FFmpeg coverage


Directory: ../../../ffmpeg/
File: src/libavformat/avio.h
Date: 2022-12-05 20:26:17
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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 #include <stdio.h>
31
32 #include "libavutil/attributes.h"
33 #include "libavutil/dict.h"
34 #include "libavutil/log.h"
35
36 #include "libavformat/version_major.h"
37
38 /**
39 * Seeking works like for a local file.
40 */
41 #define AVIO_SEEKABLE_NORMAL (1 << 0)
42
43 /**
44 * Seeking by timestamp with avio_seek_time() is possible.
45 */
46 #define AVIO_SEEKABLE_TIME (1 << 1)
47
48 /**
49 * Callback for checking whether to abort blocking functions.
50 * AVERROR_EXIT is returned in this case by the interrupted
51 * function. During blocking operations, callback is called with
52 * opaque as parameter. If the callback returns 1, the
53 * blocking operation will be aborted.
54 *
55 * No members can be added to this struct without a major bump, if
56 * new elements have been added after this struct in AVFormatContext
57 * or AVIOContext.
58 */
59 typedef struct AVIOInterruptCB {
60 int (*callback)(void*);
61 void *opaque;
62 } AVIOInterruptCB;
63
64 /**
65 * Directory entry types.
66 */
67 enum AVIODirEntryType {
68 AVIO_ENTRY_UNKNOWN,
69 AVIO_ENTRY_BLOCK_DEVICE,
70 AVIO_ENTRY_CHARACTER_DEVICE,
71 AVIO_ENTRY_DIRECTORY,
72 AVIO_ENTRY_NAMED_PIPE,
73 AVIO_ENTRY_SYMBOLIC_LINK,
74 AVIO_ENTRY_SOCKET,
75 AVIO_ENTRY_FILE,
76 AVIO_ENTRY_SERVER,
77 AVIO_ENTRY_SHARE,
78 AVIO_ENTRY_WORKGROUP,
79 };
80
81 /**
82 * Describes single entry of the directory.
83 *
84 * Only name and type fields are guaranteed be set.
85 * Rest of fields are protocol or/and platform dependent and might be unknown.
86 */
87 typedef struct AVIODirEntry {
88 char *name; /**< Filename */
89 int type; /**< Type of the entry */
90 int utf8; /**< Set to 1 when name is encoded with UTF-8, 0 otherwise.
91 Name can be encoded with UTF-8 even though 0 is set. */
92 int64_t size; /**< File size in bytes, -1 if unknown. */
93 int64_t modification_timestamp; /**< Time of last modification in microseconds since unix
94 epoch, -1 if unknown. */
95 int64_t access_timestamp; /**< Time of last access in microseconds since unix epoch,
96 -1 if unknown. */
97 int64_t status_change_timestamp; /**< Time of last status change in microseconds since unix
98 epoch, -1 if unknown. */
99 int64_t user_id; /**< User ID of owner, -1 if unknown. */
100 int64_t group_id; /**< Group ID of owner, -1 if unknown. */
101 int64_t filemode; /**< Unix file mode, -1 if unknown. */
102 } AVIODirEntry;
103
104 #if FF_API_AVIODIRCONTEXT
105 typedef struct AVIODirContext {
106 struct URLContext *url_context;
107 } AVIODirContext;
108 #else
109 typedef struct AVIODirContext AVIODirContext;
110 #endif
111
112 /**
113 * Different data types that can be returned via the AVIO
114 * write_data_type callback.
115 */
116 enum AVIODataMarkerType {
117 /**
118 * Header data; this needs to be present for the stream to be decodeable.
119 */
120 AVIO_DATA_MARKER_HEADER,
121 /**
122 * A point in the output bytestream where a decoder can start decoding
123 * (i.e. a keyframe). A demuxer/decoder given the data flagged with
124 * AVIO_DATA_MARKER_HEADER, followed by any AVIO_DATA_MARKER_SYNC_POINT,
125 * should give decodeable results.
