1/*
2 * copyright (c) 2001 Fabrice Bellard
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#ifndef AVFORMAT_AVIO_H
21#define AVFORMAT_AVIO_H
22
23/**
24 * @file
25 * @ingroup lavf_io
26 * Buffered I/O operations
27 */
28
29#include <stdint.h>
30
31#include "libavutil/common.h"
32#include "libavutil/dict.h"
33#include "libavutil/log.h"
34
35#include "libavformat/version.h"
36
37/**
38 * Seeking works like for a local file.
39 */
40#define AVIO_SEEKABLE_NORMAL (1 << 0)
41
42/**
43 * Seeking by timestamp with avio_seek_time() is possible.
44 */
45#define AVIO_SEEKABLE_TIME (1 << 1)
46
47/**
48 * Callback for checking whether to abort blocking functions.
49 * AVERROR_EXIT is returned in this case by the interrupted
50 * function. During blocking operations, callback is called with
51 * opaque as parameter. If the callback returns 1, the
52 * blocking operation will be aborted.
53 *
54 * No members can be added to this struct without a major bump, if
55 * new elements have been added after this struct in AVFormatContext
56 * or AVIOContext.
57 */
58typedef struct AVIOInterruptCB {
59 int (*callback)(void*);
60 void *opaque;
61} AVIOInterruptCB;
62
63/**
64 * Directory entry types.
65 */
66enum AVIODirEntryType {
67 AVIO_ENTRY_UNKNOWN,
68 AVIO_ENTRY_BLOCK_DEVICE,
69 AVIO_ENTRY_CHARACTER_DEVICE,
70 AVIO_ENTRY_DIRECTORY,
71 AVIO_ENTRY_NAMED_PIPE,
72 AVIO_ENTRY_SYMBOLIC_LINK,
73 AVIO_ENTRY_SOCKET,
74 AVIO_ENTRY_FILE,
75 AVIO_ENTRY_SERVER,
76 AVIO_ENTRY_SHARE,
77 AVIO_ENTRY_WORKGROUP,
78};
79
80/**
81 * Describes single entry of the directory.
82 *
83 * Only name and type fields are guaranteed be set.
84 * Rest of fields are protocol or/and platform dependent and might be unknown.
85 */
86typedef struct AVIODirEntry {
87 char *name; /**< Filename */
88 int type; /**< Type of the entry */
89 int utf8; /**< Set to 1 when name is encoded with UTF-8, 0 otherwise.
90 Name can be encoded with UTF-8 even though 0 is set. */
91 int64_t size; /**< File size in bytes, -1 if unknown. */
92 int64_t modification_timestamp; /**< Time of last modification in microseconds since unix
93 epoch, -1 if unknown. */
94 int64_t access_timestamp; /**< Time of last access in microseconds since unix epoch,
95 -1 if unknown. */
96 int64_t status_change_timestamp; /**< Time of last status change in microseconds since unix
97 epoch, -1 if unknown. */
98 int64_t user_id; /**< User ID of owner, -1 if unknown. */
99 int64_t group_id; /**< Group ID of owner, -1 if unknown. */
100 int64_t filemode; /**< Unix file mode, -1 if unknown. */
101} AVIODirEntry;
102
103typedef struct AVIODirContext {
104 struct URLContext *url_context;
105} AVIODirContext;
106
107/**
108 * Different data types that can be returned via the AVIO
109 * write_data_type callback.
110 */
111enum AVIODataMarkerType {
112 /**
113 * Header data; this needs to be present for the stream to be decodeable.
114 */
115 AVIO_DATA_MARKER_HEADER,
116 /**
117 * A point in the output bytestream where a decoder can start decoding
118 * (i.e. a keyframe). A demuxer/decoder given the data flagged with
119 * AVIO_DATA_MARKER_HEADER, followed by any AVIO_DATA_MARKER_SYNC_POINT,
120 * should give decodeable results.
