avio.h (31142B)
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 typedef struct AVIODirContext AVIODirContext; 105 106 /** 107 * Different data types that can be returned via the AVIO 108 * write_data_type callback. 109 */ 110 enum AVIODataMarkerType { 111 /** 112 * Header data; this needs to be present for the stream to be decodeable. 113 */ 114 AVIO_DATA_MARKER_HEADER, 115 /** 116 * A point in the output bytestream where a decoder can start decoding 117 * (i.e. a keyframe). A demuxer/decoder given the data flagged with 118 * AVIO_DATA_MARKER_HEADER, followed by any AVIO_DATA_MARKER_SYNC_POINT, 119 * should give decodeable results. 120 */ 121 AVIO_DATA_MARKER_SYNC_POINT, 122 /** 123 * A point in the output bytestream where a demuxer can start parsing 124 * (for non self synchronizing bytestream formats). That is, any 125 * non-keyframe packet start point. 126 */ 127 AVIO_DATA_MARKER_BOUNDARY_POINT, 128 /** 129 * This is any, unlabelled data. It can either be a muxer not marking 130 * any positions at all, it can be an actual boundary/sync point 131 * that the muxer chooses not to mark, or a later part of a packet/fragment 132 * that is cut into multiple write callbacks due to limited IO buffer size. 133 */ 134 AVIO_DATA_MARKER_UNKNOWN, 135 /** 136 * Trailer data, which doesn't contain actual content, but only for 137 * finalizing the output file. 138 */ 139 AVIO_DATA_MARKER_TRAILER, 140 /** 141 * A point in the output bytestream where the underlying AVIOContext might 142 * flush the buffer depending on latency or buffering requirements. Typically 143 * means the end of a packet. 144 */ 145 AVIO_DATA_MARKER_FLUSH_POINT, 146 }; 147 148 /** 149 * Bytestream IO Context. 150 * New public fields can be added with minor version bumps. 151 * Removal, reordering and changes to existing public fields require 152 * a major version bump. 153 * sizeof(AVIOContext) must not be used outside libav*. 154 * 155 * @note None of the function pointers in AVIOContext should be called 156 * directly, they should only be set by the client application 157 * when implementing custom I/O. Normally these are set to the 158 * function pointers specified in avio_alloc_context() 159 */ 160 typedef struct AVIOContext { 161 /** 162 * A class for private options. 163 * 164 * If this AVIOContext is created by avio_open2(), av_class is set and 165 * passes the options down to protocols. 166 * 167 * If this AVIOContext is manually allocated, then av_class may be set by 168 * the caller. 169 * 170 * warning -- this field can be NULL, be sure to not pass this AVIOContext 171 * to any av_opt_* functions in that case. 172 */ 173 const AVClass *av_class; 174 175 /* 176 * The following shows the relationship between buffer, buf_ptr, 177 * buf_ptr_max, buf_end, buf_size, and pos, when reading and when writing 178 * (since AVIOContext is used for both): 179 * 180 ********************************************************************************** 181 * READING 182 ********************************************************************************** 183 * 184 * | buffer_size | 185 * |---------------------------------------| 186 * | | 187 * 188 * buffer buf_ptr buf_end 189 * +---------------+-----------------------+ 190 * |/ / / / / / / /|/ / / / / / /| | 191 * read buffer: |/ / consumed / | to be read /| | 192 * |/ / / / / / / /|/ / / / / / /| | 193 * +---------------+-----------------------+ 194 * 195 * pos 196 * +-------------------------------------------+-----------------+ 197 * input file: | | | 198 * +-------------------------------------------+-----------------+ 199 * 200 * 201 ********************************************************************************** 202 * WRITING 203 ********************************************************************************** 204 * 205 * | buffer_size | 206 * |--------------------------------------| 207 * | | 208 * 209 * buf_ptr_max 210 * buffer (buf_ptr) buf_end 211 * +-----------------------+--------------+ 212 * |/ / / / / / / / / / / /| | 213 * write buffer: | / / to be flushed / / | | 214 * |/ / / / / / / / / / / /| | 215 * +-----------------------+--------------+ 216 * buf_ptr can be in this 217 * due to a backward seek 218 * 219 * pos 220 * +-------------+----------------------------------------------+ 221 * output file: | | | 222 * +-------------+----------------------------------------------+ 223 * 224 */ 225 unsigned char *buffer; /**< Start of the buffer. */ 226 int buffer_size; /**< Maximum buffer size */ 227 unsigned char *buf_ptr; /**< Current position in the buffer */ 228 unsigned char *buf_end; /**< End of the data, may be less than 229 buffer+buffer_size if the read function returned 230 less data than requested, e.g. for streams where 231 no more data has been received yet. */ 232 void *opaque; /**< A private pointer, passed to the read/write/seek/... 233 functions. */ 234 int (*read_packet)(void *opaque, uint8_t *buf, int buf_size); 235 int (*write_packet)(void *opaque, const uint8_t *buf, int buf_size); 236 int64_t (*seek)(void *opaque, int64_t offset, int whence); 237 int64_t pos; /**< position in the file of the current buffer */ 238 int eof_reached; /**< true if was unable to read due to error or eof */ 239 int error; /**< contains the error code or 0 if no error happened */ 240 int write_flag; /**< true if open for writing */ 241 int max_packet_size; 242 int min_packet_size; /**< Try to buffer at least this amount of data 243 before flushing it. */ 244 unsigned long checksum; 245 unsigned char *checksum_ptr; 246 unsigned long (*update_checksum)(unsigned long checksum, const uint8_t *buf, unsigned int size); 247 /** 248 * Pause or resume playback for network streaming protocols - e.g. MMS. 249 */ 250 int (*read_pause)(void *opaque, int pause); 251 /** 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 254 * to byte position. 255 */ 256 int64_t (*read_seek)(void *opaque, int stream_index, 257 int64_t timestamp, int flags); 258 /** 259 * A combination of AVIO_SEEKABLE_ flags or 0 when the stream is not seekable. 260 */ 261 int seekable; 262 263 /** 264 * avio_read and avio_write should if possible be satisfied directly 265 * instead of going through a buffer, and avio_seek will always 266 * call the underlying seek function directly. 267 */ 268 int direct; 269 270 /** 271 * ',' separated list of allowed protocols. 272 */ 273 const char *protocol_whitelist; 274 275 /** 276 * ',' separated list of disallowed protocols. 277 */ 278 const char *protocol_blacklist; 279 280 /** 281 * A callback that is used instead of write_packet. 282 */ 283 int (*write_data_type)(void *opaque, const uint8_t *buf, int buf_size, 284 enum AVIODataMarkerType type, int64_t time); 285 /** 286 * If set, don't call write_data_type separately for AVIO_DATA_MARKER_BOUNDARY_POINT, 287 * but ignore them and treat them as AVIO_DATA_MARKER_UNKNOWN (to avoid needlessly 288 * small chunks of data returned from the callback). 289 */ 290 int ignore_boundary_point; 291 292 /** 293 * Maximum reached position before a backward seek in the write buffer, 294 * used keeping track of already written data for a later flush. 295 */ 296 unsigned char *buf_ptr_max; 297 298 /** 299 * Read-only statistic of bytes read for this AVIOContext. 300 */ 301 int64_t bytes_read; 302 303 /** 304 * Read-only statistic of bytes written for this AVIOContext. 305 */ 306 int64_t bytes_written; 307 } AVIOContext; 308 309 /** 310 * Return the name of the protocol that will handle the passed URL. 311 * 312 * NULL is returned if no protocol could be found for the given URL. 313 * 314 * @return Name of the protocol or NULL. 315 */ 316 const char *avio_find_protocol_name(const char *url); 317 318 /** 319 * Return AVIO_FLAG_* access flags corresponding to the access permissions 320 * of the resource in url, or a negative value corresponding to an 321 * AVERROR code in case of failure. The returned access flags are 322 * masked by the value in flags. 