avio.h 24 KB

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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. * @file
  24. * Buffered I/O operations
  25. */
  26. #include <stdint.h>
  27. #include "libavutil/common.h"
  28. #include "libavutil/log.h"
  29. #include "libavformat/version.h"
  30. #define AVIO_SEEKABLE_NORMAL 0x0001 /**< Seeking works like for a local file */
  31. /**
  32. * Bytestream IO Context.
  33. * New fields can be added to the end with minor version bumps.
  34. * Removal, reordering and changes to existing fields require a major
  35. * version bump.
  36. * sizeof(AVIOContext) must not be used outside libav*.
  37. *
  38. * @note None of the function pointers in AVIOContext should be called
  39. * directly, they should only be set by the client application
  40. * when implementing custom I/O. Normally these are set to the
  41. * function pointers specified in avio_alloc_context()
  42. */
  43. typedef struct {
  44. unsigned char *buffer; /**< Start of the buffer. */
  45. int buffer_size; /**< Maximum buffer size */
  46. unsigned char *buf_ptr; /**< Current position in the buffer */
  47. unsigned char *buf_end; /**< End of the data, may be less than
  48. buffer+buffer_size if the read function returned
  49. less data than requested, e.g. for streams where
  50. no more data has been received yet. */
  51. void *opaque; /**< A private pointer, passed to the read/write/seek/...
  52. functions. */
  53. int (*read_packet)(void *opaque, uint8_t *buf, int buf_size);
  54. int (*write_packet)(void *opaque, uint8_t *buf, int buf_size);
  55. int64_t (*seek)(void *opaque, int64_t offset, int whence);
  56. int64_t pos; /**< position in the file of the current buffer */
  57. int must_flush; /**< true if the next seek should flush */
  58. int eof_reached; /**< true if eof reached */
  59. int write_flag; /**< true if open for writing */
  60. #if FF_API_OLD_AVIO
  61. attribute_deprecated int is_streamed;
  62. #endif
  63. int max_packet_size;
  64. unsigned long checksum;
  65. unsigned char *checksum_ptr;
  66. unsigned long (*update_checksum)(unsigned long checksum, const uint8_t *buf, unsigned int size);
  67. int error; /**< contains the error code or 0 if no error happened */
  68. /**
  69. * Pause or resume playback for network streaming protocols - e.g. MMS.
  70. */
  71. int (*read_pause)(void *opaque, int pause);
  72. /**
  73. * Seek to a given timestamp in stream with the specified stream_index.
  74. * Needed for some network streaming protocols which don't support seeking
  75. * to byte position.
  76. */
  77. int64_t (*read_seek)(void *opaque, int stream_index,
  78. int64_t timestamp, int flags);
  79. /**
  80. * A combination of AVIO_SEEKABLE_ flags or 0 when the stream is not seekable.
  81. */
  82. int seekable;
  83. } AVIOContext;
  84. /* unbuffered I/O */
  85. #if FF_API_OLD_AVIO
  86. /**
  87. * URL Context.
  88. * New fields can be added to the end with minor version bumps.
  89. * Removal, reordering and changes to existing fields require a major
  90. * version bump.
  91. * sizeof(URLContext) must not be used outside libav*.
  92. * @deprecated This struct will be made private
  93. */
  94. typedef struct URLContext {
  95. const AVClass *av_class; ///< information for av_log(). Set by url_open().
  96. struct URLProtocol *prot;
  97. int flags;
  98. int is_streamed; /**< true if streamed (no seek possible), default = false */
  99. int max_packet_size; /**< if non zero, the stream is packetized with this max packet size */
  100. void *priv_data;
  101. char *filename; /**< specified URL */
  102. int is_connected;
  103. } URLContext;
  104. #define URL_PROTOCOL_FLAG_NESTED_SCHEME 1 /*< The protocol name can be the first part of a nested protocol scheme */
  105. /**
  106. * @deprecated This struct is to be made private. Use the higher-level
  107. * AVIOContext-based API instead.
