be14e3c89d362625a9ccd8592e3ed8e32e02ccb3
[libav.git] / libavformat / avio.h
1 /*
2 * copyright (c) 2001 Fabrice Bellard
3 *
4 * This file is part of Libav.
5 *
6 * Libav 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 * Libav 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 Libav; 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 * Buffered I/O operations
26 */
27
28 #include <stdint.h>
29
30 #include "libavutil/common.h"
31 #include "libavutil/log.h"
32
33 #include "libavformat/version.h"
34
35
36 #define AVIO_SEEKABLE_NORMAL 0x0001 /**< Seeking works like for a local file */
37
38 /**
39 * Bytestream IO Context.
40 * New fields can be added to the end with minor version bumps.
41 * Removal, reordering and changes to existing fields require a major
42 * version bump.
43 * sizeof(AVIOContext) must not be used outside libav*.
44 *
45 * @note None of the function pointers in AVIOContext should be called
46 * directly, they should only be set by the client application
47 * when implementing custom I/O. Normally these are set to the
48 * function pointers specified in avio_alloc_context()
49 */
50 typedef struct {
51 unsigned char *buffer; /**< Start of the buffer. */
52 int buffer_size; /**< Maximum buffer size */
53 unsigned char *buf_ptr; /**< Current position in the buffer */
54 unsigned char *buf_end; /**< End of the data, may be less than
55 buffer+buffer_size if the read function returned
56 less data than requested, e.g. for streams where
57 no more data has been received yet. */
58 void *opaque; /**< A private pointer, passed to the read/write/seek/...
59 functions. */
60 int (*read_packet)(void *opaque, uint8_t *buf, int buf_size);
61 int (*write_packet)(void *opaque, uint8_t *buf, int buf_size);
62 int64_t (*seek)(void *opaque, int64_t offset, int whence);
63 int64_t pos; /**< position in the file of the current buffer */
64 int must_flush; /**< true if the next seek should flush */
65 int eof_reached; /**< true if eof reached */
66 int write_flag; /**< true if open for writing */
67 #if FF_API_OLD_AVIO
68 attribute_deprecated int is_streamed;
69 #endif
70 int max_packet_size;
71 unsigned long checksum;
72 unsigned char *checksum_ptr;
73 unsigned long (*update_checksum)(unsigned long checksum, const uint8_t *buf, unsigned int size);
74 int error; /**< contains the error code or 0 if no error happened */
75 /**
76 * Pause or resume playback for network streaming protocols - e.g. MMS.
77 */
78 int (*read_pause)(void *opaque, int pause);
79 /**
80 * Seek to a given timestamp in stream with the specified stream_index.
81 * Needed for some network streaming protocols which don't support seeking
82 * to byte position.
83 */
84 int64_t (*read_seek)(void *opaque, int stream_index,
85 int64_t timestamp, int flags);
86 /**
87 * A combination of AVIO_SEEKABLE_ flags or 0 when the stream is not seekable.
88 */
89 int seekable;
90 } AVIOContext;
91
92 /* unbuffered I/O */
93
94 #if FF_API_OLD_AVIO
95 /**
96 * URL Context.
97 * New fields can be added to the end with minor version bumps.
98 * Removal, reordering and changes to existing fields require a major
99 * version bump.
100 * sizeof(URLContext) must not be used outside libav*.
101 * @deprecated This struct will be made private
102 */
103 typedef struct URLContext {
104 const AVClass *av_class; ///< information for av_log(). Set by url_open().
105 struct URLProtocol *prot;
106 int flags;
107 int is_streamed; /**< true if streamed (no seek possible), default = false */
108 int max_packet_size; /**< if non zero, the stream is packetized with this max packet size */
109 void *priv_data;
110 char *filename; /**< specified URL */
111 int is_connected;
112 } URLContext;
113
114 #define URL_PROTOCOL_FLAG_NESTED_SCHEME 1 /*< The protocol name can be the first part of a nested protocol scheme */
115
116 /**
117 * @deprecated This struct is to be made private. Use the higher-level
118 * AVIOContext-based API instead.