121 */
122 AVIO_DATA_MARKER_SYNC_POINT,
123 /**
124 * A point in the output bytestream where a demuxer can start parsing
125 * (for non self synchronizing bytestream formats). That is, any
126 * non-keyframe packet start point.
127 */
128 AVIO_DATA_MARKER_BOUNDARY_POINT,
129 /**
130 * This is any, unlabelled data. It can either be a muxer not marking
131 * any positions at all, it can be an actual boundary/sync point
132 * that the muxer chooses not to mark, or a later part of a packet/fragment
133 * that is cut into multiple write callbacks due to limited IO buffer size.
134 */
135 AVIO_DATA_MARKER_UNKNOWN,
136 /**
137 * Trailer data, which doesn't contain actual content, but only for
138 * finalizing the output file.
139 */
140 AVIO_DATA_MARKER_TRAILER,
141 /**
142 * A point in the output bytestream where the underlying AVIOContext might
143 * flush the buffer depending on latency or buffering requirements. Typically
144 * means the end of a packet.
145 */
146 AVIO_DATA_MARKER_FLUSH_POINT,
147};
148
149/**
150 * Bytestream IO Context.
151 * New fields can be added to the end with minor version bumps.
152 * Removal, reordering and changes to existing fields require a major
153 * version bump.
154 * sizeof(AVIOContext) must not be used outside libav*.
155 *
156 * @note None of the function pointers in AVIOContext should be called
157 * directly, they should only be set by the client application
158 * when implementing custom I/O. Normally these are set to the
159 * function pointers specified in avio_alloc_context()
160 */
161typedef struct AVIOContext {
162 /**
163 * A class for private options.
164 *
165 * If this AVIOContext is created by avio_open2(), av_class is set and
166 * passes the options down to protocols.
167 *
168 * If this AVIOContext is manually allocated, then av_class may be set by
169 * the caller.
170 *
171 * warning -- this field can be NULL, be sure to not pass this AVIOContext
172 * to any av_opt_* functions in that case.
173 */
174 const AVClass *av_class;
175
176 /*
177 * The following shows the relationship between buffer, buf_ptr,
178 * buf_ptr_max, buf_end, buf_size, and pos, when reading and when writing
179 * (since AVIOContext is used for both):
180 *
181 **********************************************************************************
182 * READING
183 **********************************************************************************
184 *
185 * | buffer_size |
186 * |---------------------------------------|
187 * | |
188 *
189 * buffer buf_ptr buf_end
190 * +---------------+-----------------------+
191 * |/ / / / / / / /|/ / / / / / /| |
192 * read buffer: |/ / consumed / | to be read /| |
193 * |/ / / / / / / /|/ / / / / / /| |
194 * +---------------+-----------------------+
195 *
196 * pos
197 * +-------------------------------------------+-----------------+
198 * input file: | | |
199 * +-------------------------------------------+-----------------+
200 *
201 *
202 **********************************************************************************
203 * WRITING
204 **********************************************************************************
205 *
206 * | buffer_size |
207 * |--------------------------------------|
208 * | |
209 *
210 * buf_ptr_max
211 * buffer (buf_ptr) buf_end
212 * +-----------------------+--------------+
213 * |/ / / / / / / / / / / /| |
214 * write buffer: | / / to be flushed / / | |
215 * |/ / / / / / / / / / / /| |
216 * +-----------------------+--------------+
217 * buf_ptr can be in this
218 * due to a backward seek
219 *
220 * pos
221 * +-------------+----------------------------------------------+
222 * output file: | | |
223 * +-------------+----------------------------------------------+
224 *
225 */
226 unsigned char *buffer; /**< Start of the buffer. */
227 int buffer_size; /**< Maximum buffer size */
228 unsigned char *buf_ptr; /**< Current position in the buffer */
229 unsigned char *buf_end; /**< End of the data, may be less than
230 buffer+buffer_size if the read function returned
231 less data than requested, e.g. for streams where
232 no more data has been received yet. */
233 void *opaque; /**< A private pointer, passed to the read/write/seek/...
