211 
213 {
214  AVPacket *sub = q->subs + q->current_sub_idx;
215  int ret;
216 
217  if (q->current_sub_idx == q->nb_subs)
218  return AVERROR_EOF;
219  if ((ret = av_packet_ref(pkt, sub)) < 0) {
220  return ret;
221  }
222 
223  pkt->dts = pkt->pts;
224  q->current_sub_idx++;
225  return 0;
226 }
227 
228 static int search_sub_ts(const FFDemuxSubtitlesQueue *q, int64_t ts)
229 {
230  int s1 = 0, s2 = q->nb_subs - 1;
231 
232  if (s2 < s1)
233  return AVERROR(ERANGE);
234 
235  for (;;) {
236  int mid;
237 
238  if (s1 == s2)
239  return s1;
240  if (s1 == s2 - 1)
241  return q->subs[s1].pts <= q->subs[s2].pts ? s1 : s2;
242  mid = (s1 + s2) / 2;
243  if (q->subs[mid].pts <= ts)
244  s1 = mid;
245  else
246  s2 = mid;
247  }
248 }
249 
251  int64_t min_ts, int64_t ts, int64_t max_ts, int flags)
252 {
253  if (flags & AVSEEK_FLAG_BYTE) {
254  return AVERROR(ENOSYS);
255  } else if (flags & AVSEEK_FLAG_FRAME) {
256  if (ts < 0 || ts >= q->nb_subs)
257  return AVERROR(ERANGE);
258  q->current_sub_idx = ts;
259  } else {
260  int i, idx = search_sub_ts(q, ts);
261  int64_t ts_selected;
262 
263  if (idx < 0)
264  return idx;
265  for (i = idx; i < q->nb_subs && q->subs[i].pts < min_ts; i++)
266  if (stream_index == -1 || q->subs[i].stream_index == stream_index)
267  idx = i;
268  for (i = idx; i > 0 && q->subs[i].pts > max_ts; i--)
269  if (stream_index == -1 || q->subs[i].stream_index == stream_index)
270  idx = i;
271 
272  ts_selected = q->subs[idx].pts;
273  if (ts_selected < min_ts || ts_selected > max_ts)
274  return AVERROR(ERANGE);
275 
276  /* look back in the latest subtitles for overlapping subtitles */
277  for (i = idx - 1; i >= 0; i--) {
278  int64_t pts = q->subs[i].pts;
279  if (q->subs[i].duration <= 0 ||
280  (stream_index != -1 && q->subs[i].stream_index != stream_index))
281  continue;
282  if (pts >= min_ts && pts > ts_selected - q->subs[i].duration)
283  idx = i;
284  else
285  break;
286  }
287 
288  /* If the queue is used to store multiple subtitles streams (like with
289  * VobSub) and the stream index is not specified, we need to make sure
290  * to focus on the smallest file position offset for a same timestamp;
291  * queue is ordered by pts and then filepos, so we can take the first
292  * entry for a given timestamp. */
293  if (stream_index == -1)
294  while (idx > 0 && q->subs[idx - 1].pts == q->subs[idx].pts)
295  idx--;
296 
297  q->current_sub_idx = idx;
298  }
299  return 0;
300 }
301 
303 {
304  int i;
305 
306  for (i = 0; i < q->nb_subs; i++)
307  av_packet_unref(&q->subs[i]);
308  av_freep(&q->subs);
309  q->nb_subs = q->allocated_size = q->current_sub_idx = 0;
310 }
311 
312 int ff_smil_extract_next_text_chunk(FFTextReader *tr, AVBPrint *buf, char *c)
313 {
314  int i = 0;
315  char end_chr;
316 
317  if (!*c) // cached char?
318  *c = ff_text_r8(tr);
319  if (!*c)
320  return 0;
321 
322  end_chr = *c == '<' ? '>' : '<';
323  do {
324  av_bprint_chars(buf, *c, 1);
325  *c = ff_text_r8(tr);
326  i++;
327  } while (*c != end_chr && *c);
328  if (end_chr == '>') {
329  av_bprint_chars(buf, '>', 1);
330  *c = 0;
331  }
332  return i;
333 }
334 
335 const char *ff_smil_get_attr_ptr(const char *s, const char *attr)
336 {
337  int in_quotes = 0;
338  const size_t len = strlen(attr);
339 
340  while (*s) {
341  while (*s) {
342  if (!in_quotes && av_isspace(*s))
343  break;
344  in_quotes ^= *s == '"'; // XXX: support escaping?