119 */
120 typedef struct URLProtocol {
121 const char *name;
122 int (*url_open)(URLContext *h, const char *url, int flags);
123 int (*url_read)(URLContext *h, unsigned char *buf, int size);
124 int (*url_write)(URLContext *h, const unsigned char *buf, int size);
125 int64_t (*url_seek)(URLContext *h, int64_t pos, int whence);
126 int (*url_close)(URLContext *h);
127 struct URLProtocol *next;
128 int (*url_read_pause)(URLContext *h, int pause);
129 int64_t (*url_read_seek)(URLContext *h, int stream_index,
130 int64_t timestamp, int flags);
131 int (*url_get_file_handle)(URLContext *h);
132 int priv_data_size;
133 const AVClass *priv_data_class;
134 int flags;
135 int (*url_check)(URLContext *h, int mask);
136 } URLProtocol;
137
138 typedef struct URLPollEntry {
139 URLContext *handle;
140 int events;
141 int revents;
142 } URLPollEntry;
143
144 /* not implemented */
145 attribute_deprecated int url_poll(URLPollEntry *poll_table, int n, int timeout);
146
147 /**
148 * @name URL open modes
149 * The flags argument to url_open and cosins must be one of the following
150 * constants, optionally ORed with other flags.
151 * @{
152 */
153 #define URL_RDONLY 1 /**< read-only */
154 #define URL_WRONLY 2 /**< write-only */
155 #define URL_RDWR (URL_RDONLY|URL_WRONLY) /**< read-write */
156 /**
157 * @}
158 */
159
160 /**
161 * Use non-blocking mode.
162 * If this flag is set, operations on the context will return
163 * AVERROR(EAGAIN) if they can not be performed immediately.
164 * If this flag is not set, operations on the context will never return
165 * AVERROR(EAGAIN).
166 * Note that this flag does not affect the opening/connecting of the
167 * context. Connecting a protocol will always block if necessary (e.g. on
168 * network protocols) but never hang (e.g. on busy devices).
169 * Warning: non-blocking protocols is work-in-progress; this flag may be
170 * silently ignored.
171 */
172 #define URL_FLAG_NONBLOCK 4
173
174 typedef int URLInterruptCB(void);
175 extern URLInterruptCB *url_interrupt_cb;
176
177 /**
178 * @defgroup old_url_funcs Old url_* functions
179 * The following functions are deprecated. Use the buffered API based on #AVIOContext instead.
180 * @{
181 */
182 attribute_deprecated int url_open_protocol (URLContext **puc, struct URLProtocol *up,
183 const char *url, int flags);
184 attribute_deprecated int url_alloc(URLContext **h, const char *url, int flags);
185 attribute_deprecated int url_connect(URLContext *h);
186 attribute_deprecated int url_open(URLContext **h, const char *url, int flags);
187 attribute_deprecated int url_read(URLContext *h, unsigned char *buf, int size);
188 attribute_deprecated int url_read_complete(URLContext *h, unsigned char *buf, int size);
189 attribute_deprecated int url_write(URLContext *h, const unsigned char *buf, int size);
190 attribute_deprecated int64_t url_seek(URLContext *h, int64_t pos, int whence);
191 attribute_deprecated int url_close(URLContext *h);
192 attribute_deprecated int64_t url_filesize(URLContext *h);
193 attribute_deprecated int url_get_file_handle(URLContext *h);
194 attribute_deprecated int url_get_max_packet_size(URLContext *h);
195 attribute_deprecated void url_get_filename(URLContext *h, char *buf, int buf_size);
196 attribute_deprecated int av_url_read_pause(URLContext *h, int pause);
197 attribute_deprecated int64_t av_url_read_seek(URLContext *h, int stream_index,
198 int64_t timestamp, int flags);
199 attribute_deprecated void url_set_interrupt_cb(int (*interrupt_cb)(void));
200 /**
201 * If protocol is NULL, returns the first registered protocol,
202 * if protocol is non-NULL, returns the next registered protocol after protocol,
203 * or NULL if protocol is the last one.
204 */
205 attribute_deprecated URLProtocol *av_protocol_next(URLProtocol *p);
206 /**
207 * Register the URLProtocol protocol.
208 *
209 * @param size the size of the URLProtocol struct referenced
210 */
211 attribute_deprecated int av_register_protocol2(URLProtocol *protocol, int size);
212 /**
213 * @}
214 */
215
216
217 typedef attribute_deprecated AVIOContext ByteIOContext;
218
219 attribute_deprecated int init_put_byte(AVIOContext *s,
220 unsigned char *buffer,
221 int buffer_size,
222 int write_flag,
223 void *opaque,
224 int (*read_packet)(void *opaque, uint8_t *buf, int buf_size),
225 int (*write_packet)(void *opaque, uint8_t *buf, int buf_size),
226 int64_t (*seek)(void *opaque, int64_t offset, int whence));
227 attribute_deprecated AVIOContext *av_alloc_put_byte(
228 unsigned char *buffer,
229 int buffer_size,
230 int write_flag,
231 void *opaque,
232 int (*read_packet)(void *opaque, uint8_t *buf, int buf_size),
233 int (*write_packet)(void *opaque, uint8_t *buf, int buf_size),
234 int64_t (*seek)(void *opaque, int64_t offset, int whence));
235
236 /**
237 * @defgroup old_avio_funcs Old put_/get_*() functions
238 * The following functions are deprecated. Use the "avio_"-prefixed functions instead.