126 */
127 AVIO_DATA_MARKER_SYNC_POINT,
128 /**
129 * A point in the output bytestream where a demuxer can start parsing
130 * (for non self synchronizing bytestream formats). That is, any
131 * non-keyframe packet start point.
132 */
133 AVIO_DATA_MARKER_BOUNDARY_POINT,
134 /**
135 * This is any, unlabelled data. It can either be a muxer not marking
136 * any positions at all, it can be an actual boundary/sync point
137 * that the muxer chooses not to mark, or a later part of a packet/fragment
138 * that is cut into multiple write callbacks due to limited IO buffer size.
139 */
140 AVIO_DATA_MARKER_UNKNOWN,
141 /**
142 * Trailer data, which doesn't contain actual content, but only for
143 * finalizing the output file.
144 */
145 AVIO_DATA_MARKER_TRAILER,
146 /**
147 * A point in the output bytestream where the underlying AVIOContext might
148 * flush the buffer depending on latency or buffering requirements. Typically
149 * means the end of a packet.
150 */
151 AVIO_DATA_MARKER_FLUSH_POINT,
152 };
153
154 /**
155 * Bytestream IO Context.
156 * New public fields can be added with minor version bumps.
157 * Removal, reordering and changes to existing public fields require
158 * a major version bump.
159 * sizeof(AVIOContext) must not be used outside libav*.
160 *
161 * @note None of the function pointers in AVIOContext should be called
162 * directly, they should only be set by the client application
163 * when implementing custom I/O. Normally these are set to the
164 * function pointers specified in avio_alloc_context()
165 */
166 typedef struct AVIOContext {
167 /**
168 * A class for private options.
169 *
170 * If this AVIOContext is created by avio_open2(), av_class is set and
171 * passes the options down to protocols.
172 *
173 * If this AVIOContext is manually allocated, then av_class may be set by
174 * the caller.
175 *
176 * warning -- this field can be NULL, be sure to not pass this AVIOContext
177 * to any av_opt_* functions in that case.
178 */
179 const AVClass *av_class;
180
181 /*
182 * The following shows the relationship between buffer, buf_ptr,
183 * buf_ptr_max, buf_end, buf_size, and pos, when reading and when writing
184 * (since AVIOContext is used for both):
185 *
186 **********************************************************************************
187 * READING
188 **********************************************************************************
189 *
190 * | buffer_size |
191 * |---------------------------------------|
192 * | |
193 *
194 * buffer buf_ptr buf_end
195 * +---------------+-----------------------+
196 * |/ / / / / / / /|/ / / / / / /| |
197 * read buffer: |/ / consumed / | to be read /| |
198 * |/ / / / / / / /|/ / / / / / /| |
199 * +---------------+-----------------------+
200 *
201 * pos
202 * +-------------------------------------------+-----------------+
203 * input file: | | |
204 * +-------------------------------------------+-----------------+
205 *
206 *
207 **********************************************************************************
208 * WRITING
209 **********************************************************************************
210 *
211 * | buffer_size |
212 * |--------------------------------------|
213 * | |
214 *
215 * buf_ptr_max
216 * buffer (buf_ptr) buf_end
217 * +-----------------------+--------------+
218 * |/ / / / / / / / / / / /| |
219 * write buffer: | / / to be flushed / / | |
220 * |/ / / / / / / / / / / /| |
221 * +-----------------------+--------------+
222 * buf_ptr can be in this
223 * due to a backward seek
224 *
225 * pos
226 * +-------------+----------------------------------------------+
227 * output file: | | |
228 * +-------------+----------------------------------------------+
229 *
230 */
231 unsigned char *buffer; /**< Start of the buffer. */
232 int buffer_size; /**< Maximum buffer size */
233 unsigned char *buf_ptr; /**< Current position in the buffer */
234 unsigned char *buf_end; /**< End of the data, may be less than
235 buffer+buffer_size if the read function returned
236 less data than requested, e.g. for streams where
237 no more data has been received yet. */
238 void *opaque; /**< A private pointer, passed to the read/write/seek/...