  108. */
  109. typedef struct URLProtocol {
  110. const char *name;
  111. int (*url_open)(URLContext *h, const char *url, int flags);
  112. int (*url_read)(URLContext *h, unsigned char *buf, int size);
  113. int (*url_write)(URLContext *h, const unsigned char *buf, int size);
  114. int64_t (*url_seek)(URLContext *h, int64_t pos, int whence);
  115. int (*url_close)(URLContext *h);
  116. struct URLProtocol *next;
  117. int (*url_read_pause)(URLContext *h, int pause);
  118. int64_t (*url_read_seek)(URLContext *h, int stream_index,
  119. int64_t timestamp, int flags);
  120. int (*url_get_file_handle)(URLContext *h);
  121. int priv_data_size;
  122. const AVClass *priv_data_class;
  123. int flags;
  124. int (*url_check)(URLContext *h, int mask);
  125. } URLProtocol;
  126. typedef struct URLPollEntry {
  127. URLContext *handle;
  128. int events;
  129. int revents;
  130. } URLPollEntry;
  131. /* not implemented */
  132. attribute_deprecated int url_poll(URLPollEntry *poll_table, int n, int timeout);
  133. /**
  134. * @name URL open modes
  135. * The flags argument to url_open and cosins must be one of the following
  136. * constants, optionally ORed with other flags.
  137. * @{
  138. */
  139. #define URL_RDONLY 1 /**< read-only */
  140. #define URL_WRONLY 2 /**< write-only */
  141. #define URL_RDWR (URL_RDONLY|URL_WRONLY) /**< read-write */
  142. /**
  143. * @}
  144. */
  145. /**
  146. * Use non-blocking mode.
  147. * If this flag is set, operations on the context will return
  148. * AVERROR(EAGAIN) if they can not be performed immediately.
  149. * If this flag is not set, operations on the context will never return
  150. * AVERROR(EAGAIN).
  151. * Note that this flag does not affect the opening/connecting of the
  152. * context. Connecting a protocol will always block if necessary (e.g. on
  153. * network protocols) but never hang (e.g. on busy devices).
  154. * Warning: non-blocking protocols is work-in-progress; this flag may be
  155. * silently ignored.
  156. */
  157. #define URL_FLAG_NONBLOCK 4
  158. typedef int URLInterruptCB(void);
  159. extern URLInterruptCB *url_interrupt_cb;
  160. /**
  161. * @defgroup old_url_funcs Old url_* functions
  162. * The following functions are deprecated. Use the buffered API based on #AVIOContext instead.
  163. * @{
  164. */
  165. attribute_deprecated int url_open_protocol (URLContext **puc, struct URLProtocol *up,
  166. const char *url, int flags);
  167. attribute_deprecated int url_alloc(URLContext **h, const char *url, int flags);
  168. attribute_deprecated int url_connect(URLContext *h);
  169. attribute_deprecated int url_open(URLContext **h, const char *url, int flags);
  170. attribute_deprecated int url_read(URLContext *h, unsigned char *buf, int size);
  171. attribute_deprecated int url_read_complete(URLContext *h, unsigned char *buf, int size);
  172. attribute_deprecated int url_write(URLContext *h, const unsigned char *buf, int size);
  173. attribute_deprecated int64_t url_seek(URLContext *h, int64_t pos, int whence);
  174. attribute_deprecated int url_close(URLContext *h);
  175. attribute_deprecated int64_t url_filesize(URLContext *h);
  176. attribute_deprecated int url_get_file_handle(URLContext *h);
  177. attribute_deprecated int url_get_max_packet_size(URLContext *h);
  178. attribute_deprecated void url_get_filename(URLContext *h, char *buf, int buf_size);
  179. attribute_deprecated int av_url_read_pause(URLContext *h, int pause);
  180. attribute_deprecated int64_t av_url_read_seek(URLContext *h, int stream_index,
  181. int64_t timestamp, int flags);
  182. attribute_deprecated void url_set_interrupt_cb(int (*interrupt_cb)(void));
  183. /**
  184. * returns the next registered protocol after the given protocol (the first if
  185. * NULL is given), or NULL if protocol is the last one.