323 * 324 * @note This function is intrinsically unsafe, in the sense that the 325 * checked resource may change its existence or permission status from 326 * one call to another. Thus you should not trust the returned value, 327 * unless you are sure that no other processes are accessing the 328 * checked resource. 329 */ 330 int avio_check(const char *url, int flags); 331 332 /** 333 * Open directory for reading. 334 * 335 * @param s directory read context. Pointer to a NULL pointer must be passed. 336 * @param url directory to be listed. 337 * @param options A dictionary filled with protocol-private options. On return 338 * this parameter will be destroyed and replaced with a dictionary 339 * containing options that were not found. May be NULL. 340 * @return >=0 on success or negative on error. 341 */ 342 int avio_open_dir(AVIODirContext **s, const char *url, AVDictionary **options); 343 344 /** 345 * Get next directory entry. 346 * 347 * Returned entry must be freed with avio_free_directory_entry(). In particular 348 * it may outlive AVIODirContext. 349 * 350 * @param s directory read context. 351 * @param[out] next next entry or NULL when no more entries. 352 * @return >=0 on success or negative on error. End of list is not considered an 353 * error. 354 */ 355 int avio_read_dir(AVIODirContext *s, AVIODirEntry **next); 356 357 /** 358 * Close directory. 359 * 360 * @note Entries created using avio_read_dir() are not deleted and must be 361 * freeded with avio_free_directory_entry(). 362 * 363 * @param s directory read context. 364 * @return >=0 on success or negative on error. 365 */ 366 int avio_close_dir(AVIODirContext **s); 367 368 /** 369 * Free entry allocated by avio_read_dir(). 370 * 371 * @param entry entry to be freed. 372 */ 373 void avio_free_directory_entry(AVIODirEntry **entry); 374 375 /** 376 * Allocate and initialize an AVIOContext for buffered I/O. It must be later 377 * freed with avio_context_free(). 378 * 379 * @param buffer Memory block for input/output operations via AVIOContext. 380 * The buffer must be allocated with av_malloc() and friends. 381 * It may be freed and replaced with a new buffer by libavformat. 382 * AVIOContext.buffer holds the buffer currently in use, 383 * which must be later freed with av_free(). 384 * @param buffer_size The buffer size is very important for performance. 385 * For protocols with fixed blocksize it should be set to this blocksize. 386 * For others a typical size is a cache page, e.g. 4kb. 387 * @param write_flag Set to 1 if the buffer should be writable, 0 otherwise. 388 * @param opaque An opaque pointer to user-specific data. 389 * @param read_packet A function for refilling the buffer, may be NULL. 390 * For stream protocols, must never return 0 but rather 391 * a proper AVERROR code. 392 * @param write_packet A function for writing the buffer contents, may be NULL. 393 * The function may not change the input buffers content. 394 * @param seek A function for seeking to specified byte position, may be NULL. 395 * 396 * @return Allocated AVIOContext or NULL on failure. 