239 functions. */
240 int (*read_packet)(void *opaque, uint8_t *buf, int buf_size);
241 int (*write_packet)(void *opaque, uint8_t *buf, int buf_size);
242 int64_t (*seek)(void *opaque, int64_t offset, int whence);
243 int64_t pos; /**< position in the file of the current buffer */
244 int eof_reached; /**< true if was unable to read due to error or eof */
245 int error; /**< contains the error code or 0 if no error happened */
246 int write_flag; /**< true if open for writing */
247 int max_packet_size;
248 int min_packet_size; /**< Try to buffer at least this amount of data
249 before flushing it. */
250 unsigned long checksum;
251 unsigned char *checksum_ptr;
252 unsigned long (*update_checksum)(unsigned long checksum, const uint8_t *buf, unsigned int size);
253 /**
254 * Pause or resume playback for network streaming protocols - e.g. MMS.
255 */
256 int (*read_pause)(void *opaque, int pause);
257 /**
258 * Seek to a given timestamp in stream with the specified stream_index.
259 * Needed for some network streaming protocols which don't support seeking
260 * to byte position.
261 */
262 int64_t (*read_seek)(void *opaque, int stream_index,
263 int64_t timestamp, int flags);
264 /**
265 * A combination of AVIO_SEEKABLE_ flags or 0 when the stream is not seekable.
266 */
267 int seekable;
268
269 /**
270 * avio_read and avio_write should if possible be satisfied directly
271 * instead of going through a buffer, and avio_seek will always
272 * call the underlying seek function directly.
273 */
274 int direct;
275
276 /**
277 * ',' separated list of allowed protocols.
278 */
279 const char *protocol_whitelist;
280
281 /**
282 * ',' separated list of disallowed protocols.
283 */
284 const char *protocol_blacklist;
285
286 /**
287 * A callback that is used instead of write_packet.
288 */
289 int (*write_data_type)(void *opaque, uint8_t *buf, int buf_size,
290 enum AVIODataMarkerType type, int64_t time);
291 /**
292 * If set, don't call write_data_type separately for AVIO_DATA_MARKER_BOUNDARY_POINT,
293 * but ignore them and treat them as AVIO_DATA_MARKER_UNKNOWN (to avoid needlessly
294 * small chunks of data returned from the callback).
295 */
296 int ignore_boundary_point;
297
298 #if FF_API_AVIOCONTEXT_WRITTEN
299 /**
300 * @deprecated field utilized privately by libavformat. For a public
301 * statistic of how many bytes were written out, see
302 * AVIOContext::bytes_written.
303 */
304 attribute_deprecated
305 int64_t written;
306 #endif
307
308 /**
309 * Maximum reached position before a backward seek in the write buffer,
310 * used keeping track of already written data for a later flush.
311 */
312 unsigned char *buf_ptr_max;
313
314 /**
315 * Read-only statistic of bytes read for this AVIOContext.
316 */
317 int64_t bytes_read;
318
319 /**
320 * Read-only statistic of bytes written for this AVIOContext.
321 */
322 int64_t bytes_written;
323 } AVIOContext;
324
325 /**
326 * Return the name of the protocol that will handle the passed URL.
327 *
328 * NULL is returned if no protocol could be found for the given URL.
329 *
330 * @return Name of the protocol or NULL.
331 */
332 const char *avio_find_protocol_name(const char *url);
333
334 /**
335 * Return AVIO_FLAG_* access flags corresponding to the access permissions
336 * of the resource in url, or a negative value corresponding to an
337 * AVERROR code in case of failure. The returned access flags are
338 * masked by the value in flags.