  186. */
  187. URLProtocol *av_protocol_next(URLProtocol *p);
  188. /**
  189. * Register the URLProtocol protocol.
  190. *
  191. * @param size the size of the URLProtocol struct referenced
  192. */
  193. attribute_deprecated int av_register_protocol2(URLProtocol *protocol, int size);
  194. /**
  195. * @}
  196. */
  197. typedef attribute_deprecated AVIOContext ByteIOContext;
  198. attribute_deprecated int init_put_byte(AVIOContext *s,
  199. unsigned char *buffer,
  200. int buffer_size,
  201. int write_flag,
  202. void *opaque,
  203. int (*read_packet)(void *opaque, uint8_t *buf, int buf_size),
  204. int (*write_packet)(void *opaque, uint8_t *buf, int buf_size),
  205. int64_t (*seek)(void *opaque, int64_t offset, int whence));
  206. attribute_deprecated AVIOContext *av_alloc_put_byte(
  207. unsigned char *buffer,
  208. int buffer_size,
  209. int write_flag,
  210. void *opaque,
  211. int (*read_packet)(void *opaque, uint8_t *buf, int buf_size),
  212. int (*write_packet)(void *opaque, uint8_t *buf, int buf_size),
  213. int64_t (*seek)(void *opaque, int64_t offset, int whence));
  214. /**
  215. * @defgroup old_avio_funcs Old put_/get_*() functions
  216. * The following functions are deprecated. Use the "avio_"-prefixed functions instead.
  217. * @{
  218. */
  219. attribute_deprecated int get_buffer(AVIOContext *s, unsigned char *buf, int size);
  220. attribute_deprecated int get_partial_buffer(AVIOContext *s, unsigned char *buf, int size);
  221. attribute_deprecated int get_byte(AVIOContext *s);
  222. attribute_deprecated unsigned int get_le16(AVIOContext *s);
  223. attribute_deprecated unsigned int get_le24(AVIOContext *s);
  224. attribute_deprecated unsigned int get_le32(AVIOContext *s);
  225. attribute_deprecated uint64_t get_le64(AVIOContext *s);
  226. attribute_deprecated unsigned int get_be16(AVIOContext *s);
  227. attribute_deprecated unsigned int get_be24(AVIOContext *s);
  228. attribute_deprecated unsigned int get_be32(AVIOContext *s);
  229. attribute_deprecated uint64_t get_be64(AVIOContext *s);
  230. attribute_deprecated void put_byte(AVIOContext *s, int b);
  231. attribute_deprecated void put_nbyte(AVIOContext *s, int b, int count);
  232. attribute_deprecated void put_buffer(AVIOContext *s, const unsigned char *buf, int size);
  233. attribute_deprecated void put_le64(AVIOContext *s, uint64_t val);
  234. attribute_deprecated void put_be64(AVIOContext *s, uint64_t val);
  235. attribute_deprecated void put_le32(AVIOContext *s, unsigned int val);
  236. attribute_deprecated void put_be32(AVIOContext *s, unsigned int val);
  237. attribute_deprecated void put_le24(AVIOContext *s, unsigned int val);
  238. attribute_deprecated void put_be24(AVIOContext *s, unsigned int val);
  239. attribute_deprecated void put_le16(AVIOContext *s, unsigned int val);
  240. attribute_deprecated void put_be16(AVIOContext *s, unsigned int val);
  241. attribute_deprecated void put_tag(AVIOContext *s, const char *tag);
  242. /**
  243. * @}
  244. */
  245. attribute_deprecated int av_url_read_fpause(AVIOContext *h, int pause);
  246. attribute_deprecated int64_t av_url_read_fseek (AVIOContext *h, int stream_index,
  247. int64_t timestamp, int flags);
  248. /**
  249. * @defgroup old_url_f_funcs Old url_f* functions
  250. * The following functions are deprecated, use the "avio_"-prefixed functions instead.