234 functions. */
235 int (*read_packet)(void *opaque, uint8_t *buf, int buf_size);
236 int (*write_packet)(void *opaque, uint8_t *buf, int buf_size);
237 int64_t (*seek)(void *opaque, int64_t offset, int whence);
238 int64_t pos; /**< position in the file of the current buffer */
239 int eof_reached; /**< true if was unable to read due to error or eof */
240 int write_flag; /**< true if open for writing */
241 int max_packet_size;
242 unsigned long checksum;
243 unsigned char *checksum_ptr;
244 unsigned long (*update_checksum)(unsigned long checksum, const uint8_t *buf, unsigned int size);
245 int error; /**< contains the error code or 0 if no error happened */
246 /**
247 * Pause or resume playback for network streaming protocols - e.g. MMS.
248 */
249 int (*read_pause)(void *opaque, int pause);
250 /**
251 * Seek to a given timestamp in stream with the specified stream_index.
252 * Needed for some network streaming protocols which don't support seeking
253 * to byte position.
254 */
255 int64_t (*read_seek)(void *opaque, int stream_index,
256 int64_t timestamp, int flags);
257 /**
258 * A combination of AVIO_SEEKABLE_ flags or 0 when the stream is not seekable.
259 */
260 int seekable;
261
262 /**
263 * max filesize, used to limit allocations
264 * This field is internal to libavformat and access from outside is not allowed.
265 */
266 int64_t maxsize;
267
268 /**
269 * avio_read and avio_write should if possible be satisfied directly
270 * instead of going through a buffer, and avio_seek will always
271 * call the underlying seek function directly.
272 */
273 int direct;
274
275 /**
276 * Bytes read statistic
277 * This field is internal to libavformat and access from outside is not allowed.
278 */
279 int64_t bytes_read;
280
281 /**
282 * seek statistic
283 * This field is internal to libavformat and access from outside is not allowed.
284 */
285 int seek_count;
286
287 /**
288 * writeout statistic
289 * This field is internal to libavformat and access from outside is not allowed.
290 */
291 int writeout_count;
292
293 /**
294 * Original buffer size
295 * used internally after probing and ensure seekback to reset the buffer size
296 * This field is internal to libavformat and access from outside is not allowed.
297 */
298 int orig_buffer_size;
299
300 /**
301 * Threshold to favor readahead over seek.
302 * This is current internal only, do not use from outside.
303 */
304 int short_seek_threshold;
305
306 /**
307 * ',' separated list of allowed protocols.
308 */
309 const char *protocol_whitelist;
310
311 /**
312 * ',' separated list of disallowed protocols.
313 */
314 const char *protocol_blacklist;
315
316 /**
317 * A callback that is used instead of write_packet.
318 */
319 int (*write_data_type)(void *opaque, uint8_t *buf, int buf_size,
320 enum AVIODataMarkerType type, int64_t time);
321 /**
322 * If set, don't call write_data_type separately for AVIO_DATA_MARKER_BOUNDARY_POINT,
323 * but ignore them and treat them as AVIO_DATA_MARKER_UNKNOWN (to avoid needlessly
324 * small chunks of data returned from the callback).
325 */
326 int ignore_boundary_point;
327
328 /**
329 * Internal, not meant to be used from outside of AVIOContext.
330 */
331 enum AVIODataMarkerType current_type;
332 int64_t last_time;
333
334 /**
335 * A callback that is used instead of short_seek_threshold.
336 * This is current internal only, do not use from outside.
337 */
338 int (*short_seek_get)(void *opaque);
339
340 int64_t written;
341
342 /**
343 * Maximum reached position before a backward seek in the write buffer,
344 * used keeping track of already written data for a later flush.
345 */
346 unsigned char *buf_ptr_max;
347
348 /**
349 * Try to buffer at least this amount of data before flushing it
350 */
351 int min_packet_size;
352} AVIOContext;
353
354/**
355 * Return the name of the protocol that will handle the passed URL.
356 *
357 * NULL is returned if no protocol could be found for the given URL.
358 *
359 * @return Name of the protocol or NULL.