339 *
340 * @note This function is intrinsically unsafe, in the sense that the
341 * checked resource may change its existence or permission status from
342 * one call to another. Thus you should not trust the returned value,
343 * unless you are sure that no other processes are accessing the
344 * checked resource.
345 */
346 int avio_check(const char *url, int flags);
347
348 /**
349 * Open directory for reading.
350 *
351 * @param s directory read context. Pointer to a NULL pointer must be passed.
352 * @param url directory to be listed.
353 * @param options A dictionary filled with protocol-private options. On return
354 * this parameter will be destroyed and replaced with a dictionary
355 * containing options that were not found. May be NULL.
356 * @return >=0 on success or negative on error.
357 */
358 int avio_open_dir(AVIODirContext **s, const char *url, AVDictionary **options);
359
360 /**
361 * Get next directory entry.
362 *
363 * Returned entry must be freed with avio_free_directory_entry(). In particular
364 * it may outlive AVIODirContext.
365 *
366 * @param s directory read context.
367 * @param[out] next next entry or NULL when no more entries.
368 * @return >=0 on success or negative on error. End of list is not considered an
369 * error.
370 */
371 int avio_read_dir(AVIODirContext *s, AVIODirEntry **next);
372
373 /**
374 * Close directory.
375 *
376 * @note Entries created using avio_read_dir() are not deleted and must be
377 * freeded with avio_free_directory_entry().
378 *
379 * @param s directory read context.
380 * @return >=0 on success or negative on error.
381 */
382 int avio_close_dir(AVIODirContext **s);
383
384 /**
385 * Free entry allocated by avio_read_dir().
386 *
387 * @param entry entry to be freed.
388 */
389 void avio_free_directory_entry(AVIODirEntry **entry);
390
391 /**
392 * Allocate and initialize an AVIOContext for buffered I/O. It must be later
393 * freed with avio_context_free().
394 *
395 * @param buffer Memory block for input/output operations via AVIOContext.
396 * The buffer must be allocated with av_malloc() and friends.
397 * It may be freed and replaced with a new buffer by libavformat.
398 * AVIOContext.buffer holds the buffer currently in use,
399 * which must be later freed with av_free().
400 * @param buffer_size The buffer size is very important for performance.
401 * For protocols with fixed blocksize it should be set to this blocksize.
402 * For others a typical size is a cache page, e.g. 4kb.
403 * @param write_flag Set to 1 if the buffer should be writable, 0 otherwise.
404 * @param opaque An opaque pointer to user-specific data.
405 * @param read_packet A function for refilling the buffer, may be NULL.
406 * For stream protocols, must never return 0 but rather
407 * a proper AVERROR code.
408 * @param write_packet A function for writing the buffer contents, may be NULL.
409 * The function may not change the input buffers content.
410 * @param seek A function for seeking to specified byte position, may be NULL.
411 *
412 * @return Allocated AVIOContext or NULL on failure.
413 */
414 AVIOContext *avio_alloc_context(
415 unsigned char *buffer,
416 int buffer_size,
417 int write_flag,
418 void *opaque,
419 int (*read_packet)(void *opaque, uint8_t *buf, int buf_size),
420 int (*write_packet)(void *opaque, uint8_t *buf, int buf_size),
421 int64_t (*seek)(void *opaque, int64_t offset, int whence));
422
423 /**
424 * Free the supplied IO context and everything associated with it.
425 *
426 * @param s Double pointer to the IO context. This function will write NULL
427 * into s.
428 */
429 void avio_context_free(AVIOContext **s);
430
431 void avio_w8(AVIOContext *s, int b);
432 void avio_write(AVIOContext *s, const unsigned char *buf, int size);
433 void avio_wl64(AVIOContext *s, uint64_t val);
434 void avio_wb64(AVIOContext *s, uint64_t val);
435 void avio_wl32(AVIOContext *s, unsigned int val);
436 void avio_wb32(AVIOContext *s, unsigned int val);
437 void avio_wl24(AVIOContext *s, unsigned int val);
438 void avio_wb24(AVIOContext *s, unsigned int val);
439 void avio_wl16(AVIOContext *s, unsigned int val);
440 void avio_wb16(AVIOContext *s, unsigned int val);
441
442 /**
443 * Write a NULL-terminated string.