  251. * @{
  252. */
  253. attribute_deprecated int url_fopen( AVIOContext **s, const char *url, int flags);
  254. attribute_deprecated int url_fclose(AVIOContext *s);
  255. attribute_deprecated int64_t url_fseek(AVIOContext *s, int64_t offset, int whence);
  256. attribute_deprecated int url_fskip(AVIOContext *s, int64_t offset);
  257. attribute_deprecated int64_t url_ftell(AVIOContext *s);
  258. attribute_deprecated int64_t url_fsize(AVIOContext *s);
  259. #define URL_EOF (-1)
  260. attribute_deprecated int url_fgetc(AVIOContext *s);
  261. attribute_deprecated int url_setbufsize(AVIOContext *s, int buf_size);
  262. #ifdef __GNUC__
  263. attribute_deprecated int url_fprintf(AVIOContext *s, const char *fmt, ...) __attribute__ ((__format__ (__printf__, 2, 3)));
  264. #else
  265. attribute_deprecated int url_fprintf(AVIOContext *s, const char *fmt, ...);
  266. #endif
  267. attribute_deprecated void put_flush_packet(AVIOContext *s);
  268. attribute_deprecated int url_open_dyn_buf(AVIOContext **s);
  269. attribute_deprecated int url_open_dyn_packet_buf(AVIOContext **s, int max_packet_size);
  270. attribute_deprecated int url_close_dyn_buf(AVIOContext *s, uint8_t **pbuffer);
  271. attribute_deprecated int url_fdopen(AVIOContext **s, URLContext *h);
  272. /**
  273. * @}
  274. */
  275. attribute_deprecated int url_ferror(AVIOContext *s);
  276. attribute_deprecated int udp_set_remote_url(URLContext *h, const char *uri);
  277. attribute_deprecated int udp_get_local_port(URLContext *h);
  278. attribute_deprecated void init_checksum(AVIOContext *s,
  279. unsigned long (*update_checksum)(unsigned long c, const uint8_t *p, unsigned int len),
  280. unsigned long checksum);
  281. attribute_deprecated unsigned long get_checksum(AVIOContext *s);
  282. attribute_deprecated void put_strz(AVIOContext *s, const char *buf);
  283. /** @note unlike fgets, the EOL character is not returned and a whole
  284. line is parsed. return NULL if first char read was EOF */
  285. attribute_deprecated char *url_fgets(AVIOContext *s, char *buf, int buf_size);
  286. /**
  287. * @deprecated use avio_get_str instead
  288. */
  289. attribute_deprecated char *get_strz(AVIOContext *s, char *buf, int maxlen);
  290. /**
  291. * @deprecated Use AVIOContext.seekable field directly.
  292. */
  293. attribute_deprecated static inline int url_is_streamed(AVIOContext *s)
  294. {
  295. return !s->seekable;
  296. }
  297. attribute_deprecated URLContext *url_fileno(AVIOContext *s);
  298. /**
  299. * @deprecated use AVIOContext.max_packet_size directly.
  300. */
  301. attribute_deprecated int url_fget_max_packet_size(AVIOContext *s);
  302. attribute_deprecated int url_open_buf(AVIOContext **s, uint8_t *buf, int buf_size, int flags);
  303. /** return the written or read size */
  304. attribute_deprecated int url_close_buf(AVIOContext *s);
  305. /**
  306. * Return a non-zero value if the resource indicated by url
  307. * exists, 0 otherwise.
  308. * @deprecated Use avio_check instead.
  309. */
  310. attribute_deprecated int url_exist(const char *url);
  311. #endif // FF_API_OLD_AVIO
  312. /**
  313. * Return AVIO_FLAG_* access flags corresponding to the access permissions
  314. * of the resource in url, or a negative value corresponding to an
  315. * AVERROR code in case of failure. The returned access flags are
  316. * masked by the value in flags.