397 */ 398 AVIOContext *avio_alloc_context( 399 unsigned char *buffer, 400 int buffer_size, 401 int write_flag, 402 void *opaque, 403 int (*read_packet)(void *opaque, uint8_t *buf, int buf_size), 404 int (*write_packet)(void *opaque, const uint8_t *buf, int buf_size), 405 int64_t (*seek)(void *opaque, int64_t offset, int whence)); 406 407 /** 408 * Free the supplied IO context and everything associated with it. 409 * 410 * @param s Double pointer to the IO context. This function will write NULL 411 * into s. 412 */ 413 void avio_context_free(AVIOContext **s); 414 415 void avio_w8(AVIOContext *s, int b); 416 void avio_write(AVIOContext *s, const unsigned char *buf, int size); 417 void avio_wl64(AVIOContext *s, uint64_t val); 418 void avio_wb64(AVIOContext *s, uint64_t val); 419 void avio_wl32(AVIOContext *s, unsigned int val); 420 void avio_wb32(AVIOContext *s, unsigned int val); 421 void avio_wl24(AVIOContext *s, unsigned int val); 422 void avio_wb24(AVIOContext *s, unsigned int val); 423 void avio_wl16(AVIOContext *s, unsigned int val); 424 void avio_wb16(AVIOContext *s, unsigned int val); 425 426 /** 427 * Write a NULL-terminated string. 428 * @return number of bytes written. 429 */ 430 int avio_put_str(AVIOContext *s, const char *str); 431 432 /** 433 * Convert an UTF-8 string to UTF-16LE and write it. 434 * @param s the AVIOContext 435 * @param str NULL-terminated UTF-8 string 436 * 437 * @return number of bytes written. 438 */ 439 int avio_put_str16le(AVIOContext *s, const char *str); 440 441 /** 442 * Convert an UTF-8 string to UTF-16BE and write it. 443 * @param s the AVIOContext 444 * @param str NULL-terminated UTF-8 string 445 * 446 * @return number of bytes written. 447 */ 448 int avio_put_str16be(AVIOContext *s, const char *str); 449 450 /** 451 * Mark the written bytestream as a specific type. 452 * 453 * Zero-length ranges are omitted from the output. 454 * 455 * @param s the AVIOContext 456 * @param time the stream time the current bytestream pos corresponds to 457 * (in AV_TIME_BASE units), or AV_NOPTS_VALUE if unknown or not 458 * applicable 459 * @param type the kind of data written starting at the current pos 460 */ 461 void avio_write_marker(AVIOContext *s, int64_t time, enum AVIODataMarkerType type); 462 463 /** 464 * ORing this as the "whence" parameter to a seek function causes it to 465 * return the filesize without seeking anywhere. Supporting this is optional. 466 * If it is not supported then the seek function will return <0. 467 */ 468 #define AVSEEK_SIZE 0x10000 469 470 /** 471 * Passing this flag as the "whence" parameter to a seek function causes it to 472 * seek by any means (like reopening and linear reading) or other normally unreasonable 473 * means that can be extremely slow. 474 * This may be ignored by the seek code. 475 */ 476 #define AVSEEK_FORCE 0x20000 477 478 /** 479 * fseek() equivalent for AVIOContext. 480 * @return new position or AVERROR. 481 */ 482 int64_t avio_seek(AVIOContext *s, int64_t offset, int whence); 483 484 /** 485 * Skip given number of bytes forward 486 * @return new position or AVERROR. 487 */ 488 int64_t avio_skip(AVIOContext *s, int64_t offset); 489 490 /** 491 * ftell() equivalent for AVIOContext. 492 * @return position or AVERROR. 493 */ 494 static av_always_inline int64_t avio_tell(AVIOContext *s) 495 { 496 return avio_seek(s, 0, SEEK_CUR); 497 } 498 499 /** 500 * Get the filesize. 501 * @return filesize or AVERROR 502 */ 503 int64_t avio_size(AVIOContext *s); 504 505 /** 506 * Similar to feof() but also returns nonzero on read errors. 507 * @return non zero if and only if at end of file or a read error happened when reading. 508 */ 509 int avio_feof(AVIOContext *s); 510 511 /** 512 * Writes a formatted string to the context taking a va_list. 513 * @return number of bytes written, < 0 on error. 514 */ 515 int avio_vprintf(AVIOContext *s, const char *fmt, va_list ap); 516 517 /** 518 * Writes a formatted string to the context. 519 * @return number of bytes written, < 0 on error. 520 */ 521 int avio_printf(AVIOContext *s, const char *fmt, ...) av_printf_format(2, 3); 522 523 /** 524 * Write a NULL terminated array of strings to the context. 525 * Usually you don't need to use this function directly but its macro wrapper, 526 * avio_print. 