444 * @return number of bytes written.
445 */
446 int avio_put_str(AVIOContext *s, const char *str);
447
448 /**
449 * Convert an UTF-8 string to UTF-16LE and write it.
450 * @param s the AVIOContext
451 * @param str NULL-terminated UTF-8 string
452 *
453 * @return number of bytes written.
454 */
455 int avio_put_str16le(AVIOContext *s, const char *str);
456
457 /**
458 * Convert an UTF-8 string to UTF-16BE and write it.
459 * @param s the AVIOContext
460 * @param str NULL-terminated UTF-8 string
461 *
462 * @return number of bytes written.
463 */
464 int avio_put_str16be(AVIOContext *s, const char *str);
465
466 /**
467 * Mark the written bytestream as a specific type.
468 *
469 * Zero-length ranges are omitted from the output.
470 *
471 * @param s the AVIOContext
472 * @param time the stream time the current bytestream pos corresponds to
473 * (in AV_TIME_BASE units), or AV_NOPTS_VALUE if unknown or not
474 * applicable
475 * @param type the kind of data written starting at the current pos
476 */
477 void avio_write_marker(AVIOContext *s, int64_t time, enum AVIODataMarkerType type);
478
479 /**
480 * ORing this as the "whence" parameter to a seek function causes it to
481 * return the filesize without seeking anywhere. Supporting this is optional.
482 * If it is not supported then the seek function will return <0.
483 */
484 #define AVSEEK_SIZE 0x10000
485
486 /**
487 * Passing this flag as the "whence" parameter to a seek function causes it to
488 * seek by any means (like reopening and linear reading) or other normally unreasonable
489 * means that can be extremely slow.
490 * This may be ignored by the seek code.
491 */
492 #define AVSEEK_FORCE 0x20000
493
494 /**
495 * fseek() equivalent for AVIOContext.
496 * @return new position or AVERROR.
497 */
498 int64_t avio_seek(AVIOContext *s, int64_t offset, int whence);
499
500 /**
501 * Skip given number of bytes forward
502 * @return new position or AVERROR.
503 */
504 int64_t avio_skip(AVIOContext *s, int64_t offset);
505
506 /**
507 * ftell() equivalent for AVIOContext.
508 * @return position or AVERROR.
509 */
510 3505138 static av_always_inline int64_t avio_tell(AVIOContext *s)
511 {
512 3505138 return avio_seek(s, 0, SEEK_CUR);
513 }
514
515 /**
516 * Get the filesize.
517 * @return filesize or AVERROR
518 */
519 int64_t avio_size(AVIOContext *s);
520
521 /**
522 * Similar to feof() but also returns nonzero on read errors.
523 * @return non zero if and only if at end of file or a read error happened when reading.
524 */
525 int avio_feof(AVIOContext *s);
526
527 /**
528 * Writes a formatted string to the context taking a va_list.
529 * @return number of bytes written, < 0 on error.
530 */
531 int avio_vprintf(AVIOContext *s, const char *fmt, va_list ap);
532
533 /**
534 * Writes a formatted string to the context.
535 * @return number of bytes written, < 0 on error.
536 */
537 int avio_printf(AVIOContext *s, const char *fmt, ...) av_printf_format(2, 3);
538
539 /**
540 * Write a NULL terminated array of strings to the context.
541 * Usually you don't need to use this function directly but its macro wrapper,
542 * avio_print.
543 */
544 void avio_print_string_array(AVIOContext *s, const char *strings[]);
545
546 /**
547 * Write strings (const char *) to the context.
548 * This is a convenience macro around avio_print_string_array and it
549 * automatically creates the string array from the variable argument list.