  317. *
  318. * @note This function is intrinsically unsafe, in the sense that the
  319. * checked resource may change its existence or permission status from
  320. * one call to another. Thus you should not trust the returned value,
  321. * unless you are sure that no other processes are accessing the
  322. * checked resource.
  323. */
  324. int avio_check(const char *url, int flags);
  325. /**
  326. * The callback is called in blocking functions to test regulary if
  327. * asynchronous interruption is needed. AVERROR_EXIT is returned
  328. * in this case by the interrupted function. 'NULL' means no interrupt
  329. * callback is given.
  330. */
  331. void avio_set_interrupt_cb(int (*interrupt_cb)(void));
  332. /**
  333. * Allocate and initialize an AVIOContext for buffered I/O. It must be later
  334. * freed with av_free().
  335. *
  336. * @param buffer Memory block for input/output operations via AVIOContext.
  337. * The buffer must be allocated with av_malloc() and friends.
  338. * @param buffer_size The buffer size is very important for performance.
  339. * For protocols with fixed blocksize it should be set to this blocksize.
  340. * For others a typical size is a cache page, e.g. 4kb.
  341. * @param write_flag Set to 1 if the buffer should be writable, 0 otherwise.
  342. * @param opaque An opaque pointer to user-specific data.
  343. * @param read_packet A function for refilling the buffer, may be NULL.
  344. * @param write_packet A function for writing the buffer contents, may be NULL.
  345. * @param seek A function for seeking to specified byte position, may be NULL.
  346. *
  347. * @return Allocated AVIOContext or NULL on failure.
  348. */
  349. AVIOContext *avio_alloc_context(
  350. unsigned char *buffer,
  351. int buffer_size,
  352. int write_flag,
  353. void *opaque,
  354. int (*read_packet)(void *opaque, uint8_t *buf, int buf_size),
  355. int (*write_packet)(void *opaque, uint8_t *buf, int buf_size),
  356. int64_t (*seek)(void *opaque, int64_t offset, int whence));
  357. void avio_w8(AVIOContext *s, int b);
  358. void avio_write(AVIOContext *s, const unsigned char *buf, int size);
  359. void avio_wl64(AVIOContext *s, uint64_t val);
  360. void avio_wb64(AVIOContext *s, uint64_t val);
  361. void avio_wl32(AVIOContext *s, unsigned int val);
  362. void avio_wb32(AVIOContext *s, unsigned int val);
  363. void avio_wl24(AVIOContext *s, unsigned int val);
  364. void avio_wb24(AVIOContext *s, unsigned int val);
  365. void avio_wl16(AVIOContext *s, unsigned int val);
  366. void avio_wb16(AVIOContext *s, unsigned int val);
  367. /**
  368. * Write a NULL-terminated string.
  369. * @return number of bytes written.
  370. */
  371. int avio_put_str(AVIOContext *s, const char *str);
  372. /**
  373. * Convert an UTF-8 string to UTF-16LE and write it.
  374. * @return number of bytes written.
  375. */
  376. int avio_put_str16le(AVIOContext *s, const char *str);
  377. /**
  378. * Passing this as the "whence" parameter to a seek function causes it to
  379. * return the filesize without seeking anywhere. Supporting this is optional.
  380. * If it is not supported then the seek function will return <0.
  381. */
  382. #define AVSEEK_SIZE 0x10000
  383. /**
  384. * Oring this flag as into the "whence" parameter to a seek function causes it to
  385. * seek by any means (like reopening and linear reading) or other normally unreasonble
  386. * means that can be extreemly slow.
  387. * This may be ignored by the seek code.
  388. */
  389. #define AVSEEK_FORCE 0x20000
  390. /**
  391. * fseek() equivalent for AVIOContext.
  392. * @return new position or AVERROR.
  393. */
  394. int64_t avio_seek(AVIOContext *s, int64_t offset, int whence);
  395. /**
  396. * Skip given number of bytes forward
  397. * @return new position or AVERROR.
  398. */
  399. int64_t avio_skip(AVIOContext *s, int64_t offset);
  400. /**
  401. * ftell() equivalent for AVIOContext.
