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 eof_reached; /**< true if was unable to read due to error or eof */
240 int write_flag; /**< true if open for writing */
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 */
247 * Pause or resume playback for network streaming protocols - e.g. MMS.
249 int (*read_pause)(void *opaque, int pause);
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
255 int64_t (*read_seek)(void *opaque, int stream_index,
256 int64_t timestamp, int flags);
258 * A combination of AVIO_SEEKABLE_ flags or 0 when the stream is not seekable.
263 * max filesize, used to limit allocations
264 * This field is internal to libavformat and access from outside is not allowed.
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.
276 * Bytes read statistic
277 * This field is internal to libavformat and access from outside is not allowed.
283 * This field is internal to libavformat and access from outside is not allowed.
289 * This field is internal to libavformat and access from outside is not allowed.
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.
298 int orig_buffer_size;
301 * Threshold to favor readahead over seek.
302 * This is current internal only, do not use from outside.
304 int short_seek_threshold;
307 * ',' separated list of allowed protocols.
309 const char *protocol_whitelist;
312 * ',' separated list of disallowed protocols.
314 const char *protocol_blacklist;
317 * A callback that is used instead of write_packet.
319 int (*write_data_type)(void *opaque, uint8_t *buf, int buf_size,
320 enum AVIODataMarkerType type, int64_t time);
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).
326 int ignore_boundary_point;
329 * Internal, not meant to be used from outside of AVIOContext.
331 enum AVIODataMarkerType current_type;
335 * A callback that is used instead of short_seek_threshold.
336 * This is current internal only, do not use from outside.
338 int (*short_seek_get)(void *opaque);
343 * Maximum reached position before a backward seek in the write buffer,
344 * used keeping track of already written data for a later flush.
346 unsigned char *buf_ptr_max;
349 * Try to buffer at least this amount of data before flushing it
354 * If set, all output will be wrapped in the Metacube format,
355 * for consumption by the Cubemap reflector. This is so that Cubemap
356 * can know what the header is, and where it is possible to start
357 * the stream (ie., from keyframes) without actually parsing and
358 * understanding the mux. Only relevant if write_flag is set.
360 * When wrapping in Metacube, s->buffer will have room for a 16-byte
361 * Metacube header while writing, which is constructed in avio_flush()
362 * before sending. This header is invisible to the calling code;
363 * e.g., it will not be counted in seeks and similar.
368 * If the metacube flag is set, we need to know whether we've seen
369 * at least one sync point marker (AVIO_DATA_MARKER_SYNC_POINT),
370 * as many muxes don't send them out at all. If we haven't seen any sync
371 * point markers, we assume that all packets (in particular
372 * AVIO_DATA_MARKER_UNKNOWN) are valid sync start points.
373 * (This may not hold for all codecs in practice.)
379 * Return the name of the protocol that will handle the passed URL.
381 * NULL is returned if no protocol could be found for the given URL.
383 * @return Name of the protocol or NULL.
385 const char *avio_find_protocol_name(const char *url);
388 * Return AVIO_FLAG_* access flags corresponding to the access permissions
389 * of the resource in url, or a negative value corresponding to an
390 * AVERROR code in case of failure. The returned access flags are
391 * masked by the value in flags.
393 * @note This function is intrinsically unsafe, in the sense that the
394 * checked resource may change its existence or permission status from
395 * one call to another. Thus you should not trust the returned value,
396 * unless you are sure that no other processes are accessing the
399 int avio_check(const char *url, int flags);
402 * Move or rename a resource.
404 * @note url_src and url_dst should share the same protocol and authority.
406 * @param url_src url to resource to be moved
407 * @param url_dst new url to resource if the operation succeeded
408 * @return >=0 on success or negative on error.
410 int avpriv_io_move(const char *url_src, const char *url_dst);
415 * @param url resource to be deleted.
416 * @return >=0 on success or negative on error.
418 int avpriv_io_delete(const char *url);
421 * Open directory for reading.
423 * @param s directory read context. Pointer to a NULL pointer must be passed.
424 * @param url directory to be listed.
425 * @param options A dictionary filled with protocol-private options. On return
426 * this parameter will be destroyed and replaced with a dictionary
427 * containing options that were not found. May be NULL.