550 * For simple string concatenations this function is more performant than using
551 * avio_printf since it does not need a temporary buffer.
552 */
553 #define avio_print(s, ...) \
554 avio_print_string_array(s, (const char*[]){__VA_ARGS__, NULL})
555
556 /**
557 * Force flushing of buffered data.
558 *
559 * For write streams, force the buffered data to be immediately written to the output,
560 * without to wait to fill the internal buffer.
561 *
562 * For read streams, discard all currently buffered data, and advance the
563 * reported file position to that of the underlying stream. This does not
564 * read new data, and does not perform any seeks.
565 */
566 void avio_flush(AVIOContext *s);
567
568 /**
569 * Read size bytes from AVIOContext into buf.
570 * @return number of bytes read or AVERROR
571 */
572 int avio_read(AVIOContext *s, unsigned char *buf, int size);
573
574 /**
575 * Read size bytes from AVIOContext into buf. Unlike avio_read(), this is allowed
576 * to read fewer bytes than requested. The missing bytes can be read in the next
577 * call. This always tries to read at least 1 byte.
578 * Useful to reduce latency in certain cases.
579 * @return number of bytes read or AVERROR
580 */
581 int avio_read_partial(AVIOContext *s, unsigned char *buf, int size);
582
583 /**
584 * @name Functions for reading from AVIOContext
585 * @{
586 *
587 * @note return 0 if EOF, so you cannot use it if EOF handling is
588 * necessary
589 */
590 int avio_r8 (AVIOContext *s);
591 unsigned int avio_rl16(AVIOContext *s);
592 unsigned int avio_rl24(AVIOContext *s);
593 unsigned int avio_rl32(AVIOContext *s);
594 uint64_t avio_rl64(AVIOContext *s);
595 unsigned int avio_rb16(AVIOContext *s);
596 unsigned int avio_rb24(AVIOContext *s);
597 unsigned int avio_rb32(AVIOContext *s);
598 uint64_t avio_rb64(AVIOContext *s);
599 /**
600 * @}
601 */
602
603 /**
604 * Read a string from pb into buf. The reading will terminate when either
605 * a NULL character was encountered, maxlen bytes have been read, or nothing
606 * more can be read from pb. The result is guaranteed to be NULL-terminated, it
607 * will be truncated if buf is too small.
608 * Note that the string is not interpreted or validated in any way, it
609 * might get truncated in the middle of a sequence for multi-byte encodings.
610 *
611 * @return number of bytes read (is always <= maxlen).
612 * If reading ends on EOF or error, the return value will be one more than
613 * bytes actually read.
614 */
615 int avio_get_str(AVIOContext *pb, int maxlen, char *buf, int buflen);
616
617 /**
618 * Read a UTF-16 string from pb and convert it to UTF-8.
619 * The reading will terminate when either a null or invalid character was
620 * encountered or maxlen bytes have been read.
621 * @return number of bytes read (is always <= maxlen)
622 */
623 int avio_get_str16le(AVIOContext *pb, int maxlen, char *buf, int buflen);
624 int avio_get_str16be(AVIOContext *pb, int maxlen, char *buf, int buflen);
625
626
627 /**
628 * @name URL open modes
629 * The flags argument to avio_open must be one of the following
630 * constants, optionally ORed with other flags.
631 * @{
632 */
633 #define AVIO_FLAG_READ 1 /**< read-only */
634 #define AVIO_FLAG_WRITE 2 /**< write-only */
635 #define AVIO_FLAG_READ_WRITE (AVIO_FLAG_READ|AVIO_FLAG_WRITE) /**< read-write pseudo flag */
636 /**
637 * @}
638 */
639
640 /**
641 * Use non-blocking mode.
642 * If this flag is set, operations on the context will return
643 * AVERROR(EAGAIN) if they can not be performed immediately.
644 * If this flag is not set, operations on the context will never return
645 * AVERROR(EAGAIN).
