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subtitles.h
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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 #ifndef AVFORMAT_SUBTITLES_H
22 #define AVFORMAT_SUBTITLES_H
23 
24 #include <stdint.h>
25 #include <stddef.h>
26 #include "avformat.h"
27 #include "libavutil/bprint.h"
28 
29 enum sub_sort {
30  SUB_SORT_TS_POS = 0, ///< sort by timestamps, then position
31  SUB_SORT_POS_TS, ///< sort by position, then timestamps
32 };
33 
35  FF_UTF_8, // or other 8 bit encodings
38 };
39 
40 typedef struct {
41  int type;
43  unsigned char buf[8];
44  int buf_pos, buf_len;
46 } FFTextReader;
47 
48 /**
49  * Initialize the FFTextReader from the given AVIOContext. This function will
50  * read some bytes from pb, and test for UTF-8 or UTF-16 BOMs. Further accesses
51  * to FFTextReader will read more data from pb.
52  * If s is not NULL, the user will be warned if a UTF-16 conversion takes place.
53  *
54  * The purpose of FFTextReader is to transparently convert read data to UTF-8
55  * if the stream had a UTF-16 BOM.
56  *
57  * @param s Pointer to provide av_log context
58  * @param r object which will be initialized
59  * @param pb stream to read from (referenced as long as FFTextReader is in use)
60  */
61 void ff_text_init_avio(void *s, FFTextReader *r, AVIOContext *pb);
62 
63 /**
64  * Similar to ff_text_init_avio(), but sets it up to read from a bounded buffer.
65  *
66  * @param r object which will be initialized
67  * @param buf buffer to read from (referenced as long as FFTextReader is in use)
68  * @param size size of buf
69  */
70 void ff_text_init_buf(FFTextReader *r, void *buf, size_t size);
71 
72 /**
73  * Return the byte position of the next byte returned by ff_text_r8(). For
74  * UTF-16 source streams, this will return the original position, but it will
75  * be incorrect if a codepoint was only partially read with ff_text_r8().
76  */
77 int64_t ff_text_pos(FFTextReader *r);
78 
79 /**
80  * Return the next byte. The return value is always 0 - 255. Returns 0 on EOF.
81  * If the source stream is UTF-16, this reads from the stream converted to
82  * UTF-8. On invalid UTF-16, 0 is returned.
83  */
85 
86 /**
87  * Return non-zero if EOF was reached.
88  */
90 
91 /**
92  * Like ff_text_r8(), but don't remove the byte from the buffer.
93  */
95 
96 /**
97  * Read the given number of bytes (in UTF-8). On error or EOF, \0 bytes are
98  * written.
99  */
100 void ff_text_read(FFTextReader *r, char *buf, size_t size);
101 
102 typedef struct {
103  AVPacket *subs; ///< array of subtitles packets
104  int nb_subs; ///< number of subtitles packets
105  int allocated_size; ///< allocated size for subs
106  int current_sub_idx; ///< current position for the read packet callback
107  enum sub_sort sort; ///< sort method to use when finalizing subtitles
108  int keep_duplicates; ///< set to 1 to keep duplicated subtitle events
110 
111 /**
112  * Insert a new subtitle event.
113  *
114  * @param event the subtitle line, may not be zero terminated
115  * @param len the length of the event (in strlen() sense, so without '\0')
116  * @param merge set to 1 if the current event should be concatenated with the
117  * previous one instead of adding a new entry, 0 otherwise
118  */
120  const uint8_t *event, size_t len, int merge);
121 
122 /**
123  * Set missing durations, sort subtitles by PTS (and then byte position), and
124  * drop duplicated events.
125  */
126 void ff_subtitles_queue_finalize(void *log_ctx, FFDemuxSubtitlesQueue *q);
127 
128 /**
129  * Generic read_packet() callback for subtitles demuxers using this queue
130  * system.
131  */
133 
134 /**
135  * Update current_sub_idx to emulate a seek. Except the first parameter, it
136  * matches AVInputFormat->read_seek2 prototypes.
137  */
139  int64_t min_ts, int64_t ts, int64_t max_ts, int flags);
140 
141 /**
142  * Remove and destroy all the subtitles packets.
143  */
145 
146 /**
147  * SMIL helper to load next chunk ("<...>" or untagged content) in buf.
148  *
149  * @param c cached character, to avoid a backward seek
150  */
151 int ff_smil_extract_next_text_chunk(FFTextReader *tr, AVBPrint *buf, char *c);
152 
153 /**
154  * SMIL helper to point on the value of an attribute in the given tag.
155  *
156  * @param s SMIL tag ("<...>")
157  * @param attr the attribute to look for
158  */
159 const char *ff_smil_get_attr_ptr(const char *s, const char *attr);
160 
161 /**
162  * @brief Same as ff_subtitles_read_text_chunk(), but read from an AVIOContext.
163  */
164 void ff_subtitles_read_chunk(AVIOContext *pb, AVBPrint *buf);
165 
166 /**
167  * @brief Read a subtitles chunk from FFTextReader.