428 * @return >=0 on success or negative on error.
430 int avio_open_dir(AVIODirContext **s, const char *url, AVDictionary **options);
433 * Get next directory entry.
435 * Returned entry must be freed with avio_free_directory_entry(). In particular
436 * it may outlive AVIODirContext.
438 * @param s directory read context.
439 * @param[out] next next entry or NULL when no more entries.
440 * @return >=0 on success or negative on error. End of list is not considered an
443 int avio_read_dir(AVIODirContext *s, AVIODirEntry **next);
448 * @note Entries created using avio_read_dir() are not deleted and must be
449 * freeded with avio_free_directory_entry().
451 * @param s directory read context.
452 * @return >=0 on success or negative on error.
454 int avio_close_dir(AVIODirContext **s);
457 * Free entry allocated by avio_read_dir().
459 * @param entry entry to be freed.
461 void avio_free_directory_entry(AVIODirEntry **entry);
464 * Allocate and initialize an AVIOContext for buffered I/O. It must be later
465 * freed with avio_context_free().
467 * @param buffer Memory block for input/output operations via AVIOContext.
468 * The buffer must be allocated with av_malloc() and friends.
469 * It may be freed and replaced with a new buffer by libavformat.
470 * AVIOContext.buffer holds the buffer currently in use,
471 * which must be later freed with av_free().
472 * @param buffer_size The buffer size is very important for performance.
473 * For protocols with fixed blocksize it should be set to this blocksize.
474 * For others a typical size is a cache page, e.g. 4kb.
475 * @param write_flag Set to 1 if the buffer should be writable, 0 otherwise.
476 * @param opaque An opaque pointer to user-specific data.
477 * @param read_packet A function for refilling the buffer, may be NULL.
478 * For stream protocols, must never return 0 but rather
479 * a proper AVERROR code.
480 * @param write_packet A function for writing the buffer contents, may be NULL.
481 * The function may not change the input buffers content.
482 * @param seek A function for seeking to specified byte position, may be NULL.
484 * @return Allocated AVIOContext or NULL on failure.
486 AVIOContext *avio_alloc_context(
487 unsigned char *buffer,
491 int (*read_packet)(void *opaque, uint8_t *buf, int buf_size),
492 int (*write_packet)(void *opaque, uint8_t *buf, int buf_size),
493 int64_t (*seek)(void *opaque, int64_t offset, int whence));
496 * Free the supplied IO context and everything associated with it.
498 * @param s Double pointer to the IO context. This function will write NULL
501 void avio_context_free(AVIOContext **s);
503 void avio_w8(AVIOContext *s, int b);
504 void avio_write(AVIOContext *s, const unsigned char *buf, int size);
505 void avio_wl64(AVIOContext *s, uint64_t val);
506 void avio_wb64(AVIOContext *s, uint64_t val);
507 void avio_wl32(AVIOContext *s, unsigned int val);
508 void avio_wb32(AVIOContext *s, unsigned int val);
509 void avio_wl24(AVIOContext *s, unsigned int val);
510 void avio_wb24(AVIOContext *s, unsigned int val);
511 void avio_wl16(AVIOContext *s, unsigned int val);
512 void avio_wb16(AVIOContext *s, unsigned int val);
515 * Write a NULL-terminated string.
516 * @return number of bytes written.
518 int avio_put_str(AVIOContext *s, const char *str);
521 * Convert an UTF-8 string to UTF-16LE and write it.
522 * @param s the AVIOContext
523 * @param str NULL-terminated UTF-8 string
525 * @return number of bytes written.
527 int avio_put_str16le(AVIOContext *s, const char *str);
530 * Convert an UTF-8 string to UTF-16BE and write it.
531 * @param s the AVIOContext
532 * @param str NULL-terminated UTF-8 string
534 * @return number of bytes written.
536 int avio_put_str16be(AVIOContext *s, const char *str);
539 * Mark the written bytestream as a specific type.
541 * Zero-length ranges are omitted from the output.
543 * @param time the stream time the current bytestream pos corresponds to
544 * (in AV_TIME_BASE units), or AV_NOPTS_VALUE if unknown or not
546 * @param type the kind of data written starting at the current pos
548 void avio_write_marker(AVIOContext *s, int64_t time, enum AVIODataMarkerType type);
551 * ORing this as the "whence" parameter to a seek function causes it to
552 * return the filesize without seeking anywhere. Supporting this is optional.