360 */
361const char *avio_find_protocol_name(const char *url);
362
363/**
364 * Return AVIO_FLAG_* access flags corresponding to the access permissions
365 * of the resource in url, or a negative value corresponding to an
366 * AVERROR code in case of failure. The returned access flags are
367 * masked by the value in flags.
368 *
369 * @note This function is intrinsically unsafe, in the sense that the
370 * checked resource may change its existence or permission status from
371 * one call to another. Thus you should not trust the returned value,
372 * unless you are sure that no other processes are accessing the
373 * checked resource.
374 */
375int avio_check(const char *url, int flags);
376
377/**
378 * Move or rename a resource.
379 *
380 * @note url_src and url_dst should share the same protocol and authority.
381 *
382 * @param url_src url to resource to be moved
383 * @param url_dst new url to resource if the operation succeeded
384 * @return >=0 on success or negative on error.
385 */
386int avpriv_io_move(const char *url_src, const char *url_dst);
387
388/**
389 * Delete a resource.
390 *
391 * @param url resource to be deleted.
392 * @return >=0 on success or negative on error.
393 */
394int avpriv_io_delete(const char *url);
395
396/**
397 * Open directory for reading.
398 *
399 * @param s directory read context. Pointer to a NULL pointer must be passed.
400 * @param url directory to be listed.
401 * @param options A dictionary filled with protocol-private options. On return
402 * this parameter will be destroyed and replaced with a dictionary
403 * containing options that were not found. May be NULL.
404 * @return >=0 on success or negative on error.
405 */
406int avio_open_dir(AVIODirContext **s, const char *url, AVDictionary **options);
407
408/**
409 * Get next directory entry.
410 *
411 * Returned entry must be freed with avio_free_directory_entry(). In particular
412 * it may outlive AVIODirContext.
413 *
414 * @param s directory read context.
415 * @param[out] next next entry or NULL when no more entries.
416 * @return >=0 on success or negative on error. End of list is not considered an
417 * error.
418 */
419int avio_read_dir(AVIODirContext *s, AVIODirEntry **next);
420
421/**
422 * Close directory.
423 *
424 * @note Entries created using avio_read_dir() are not deleted and must be
425 * freeded with avio_free_directory_entry().
426 *
427 * @param s directory read context.
428 * @return >=0 on success or negative on error.
429 */
430int avio_close_dir(AVIODirContext **s);
431
432/**
433 * Free entry allocated by avio_read_dir().
434 *
435 * @param entry entry to be freed.
436 */
437void avio_free_directory_entry(AVIODirEntry **entry);
438
439/**
440 * Allocate and initialize an AVIOContext for buffered I/O. It must be later
441 * freed with avio_context_free().
442 *
443 * @param buffer Memory block for input/output operations via AVIOContext.
444 * The buffer must be allocated with av_malloc() and friends.
445 * It may be freed and replaced with a new buffer by libavformat.
446 * AVIOContext.buffer holds the buffer currently in use,
447 * which must be later freed with av_free().
448 * @param buffer_size The buffer size is very important for performance.
449 * For protocols with fixed blocksize it should be set to this blocksize.
450 * For others a typical size is a cache page, e.g. 4kb.
451 * @param write_flag Set to 1 if the buffer should be writable, 0 otherwise.
452 * @param opaque An opaque pointer to user-specific data.
453 * @param read_packet A function for refilling the buffer, may be NULL.
454 * For stream protocols, must never return 0 but rather
455 * a proper AVERROR code.
456 * @param write_packet A function for writing the buffer contents, may be NULL.
457 * The function may not change the input buffers content.
458 * @param seek A function for seeking to specified byte position, may be NULL.
459 *
460 * @return Allocated AVIOContext or NULL on failure.
461 */
462AVIOContext *avio_alloc_context(
463 unsigned char *buffer,
464 int buffer_size,
465 int write_flag,
466 void *opaque,
467 int (*read_packet)(void *opaque, uint8_t *buf, int buf_size),
468 int (*write_packet)(void *opaque, uint8_t *buf, int buf_size),
469 int64_t (*seek)(void *opaque, int64_t offset, int whence));
470
471/**
472 * Free the supplied IO context and everything associated with it.