646 * Note that this flag does not affect the opening/connecting of the
647 * context. Connecting a protocol will always block if necessary (e.g. on
648 * network protocols) but never hang (e.g. on busy devices).
649 * Warning: non-blocking protocols is work-in-progress; this flag may be
650 * silently ignored.
651 */
652 #define AVIO_FLAG_NONBLOCK 8
653
654 /**
655 * Use direct mode.
656 * avio_read and avio_write should if possible be satisfied directly
657 * instead of going through a buffer, and avio_seek will always
658 * call the underlying seek function directly.
659 */
660 #define AVIO_FLAG_DIRECT 0x8000
661
662 /**
663 * Create and initialize a AVIOContext for accessing the
664 * resource indicated by url.
665 * @note When the resource indicated by url has been opened in
666 * read+write mode, the AVIOContext can be used only for writing.
667 *
668 * @param s Used to return the pointer to the created AVIOContext.
669 * In case of failure the pointed to value is set to NULL.
670 * @param url resource to access
671 * @param flags flags which control how the resource indicated by url
672 * is to be opened
673 * @return >= 0 in case of success, a negative value corresponding to an
674 * AVERROR code in case of failure
675 */
676 int avio_open(AVIOContext **s, const char *url, int flags);
677
678 /**
679 * Create and initialize a AVIOContext for accessing the
680 * resource indicated by url.
681 * @note When the resource indicated by url has been opened in
682 * read+write mode, the AVIOContext can be used only for writing.
683 *
684 * @param s Used to return the pointer to the created AVIOContext.
685 * In case of failure the pointed to value is set to NULL.
686 * @param url resource to access
687 * @param flags flags which control how the resource indicated by url
688 * is to be opened
689 * @param int_cb an interrupt callback to be used at the protocols level
690 * @param options A dictionary filled with protocol-private options. On return
691 * this parameter will be destroyed and replaced with a dict containing options
692 * that were not found. May be NULL.
693 * @return >= 0 in case of success, a negative value corresponding to an
694 * AVERROR code in case of failure
695 */
696 int avio_open2(AVIOContext **s, const char *url, int flags,
697 const AVIOInterruptCB *int_cb, AVDictionary **options);
698
699 /**
700 * Close the resource accessed by the AVIOContext s and free it.
701 * This function can only be used if s was opened by avio_open().
702 *
703 * The internal buffer is automatically flushed before closing the
704 * resource.
705 *
706 * @return 0 on success, an AVERROR < 0 on error.
707 * @see avio_closep
708 */
709 int avio_close(AVIOContext *s);
710
711 /**
712 * Close the resource accessed by the AVIOContext *s, free it
713 * and set the pointer pointing to it to NULL.
714 * This function can only be used if s was opened by avio_open().
715 *
716 * The internal buffer is automatically flushed before closing the
717 * resource.
718 *
719 * @return 0 on success, an AVERROR < 0 on error.
720 * @see avio_close
721 */
722 int avio_closep(AVIOContext **s);
723
724
725 /**
726 * Open a write only memory stream.
727 *
728 * @param s new IO context
729 * @return zero if no error.
730 */
731 int avio_open_dyn_buf(AVIOContext **s);
732
733 /**
734 * Return the written size and a pointer to the buffer.
735 * The AVIOContext stream is left intact.
736 * The buffer must NOT be freed.
737 * No padding is added to the buffer.
738 *
739 * @param s IO context
740 * @param pbuffer pointer to a byte buffer
741 * @return the length of the byte buffer
742 */
743 int avio_get_dyn_buf(AVIOContext *s, uint8_t **pbuffer);
744
745 /**
746 * Return the written size and a pointer to the buffer. The buffer
747 * must be freed with av_free().
748 * Padding of AV_INPUT_BUFFER_PADDING_SIZE is added to the buffer.
749 *
750 * @param s IO context
751 * @param pbuffer pointer to a byte buffer
752 * @return the length of the byte buffer
753 */
754 int avio_close_dyn_buf(AVIOContext *s, uint8_t **pbuffer);
755
756 /**
757 * Iterate through names of available protocols.