553 * If it is not supported then the seek function will return <0.
555 #define AVSEEK_SIZE 0x10000
558 * Passing this flag as the "whence" parameter to a seek function causes it to
559 * seek by any means (like reopening and linear reading) or other normally unreasonable
560 * means that can be extremely slow.
561 * This may be ignored by the seek code.
563 #define AVSEEK_FORCE 0x20000
566 * fseek() equivalent for AVIOContext.
567 * @return new position or AVERROR.
569 int64_t avio_seek(AVIOContext *s, int64_t offset, int whence);
572 * Skip given number of bytes forward
573 * @return new position or AVERROR.
575 int64_t avio_skip(AVIOContext *s, int64_t offset);
578 * ftell() equivalent for AVIOContext.
579 * @return position or AVERROR.
581 static av_always_inline int64_t avio_tell(AVIOContext *s)
583 return avio_seek(s, 0, SEEK_CUR);
588 * @return filesize or AVERROR
590 int64_t avio_size(AVIOContext *s);
593 * Similar to feof() but also returns nonzero on read errors.
594 * @return non zero if and only if at end of file or a read error happened when reading.
596 int avio_feof(AVIOContext *s);
599 * Writes a formatted string to the context.
600 * @return number of bytes written, < 0 on error.
602 int avio_printf(AVIOContext *s, const char *fmt, ...) av_printf_format(2, 3);
605 * Write a NULL terminated array of strings to the context.
606 * Usually you don't need to use this function directly but its macro wrapper,
609 void avio_print_string_array(AVIOContext *s, const char *strings[]);
612 * Write strings (const char *) to the context.
613 * This is a convenience macro around avio_print_string_array and it
614 * automatically creates the string array from the variable argument list.
615 * For simple string concatenations this function is more performant than using
616 * avio_printf since it does not need a temporary buffer.
618 #define avio_print(s, ...) \
619 avio_print_string_array(s, (const char*[]){__VA_ARGS__, NULL})
622 * Force flushing of buffered data.
624 * For write streams, force the buffered data to be immediately written to the output,
625 * without to wait to fill the internal buffer.
627 * For read streams, discard all currently buffered data, and advance the
628 * reported file position to that of the underlying stream. This does not
629 * read new data, and does not perform any seeks.
631 void avio_flush(AVIOContext *s);
634 * Read size bytes from AVIOContext into buf.
635 * @return number of bytes read or AVERROR
637 int avio_read(AVIOContext *s, unsigned char *buf, int size);
640 * Read size bytes from AVIOContext into buf. Unlike avio_read(), this is allowed
641 * to read fewer bytes than requested. The missing bytes can be read in the next
642 * call. This always tries to read at least 1 byte.
643 * Useful to reduce latency in certain cases.
644 * @return number of bytes read or AVERROR
646 int avio_read_partial(AVIOContext *s, unsigned char *buf, int size);
649 * @name Functions for reading from AVIOContext
652 * @note return 0 if EOF, so you cannot use it if EOF handling is
655 int avio_r8 (AVIOContext *s);
656 unsigned int avio_rl16(AVIOContext *s);
657 unsigned int avio_rl24(AVIOContext *s);
658 unsigned int avio_rl32(AVIOContext *s);
659 uint64_t avio_rl64(AVIOContext *s);
660 unsigned int avio_rb16(AVIOContext *s);
661 unsigned int avio_rb24(AVIOContext *s);
662 unsigned int avio_rb32(AVIOContext *s);
663 uint64_t avio_rb64(AVIOContext *s);
669 * Read a string from pb into buf. The reading will terminate when either
670 * a NULL character was encountered, maxlen bytes have been read, or nothing
671 * more can be read from pb. The result is guaranteed to be NULL-terminated, it
672 * will be truncated if buf is too small.
673 * Note that the string is not interpreted or validated in any way, it
674 * might get truncated in the middle of a sequence for multi-byte encodings.
676 * @return number of bytes read (is always <= maxlen).
