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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 "avformat.h"
26 #include "libavutil/bprint.h"
27 
28 enum sub_sort {
29  SUB_SORT_TS_POS = 0, ///< sort by timestamps, then position
30  SUB_SORT_POS_TS, ///< sort by position, then timestamps
31 };
32 
33 typedef struct {
34  AVPacket *subs; ///< array of subtitles packets
35  int nb_subs; ///< number of subtitles packets
36  int allocated_size; ///< allocated size for subs
37  int current_sub_idx; ///< current position for the read packet callback
38  enum sub_sort sort; ///< sort method to use when finalizing subtitles
39 } FFDemuxSubtitlesQueue;
40 
41 /**
42  * Insert a new subtitle event.
43  *
44  * @param event the subtitle line, may not be zero terminated
45  * @param len the length of the event (in strlen() sense, so without '\0')
46  * @param merge set to 1 if the current event should be concatenated with the
47  * previous one instead of adding a new entry, 0 otherwise
48  */
49 AVPacket *ff_subtitles_queue_insert(FFDemuxSubtitlesQueue *q,
50  const uint8_t *event, int len, int merge);
51 
52 /**
53  * Set missing durations and sort subtitles by PTS, and then byte position.
54  */
55 void ff_subtitles_queue_finalize(FFDemuxSubtitlesQueue *q);
56 
57 /**
58  * Generic read_packet() callback for subtitles demuxers using this queue
59  * system.
60  */
61 int ff_subtitles_queue_read_packet(FFDemuxSubtitlesQueue *q, AVPacket *pkt);
62 
63 /**
64  * Update current_sub_idx to emulate a seek. Except the first parameter, it
65  * matches AVInputFormat->read_seek2 prototypes.
66  */
67 int ff_subtitles_queue_seek(FFDemuxSubtitlesQueue *q, AVFormatContext *s, int stream_index,
68  int64_t min_ts, int64_t ts, int64_t max_ts, int flags);
69 
70 /**
71  * Remove and destroy all the subtitles packets.
72  */
73 void ff_subtitles_queue_clean(FFDemuxSubtitlesQueue *q);
74 
75 /**
76  * SMIL helper to load next chunk ("<...>" or untagged content) in buf.
77  *
78  * @param c cached character, to avoid a backward seek
79  */
80 int ff_smil_extract_next_chunk(AVIOContext *pb, AVBPrint *buf, char *c);
81 
82 /**
83  * SMIL helper to point on the value of an attribute in the given tag.
84  *
85  * @param s SMIL tag ("<...>")
86  * @param attr the attribute to look for
87  */
88 const char *ff_smil_get_attr_ptr(const char *s, const char *attr);
89 
90 /**
91  * @brief Read a subtitles chunk.
92  *
93  * A chunk is defined by a multiline "event", ending with a second line break.
94  * The trailing line breaks are trimmed. CRLF are supported.
95  * Example: "foo\r\nbar\r\n\r\nnext" will print "foo\r\nbar" into buf, and pb
96  * will focus on the 'n' of the "next" string.
97  *
98  * @param pb I/O context
99  * @param buf an initialized buf where the chunk is written
100  *
101  * @note buf is cleared before writing into it.
102  */
103 void ff_subtitles_read_chunk(AVIOContext *pb, AVBPrint *buf);
104 
105 /**
106  * Get the number of characters to increment to jump to the next line, or to
107  * the end of the string.
108  * The function handles the following line breaks schemes:
109  * LF, CRLF (MS), or standalone CR (old MacOS).
110  */
111 static av_always_inline int ff_subtitles_next_line(const char *ptr)
112 {
113  int n = strcspn(ptr, "\r\n");
114  ptr += n;
115  if (*ptr == '\r') {
116  ptr++;
117  n++;
118  }
119  if (*ptr == '\n')
120  n++;
121  return n;
122 }
123 
124 #endif /* AVFORMAT_SUBTITLES_H */
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