527 */ 528 void avio_print_string_array(AVIOContext *s, const char * const strings[]); 529 530 /** 531 * Write strings (const char *) to the context. 532 * This is a convenience macro around avio_print_string_array and it 533 * automatically creates the string array from the variable argument list. 534 * For simple string concatenations this function is more performant than using 535 * avio_printf since it does not need a temporary buffer. 536 */ 537 #define avio_print(s, ...) \ 538 avio_print_string_array(s, (const char*[]){__VA_ARGS__, NULL}) 539 540 /** 541 * Force flushing of buffered data. 542 * 543 * For write streams, force the buffered data to be immediately written to the output, 544 * without to wait to fill the internal buffer. 545 * 546 * For read streams, discard all currently buffered data, and advance the 547 * reported file position to that of the underlying stream. This does not 548 * read new data, and does not perform any seeks. 549 */ 550 void avio_flush(AVIOContext *s); 551 552 /** 553 * Read size bytes from AVIOContext into buf. 554 * @return number of bytes read or AVERROR 555 */ 556 int avio_read(AVIOContext *s, unsigned char *buf, int size); 557 558 /** 559 * Read size bytes from AVIOContext into buf. Unlike avio_read(), this is allowed 560 * to read fewer bytes than requested. The missing bytes can be read in the next 561 * call. This always tries to read at least 1 byte. 562 * Useful to reduce latency in certain cases. 563 * @return number of bytes read or AVERROR 564 */ 565 int avio_read_partial(AVIOContext *s, unsigned char *buf, int size); 566 567 /** 568 * @name Functions for reading from AVIOContext 569 * @{ 570 * 571 * @note return 0 if EOF, so you cannot use it if EOF handling is 572 * necessary 573 */ 574 int avio_r8 (AVIOContext *s); 575 unsigned int avio_rl16(AVIOContext *s); 576 unsigned int avio_rl24(AVIOContext *s); 577 unsigned int avio_rl32(AVIOContext *s); 578 uint64_t avio_rl64(AVIOContext *s); 579 unsigned int avio_rb16(AVIOContext *s); 580 unsigned int avio_rb24(AVIOContext *s); 581 unsigned int avio_rb32(AVIOContext *s); 582 uint64_t avio_rb64(AVIOContext *s); 583 /** 584 * @} 585 */ 586 587 /** 588 * Read a string from pb into buf. The reading will terminate when either 589 * a NULL character was encountered, maxlen bytes have been read, or nothing 590 * more can be read from pb. The result is guaranteed to be NULL-terminated, it 591 * will be truncated if buf is too small. 592 * Note that the string is not interpreted or validated in any way, it 593 * might get truncated in the middle of a sequence for multi-byte encodings. 594 * 595 * @return number of bytes read (is always <= maxlen). 596 * If reading ends on EOF or error, the return value will be one more than 597 * bytes actually read. 598 */ 599 int avio_get_str(AVIOContext *pb, int maxlen, char *buf, int buflen); 600 601 /** 602 * Read a UTF-16 string from pb and convert it to UTF-8. 603 * The reading will terminate when either a null or invalid character was 604 * encountered or maxlen bytes have been read. 605 * @return number of bytes read (is always <= maxlen) 606 */ 607 int avio_get_str16le(AVIOContext *pb, int maxlen, char *buf, int buflen); 608 int avio_get_str16be(AVIOContext *pb, int maxlen, char *buf, int buflen); 609 610 611 /** 612 * @name URL open modes 613 * The flags argument to avio_open must be one of the following 614 * constants, optionally ORed with other flags. 615 * @{ 616 */ 617 #define AVIO_FLAG_READ 1 /**< read-only */ 618 #define AVIO_FLAG_WRITE 2 /**< write-only */ 619 #define AVIO_FLAG_READ_WRITE (AVIO_FLAG_READ|AVIO_FLAG_WRITE) /**< read-write pseudo flag */ 620 /** 621 * @} 622 */ 623 624 /** 625 * Use non-blocking mode. 626 * If this flag is set, operations on the context will return 627 * AVERROR(EAGAIN) if they can not be performed immediately. 