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
34 enum ff_utf_type {
35 FF_UTF_8, // or other 8 bit encodings
36 FF_UTF16LE,
37 FF_UTF16BE,
38 };
39
40 typedef struct {
41 int type;
42 AVIOContext *pb;
43 unsigned char buf[8];
44 int buf_pos, buf_len;
45 AVIOContext buf_pb;
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 */
84 int ff_text_r8(FFTextReader *r);
85
86 /**
87 * Return non-zero if EOF was reached.
88 */
89 int ff_text_eof(FFTextReader *r);
90
91 /**
92 * Like ff_text_r8(), but don't remove the byte from the buffer.
93 */
94 int ff_text_peek_r8(FFTextReader *r);
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
109 } FFDemuxSubtitlesQueue;
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 */
119 AVPacket *ff_subtitles_queue_insert(FFDemuxSubtitlesQueue *q,
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 */
132 int ff_subtitles_queue_read_packet(FFDemuxSubtitlesQueue *q, AVPacket *pkt);
133
134 /**
135 * Update current_sub_idx to emulate a seek. Except the first parameter, it
136 * matches AVInputFormat->read_seek2 prototypes.
137 */
138 int ff_subtitles_queue_seek(FFDemuxSubtitlesQueue *q, AVFormatContext *s, int stream_index,
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 */
144 void ff_subtitles_queue_clean(FFDemuxSubtitlesQueue *q);
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 */
ff_subtitles_next_line(const char * ptr)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 while (*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 */
213