168  *
169  * A chunk is defined by a multiline "event", ending with a second line break.
170  * The trailing line breaks are trimmed. CRLF are supported.
171  * Example: "foo\r\nbar\r\n\r\nnext" will print "foo\r\nbar" into buf, and pb
172  * will focus on the 'n' of the "next" string.
173  *
174  * @param tr I/O context
175  * @param buf an initialized buf where the chunk is written
176  *
177  * @note buf is cleared before writing into it.
178  */
179 void ff_subtitles_read_text_chunk(FFTextReader *tr, AVBPrint *buf);
180 
181 /**
182  * Get the number of characters to increment to jump to the next line, or to
183  * the end of the string.
184  * The function handles the following line breaks schemes:
185  * LF, CRLF (MS), or standalone CR (old MacOS).
186  */
187 static av_always_inline int ff_subtitles_next_line(const char *ptr)
188 {
189  int n = strcspn(ptr, "\r\n");
190  ptr += n;
191  if (*ptr == '\r') {
192  ptr++;
193  n++;
194  }
195  if (*ptr == '\n')
196  n++;
197  return n;
198 }
199 
200 /**
201  * Read a line of text. Discards line ending characters.
202  * The function handles the following line breaks schemes:
203  * LF, CRLF (MS), or standalone CR (old MacOS).
204  *
205  * Returns the number of bytes written to buf. Always writes a terminating 0,
206  * similar as with snprintf.
207  *
208  * @note returns a negative error code if a \0 byte is found
209  */
210 ptrdiff_t ff_subtitles_read_line(FFTextReader *tr, char *buf, size_t size);
211 
212 #endif /* AVFORMAT_SUBTITLES_H */
int keep_duplicates
set to 1 to keep duplicated subtitle events
Definition: subtitles.h:108
Bytestream IO Context.
Definition: avio.h:161
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:245
void ff_text_init_avio(void *s, FFTextReader *r, AVIOContext *pb)
Initialize the FFTextReader from the given AVIOContext.
Definition: subtitles.c:27
int64_t ff_text_pos(FFTextReader *r)
Return the byte position of the next byte returned by ff_text_r8().
Definition: subtitles.c:60
sort by position, then timestamps
Definition: subtitles.h:31
int allocated_size
allocated size for subs
Definition: subtitles.h:105
static AVPacket pkt
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
Format I/O context.
Definition: avformat.h:1351
uint8_t
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
AVIOContext * pb
Definition: subtitles.h:42
ptrdiff_t size
Definition: opengl_enc.c:101
void ff_text_read(FFTextReader *r, char *buf, size_t size)
Read the given number of bytes (in UTF-8).
Definition: subtitles.c:86
void ff_subtitles_queue_clean(FFDemuxSubtitlesQueue *q)
Remove and destroy all the subtitles packets.
Definition: subtitles.c:297
int ff_text_r8(FFTextReader *r)
Return the next byte.
Definition: subtitles.c:65
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:193
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:307
const char * r
Definition: vf_curves.c:114
void ff_subtitles_read_text_chunk(FFTextReader *tr, AVBPrint *buf)
Read a subtitles chunk from FFTextReader.
Definition: subtitles.c:355
AVIOContext buf_pb
Definition: subtitles.h:45
#define s(width, name)
Definition: cbs_vp9.c:257
int n
Definition: avisynth_c.h:684
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:330
ff_utf_type
Definition: subtitles.h:34
void * buf
Definition: avisynth_c.h:690
void ff_subtitles_read_chunk(AVIOContext *pb, AVBPrint *buf)
Same as ff_subtitles_read_text_chunk(), but read from an AVIOContext.
Definition: subtitles.c:397
sub_sort
Definition: subtitles.h:29
int ff_text_peek_r8(FFTextReader *r)
Like ff_text_r8(), but don't remove the byte from the buffer.
Definition: subtitles.c:97
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:217
#define flags(name, subs,...)
Definition: cbs_av1.c:596
static av_always_inline int ff_subtitles_next_line(const char *ptr)
Get the number of characters to increment to jump to the next line, or to the end of the string...
Definition: subtitles.h:187
Main libavformat public API header.
ptrdiff_t ff_subtitles_read_line(FFTextReader *tr, char *buf, size_t size)
Read a line of text.
Definition: subtitles.c:406
static double c[64]
AVPacket * subs
array of subtitles packets
Definition: subtitles.h:103
int current_sub_idx
current position for the read packet callback
Definition: subtitles.h:106
int ff_subtitles_queue_read_packet(FFDemuxSubtitlesQueue *q, AVPacket *pkt)
Generic read_packet() callback for subtitles demuxers using this queue system.
Definition: subtitles.c:208
int len
#define av_always_inline
Definition: attributes.h:39
This structure stores compressed data.
Definition: avcodec.h:1422
int nb_subs
number of subtitles packets
Definition: subtitles.h:104
sort by timestamps, then position
Definition: subtitles.h:30
int ff_text_eof(FFTextReader *r)
Return non-zero if EOF was reached.
Definition: subtitles.c:92