239 * @{
240 */
241 attribute_deprecated int get_buffer(AVIOContext *s, unsigned char *buf, int size);
242 attribute_deprecated int get_partial_buffer(AVIOContext *s, unsigned char *buf, int size);
243 attribute_deprecated int get_byte(AVIOContext *s);
244 attribute_deprecated unsigned int get_le16(AVIOContext *s);
245 attribute_deprecated unsigned int get_le24(AVIOContext *s);
246 attribute_deprecated unsigned int get_le32(AVIOContext *s);
247 attribute_deprecated uint64_t get_le64(AVIOContext *s);
248 attribute_deprecated unsigned int get_be16(AVIOContext *s);
249 attribute_deprecated unsigned int get_be24(AVIOContext *s);
250 attribute_deprecated unsigned int get_be32(AVIOContext *s);
251 attribute_deprecated uint64_t get_be64(AVIOContext *s);
252
253 attribute_deprecated void put_byte(AVIOContext *s, int b);
254 attribute_deprecated void put_nbyte(AVIOContext *s, int b, int count);
255 attribute_deprecated void put_buffer(AVIOContext *s, const unsigned char *buf, int size);
256 attribute_deprecated void put_le64(AVIOContext *s, uint64_t val);
257 attribute_deprecated void put_be64(AVIOContext *s, uint64_t val);
258 attribute_deprecated void put_le32(AVIOContext *s, unsigned int val);
259 attribute_deprecated void put_be32(AVIOContext *s, unsigned int val);
260 attribute_deprecated void put_le24(AVIOContext *s, unsigned int val);
261 attribute_deprecated void put_be24(AVIOContext *s, unsigned int val);
262 attribute_deprecated void put_le16(AVIOContext *s, unsigned int val);
263 attribute_deprecated void put_be16(AVIOContext *s, unsigned int val);
264 attribute_deprecated void put_tag(AVIOContext *s, const char *tag);
265 /**
266 * @}
267 */
268
269 attribute_deprecated int av_url_read_fpause(AVIOContext *h, int pause);
270 attribute_deprecated int64_t av_url_read_fseek (AVIOContext *h, int stream_index,
271 int64_t timestamp, int flags);
272
273 /**
274 * @defgroup old_url_f_funcs Old url_f* functions
275 * The following functions are deprecated, use the "avio_"-prefixed functions instead.
276 * @{
277 */
278 attribute_deprecated int url_fopen( AVIOContext **s, const char *url, int flags);
279 attribute_deprecated int url_fclose(AVIOContext *s);
280 attribute_deprecated int64_t url_fseek(AVIOContext *s, int64_t offset, int whence);
281 attribute_deprecated int url_fskip(AVIOContext *s, int64_t offset);
282 attribute_deprecated int64_t url_ftell(AVIOContext *s);
283 attribute_deprecated int64_t url_fsize(AVIOContext *s);
284 #define URL_EOF (-1)
285 attribute_deprecated int url_fgetc(AVIOContext *s);
286 attribute_deprecated int url_setbufsize(AVIOContext *s, int buf_size);
287 attribute_deprecated int url_fprintf(AVIOContext *s, const char *fmt, ...) av_printf_format(2, 3);
288 attribute_deprecated void put_flush_packet(AVIOContext *s);
289 attribute_deprecated int url_open_dyn_buf(AVIOContext **s);
290 attribute_deprecated int url_open_dyn_packet_buf(AVIOContext **s, int max_packet_size);
291 attribute_deprecated int url_close_dyn_buf(AVIOContext *s, uint8_t **pbuffer);
292 attribute_deprecated int url_fdopen(AVIOContext **s, URLContext *h);
293 /**
294 * @}
295 */
296
297 /**
298 * @deprecated use AVIOContext.eof_reached
299 */
300 attribute_deprecated int url_feof(AVIOContext *s);
301 attribute_deprecated int url_ferror(AVIOContext *s);
302
303 attribute_deprecated int udp_set_remote_url(URLContext *h, const char *uri);
304 attribute_deprecated int udp_get_local_port(URLContext *h);
305
306 attribute_deprecated void init_checksum(AVIOContext *s,
307 unsigned long (*update_checksum)(unsigned long c, const uint8_t *p, unsigned int len),
308 unsigned long checksum);
309 attribute_deprecated unsigned long get_checksum(AVIOContext *s);
310 attribute_deprecated void put_strz(AVIOContext *s, const char *buf);
311 /** @note unlike fgets, the EOL character is not returned and a whole
312 line is parsed. return NULL if first char read was EOF */
313 attribute_deprecated char *url_fgets(AVIOContext *s, char *buf, int buf_size);
314 /**
315 * @deprecated use avio_get_str instead
316 */
317 attribute_deprecated char *get_strz(AVIOContext *s, char *buf, int maxlen);
318 /**
319 * @deprecated Use AVIOContext.seekable field directly.
