2 * copyright (c) 2001 Fabrice Bellard
4 * This file is part of FFmpeg.
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.
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.
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
20 #ifndef AVFORMAT_AVIO_H
21 #define AVFORMAT_AVIO_H
26 * Buffered I/O operations
31 #include "libavutil/common.h"
32 #include "libavutil/dict.h"
33 #include "libavutil/log.h"
35 #include "libavformat/version.h"
38 * Seeking works like for a local file.
40 #define AVIO_SEEKABLE_NORMAL (1 << 0)
43 * Seeking by timestamp with avio_seek_time() is possible.
45 #define AVIO_SEEKABLE_TIME (1 << 1)
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.
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
58 typedef struct AVIOInterruptCB {
59 int (*callback)(void*);
64 * Directory entry types.
66 enum AVIODirEntryType {
68 AVIO_ENTRY_BLOCK_DEVICE,
69 AVIO_ENTRY_CHARACTER_DEVICE,
71 AVIO_ENTRY_NAMED_PIPE,
72 AVIO_ENTRY_SYMBOLIC_LINK,
81 * Describes single entry of the directory.
83 * Only name and type fields are guaranteed be set.
84 * Rest of fields are protocol or/and platform dependent and might be unknown.
86 typedef 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,
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. */
103 typedef struct AVIODirContext {
104 struct URLContext *url_context;
108 * Different data types that can be returned via the AVIO
109 * write_data_type callback.
111 enum AVIODataMarkerType {
113 * Header data; this needs to be present for the stream to be decodeable.
115 AVIO_DATA_MARKER_HEADER,
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.
122 AVIO_DATA_MARKER_SYNC_POINT,
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.
128 AVIO_DATA_MARKER_BOUNDARY_POINT,
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.
135 AVIO_DATA_MARKER_UNKNOWN,
137 * Trailer data, which doesn't contain actual content, but only for
138 * finalizing the output file.
140 AVIO_DATA_MARKER_TRAILER,
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.
146 AVIO_DATA_MARKER_FLUSH_POINT,
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
154 * sizeof(AVIOContext) must not be used outside libav*.
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()
161 typedef struct AVIOContext {
163 * A class for private options.
165 * If this AVIOContext is created by avio_open2(), av_class is set and
166 * passes the options down to protocols.
168 * If this AVIOContext is manually allocated, then av_class may be set by
171 * warning -- this field can be NULL, be sure to not pass this AVIOContext
172 * to any av_opt_* functions in that case.
174 const AVClass *av_class;
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):
181 **********************************************************************************
183 **********************************************************************************
186 * |---------------------------------------|
189 * buffer buf_ptr buf_end
190 * +---------------+-----------------------+
191 * |/ / / / / / / /|/ / / / / / /| |
192 * read buffer: |/ / consumed / | to be read /| |
193 * |/ / / / / / / /|/ / / / / / /| |
194 * +---------------+-----------------------+
197 * +-------------------------------------------+-----------------+
199 * +-------------------------------------------+-----------------+
202 **********************************************************************************
204 **********************************************************************************
207 * |--------------------------------------|
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
221 * +-------------+----------------------------------------------+
223 * +-------------+----------------------------------------------+
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/...
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 must_flush; /**< unused */
240 int eof_reached; /**< true if eof reached */
241 int write_flag; /**< true if open for writing */
243 unsigned long checksum;
244 unsigned char *checksum_ptr;
245 unsigned long (*update_checksum)(unsigned long checksum, const uint8_t *buf, unsigned int size);
246 int error; /**< contains the error code or 0 if no error happened */
248 * Pause or resume playback for network streaming protocols - e.g. MMS.
250 int (*read_pause)(void *opaque, int pause);
252 * Seek to a given timestamp in stream with the specified stream_index.
253 * Needed for some network streaming protocols which don't support seeking
256 int64_t (*read_seek)(void *opaque, int stream_index,
257 int64_t timestamp, int flags);
259 * A combination of AVIO_SEEKABLE_ flags or 0 when the stream is not seekable.
264 * max filesize, used to limit allocations
265 * This field is internal to libavformat and access from outside is not allowed.
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.
277 * Bytes read statistic
278 * This field is internal to libavformat and access from outside is not allowed.
284 * This field is internal to libavformat and access from outside is not allowed.
290 * This field is internal to libavformat and access from outside is not allowed.
295 * Original buffer size
296 * used internally after probing and ensure seekback to reset the buffer size
297 * This field is internal to libavformat and access from outside is not allowed.
299 int orig_buffer_size;
302 * Threshold to favor readahead over seek.
303 * This is current internal only, do not use from outside.