345  s++;
346  }
347  while (av_isspace(*s))
348  s++;
349  if (!av_strncasecmp(s, attr, len) && s[len] == '=')
350  return s + len + 1 + (s[len + 1] == '"');
351  }
352  return NULL;
353 }
354 
355 static inline int is_eol(char c)
356 {
357  return c == '\r' || c == '\n';
358 }
359 
361 {
362  char eol_buf[5], last_was_cr = 0;
363  int n = 0, i = 0, nb_eol = 0;
364 
365  av_bprint_clear(buf);
366 
367  for (;;) {
368  char c = ff_text_r8(tr);
369 
370  if (!c)
371  break;
372 
373  /* ignore all initial line breaks */
374  if (n == 0 && is_eol(c))
375  continue;
376 
377  /* line break buffering: we don't want to add the trailing \r\n */
378  if (is_eol(c)) {
379  nb_eol += c == '\n' || last_was_cr;
380  if (nb_eol == 2)
381  break;
382  eol_buf[i++] = c;
383  if (i == sizeof(eol_buf) - 1)
384  break;
385  last_was_cr = c == '\r';
386  continue;
387  }
388 
389  /* only one line break followed by data: we flush the line breaks
390  * buffer */
391  if (i) {
392  eol_buf[i] = 0;
393  av_bprintf(buf, "%s", eol_buf);
394  i = nb_eol = 0;
395  }
396 
397  av_bprint_chars(buf, c, 1);
398  n++;
399  }
400 }
401 
402 void ff_subtitles_read_chunk(AVIOContext *pb, AVBPrint *buf)
403 {
404  FFTextReader tr;
405  tr.buf_pos = tr.buf_len = 0;
406  tr.type = 0;
407  tr.pb = pb;
409 }
410 
411 ptrdiff_t ff_subtitles_read_line(FFTextReader *tr, char *buf, size_t size)
412 {
413  size_t cur = 0;
414  if (!size)
415  return 0;
416  while (cur + 1 < size) {
417  unsigned char c = ff_text_r8(tr);
418  if (!c)
419  return ff_text_eof(tr) ? cur : AVERROR_INVALIDDATA;
420  if (c == '\r' || c == '\n')
421  break;
422  buf[cur++] = c;
423  buf[cur] = '\0';
424  }
425  while (ff_text_peek_r8(tr) == '\r')
426  ff_text_r8(tr);
427  if (ff_text_peek_r8(tr) == '\n')
428  ff_text_r8(tr);
429  return cur;
430 }
int keep_duplicates
set to 1 to keep duplicated subtitle events
Definition: subtitles.h:108
#define NULL
Definition: coverity.c:32
Bytestream IO Context.
Definition: avio.h:161
#define AVERROR_INVALIDDATA
Invalid data found when processing input.
Definition: error.h:59
void av_bprintf(AVBPrint *buf, const char *fmt,...)
Definition: bprint.c:94
#define AV_LOG_WARNING
Something somehow does not look correct.
Definition: log.h:200
int64_t pos
byte position in stream, -1 if unknown
Definition: packet.h:383
static int cmp_pkt_sub_pos_ts(const void *a, const void *b)
Definition: subtitles.c:155
static int search_sub_ts(const FFDemuxSubtitlesQueue *q, int64_t ts)
Definition: subtitles.c:228
void ff_subtitles_read_chunk(AVIOContext *pb, AVBPrint *buf)
Same as ff_subtitles_read_text_chunk(), but read from an AVIOContext.
Definition: subtitles.c:402
int size
Definition: packet.h:364
static av_const int av_isspace(int c)
Locale-independent conversion of ASCII isspace.
Definition: avstring.h:227
void ff_subtitles_queue_clean(FFDemuxSubtitlesQueue *q)
Remove and destroy all the subtitles packets.
Definition: subtitles.c:302
int av_strncasecmp(const char *a, const char *b, size_t n)
Locale-independent case-insensitive compare.
Definition: avstring.c:225
The reader does not expect b to be semantically here and if the code is changed by maybe adding a a division or other the signedness will almost certainly be mistaken To avoid this confusion a new type was SUINT is the C unsigned type but it holds a signed int to use the same example SUINT a
Definition: undefined.txt:36
int ff_text_peek_r8(FFTextReader *r)
Like ff_text_r8(), but don&#39;t remove the byte from the buffer.
Definition: subtitles.c:97
#define PUT_UTF8(val, tmp, PUT_BYTE)
Convert a 32-bit Unicode character to its UTF-8 encoded form (up to 4 bytes long).