628 * If this flag is not set, operations on the context will never return 629 * AVERROR(EAGAIN). 630 * Note that this flag does not affect the opening/connecting of the 631 * context. Connecting a protocol will always block if necessary (e.g. on 632 * network protocols) but never hang (e.g. on busy devices). 633 * Warning: non-blocking protocols is work-in-progress; this flag may be 634 * silently ignored. 635 */ 636 #define AVIO_FLAG_NONBLOCK 8 637 638 /** 639 * Use direct mode. 640 * avio_read and avio_write should if possible be satisfied directly 641 * instead of going through a buffer, and avio_seek will always 642 * call the underlying seek function directly. 643 */ 644 #define AVIO_FLAG_DIRECT 0x8000 645 646 /** 647 * Create and initialize a AVIOContext for accessing the 648 * resource indicated by url. 649 * @note When the resource indicated by url has been opened in 650 * read+write mode, the AVIOContext can be used only for writing. 651 * 652 * @param s Used to return the pointer to the created AVIOContext. 653 * In case of failure the pointed to value is set to NULL. 654 * @param url resource to access 655 * @param flags flags which control how the resource indicated by url 656 * is to be opened 657 * @return >= 0 in case of success, a negative value corresponding to an 658 * AVERROR code in case of failure 659 */ 660 int avio_open(AVIOContext **s, const char *url, int flags); 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 * @param int_cb an interrupt callback to be used at the protocols level 674 * @param options A dictionary filled with protocol-private options. On return 675 * this parameter will be destroyed and replaced with a dict containing options 676 * that were not found. May be NULL. 677 * @return >= 0 in case of success, a negative value corresponding to an 678 * AVERROR code in case of failure 679 */ 680 int avio_open2(AVIOContext **s, const char *url, int flags, 681 const AVIOInterruptCB *int_cb, AVDictionary **options); 682 683 /** 684 * Close the resource accessed by the AVIOContext s and free it. 685 * This function can only be used if s was opened by avio_open(). 686 * 687 * The internal buffer is automatically flushed before closing the 688 * resource. 689 * 690 * @return 0 on success, an AVERROR < 0 on error. 691 * @see avio_closep 692 */ 693 int avio_close(AVIOContext *s); 694 695 /** 696 * Close the resource accessed by the AVIOContext *s, free it 697 * and set the pointer pointing to it to NULL. 698 * This function can only be used if s was opened by avio_open(). 699 * 700 * The internal buffer is automatically flushed before closing the 701 * resource. 702 * 703 * @return 0 on success, an AVERROR < 0 on error. 704 * @see avio_close 705 */ 706 int avio_closep(AVIOContext **s); 707 708 709 /** 710 * Open a write only memory stream. 711 * 712 * @param s new IO context 713 * @return zero if no error. 714 */ 715 int avio_open_dyn_buf(AVIOContext **s); 716 717 /** 718 * Return the written size and a pointer to the buffer. 719 * The AVIOContext stream is left intact. 720 * The buffer must NOT be freed. 721 * No padding is added to the buffer. 722 * 723 * @param s IO context 724 * @param pbuffer pointer to a byte buffer 725 * @return the length of the byte buffer 726 */ 727 int avio_get_dyn_buf(AVIOContext *s, uint8_t **pbuffer); 728 729 /** 730 * Return the written size and a pointer to the buffer. The buffer 731 * must be freed with av_free(). 732 * Padding of AV_INPUT_BUFFER_PADDING_SIZE is added to the buffer. 733 * 734 * @param s IO context 735 * @param pbuffer pointer to a byte buffer 736 * @return the length of the byte buffer 737 */ 738 int avio_close_dyn_buf(AVIOContext *s, uint8_t **pbuffer); 739 740 /** 741 * Iterate through names of available protocols. 