305 int short_seek_threshold;
308 * ',' separated list of allowed protocols.
310 const char *protocol_whitelist;
313 * ',' separated list of disallowed protocols.
315 const char *protocol_blacklist;
318 * A callback that is used instead of write_packet.
320 int (*write_data_type)(void *opaque, uint8_t *buf, int buf_size,
321 enum AVIODataMarkerType type, int64_t time);
323 * If set, don't call write_data_type separately for AVIO_DATA_MARKER_BOUNDARY_POINT,
324 * but ignore them and treat them as AVIO_DATA_MARKER_UNKNOWN (to avoid needlessly
325 * small chunks of data returned from the callback).
327 int ignore_boundary_point;
330 * Internal, not meant to be used from outside of AVIOContext.
332 enum AVIODataMarkerType current_type;
336 * A callback that is used instead of short_seek_threshold.
337 * This is current internal only, do not use from outside.
339 int (*short_seek_get)(void *opaque);
344 * Maximum reached position before a backward seek in the write buffer,
345 * used keeping track of already written data for a later flush.
347 unsigned char *buf_ptr_max;
350 * Try to buffer at least this amount of data before flushing it
356 * Return the name of the protocol that will handle the passed URL.
358 * NULL is returned if no protocol could be found for the given URL.
360 * @return Name of the protocol or NULL.
362 const char *avio_find_protocol_name(const char *url);
365 * Return AVIO_FLAG_* access flags corresponding to the access permissions
366 * of the resource in url, or a negative value corresponding to an
367 * AVERROR code in case of failure. The returned access flags are
368 * masked by the value in flags.
370 * @note This function is intrinsically unsafe, in the sense that the
371 * checked resource may change its existence or permission status from
372 * one call to another. Thus you should not trust the returned value,
373 * unless you are sure that no other processes are accessing the
376 int avio_check(const char *url, int flags);
379 * Move or rename a resource.
381 * @note url_src and url_dst should share the same protocol and authority.
383 * @param url_src url to resource to be moved
384 * @param url_dst new url to resource if the operation succeeded
385 * @return >=0 on success or negative on error.
387 int avpriv_io_move(const char *url_src, const char *url_dst);
392 * @param url resource to be deleted.
393 * @return >=0 on success or negative on error.
395 int avpriv_io_delete(const char *url);
398 * Open directory for reading.
400 * @param s directory read context. Pointer to a NULL pointer must be passed.
401 * @param url directory to be listed.
402 * @param options A dictionary filled with protocol-private options. On return
403 * this parameter will be destroyed and replaced with a dictionary
404 * containing options that were not found. May be NULL.
405 * @return >=0 on success or negative on error.
407 int avio_open_dir(AVIODirContext **s, const char *url, AVDictionary **options);
410 * Get next directory entry.
412 * Returned entry must be freed with avio_free_directory_entry(). In particular
413 * it may outlive AVIODirContext.
415 * @param s directory read context.
416 * @param[out] next next entry or NULL when no more entries.
417 * @return >=0 on success or negative on error. End of list is not considered an
420 int avio_read_dir(AVIODirContext *s, AVIODirEntry **next);
425 * @note Entries created using avio_read_dir() are not deleted and must be
426 * freeded with avio_free_directory_entry().
428 * @param s directory read context.
429 * @return >=0 on success or negative on error.
431 int avio_close_dir(AVIODirContext **s);
434 * Free entry allocated by avio_read_dir().
436 * @param entry entry to be freed.
438 void avio_free_directory_entry(AVIODirEntry **entry);
441 * Allocate and initialize an AVIOContext for buffered I/O. It must be later
442 * freed with avio_context_free().
444 * @param buffer Memory block for input/output operations via AVIOContext.
445 * The buffer must be allocated with av_malloc() and friends.
446 * It may be freed and replaced with a new buffer by libavformat.
447 * AVIOContext.buffer holds the buffer currently in use,
448 * which must be later freed with av_free().
449 * @param buffer_size The buffer size is very important for performance.
450 * For protocols with fixed blocksize it should be set to this blocksize.
451 * For others a typical size is a cache page, e.g. 4kb.
452 * @param write_flag Set to 1 if the buffer should be writable, 0 otherwise.
453 * @param opaque An opaque pointer to user-specific data.
454 * @param read_packet A function for refilling the buffer, may be NULL.
455 * @param write_packet A function for writing the buffer contents, may be NULL.
456 * The function may not change the input buffers content.
457 * @param seek A function for seeking to specified byte position, may be NULL.
459 * @return Allocated AVIOContext or NULL on failure.