473 *
474 * @param s Double pointer to the IO context. This function will write NULL
475 * into s.
476 */
477void avio_context_free(AVIOContext **s);
478
479void avio_w8(AVIOContext *s, int b);
480void avio_write(AVIOContext *s, const unsigned char *buf, int size);
481void avio_wl64(AVIOContext *s, uint64_t val);
482void avio_wb64(AVIOContext *s, uint64_t val);
483void avio_wl32(AVIOContext *s, unsigned int val);
484void avio_wb32(AVIOContext *s, unsigned int val);
485void avio_wl24(AVIOContext *s, unsigned int val);
486void avio_wb24(AVIOContext *s, unsigned int val);
487void avio_wl16(AVIOContext *s, unsigned int val);
488void avio_wb16(AVIOContext *s, unsigned int val);
489
490/**
491 * Write a NULL-terminated string.
492 * @return number of bytes written.
493 */
494int avio_put_str(AVIOContext *s, const char *str);
495
496/**
497 * Convert an UTF-8 string to UTF-16LE and write it.
498 * @param s the AVIOContext
499 * @param str NULL-terminated UTF-8 string
500 *
501 * @return number of bytes written.
502 */
503int avio_put_str16le(AVIOContext *s, const char *str);
504
505/**
506 * Convert an UTF-8 string to UTF-16BE and write it.
507 * @param s the AVIOContext
508 * @param str NULL-terminated UTF-8 string
509 *
510 * @return number of bytes written.
511 */
512int avio_put_str16be(AVIOContext *s, const char *str);
513
514/**
515 * Mark the written bytestream as a specific type.
516 *
517 * Zero-length ranges are omitted from the output.
518 *
519 * @param time the stream time the current bytestream pos corresponds to
520 * (in AV_TIME_BASE units), or AV_NOPTS_VALUE if unknown or not
521 * applicable
522 * @param type the kind of data written starting at the current pos
523 */
524void avio_write_marker(AVIOContext *s, int64_t time, enum AVIODataMarkerType type);
525
526/**
527 * ORing this as the "whence" parameter to a seek function causes it to
528 * return the filesize without seeking anywhere. Supporting this is optional.
529 * If it is not supported then the seek function will return <0.
530 */
531#define AVSEEK_SIZE 0x10000
532
533/**
534 * Passing this flag as the "whence" parameter to a seek function causes it to
535 * seek by any means (like reopening and linear reading) or other normally unreasonable
536 * means that can be extremely slow.
537 * This may be ignored by the seek code.
538 */
539#define AVSEEK_FORCE 0x20000
540
541/**
542 * fseek() equivalent for AVIOContext.
543 * @return new position or AVERROR.
544 */
545int64_t avio_seek(AVIOContext *s, int64_t offset, int whence);
546
547/**
548 * Skip given number of bytes forward
549 * @return new position or AVERROR.
550 */
551int64_t avio_skip(AVIOContext *s, int64_t offset);
552
553/**
554 * ftell() equivalent for AVIOContext.
555 * @return position or AVERROR.
556 */
557static av_always_inline int64_t avio_tell(AVIOContext *s)
558{
559 return avio_seek(s, offset: 0, SEEK_CUR);
560}
561
562/**
563 * Get the filesize.
564 * @return filesize or AVERROR
565 */
566int64_t avio_size(AVIOContext *s);
567
568/**
569 * Similar to feof() but also returns nonzero on read errors.
570 * @return non zero if and only if at end of file or a read error happened when reading.
571 */
572int avio_feof(AVIOContext *s);
573
574/**
575 * Writes a formatted string to the context.
576 * @return number of bytes written, < 0 on error.
577 */
578int avio_printf(AVIOContext *s, const char *fmt, ...) av_printf_format(2, 3);
579
580/**
581 * Write a NULL terminated array of strings to the context.