320 */
321 attribute_deprecated static inline int url_is_streamed(AVIOContext *s)
322 {
323 return !s->seekable;
324 }
325 attribute_deprecated URLContext *url_fileno(AVIOContext *s);
326
327 /**
328 * @deprecated use AVIOContext.max_packet_size directly.
329 */
330 attribute_deprecated int url_fget_max_packet_size(AVIOContext *s);
331
332 attribute_deprecated int url_open_buf(AVIOContext **s, uint8_t *buf, int buf_size, int flags);
333
334 /** return the written or read size */
335 attribute_deprecated int url_close_buf(AVIOContext *s);
336
337 /**
338 * Return a non-zero value if the resource indicated by url
339 * exists, 0 otherwise.
340 * @deprecated Use avio_check instead.
341 */
342 attribute_deprecated int url_exist(const char *url);
343 #endif // FF_API_OLD_AVIO
344
345 /**
346 * Return AVIO_FLAG_* access flags corresponding to the access permissions
347 * of the resource in url, or a negative value corresponding to an
348 * AVERROR code in case of failure. The returned access flags are
349 * masked by the value in flags.
350 *
351 * @note This function is intrinsically unsafe, in the sense that the
352 * checked resource may change its existence or permission status from
353 * one call to another. Thus you should not trust the returned value,
354 * unless you are sure that no other processes are accessing the
355 * checked resource.
356 */
357 int avio_check(const char *url, int flags);
358
359 /**
360 * The callback is called in blocking functions to test regulary if
361 * asynchronous interruption is needed. AVERROR_EXIT is returned
362 * in this case by the interrupted function. 'NULL' means no interrupt
363 * callback is given.
364 */
365 void avio_set_interrupt_cb(int (*interrupt_cb)(void));
366
367 /**
368 * Allocate and initialize an AVIOContext for buffered I/O. It must be later
369 * freed with av_free().
370 *
371 * @param buffer Memory block for input/output operations via AVIOContext.
372 * The buffer must be allocated with av_malloc() and friends.
373 * @param buffer_size The buffer size is very important for performance.
374 * For protocols with fixed blocksize it should be set to this blocksize.
375 * For others a typical size is a cache page, e.g. 4kb.
376 * @param write_flag Set to 1 if the buffer should be writable, 0 otherwise.
377 * @param opaque An opaque pointer to user-specific data.
378 * @param read_packet A function for refilling the buffer, may be NULL.
379 * @param write_packet A function for writing the buffer contents, may be NULL.
380 * @param seek A function for seeking to specified byte position, may be NULL.
381 *
382 * @return Allocated AVIOContext or NULL on failure.
383 */
384 AVIOContext *avio_alloc_context(
385 unsigned char *buffer,
386 int buffer_size,
387 int write_flag,
388 void *opaque,
389 int (*read_packet)(void *opaque, uint8_t *buf, int buf_size),
390 int (*write_packet)(void *opaque, uint8_t *buf, int buf_size),
391 int64_t (*seek)(void *opaque, int64_t offset, int whence));
392
393 void avio_w8(AVIOContext *s, int b);
394 void avio_write(AVIOContext *s, const unsigned char *buf, int size);
395 void avio_wl64(AVIOContext *s, uint64_t val);
396 void avio_wb64(AVIOContext *s, uint64_t val);
397 void avio_wl32(AVIOContext *s, unsigned int val);
398 void avio_wb32(AVIOContext *s, unsigned int val);
399 void avio_wl24(AVIOContext *s, unsigned int val);
400 void avio_wb24(AVIOContext *s, unsigned int val);
401 void avio_wl16(AVIOContext *s, unsigned int val);
402 void avio_wb16(AVIOContext *s, unsigned int val);
403
404 /**
405 * Write a NULL-terminated string.