677 * If reading ends on EOF or error, the return value will be one more than
678 * bytes actually read.
680 int avio_get_str(AVIOContext *pb, int maxlen, char *buf, int buflen);
683 * Read a UTF-16 string from pb and convert it to UTF-8.
684 * The reading will terminate when either a null or invalid character was
685 * encountered or maxlen bytes have been read.
686 * @return number of bytes read (is always <= maxlen)
688 int avio_get_str16le(AVIOContext *pb, int maxlen, char *buf, int buflen);
689 int avio_get_str16be(AVIOContext *pb, int maxlen, char *buf, int buflen);
693 * @name URL open modes
694 * The flags argument to avio_open must be one of the following
695 * constants, optionally ORed with other flags.
698 #define AVIO_FLAG_READ 1 /**< read-only */
699 #define AVIO_FLAG_WRITE 2 /**< write-only */
700 #define AVIO_FLAG_READ_WRITE (AVIO_FLAG_READ|AVIO_FLAG_WRITE) /**< read-write pseudo flag */
706 * Use non-blocking mode.
707 * If this flag is set, operations on the context will return
708 * AVERROR(EAGAIN) if they can not be performed immediately.
709 * If this flag is not set, operations on the context will never return
711 * Note that this flag does not affect the opening/connecting of the
712 * context. Connecting a protocol will always block if necessary (e.g. on
713 * network protocols) but never hang (e.g. on busy devices).
714 * Warning: non-blocking protocols is work-in-progress; this flag may be
717 #define AVIO_FLAG_NONBLOCK 8
720 * If set, all output will be wrapped in the Metacube format.
721 * See AVIOContext::metacube for more information.
723 #define AVIO_FLAG_METACUBE 16
727 * avio_read and avio_write should if possible be satisfied directly
728 * instead of going through a buffer, and avio_seek will always
729 * call the underlying seek function directly.
731 #define AVIO_FLAG_DIRECT 0x8000
734 * Create and initialize a AVIOContext for accessing the
735 * resource indicated by url.
736 * @note When the resource indicated by url has been opened in
737 * read+write mode, the AVIOContext can be used only for writing.
739 * @param s Used to return the pointer to the created AVIOContext.
740 * In case of failure the pointed to value is set to NULL.
741 * @param url resource to access
742 * @param flags flags which control how the resource indicated by url
744 * @return >= 0 in case of success, a negative value corresponding to an
745 * AVERROR code in case of failure
747 int avio_open(AVIOContext **s, const char *url, int flags);
750 * Create and initialize a AVIOContext for accessing the
751 * resource indicated by url.
752 * @note When the resource indicated by url has been opened in
753 * read+write mode, the AVIOContext can be used only for writing.
755 * @param s Used to return the pointer to the created AVIOContext.
756 * In case of failure the pointed to value is set to NULL.
757 * @param url resource to access
758 * @param flags flags which control how the resource indicated by url
760 * @param int_cb an interrupt callback to be used at the protocols level
761 * @param options A dictionary filled with protocol-private options. On return
762 * this parameter will be destroyed and replaced with a dict containing options
763 * that were not found. May be NULL.
764 * @return >= 0 in case of success, a negative value corresponding to an
765 * AVERROR code in case of failure
767 int avio_open2(AVIOContext **s, const char *url, int flags,
768 const AVIOInterruptCB *int_cb, AVDictionary **options);
771 * Close the resource accessed by the AVIOContext s and free it.
772 * This function can only be used if s was opened by avio_open().
774 * The internal buffer is automatically flushed before closing the
777 * @return 0 on success, an AVERROR < 0 on error.
780 int avio_close(AVIOContext *s);
783 * Close the resource accessed by the AVIOContext *s, free it
784 * and set the pointer pointing to it to NULL.
785 * This function can only be used if s was opened by avio_open().
787 * The internal buffer is automatically flushed before closing the
790 * @return 0 on success, an AVERROR < 0 on error.
793 int avio_closep(AVIOContext **s);
797 * Open a write only memory stream.
799 * @param s new IO context
800 * @return zero if no error.
802 int avio_open_dyn_buf(AVIOContext **s);
805 * Return the written size and a pointer to the buffer.
806 * The AVIOContext stream is left intact.