582 * Usually you don't need to use this function directly but its macro wrapper,
583 * avio_print.
584 */
585void avio_print_string_array(AVIOContext *s, const char *strings[]);
586
587/**
588 * Write strings (const char *) to the context.
589 * This is a convenience macro around avio_print_string_array and it
590 * automatically creates the string array from the variable argument list.
591 * For simple string concatenations this function is more performant than using
592 * avio_printf since it does not need a temporary buffer.
593 */
594#define avio_print(s, ...) \
595 avio_print_string_array(s, (const char*[]){__VA_ARGS__, NULL})
596
597/**
598 * Force flushing of buffered data.
599 *
600 * For write streams, force the buffered data to be immediately written to the output,
601 * without to wait to fill the internal buffer.
602 *
603 * For read streams, discard all currently buffered data, and advance the
604 * reported file position to that of the underlying stream. This does not
605 * read new data, and does not perform any seeks.
606 */
607void avio_flush(AVIOContext *s);
608
609/**
610 * Read size bytes from AVIOContext into buf.
611 * @return number of bytes read or AVERROR
612 */
613int avio_read(AVIOContext *s, unsigned char *buf, int size);
614
615/**
616 * Read size bytes from AVIOContext into buf. Unlike avio_read(), this is allowed
617 * to read fewer bytes than requested. The missing bytes can be read in the next
618 * call. This always tries to read at least 1 byte.
619 * Useful to reduce latency in certain cases.
620 * @return number of bytes read or AVERROR
621 */
622int avio_read_partial(AVIOContext *s, unsigned char *buf, int size);
623
624/**
625 * @name Functions for reading from AVIOContext
626 * @{
627 *
628 * @note return 0 if EOF, so you cannot use it if EOF handling is
629 * necessary
630 */
631int avio_r8 (AVIOContext *s);
632unsigned int avio_rl16(AVIOContext *s);
633unsigned int avio_rl24(AVIOContext *s);
634unsigned int avio_rl32(AVIOContext *s);
635uint64_t avio_rl64(AVIOContext *s);
636unsigned int avio_rb16(AVIOContext *s);
637unsigned int avio_rb24(AVIOContext *s);
638unsigned int avio_rb32(AVIOContext *s);
639uint64_t avio_rb64(AVIOContext *s);
640/**
641 * @}
642 */
643
644/**
645 * Read a string from pb into buf. The reading will terminate when either
646 * a NULL character was encountered, maxlen bytes have been read, or nothing
647 * more can be read from pb. The result is guaranteed to be NULL-terminated, it
648 * will be truncated if buf is too small.
649 * Note that the string is not interpreted or validated in any way, it
650 * might get truncated in the middle of a sequence for multi-byte encodings.
651 *
652 * @return number of bytes read (is always <= maxlen).
653 * If reading ends on EOF or error, the return value will be one more than
654 * bytes actually read.
655 */
656int avio_get_str(AVIOContext *pb, int maxlen, char *buf, int buflen);
657
658/**
659 * Read a UTF-16 string from pb and convert it to UTF-8.
660 * The reading will terminate when either a null or invalid character was
661 * encountered or maxlen bytes have been read.
662 * @return number of bytes read (is always <= maxlen)
663 */
664int avio_get_str16le(AVIOContext *pb, int maxlen, char *buf, int buflen);
665int avio_get_str16be(AVIOContext *pb, int maxlen, char *buf, int buflen);
666
667
668/**
669 * @name URL open modes
670 * The flags argument to avio_open must be one of the following
671 * constants, optionally ORed with other flags.
672 * @{
673 */
674#define AVIO_FLAG_READ 1 /**< read-only */
675#define AVIO_FLAG_WRITE 2 /**< write-only */
676#define AVIO_FLAG_READ_WRITE (AVIO_FLAG_READ|AVIO_FLAG_WRITE) /**< read-write pseudo flag */
677/**
678 * @}
679 */
680
681/**
682 * Use non-blocking mode.
683 * If this flag is set, operations on the context will return
684 * AVERROR(EAGAIN) if they can not be performed immediately.