461 AVIOContext *avio_alloc_context(
462 unsigned char *buffer,
466 int (*read_packet)(void *opaque, uint8_t *buf, int buf_size),
467 int (*write_packet)(void *opaque, uint8_t *buf, int buf_size),
468 int64_t (*seek)(void *opaque, int64_t offset, int whence));
471 * Free the supplied IO context and everything associated with it.
473 * @param s Double pointer to the IO context. This function will write NULL
476 void avio_context_free(AVIOContext **s);
478 void avio_w8(AVIOContext *s, int b);
479 void avio_write(AVIOContext *s, const unsigned char *buf, int size);
480 void avio_wl64(AVIOContext *s, uint64_t val);
481 void avio_wb64(AVIOContext *s, uint64_t val);
482 void avio_wl32(AVIOContext *s, unsigned int val);
483 void avio_wb32(AVIOContext *s, unsigned int val);
484 void avio_wl24(AVIOContext *s, unsigned int val);
485 void avio_wb24(AVIOContext *s, unsigned int val);
486 void avio_wl16(AVIOContext *s, unsigned int val);
487 void avio_wb16(AVIOContext *s, unsigned int val);
490 * Write a NULL-terminated string.
491 * @return number of bytes written.
493 int avio_put_str(AVIOContext *s, const char *str);
496 * Convert an UTF-8 string to UTF-16LE and write it.
497 * @param s the AVIOContext
498 * @param str NULL-terminated UTF-8 string
500 * @return number of bytes written.
502 int avio_put_str16le(AVIOContext *s, const char *str);
505 * Convert an UTF-8 string to UTF-16BE and write it.
506 * @param s the AVIOContext
507 * @param str NULL-terminated UTF-8 string
509 * @return number of bytes written.
511 int avio_put_str16be(AVIOContext *s, const char *str);
514 * Mark the written bytestream as a specific type.
516 * Zero-length ranges are omitted from the output.
518 * @param time the stream time the current bytestream pos corresponds to
519 * (in AV_TIME_BASE units), or AV_NOPTS_VALUE if unknown or not
521 * @param type the kind of data written starting at the current pos
523 void avio_write_marker(AVIOContext *s, int64_t time, enum AVIODataMarkerType type);
526 * ORing this as the "whence" parameter to a seek function causes it to
527 * return the filesize without seeking anywhere. Supporting this is optional.
528 * If it is not supported then the seek function will return <0.
530 #define AVSEEK_SIZE 0x10000
533 * Passing this flag as the "whence" parameter to a seek function causes it to
534 * seek by any means (like reopening and linear reading) or other normally unreasonable
535 * means that can be extremely slow.
536 * This may be ignored by the seek code.
538 #define AVSEEK_FORCE 0x20000
541 * fseek() equivalent for AVIOContext.
542 * @return new position or AVERROR.
544 int64_t avio_seek(AVIOContext *s, int64_t offset, int whence);
547 * Skip given number of bytes forward
548 * @return new position or AVERROR.
550 int64_t avio_skip(AVIOContext *s, int64_t offset);
553 * ftell() equivalent for AVIOContext.
554 * @return position or AVERROR.
556 static av_always_inline int64_t avio_tell(AVIOContext *s)
558 return avio_seek(s, 0, SEEK_CUR);
563 * @return filesize or AVERROR
565 int64_t avio_size(AVIOContext *s);
568 * feof() equivalent for AVIOContext.
569 * @return non zero if and only if end of file
571 int avio_feof(AVIOContext *s);
574 * @deprecated use avio_feof()
577 int url_feof(AVIOContext *s);
580 /** @warning Writes up to 4 KiB per call */
581 int avio_printf(AVIOContext *s, const char *fmt, ...) av_printf_format(2, 3);
584 * Force flushing of buffered data.
586 * For write streams, force the buffered data to be immediately written to the output,
587 * without to wait to fill the internal buffer.
589 * For read streams, discard all currently buffered data, and advance the
590 * reported file position to that of the underlying stream. This does not
591 * read new data, and does not perform any seeks.
593 void avio_flush(AVIOContext *s);
596 * Read size bytes from AVIOContext into buf.
597 * @return number of bytes read or AVERROR
599 int avio_read(AVIOContext *s, unsigned char *buf, int size);
602 * Read size bytes from AVIOContext into buf. Unlike avio_read(), this is allowed
603 * to read fewer bytes than requested. The missing bytes can be read in the next
604 * call. This always tries to read at least 1 byte.
605 * Useful to reduce latency in certain cases.