  402. * @return position or AVERROR.
  403. */
  404. static av_always_inline int64_t avio_tell(AVIOContext *s)
  405. {
  406. return avio_seek(s, 0, SEEK_CUR);
  407. }
  408. /**
  409. * Get the filesize.
  410. * @return filesize or AVERROR
  411. */
  412. int64_t avio_size(AVIOContext *s);
  413. /**
  414. * feof() equivalent for AVIOContext.
  415. * @return non zero if and only if end of file
  416. */
  417. int url_feof(AVIOContext *s);
  418. /** @warning currently size is limited */
  419. #ifdef __GNUC__
  420. int avio_printf(AVIOContext *s, const char *fmt, ...) __attribute__ ((__format__ (__printf__, 2, 3)));
  421. #else
  422. int avio_printf(AVIOContext *s, const char *fmt, ...);
  423. #endif
  424. void avio_flush(AVIOContext *s);
  425. /**
  426. * Read size bytes from AVIOContext into buf.
  427. * @return number of bytes read or AVERROR
  428. */
  429. int avio_read(AVIOContext *s, unsigned char *buf, int size);
  430. /**
  431. * @name Functions for reading from AVIOContext
  432. * @{
  433. *
  434. * @note return 0 if EOF, so you cannot use it if EOF handling is
  435. * necessary
  436. */
  437. int avio_r8 (AVIOContext *s);
  438. unsigned int avio_rl16(AVIOContext *s);
  439. unsigned int avio_rl24(AVIOContext *s);
  440. unsigned int avio_rl32(AVIOContext *s);
  441. uint64_t avio_rl64(AVIOContext *s);
  442. unsigned int avio_rb16(AVIOContext *s);
  443. unsigned int avio_rb24(AVIOContext *s);
  444. unsigned int avio_rb32(AVIOContext *s);
  445. uint64_t avio_rb64(AVIOContext *s);
  446. /**
  447. * @}
  448. */
  449. /**
  450. * Read a string from pb into buf. The reading will terminate when either
  451. * a NULL character was encountered, maxlen bytes have been read, or nothing
  452. * more can be read from pb. The result is guaranteed to be NULL-terminated, it
  453. * will be truncated if buf is too small.
  454. * Note that the string is not interpreted or validated in any way, it
  455. * might get truncated in the middle of a sequence for multi-byte encodings.
  456. *
  457. * @return number of bytes read (is always <= maxlen).
  458. * If reading ends on EOF or error, the return value will be one more than
  459. * bytes actually read.
  460. */
  461. int avio_get_str(AVIOContext *pb, int maxlen, char *buf, int buflen);
  462. /**
  463. * Read a UTF-16 string from pb and convert it to UTF-8.
  464. * The reading will terminate when either a null or invalid character was
  465. * encountered or maxlen bytes have been read.
  466. * @return number of bytes read (is always <= maxlen)
  467. */
  468. int avio_get_str16le(AVIOContext *pb, int maxlen, char *buf, int buflen);
  469. int avio_get_str16be(AVIOContext *pb, int maxlen, char *buf, int buflen);
  470. /**
  471. * @name URL open modes
  472. * The flags argument to avio_open must be one of the following
  473. * constants, optionally ORed with other flags.
  474. * @{
  475. */
  476. #define AVIO_FLAG_READ 1 /**< read-only */
  477. #define AVIO_FLAG_WRITE 2 /**< write-only */
  478. #define AVIO_FLAG_READ_WRITE (AVIO_FLAG_READ|AVIO_FLAG_WRITE) /**< read-write pseudo flag */
  479. /**
  480. * @}
  481. */
  482. /**
  483. * Use non-blocking mode.
  484. * If this flag is set, operations on the context will return
  485. * AVERROR(EAGAIN) if they can not be performed immediately.
  486. * If this flag is not set, operations on the context will never return
  487. * AVERROR(EAGAIN).