685 * If this flag is not set, operations on the context will never return
686 * AVERROR(EAGAIN).
687 * Note that this flag does not affect the opening/connecting of the
688 * context. Connecting a protocol will always block if necessary (e.g. on
689 * network protocols) but never hang (e.g. on busy devices).
690 * Warning: non-blocking protocols is work-in-progress; this flag may be
691 * silently ignored.
692 */
693#define AVIO_FLAG_NONBLOCK 8
694
695/**
696 * Use direct mode.
697 * avio_read and avio_write should if possible be satisfied directly
698 * instead of going through a buffer, and avio_seek will always
699 * call the underlying seek function directly.
700 */
701#define AVIO_FLAG_DIRECT 0x8000
702
703/**
704 * Create and initialize a AVIOContext for accessing the
705 * resource indicated by url.
706 * @note When the resource indicated by url has been opened in
707 * read+write mode, the AVIOContext can be used only for writing.
708 *
709 * @param s Used to return the pointer to the created AVIOContext.
710 * In case of failure the pointed to value is set to NULL.
711 * @param url resource to access
712 * @param flags flags which control how the resource indicated by url
713 * is to be opened
714 * @return >= 0 in case of success, a negative value corresponding to an
715 * AVERROR code in case of failure
716 */
717int avio_open(AVIOContext **s, const char *url, int flags);
718
719/**
720 * Create and initialize a AVIOContext for accessing the
721 * resource indicated by url.
722 * @note When the resource indicated by url has been opened in
723 * read+write mode, the AVIOContext can be used only for writing.
724 *
725 * @param s Used to return the pointer to the created AVIOContext.
726 * In case of failure the pointed to value is set to NULL.
727 * @param url resource to access
728 * @param flags flags which control how the resource indicated by url
729 * is to be opened
730 * @param int_cb an interrupt callback to be used at the protocols level
731 * @param options A dictionary filled with protocol-private options. On return
732 * this parameter will be destroyed and replaced with a dict containing options
733 * that were not found. May be NULL.
734 * @return >= 0 in case of success, a negative value corresponding to an
735 * AVERROR code in case of failure
736 */
737int avio_open2(AVIOContext **s, const char *url, int flags,
738 const AVIOInterruptCB *int_cb, AVDictionary **options);
739
740/**
741 * Close the resource accessed by the AVIOContext s and free it.
742 * This function can only be used if s was opened by avio_open().
743 *
744 * The internal buffer is automatically flushed before closing the
745 * resource.
746 *
747 * @return 0 on success, an AVERROR < 0 on error.
748 * @see avio_closep
749 */
750int avio_close(AVIOContext *s);
751
752/**
753 * Close the resource accessed by the AVIOContext *s, free it
754 * and set the pointer pointing to it to NULL.
755 * This function can only be used if s was opened by avio_open().
756 *
757 * The internal buffer is automatically flushed before closing the
758 * resource.
759 *
760 * @return 0 on success, an AVERROR < 0 on error.
761 * @see avio_close
762 */
763int avio_closep(AVIOContext **s);
764
765
766/**
767 * Open a write only memory stream.
768 *
769 * @param s new IO context
770 * @return zero if no error.
771 */
772int avio_open_dyn_buf(AVIOContext **s);
773
774/**
775 * Return the written size and a pointer to the buffer.
776 * The AVIOContext stream is left intact.
777 * The buffer must NOT be freed.
778 * No padding is added to the buffer.
779 *
780 * @param s IO context
781 * @param pbuffer pointer to a byte buffer
782 * @return the length of the byte buffer
783 */
784int avio_get_dyn_buf(AVIOContext *s, uint8_t **pbuffer);
785
786/**
787 * Return the written size and a pointer to the buffer. The buffer
788 * must be freed with av_free().
789 * Padding of AV_INPUT_BUFFER_PADDING_SIZE is added to the buffer.