807 * The buffer must NOT be freed.
808 * No padding is added to the buffer.
810 * @param s IO context
811 * @param pbuffer pointer to a byte buffer
812 * @return the length of the byte buffer
814 int avio_get_dyn_buf(AVIOContext *s, uint8_t **pbuffer);
817 * Return the written size and a pointer to the buffer. The buffer
818 * must be freed with av_free().
819 * Padding of AV_INPUT_BUFFER_PADDING_SIZE is added to the buffer.
821 * @param s IO context
822 * @param pbuffer pointer to a byte buffer
823 * @return the length of the byte buffer
825 int avio_close_dyn_buf(AVIOContext *s, uint8_t **pbuffer);
828 * Iterate through names of available protocols.
830 * @param opaque A private pointer representing current protocol.
831 * It must be a pointer to NULL on first iteration and will
832 * be updated by successive calls to avio_enum_protocols.
833 * @param output If set to 1, iterate over output protocols,
834 * otherwise over input protocols.
836 * @return A static string containing the name of current protocol or NULL
838 const char *avio_enum_protocols(void **opaque, int output);
841 * Get AVClass by names of available protocols.
843 * @return A AVClass of input protocol name or NULL
845 const AVClass *avio_protocol_get_class(const char *name);
848 * Pause and resume playing - only meaningful if using a network streaming
849 * protocol (e.g. MMS).
851 * @param h IO context from which to call the read_pause function pointer
852 * @param pause 1 for pause, 0 for resume
854 int avio_pause(AVIOContext *h, int pause);
857 * Seek to a given timestamp relative to some component stream.
858 * Only meaningful if using a network streaming protocol (e.g. MMS.).
860 * @param h IO context from which to call the seek function pointers
861 * @param stream_index The stream index that the timestamp is relative to.
862 * If stream_index is (-1) the timestamp should be in AV_TIME_BASE
863 * units from the beginning of the presentation.
864 * If a stream_index >= 0 is used and the protocol does not support
865 * seeking based on component streams, the call will fail.
866 * @param timestamp timestamp in AVStream.time_base units
867 * or if there is no stream specified then in AV_TIME_BASE units.
868 * @param flags Optional combination of AVSEEK_FLAG_BACKWARD, AVSEEK_FLAG_BYTE
869 * and AVSEEK_FLAG_ANY. The protocol may silently ignore
870 * AVSEEK_FLAG_BACKWARD and AVSEEK_FLAG_ANY, but AVSEEK_FLAG_BYTE will
871 * fail if used and not supported.
872 * @return >= 0 on success
873 * @see AVInputFormat::read_seek
875 int64_t avio_seek_time(AVIOContext *h, int stream_index,
876 int64_t timestamp, int flags);
878 /* Avoid a warning. The header can not be included because it breaks c++. */
882 * Read contents of h into print buffer, up to max_size bytes, or up to EOF.
884 * @return 0 for success (max_size bytes read or EOF reached), negative error
887 int avio_read_to_bprint(AVIOContext *h, struct AVBPrint *pb, size_t max_size);
890 * Accept and allocate a client context on a server context.
891 * @param s the server context
892 * @param c the client context, must be unallocated
893 * @return >= 0 on success or a negative value corresponding
894 * to an AVERROR on failure
896 int avio_accept(AVIOContext *s, AVIOContext **c);
899 * Perform one step of the protocol handshake to accept a new client.
900 * This function must be called on a client returned by avio_accept() before
901 * using it as a read/write context.
902 * It is separate from avio_accept() because it may block.
903 * A step of the handshake is defined by places where the application may
904 * decide to change the proceedings.
905 * For example, on a protocol with a request header and a reply header, each
906 * one can constitute a step because the application may use the parameters
907 * from the request to change parameters in the reply; or each individual
908 * chunk of the request can constitute a step.
909 * If the handshake is already finished, avio_handshake() does nothing and
910 * returns 0 immediately.
912 * @param c the client context to perform the handshake on
913 * @return 0 on a complete and successful handshake
914 * > 0 if the handshake progressed, but is not complete
915 * < 0 for an AVERROR code
917 int avio_handshake(AVIOContext *c);
918 #endif /* AVFORMAT_AVIO_H */