Definition: common.h:479
int allocated_size
allocated size for subs
Definition: subtitles.h:105
static AVPacket pkt
unsigned int avio_rb16(AVIOContext *s)
Definition: aviobuf.c:768
Format I/O context.
Definition: avformat.h:1355
const char * ff_smil_get_attr_ptr(const char *s, const char *attr)
SMIL helper to point on the value of an attribute in the given tag.
Definition: subtitles.c:335
uint8_t
int ff_subtitles_queue_read_packet(FFDemuxSubtitlesQueue *q, AVPacket *pkt)
Generic read_packet() callback for subtitles demuxers using this queue system.
Definition: subtitles.c:212
int64_t duration
Duration of this packet in AVStream->time_base units, 0 if unknown.
Definition: packet.h:381
Undefined Behavior In the C some operations are like signed integer dereferencing freed accessing outside allocated Undefined Behavior must not occur in a C it is not safe even if the output of undefined operations is unused The unsafety may seem nit picking but Optimizing compilers have in fact optimized code on the assumption that no undefined Behavior occurs Optimizing code based on wrong assumptions can and has in some cases lead to effects beyond the output of computations The signed integer overflow problem in speed critical code Code which is highly optimized and works with signed integers sometimes has the problem that often the output of the computation does not c
Definition: undefined.txt:32
AVIOContext * pb
Definition: subtitles.h:42
enum sub_sort sort
sort method to use when finalizing subtitles
Definition: subtitles.h:107
uint8_t * data
Definition: packet.h:363
#define AVERROR_EOF
End of file.
Definition: error.h:55
ptrdiff_t size
Definition: opengl_enc.c:100
static av_always_inline int64_t avio_tell(AVIOContext *s)
ftell() equivalent for AVIOContext.
Definition: avio.h:557
#define av_log(a,...)
int av_packet_ref(AVPacket *dst, const AVPacket *src)
Setup a new reference to the data described by a given packet.
Definition: avpacket.c:615
#define AV_PKT_FLAG_KEY
The packet contains a keyframe.
Definition: packet.h:401
#define GET_UTF16(val, GET_16BIT, ERROR)
Convert a UTF-16 character (2 or 4 bytes) to its 32-bit UCS-4 encoded form.
Definition: common.h:451
int av_new_packet(AVPacket *pkt, int size)
Allocate the payload of a packet and initialize its fields with default values.
Definition: avpacket.c:88
static void drop_dups(void *log_ctx, FFDemuxSubtitlesQueue *q)
Definition: subtitles.c:167
#define s2
Definition: regdef.h:39
static int is_eol(char c)
Definition: subtitles.c:355
int ff_text_eof(FFTextReader *r)
Return non-zero if EOF was reached.
Definition: subtitles.c:92
ptrdiff_t ff_subtitles_read_line(FFTextReader *tr, char *buf, size_t size)
Read a line of text.
Definition: subtitles.c:411
const char * r
Definition: vf_curves.c:114
simple assert() macros that are a bit more flexible than ISO C assert().
void ff_text_init_avio(void *s, FFTextReader *r, AVIOContext *pb)
Initialize the FFTextReader from the given AVIOContext.
Definition: subtitles.c:27
int flags
A combination of AV_PKT_FLAG values.
Definition: packet.h:369
unsigned char buf[8]
Definition: subtitles.h:43
int avio_r8(AVIOContext *s)
Definition: aviobuf.c:628
#define FFDIFFSIGN(x, y)
Comparator.
Definition: common.h:92
int64_t ff_text_pos(FFTextReader *r)
Return the byte position of the next byte returned by ff_text_r8().
Definition: subtitles.c:60
AVIOContext buf_pb
Definition: subtitles.h:45
#define b
Definition: input.c:41
static int cmp_pkt_sub_ts_pos(const void *a, const void *b)
Definition: subtitles.c:146
#define s(width, name)
Definition: cbs_vp9.c:257
void * av_fast_realloc(void *ptr, unsigned int *size, size_t min_size)
Reallocate the given buffer if it is not large enough, otherwise do nothing.
Definition: mem.c:478
void ff_text_read(FFTextReader *r, char *buf, size_t size)
Read the given number of bytes (in UTF-8).
Definition: subtitles.c:86
int ff_text_r8(FFTextReader *r)
Return the next byte.
Definition: subtitles.c:65
#define AV_LOG_INFO
Standard information.