  488. * Note that this flag does not affect the opening/connecting of the
  489. * context. Connecting a protocol will always block if necessary (e.g. on
  490. * network protocols) but never hang (e.g. on busy devices).
  491. * Warning: non-blocking protocols is work-in-progress; this flag may be
  492. * silently ignored.
  493. */
  494. #define AVIO_FLAG_NONBLOCK 8
  495. /**
  496. * Create and initialize a AVIOContext for accessing the
  497. * resource indicated by url.
  498. * @note When the resource indicated by url has been opened in
  499. * read+write mode, the AVIOContext can be used only for writing.
  500. *
  501. * @param s Used to return the pointer to the created AVIOContext.
  502. * In case of failure the pointed to value is set to NULL.
  503. * @param flags flags which control how the resource indicated by url
  504. * is to be opened
  505. * @return 0 in case of success, a negative value corresponding to an
  506. * AVERROR code in case of failure
  507. */
  508. int avio_open(AVIOContext **s, const char *url, int flags);
  509. /**
  510. * Close the resource accessed by the AVIOContext s and free it.
  511. * This function can only be used if s was opened by avio_open().
  512. *
  513. * @return 0 on success, an AVERROR < 0 on error.
  514. */
  515. int avio_close(AVIOContext *s);
  516. /**
  517. * Open a write only memory stream.
  518. *
  519. * @param s new IO context
  520. * @return zero if no error.
  521. */
  522. int avio_open_dyn_buf(AVIOContext **s);
  523. /**
  524. * Return the written size and a pointer to the buffer. The buffer
  525. * must be freed with av_free().
  526. * Padding of FF_INPUT_BUFFER_PADDING_SIZE is added to the buffer.
  527. *
  528. * @param s IO context
  529. * @param pbuffer pointer to a byte buffer
  530. * @return the length of the byte buffer
  531. */
  532. int avio_close_dyn_buf(AVIOContext *s, uint8_t **pbuffer);
  533. /**
  534. * Iterate through names of available protocols.
  535. * @note it is recommanded to use av_protocol_next() instead of this
  536. *
  537. * @param opaque A private pointer representing current protocol.
  538. * It must be a pointer to NULL on first iteration and will
  539. * be updated by successive calls to avio_enum_protocols.
  540. * @param output If set to 1, iterate over output protocols,
  541. * otherwise over input protocols.
  542. *
  543. * @return A static string containing the name of current protocol or NULL
  544. */
  545. const char *avio_enum_protocols(void **opaque, int output);
  546. /**
  547. * Pause and resume playing - only meaningful if using a network streaming
  548. * protocol (e.g. MMS).
  549. * @param pause 1 for pause, 0 for resume
  550. */
  551. int avio_pause(AVIOContext *h, int pause);
  552. /**
  553. * Seek to a given timestamp relative to some component stream.
  554. * Only meaningful if using a network streaming protocol (e.g. MMS.).
  555. * @param stream_index The stream index that the timestamp is relative to.
  556. * If stream_index is (-1) the timestamp should be in AV_TIME_BASE
  557. * units from the beginning of the presentation.
  558. * If a stream_index >= 0 is used and the protocol does not support
  559. * seeking based on component streams, the call will fail with ENOTSUP.
  560. * @param timestamp timestamp in AVStream.time_base units
  561. * or if there is no stream specified then in AV_TIME_BASE units.
  562. * @param flags Optional combination of AVSEEK_FLAG_BACKWARD, AVSEEK_FLAG_BYTE
  563. * and AVSEEK_FLAG_ANY. The protocol may silently ignore
  564. * AVSEEK_FLAG_BACKWARD and AVSEEK_FLAG_ANY, but AVSEEK_FLAG_BYTE will
  565. * fail with ENOTSUP if used and not supported.
  566. * @return >= 0 on success
  567. * @see AVInputFormat::read_seek
  568. */
  569. int64_t avio_seek_time(AVIOContext *h, int stream_index,
  570. int64_t timestamp, int flags);
  571. #endif /* AVFORMAT_AVIO_H */