606 * @return number of bytes read or AVERROR
608 int avio_read_partial(AVIOContext *s, unsigned char *buf, int size);
611 * @name Functions for reading from AVIOContext
614 * @note return 0 if EOF, so you cannot use it if EOF handling is
617 int avio_r8 (AVIOContext *s);
618 unsigned int avio_rl16(AVIOContext *s);
619 unsigned int avio_rl24(AVIOContext *s);
620 unsigned int avio_rl32(AVIOContext *s);
621 uint64_t avio_rl64(AVIOContext *s);
622 unsigned int avio_rb16(AVIOContext *s);
623 unsigned int avio_rb24(AVIOContext *s);
624 unsigned int avio_rb32(AVIOContext *s);
625 uint64_t avio_rb64(AVIOContext *s);
631 * Read a string from pb into buf. The reading will terminate when either
632 * a NULL character was encountered, maxlen bytes have been read, or nothing
633 * more can be read from pb. The result is guaranteed to be NULL-terminated, it
634 * will be truncated if buf is too small.
635 * Note that the string is not interpreted or validated in any way, it
636 * might get truncated in the middle of a sequence for multi-byte encodings.
638 * @return number of bytes read (is always <= maxlen).
639 * If reading ends on EOF or error, the return value will be one more than
640 * bytes actually read.
642 int avio_get_str(AVIOContext *pb, int maxlen, char *buf, int buflen);
645 * Read a UTF-16 string from pb and convert it to UTF-8.
646 * The reading will terminate when either a null or invalid character was
647 * encountered or maxlen bytes have been read.
648 * @return number of bytes read (is always <= maxlen)
650 int avio_get_str16le(AVIOContext *pb, int maxlen, char *buf, int buflen);
651 int avio_get_str16be(AVIOContext *pb, int maxlen, char *buf, int buflen);
655 * @name URL open modes
656 * The flags argument to avio_open must be one of the following
657 * constants, optionally ORed with other flags.
660 #define AVIO_FLAG_READ 1 /**< read-only */
661 #define AVIO_FLAG_WRITE 2 /**< write-only */
662 #define AVIO_FLAG_READ_WRITE (AVIO_FLAG_READ|AVIO_FLAG_WRITE) /**< read-write pseudo flag */
668 * Use non-blocking mode.
669 * If this flag is set, operations on the context will return
670 * AVERROR(EAGAIN) if they can not be performed immediately.
671 * If this flag is not set, operations on the context will never return
673 * Note that this flag does not affect the opening/connecting of the
674 * context. Connecting a protocol will always block if necessary (e.g. on
675 * network protocols) but never hang (e.g. on busy devices).
676 * Warning: non-blocking protocols is work-in-progress; this flag may be
679 #define AVIO_FLAG_NONBLOCK 8
683 * avio_read and avio_write should if possible be satisfied directly
684 * instead of going through a buffer, and avio_seek will always
685 * call the underlying seek function directly.
687 #define AVIO_FLAG_DIRECT 0x8000
690 * Create and initialize a AVIOContext for accessing the
691 * resource indicated by url.
692 * @note When the resource indicated by url has been opened in
693 * read+write mode, the AVIOContext can be used only for writing.
695 * @param s Used to return the pointer to the created AVIOContext.
696 * In case of failure the pointed to value is set to NULL.
697 * @param url resource to access
698 * @param flags flags which control how the resource indicated by url
700 * @return >= 0 in case of success, a negative value corresponding to an
701 * AVERROR code in case of failure
703 int avio_open(AVIOContext **s, const char *url, int flags);
706 * Create and initialize a AVIOContext for accessing the
707 * resource indicated by url.
708 * @note When the resource indicated by url has been opened in
709 * read+write mode, the AVIOContext can be used only for writing.
711 * @param s Used to return the pointer to the created AVIOContext.
712 * In case of failure the pointed to value is set to NULL.
713 * @param url resource to access
714 * @param flags flags which control how the resource indicated by url
716 * @param int_cb an interrupt callback to be used at the protocols level
717 * @param options A dictionary filled with protocol-private options. On return
718 * this parameter will be destroyed and replaced with a dict containing options
719 * that were not found. May be NULL.
720 * @return >= 0 in case of success, a negative value corresponding to an
721 * AVERROR code in case of failure
723 int avio_open2(AVIOContext **s, const char *url, int flags,
724 const AVIOInterruptCB *int_cb, AVDictionary **options);
727 * Close the resource accessed by the AVIOContext s and free it.
728 * This function can only be used if s was opened by avio_open().
730 * The internal buffer is automatically flushed before closing the
733 * @return 0 on success, an AVERROR < 0 on error.