406 * @return number of bytes written.
407 */
408 int avio_put_str(AVIOContext *s, const char *str);
409
410 /**
411 * Convert an UTF-8 string to UTF-16LE and write it.
412 * @return number of bytes written.
413 */
414 int avio_put_str16le(AVIOContext *s, const char *str);
415
416 /**
417 * Passing this as the "whence" parameter to a seek function causes it to
418 * return the filesize without seeking anywhere. Supporting this is optional.
419 * If it is not supported then the seek function will return <0.
420 */
421 #define AVSEEK_SIZE 0x10000
422
423 /**
424 * Oring this flag as into the "whence" parameter to a seek function causes it to
425 * seek by any means (like reopening and linear reading) or other normally unreasonble
426 * means that can be extreemly slow.
427 * This may be ignored by the seek code.
428 */
429 #define AVSEEK_FORCE 0x20000
430
431 /**
432 * fseek() equivalent for AVIOContext.
433 * @return new position or AVERROR.
434 */
435 int64_t avio_seek(AVIOContext *s, int64_t offset, int whence);
436
437 /**
438 * Skip given number of bytes forward
439 * @return new position or AVERROR.
440 */
441 static av_always_inline int64_t avio_skip(AVIOContext *s, int64_t offset)
442 {
443 return avio_seek(s, offset, SEEK_CUR);
444 }
445
446 /**
447 * ftell() equivalent for AVIOContext.
448 * @return position or AVERROR.
449 */
450 static av_always_inline int64_t avio_tell(AVIOContext *s)
451 {
452 return avio_seek(s, 0, SEEK_CUR);
453 }
454
455 /**
456 * Get the filesize.
457 * @return filesize or AVERROR
458 */
459 int64_t avio_size(AVIOContext *s);
460
461 /** @warning currently size is limited */
462 int avio_printf(AVIOContext *s, const char *fmt, ...) av_printf_format(2, 3);
463
464 void avio_flush(AVIOContext *s);
465
466
467 /**
468 * Read size bytes from AVIOContext into buf.
469 * @return number of bytes read or AVERROR
470 */
471 int avio_read(AVIOContext *s, unsigned char *buf, int size);
472
473 /**
474 * @name Functions for reading from AVIOContext
475 * @{
476 *
477 * @note return 0 if EOF, so you cannot use it if EOF handling is
478 * necessary
479 */
480 int avio_r8 (AVIOContext *s);
481 unsigned int avio_rl16(AVIOContext *s);
482 unsigned int avio_rl24(AVIOContext *s);
483 unsigned int avio_rl32(AVIOContext *s);
484 uint64_t avio_rl64(AVIOContext *s);
485 unsigned int avio_rb16(AVIOContext *s);
486 unsigned int avio_rb24(AVIOContext *s);
487 unsigned int avio_rb32(AVIOContext *s);
488 uint64_t avio_rb64(AVIOContext *s);
489 /**
490 * @}
491 */
492
493 /**
494 * Read a string from pb into buf. The reading will terminate when either
495 * a NULL character was encountered, maxlen bytes have been read, or nothing
496 * more can be read from pb. The result is guaranteed to be NULL-terminated, it
497 * will be truncated if buf is too small.
498 * Note that the string is not interpreted or validated in any way, it
499 * might get truncated in the middle of a sequence for multi-byte encodings.
500 *
501 * @return number of bytes read (is always <= maxlen).
502 * If reading ends on EOF or error, the return value will be one more than
503 * bytes actually read.
504 */
505 int avio_get_str(AVIOContext *pb, int maxlen, char *buf, int buflen);
506
507 /**
508 * Read a UTF-16 string from pb and convert it to UTF-8.
509 * The reading will terminate when either a null or invalid character was
510 * encountered or maxlen bytes have been read.
511 * @return number of bytes read (is always <= maxlen)
512 */
513 int avio_get_str16le(AVIOContext *pb, int maxlen, char *buf, int buflen);
514 int avio_get_str16be(AVIOContext *pb, int maxlen, char *buf, int buflen);
515
516
517 /**
518 * @name URL open modes
519 * The flags argument to avio_open must be one of the following
520 * constants, optionally ORed with other flags.
