path: root/libavformat/subtitles.h (plain)
blob: ca78db224d52f26fa4e8d7dffce68b05df579594

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	*/
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 */
213