736 int avio_close(AVIOContext *s);
739 * Close the resource accessed by the AVIOContext *s, free it
740 * and set the pointer pointing to it to NULL.
741 * This function can only be used if s was opened by avio_open().
743 * The internal buffer is automatically flushed before closing the
746 * @return 0 on success, an AVERROR < 0 on error.
749 int avio_closep(AVIOContext **s);
753 * Open a write only memory stream.
755 * @param s new IO context
756 * @return zero if no error.
758 int avio_open_dyn_buf(AVIOContext **s);
761 * Return the written size and a pointer to the buffer.
762 * The AVIOContext stream is left intact.
763 * The buffer must NOT be freed.
764 * No padding is added to the buffer.
766 * @param s IO context
767 * @param pbuffer pointer to a byte buffer
768 * @return the length of the byte buffer
770 int avio_get_dyn_buf(AVIOContext *s, uint8_t **pbuffer);
773 * Return the written size and a pointer to the buffer. The buffer
774 * must be freed with av_free().
775 * Padding of AV_INPUT_BUFFER_PADDING_SIZE is added to the buffer.
777 * @param s IO context
778 * @param pbuffer pointer to a byte buffer
779 * @return the length of the byte buffer
781 int avio_close_dyn_buf(AVIOContext *s, uint8_t **pbuffer);
784 * Iterate through names of available protocols.
786 * @param opaque A private pointer representing current protocol.
787 * It must be a pointer to NULL on first iteration and will
788 * be updated by successive calls to avio_enum_protocols.
789 * @param output If set to 1, iterate over output protocols,
790 * otherwise over input protocols.
792 * @return A static string containing the name of current protocol or NULL
794 const char *avio_enum_protocols(void **opaque, int output);
797 * Pause and resume playing - only meaningful if using a network streaming
798 * protocol (e.g. MMS).
800 * @param h IO context from which to call the read_pause function pointer
801 * @param pause 1 for pause, 0 for resume
803 int avio_pause(AVIOContext *h, int pause);
806 * Seek to a given timestamp relative to some component stream.
807 * Only meaningful if using a network streaming protocol (e.g. MMS.).
809 * @param h IO context from which to call the seek function pointers
810 * @param stream_index The stream index that the timestamp is relative to.
811 * If stream_index is (-1) the timestamp should be in AV_TIME_BASE
812 * units from the beginning of the presentation.
813 * If a stream_index >= 0 is used and the protocol does not support
814 * seeking based on component streams, the call will fail.
815 * @param timestamp timestamp in AVStream.time_base units
816 * or if there is no stream specified then in AV_TIME_BASE units.
817 * @param flags Optional combination of AVSEEK_FLAG_BACKWARD, AVSEEK_FLAG_BYTE
818 * and AVSEEK_FLAG_ANY. The protocol may silently ignore
819 * AVSEEK_FLAG_BACKWARD and AVSEEK_FLAG_ANY, but AVSEEK_FLAG_BYTE will
820 * fail if used and not supported.
821 * @return >= 0 on success
822 * @see AVInputFormat::read_seek
824 int64_t avio_seek_time(AVIOContext *h, int stream_index,
825 int64_t timestamp, int flags);
827 /* Avoid a warning. The header can not be included because it breaks c++. */
831 * Read contents of h into print buffer, up to max_size bytes, or up to EOF.
833 * @return 0 for success (max_size bytes read or EOF reached), negative error
836 int avio_read_to_bprint(AVIOContext *h, struct AVBPrint *pb, size_t max_size);
839 * Accept and allocate a client context on a server context.
840 * @param s the server context
841 * @param c the client context, must be unallocated
842 * @return >= 0 on success or a negative value corresponding
843 * to an AVERROR on failure
845 int avio_accept(AVIOContext *s, AVIOContext **c);
848 * Perform one step of the protocol handshake to accept a new client.
849 * This function must be called on a client returned by avio_accept() before
850 * using it as a read/write context.
851 * It is separate from avio_accept() because it may block.
852 * A step of the handshake is defined by places where the application may
853 * decide to change the proceedings.
854 * For example, on a protocol with a request header and a reply header, each
855 * one can constitute a step because the application may use the parameters
856 * from the request to change parameters in the reply; or each individual
857 * chunk of the request can constitute a step.
858 * If the handshake is already finished, avio_handshake() does nothing and
859 * returns 0 immediately.
861 * @param c the client context to perform the handshake on
862 * @return 0 on a complete and successful handshake
863 * > 0 if the handshake progressed, but is not complete
864 * < 0 for an AVERROR code
866 int avio_handshake(AVIOContext *c);
867 #endif /* AVFORMAT_AVIO_H */