521 * @{
522 */
523 #define AVIO_FLAG_READ 1 /**< read-only */
524 #define AVIO_FLAG_WRITE 2 /**< write-only */
525 #define AVIO_FLAG_READ_WRITE (AVIO_FLAG_READ|AVIO_FLAG_WRITE) /**< read-write pseudo flag */
526 /**
527 * @}
528 */
529
530 /**
531 * Use non-blocking mode.
532 * If this flag is set, operations on the context will return
533 * AVERROR(EAGAIN) if they can not be performed immediately.
534 * If this flag is not set, operations on the context will never return
535 * AVERROR(EAGAIN).
536 * Note that this flag does not affect the opening/connecting of the
537 * context. Connecting a protocol will always block if necessary (e.g. on
538 * network protocols) but never hang (e.g. on busy devices).
539 * Warning: non-blocking protocols is work-in-progress; this flag may be
540 * silently ignored.
541 */
542 #define AVIO_FLAG_NONBLOCK 8
543
544 /**
545 * Create and initialize a AVIOContext for accessing the
546 * resource indicated by url.
547 * @note When the resource indicated by url has been opened in
548 * read+write mode, the AVIOContext can be used only for writing.
549 *
550 * @param s Used to return the pointer to the created AVIOContext.
551 * In case of failure the pointed to value is set to NULL.
552 * @param flags flags which control how the resource indicated by url
553 * is to be opened
554 * @return 0 in case of success, a negative value corresponding to an
555 * AVERROR code in case of failure
556 */
557 int avio_open(AVIOContext **s, const char *url, int flags);
558
559 /**
560 * Close the resource accessed by the AVIOContext s and free it.
561 * This function can only be used if s was opened by avio_open().
562 *
563 * @return 0 on success, an AVERROR < 0 on error.
564 */
565 int avio_close(AVIOContext *s);
566
567 /**
568 * Open a write only memory stream.
569 *
570 * @param s new IO context
571 * @return zero if no error.
572 */
573 int avio_open_dyn_buf(AVIOContext **s);
574
575 /**
576 * Return the written size and a pointer to the buffer. The buffer
577 * must be freed with av_free().
578 * Padding of FF_INPUT_BUFFER_PADDING_SIZE is added to the buffer.
579 *
580 * @param s IO context
581 * @param pbuffer pointer to a byte buffer
582 * @return the length of the byte buffer
583 */
584 int avio_close_dyn_buf(AVIOContext *s, uint8_t **pbuffer);
585
586 /**
587 * Iterate through names of available protocols.
588 *
589 * @param opaque A private pointer representing current protocol.
590 * It must be a pointer to NULL on first iteration and will
591 * be updated by successive calls to avio_enum_protocols.
592 * @param output If set to 1, iterate over output protocols,
593 * otherwise over input protocols.
594 *
595 * @return A static string containing the name of current protocol or NULL
596 */
597 const char *avio_enum_protocols(void **opaque, int output);
598
599 /**
600 * Pause and resume playing - only meaningful if using a network streaming
601 * protocol (e.g. MMS).
602 * @param pause 1 for pause, 0 for resume
603 */
604 int avio_pause(AVIOContext *h, int pause);
605
606 /**
607 * Seek to a given timestamp relative to some component stream.
608 * Only meaningful if using a network streaming protocol (e.g. MMS.).
609 * @param stream_index The stream index that the timestamp is relative to.
610 * If stream_index is (-1) the timestamp should be in AV_TIME_BASE
611 * units from the beginning of the presentation.
612 * If a stream_index >= 0 is used and the protocol does not support
613 * seeking based on component streams, the call will fail with ENOTSUP.
614 * @param timestamp timestamp in AVStream.time_base units
615 * or if there is no stream specified then in AV_TIME_BASE units.
616 * @param flags Optional combination of AVSEEK_FLAG_BACKWARD, AVSEEK_FLAG_BYTE
617 * and AVSEEK_FLAG_ANY. The protocol may silently ignore
618 * AVSEEK_FLAG_BACKWARD and AVSEEK_FLAG_ANY, but AVSEEK_FLAG_BYTE will
619 * fail with ENOTSUP if used and not supported.
620 * @return >= 0 on success
621 * @see AVInputFormat::read_seek
622 */
623 int64_t avio_seek_time(AVIOContext *h, int stream_index,
624 int64_t timestamp, int flags);
625
626 #endif /* AVFORMAT_AVIO_H */