758 *
759 * @param opaque A private pointer representing current protocol.
760 * It must be a pointer to NULL on first iteration and will
761 * be updated by successive calls to avio_enum_protocols.
762 * @param output If set to 1, iterate over output protocols,
763 * otherwise over input protocols.
764 *
765 * @return A static string containing the name of current protocol or NULL
766 */
767 const char *avio_enum_protocols(void **opaque, int output);
768
769 /**
770 * Get AVClass by names of available protocols.
771 *
772 * @return A AVClass of input protocol name or NULL
773 */
774 const AVClass *avio_protocol_get_class(const char *name);
775
776 /**
777 * Pause and resume playing - only meaningful if using a network streaming
778 * protocol (e.g. MMS).
779 *
780 * @param h IO context from which to call the read_pause function pointer
781 * @param pause 1 for pause, 0 for resume
782 */
783 int avio_pause(AVIOContext *h, int pause);
784
785 /**
786 * Seek to a given timestamp relative to some component stream.
787 * Only meaningful if using a network streaming protocol (e.g. MMS.).
788 *
789 * @param h IO context from which to call the seek function pointers
790 * @param stream_index The stream index that the timestamp is relative to.
791 * If stream_index is (-1) the timestamp should be in AV_TIME_BASE
792 * units from the beginning of the presentation.
793 * If a stream_index >= 0 is used and the protocol does not support
794 * seeking based on component streams, the call will fail.
795 * @param timestamp timestamp in AVStream.time_base units
796 * or if there is no stream specified then in AV_TIME_BASE units.
797 * @param flags Optional combination of AVSEEK_FLAG_BACKWARD, AVSEEK_FLAG_BYTE
798 * and AVSEEK_FLAG_ANY. The protocol may silently ignore
799 * AVSEEK_FLAG_BACKWARD and AVSEEK_FLAG_ANY, but AVSEEK_FLAG_BYTE will
800 * fail if used and not supported.
801 * @return >= 0 on success
802 * @see AVInputFormat::read_seek
803 */
804 int64_t avio_seek_time(AVIOContext *h, int stream_index,
805 int64_t timestamp, int flags);
806
807 /* Avoid a warning. The header can not be included because it breaks c++. */
808 struct AVBPrint;
809
810 /**
811 * Read contents of h into print buffer, up to max_size bytes, or up to EOF.
812 *
813 * @return 0 for success (max_size bytes read or EOF reached), negative error
814 * code otherwise
815 */
816 int avio_read_to_bprint(AVIOContext *h, struct AVBPrint *pb, size_t max_size);
817
818 /**
819 * Accept and allocate a client context on a server context.
820 * @param s the server context
821 * @param c the client context, must be unallocated
822 * @return >= 0 on success or a negative value corresponding
823 * to an AVERROR on failure
824 */
825 int avio_accept(AVIOContext *s, AVIOContext **c);
826
827 /**
828 * Perform one step of the protocol handshake to accept a new client.
829 * This function must be called on a client returned by avio_accept() before
830 * using it as a read/write context.
831 * It is separate from avio_accept() because it may block.
832 * A step of the handshake is defined by places where the application may
833 * decide to change the proceedings.
834 * For example, on a protocol with a request header and a reply header, each
835 * one can constitute a step because the application may use the parameters
836 * from the request to change parameters in the reply; or each individual
837 * chunk of the request can constitute a step.
838 * If the handshake is already finished, avio_handshake() does nothing and
839 * returns 0 immediately.
840 *
841 * @param c the client context to perform the handshake on
842 * @return 0 on a complete and successful handshake
843 * > 0 if the handshake progressed, but is not complete
844 * < 0 for an AVERROR code
845 */
846 int avio_handshake(AVIOContext *c);
847 #endif /* AVFORMAT_AVIO_H */
848