742 * 743 * @param opaque A private pointer representing current protocol. 744 * It must be a pointer to NULL on first iteration and will 745 * be updated by successive calls to avio_enum_protocols. 746 * @param output If set to 1, iterate over output protocols, 747 * otherwise over input protocols. 748 * 749 * @return A static string containing the name of current protocol or NULL 750 */ 751 const char *avio_enum_protocols(void **opaque, int output); 752 753 /** 754 * Get AVClass by names of available protocols. 755 * 756 * @return A AVClass of input protocol name or NULL 757 */ 758 const AVClass *avio_protocol_get_class(const char *name); 759 760 /** 761 * Pause and resume playing - only meaningful if using a network streaming 762 * protocol (e.g. MMS). 763 * 764 * @param h IO context from which to call the read_pause function pointer 765 * @param pause 1 for pause, 0 for resume 766 */ 767 int avio_pause(AVIOContext *h, int pause); 768 769 /** 770 * Seek to a given timestamp relative to some component stream. 771 * Only meaningful if using a network streaming protocol (e.g. MMS.). 772 * 773 * @param h IO context from which to call the seek function pointers 774 * @param stream_index The stream index that the timestamp is relative to. 775 * If stream_index is (-1) the timestamp should be in AV_TIME_BASE 776 * units from the beginning of the presentation. 777 * If a stream_index >= 0 is used and the protocol does not support 778 * seeking based on component streams, the call will fail. 779 * @param timestamp timestamp in AVStream.time_base units 780 * or if there is no stream specified then in AV_TIME_BASE units. 781 * @param flags Optional combination of AVSEEK_FLAG_BACKWARD, AVSEEK_FLAG_BYTE 782 * and AVSEEK_FLAG_ANY. The protocol may silently ignore 783 * AVSEEK_FLAG_BACKWARD and AVSEEK_FLAG_ANY, but AVSEEK_FLAG_BYTE will 784 * fail if used and not supported. 785 * @return >= 0 on success 786 * @see AVInputFormat::read_seek 787 */ 788 int64_t avio_seek_time(AVIOContext *h, int stream_index, 789 int64_t timestamp, int flags); 790 791 /* Avoid a warning. The header can not be included because it breaks c++. */ 792 struct AVBPrint; 793 794 /** 795 * Read contents of h into print buffer, up to max_size bytes, or up to EOF. 796 * 797 * @return 0 for success (max_size bytes read or EOF reached), negative error 798 * code otherwise 799 */ 800 int avio_read_to_bprint(AVIOContext *h, struct AVBPrint *pb, size_t max_size); 801 802 /** 803 * Accept and allocate a client context on a server context. 804 * @param s the server context 805 * @param c the client context, must be unallocated 806 * @return >= 0 on success or a negative value corresponding 807 * to an AVERROR on failure 808 */ 809 int avio_accept(AVIOContext *s, AVIOContext **c); 810 811 /** 812 * Perform one step of the protocol handshake to accept a new client. 813 * This function must be called on a client returned by avio_accept() before 814 * using it as a read/write context. 815 * It is separate from avio_accept() because it may block. 816 * A step of the handshake is defined by places where the application may 817 * decide to change the proceedings. 818 * For example, on a protocol with a request header and a reply header, each 819 * one can constitute a step because the application may use the parameters 820 * from the request to change parameters in the reply; or each individual 821 * chunk of the request can constitute a step. 822 * If the handshake is already finished, avio_handshake() does nothing and 823 * returns 0 immediately. 824 * 825 * @param c the client context to perform the handshake on 826 * @return 0 on a complete and successful handshake 827 * > 0 if the handshake progressed, but is not complete 828 * < 0 for an AVERROR code 829 */ 830 int avio_handshake(AVIOContext *c); 831 #endif /* AVFORMAT_AVIO_H */