790 *
791 * @param s IO context
792 * @param pbuffer pointer to a byte buffer
793 * @return the length of the byte buffer
794 */
795int avio_close_dyn_buf(AVIOContext *s, uint8_t **pbuffer);
796
797/**
798 * Iterate through names of available protocols.
799 *
800 * @param opaque A private pointer representing current protocol.
801 * It must be a pointer to NULL on first iteration and will
802 * be updated by successive calls to avio_enum_protocols.
803 * @param output If set to 1, iterate over output protocols,
804 * otherwise over input protocols.
805 *
806 * @return A static string containing the name of current protocol or NULL
807 */
808const char *avio_enum_protocols(void **opaque, int output);
809
810/**
811 * Get AVClass by names of available protocols.
812 *
813 * @return A AVClass of input protocol name or NULL
814 */
815const AVClass *avio_protocol_get_class(const char *name);
816
817/**
818 * Pause and resume playing - only meaningful if using a network streaming
819 * protocol (e.g. MMS).
820 *
821 * @param h IO context from which to call the read_pause function pointer
822 * @param pause 1 for pause, 0 for resume
823 */
824int avio_pause(AVIOContext *h, int pause);
825
826/**
827 * Seek to a given timestamp relative to some component stream.
828 * Only meaningful if using a network streaming protocol (e.g. MMS.).
829 *
830 * @param h IO context from which to call the seek function pointers
831 * @param stream_index The stream index that the timestamp is relative to.
832 * If stream_index is (-1) the timestamp should be in AV_TIME_BASE
833 * units from the beginning of the presentation.
834 * If a stream_index >= 0 is used and the protocol does not support
835 * seeking based on component streams, the call will fail.
836 * @param timestamp timestamp in AVStream.time_base units
837 * or if there is no stream specified then in AV_TIME_BASE units.
838 * @param flags Optional combination of AVSEEK_FLAG_BACKWARD, AVSEEK_FLAG_BYTE
839 * and AVSEEK_FLAG_ANY. The protocol may silently ignore
840 * AVSEEK_FLAG_BACKWARD and AVSEEK_FLAG_ANY, but AVSEEK_FLAG_BYTE will
841 * fail if used and not supported.
842 * @return >= 0 on success
843 * @see AVInputFormat::read_seek
844 */
845int64_t avio_seek_time(AVIOContext *h, int stream_index,
846 int64_t timestamp, int flags);
847
848/* Avoid a warning. The header can not be included because it breaks c++. */
849struct AVBPrint;
850
851/**
852 * Read contents of h into print buffer, up to max_size bytes, or up to EOF.
853 *
854 * @return 0 for success (max_size bytes read or EOF reached), negative error
855 * code otherwise
856 */
857int avio_read_to_bprint(AVIOContext *h, struct AVBPrint *pb, size_t max_size);
858
859/**
860 * Accept and allocate a client context on a server context.
861 * @param s the server context
862 * @param c the client context, must be unallocated
863 * @return >= 0 on success or a negative value corresponding
864 * to an AVERROR on failure
865 */
866int avio_accept(AVIOContext *s, AVIOContext **c);
867
868/**
869 * Perform one step of the protocol handshake to accept a new client.
870 * This function must be called on a client returned by avio_accept() before
871 * using it as a read/write context.
872 * It is separate from avio_accept() because it may block.
873 * A step of the handshake is defined by places where the application may
874 * decide to change the proceedings.
875 * For example, on a protocol with a request header and a reply header, each
876 * one can constitute a step because the application may use the parameters
877 * from the request to change parameters in the reply; or each individual
878 * chunk of the request can constitute a step.
879 * If the handshake is already finished, avio_handshake() does nothing and
880 * returns 0 immediately.
881 *
882 * @param c the client context to perform the handshake on
883 * @return 0 on a complete and successful handshake
884 * > 0 if the handshake progressed, but is not complete
885 * < 0 for an AVERROR code
886 */
887int avio_handshake(AVIOContext *c);
888#endif /* AVFORMAT_AVIO_H */
889

source code of include/x86_64-linux-gnu/libavformat/avio.h