Definition: log.h:205
int ff_subtitles_queue_seek(FFDemuxSubtitlesQueue *q, AVFormatContext *s, int stream_index, int64_t min_ts, int64_t ts, int64_t max_ts, int flags)
Update current_sub_idx to emulate a seek.
Definition: subtitles.c:250
int ff_smil_extract_next_text_chunk(FFTextReader *tr, AVBPrint *buf, char *c)
SMIL helper to load next chunk ("<...>" or untagged content) in buf.
Definition: subtitles.c:312
void ff_subtitles_read_text_chunk(FFTextReader *tr, AVBPrint *buf)
Read a subtitles chunk from FFTextReader.
Definition: subtitles.c:360
void av_packet_unref(AVPacket *pkt)
Wipe the packet.
Definition: avpacket.c:606
#define AVSEEK_FLAG_BYTE
seeking based on position in bytes
Definition: avformat.h:2512
#define s1
Definition: regdef.h:38
static void merge(GetBitContext *gb, uint8_t *dst, uint8_t *src, int size)
Merge two consequent lists of equal size depending on bits read.
Definition: bink.c:218
static int64_t pts
#define flags(name, subs,...)
Definition: cbs_av1.c:560
void av_bprint_clear(AVBPrint *buf)
Reset the string to "" but keep internal allocated data.
Definition: bprint.c:227
unsigned int avio_rl16(AVIOContext *s)
Definition: aviobuf.c:736
Main libavformat public API header.
int ffio_init_context(AVIOContext *s, unsigned char *buffer, int buffer_size, int write_flag, void *opaque, int(*read_packet)(void *opaque, uint8_t *buf, int buf_size), int(*write_packet)(void *opaque, uint8_t *buf, int buf_size), int64_t(*seek)(void *opaque, int64_t offset, int whence))
Definition: aviobuf.c:88
AVPacket * subs
array of subtitles packets
Definition: subtitles.h:103
void ff_text_init_buf(FFTextReader *r, void *buf, size_t size)
Similar to ff_text_init_avio(), but sets it up to read from a bounded buffer.
Definition: subtitles.c:53
int av_grow_packet(AVPacket *pkt, int grow_by)
Increase packet size, correctly zeroing padding.
Definition: avpacket.c:111
int current_sub_idx
current position for the read packet callback
Definition: subtitles.h:106
int len
#define AVSEEK_FLAG_FRAME
seeking based on frame number
Definition: avformat.h:2514
int64_t dts
Decompression timestamp in AVStream->time_base units; the time at which the packet is decompressed...
Definition: packet.h:362
#define av_freep(p)
static float sub(float src0, float src1)
int avio_feof(AVIOContext *s)
Similar to feof() but also returns nonzero on read errors.
Definition: aviobuf.c:368
int stream_index
Definition: packet.h:365
AVPacket * ff_subtitles_queue_insert(FFDemuxSubtitlesQueue *q, const uint8_t *event, size_t len, int merge)
Insert a new subtitle event.
Definition: subtitles.c:111
Filter the word “frame” indicates either a video frame or a group of audio as stored in an AVFrame structure Format for each input and each output the list of supported formats For video that means pixel format For audio that means channel sample they are references to shared objects When the negotiation mechanism computes the intersection of the formats supported at each end of a all references to both lists are replaced with a reference to the intersection And when a single format is eventually chosen for a link amongst the remaining all references to the list are updated That means that if a filter requires that its input and output have the same format amongst a supported all it has to do is use a reference to the same list of formats query_formats can leave some formats unset and return AVERROR(EAGAIN) to cause the negotiation mechanism toagain later.That can be used by filters with complex requirements to use the format negotiated on one link to set the formats supported on another.Frame references ownership and permissions
static double val(void *priv, double ch)
Definition: aeval.c:76
This structure stores compressed data.
Definition: packet.h:340
int nb_subs
number of subtitles packets
Definition: subtitles.h:104
sort by timestamps, then position
Definition: subtitles.h:30
void ff_subtitles_queue_finalize(void *log_ctx, FFDemuxSubtitlesQueue *q)
Set missing durations, sort subtitles by PTS (and then byte position), and drop duplicated events...
Definition: subtitles.c:194
int64_t pts
Presentation timestamp in AVStream->time_base units; the time at which the decompressed packet will b...
Definition: packet.h:356
int i
Definition: input.c:407
void av_bprint_chars(AVBPrint *buf, char c, unsigned n)
Append char c n times to a print buffer.
Definition: bprint.c:140
static uint8_t tmp[11]
Definition: aes_ctr.c:26