Document url_seek().
[libav.git] / libavformat / avio.h
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 libavformat/avio.h
25 * unbuffered I/O operations
26 *
27 * @warning This file has to be considered an internal but installed
28 * header, so it should not be directly included in your projects.
29 */
30
31 #include <stdint.h>
32
33 #include "libavutil/common.h"
34
35 /* unbuffered I/O */
36
37 /**
38 * URL Context.
39 * New fields can be added to the end with minor version bumps.
40 * Removal, reordering and changes to existing fields require a major
41 * version bump.
42 * sizeof(URLContext) must not be used outside libav*.
43 */
44 typedef struct URLContext {
45 #if LIBAVFORMAT_VERSION_MAJOR >= 53
46 const AVClass *av_class; ///< information for av_log(). Set by url_open().
47 #endif
48 struct URLProtocol *prot;
49 int flags;
50 int is_streamed; /**< true if streamed (no seek possible), default = false */
51 int max_packet_size; /**< if non zero, the stream is packetized with this max packet size */
52 void *priv_data;
53 char *filename; /**< specified URL */
54 } URLContext;
55
56 typedef struct URLPollEntry {
57 URLContext *handle;
58 int events;
59 int revents;
60 } URLPollEntry;
61
62 #define URL_RDONLY 0
63 #define URL_WRONLY 1
64 #define URL_RDWR 2
65
66 typedef int URLInterruptCB(void);
67
68 /**
69 * Creates an URLContext for accessing to the resource indicated by
70 * url, and opens it using the URLProtocol up.
71 *
72 * @param puc pointer to the location where, in case of success, the
73 * function puts the pointer to the created URLContext
74 * @param flags flags which control how the resource indicated by url
75 * is to be opened
76 * @return 0 in case of success, a negative value corresponding to an
77 * AVERROR code in case of failure
78 */
79 int url_open_protocol (URLContext **puc, struct URLProtocol *up,
80 const char *url, int flags);
81
82 /**
83 * Creates an URLContext for accessing to the resource indicated by
84 * url, and opens it.
85 *
86 * @param puc pointer to the location where, in case of success, the
87 * function puts the pointer to the created URLContext
88 * @param flags flags which control how the resource indicated by url
89 * is to be opened
90 * @return 0 in case of success, a negative value corresponding to an
91 * AVERROR code in case of failure
92 */
93 int url_open(URLContext **h, const char *url, int flags);
94
95 /**
96 * Reads up to size bytes from the resource accessed by h, and stores
97 * the read bytes in buf.
98 *
99 * @return The number of bytes actually read, or a negative value
100 * corresponding to an AVERROR code in case of error. A value of zero
101 * indicates that it is not possible to read more from the accessed
102 * resource (except if the value of the size argument is also zero).
103 */
104 int url_read(URLContext *h, unsigned char *buf, int size);
105
106 /**
107 * Read as many bytes as possible (up to size), calling the
108 * read function multiple times if necessary.
109 * Will also retry if the read function returns AVERROR(EAGAIN).
110 * This makes special short-read handling in applications
111 * unnecessary, if the return value is < size then it is
112 * certain there was either an error or the end of file was reached.
113 */
114 int url_read_complete(URLContext *h, unsigned char *buf, int size);
115 int url_write(URLContext *h, unsigned char *buf, int size);
116
117 /**
118 * Changes the position that will be used by the next read/write
119 * operation on the resource accessed by h.
120 *
121 * @param pos specifies the new position to set
122 * @param whence specifies how pos should be interpreted, it must be
123 * one of SEEK_SET (seek from the beginning), SEEK_CUR (seek from the
124 * current position), SEEK_END (seek from the end), or AVSEEK_SIZE
125 * (return the filesize of the requested resource, pos is ignored).
126 * @return a negative value corresponding to an AVERROR code in case
127 * of failure, or the resulting file position, measured in bytes from
128 * the beginning of the file. You can use this feature together with
129 * SEEK_CUR to read the current file position.
130 */
131 int64_t url_seek(URLContext *h, int64_t pos, int whence);
132
133 /**
134 * Closes the resource accessed by the URLContext h, and frees the
135 * memory used by it.
136 *
137 * @return a negative value if an error condition occurred, 0
138 * otherwise
139 */
140 int url_close(URLContext *h);
141
142 int url_exist(const char *url);
143 int64_t url_filesize(URLContext *h);
144
145 /**
146 * Return the file descriptor associated with this URL. For RTP, this
147 * will return only the RTP file descriptor, not the RTCP file descriptor.
148 * To get both, use rtp_get_file_handles().
149 *
150 * @return the file descriptor associated with this URL, or <0 on error.
151 */
152 int url_get_file_handle(URLContext *h);
153
154 /**
155 * Return the maximum packet size associated to packetized file
156 * handle. If the file is not packetized (stream like HTTP or file on
157 * disk), then 0 is returned.
158 *
159 * @param h file handle
160 * @return maximum packet size in bytes
161 */
162 int url_get_max_packet_size(URLContext *h);
163 void url_get_filename(URLContext *h, char *buf, int buf_size);
164
165 /**
166 * The callback is called in blocking functions to test regulary if
167 * asynchronous interruption is needed. AVERROR(EINTR) is returned
168 * in this case by the interrupted function. 'NULL' means no interrupt
169 * callback is given.
170 */
171 void url_set_interrupt_cb(URLInterruptCB *interrupt_cb);
172
173 /* not implemented */
174 int url_poll(URLPollEntry *poll_table, int n, int timeout);
175
176 /**
177 * Pause and resume playing - only meaningful if using a network streaming
178 * protocol (e.g. MMS).
179 * @param pause 1 for pause, 0 for resume
180 */
181 int av_url_read_pause(URLContext *h, int pause);
182
183 /**
184 * Seek to a given timestamp relative to some component stream.
185 * Only meaningful if using a network streaming protocol (e.g. MMS.).
186 * @param stream_index The stream index that the timestamp is relative to.
187 * If stream_index is (-1) the timestamp should be in AV_TIME_BASE
188 * units from the beginning of the presentation.
189 * If a stream_index >= 0 is used and the protocol does not support
190 * seeking based on component streams, the call will fail with ENOTSUP.
191 * @param timestamp timestamp in AVStream.time_base units
192 * or if there is no stream specified then in AV_TIME_BASE units.
193 * @param flags Optional combination of AVSEEK_FLAG_BACKWARD, AVSEEK_FLAG_BYTE
194 * and AVSEEK_FLAG_ANY. The protocol may silently ignore
195 * AVSEEK_FLAG_BACKWARD and AVSEEK_FLAG_ANY, but AVSEEK_FLAG_BYTE will
196 * fail with ENOTSUP if used and not supported.
197 * @return >= 0 on success
198 * @see AVInputFormat::read_seek
199 */
200 int64_t av_url_read_seek(URLContext *h, int stream_index,
201 int64_t timestamp, int flags);
202
203 /**
204 * Passing this as the "whence" parameter to a seek function causes it to
205 * return the filesize without seeking anywhere. Supporting this is optional.
206 * If it is not supported then the seek function will return <0.
207 */
208 #define AVSEEK_SIZE 0x10000
209
210 /**
211 * Oring this flag as into the "whence" parameter to a seek function causes it to
212 * seek by any means (like reopening and linear reading) or other normally unreasonble
213 * means that can be extreemly slow.
214 * This may be ignored by the seek code.
215 */
216 #define AVSEEK_FORCE 0x20000
217
218 typedef struct URLProtocol {
219 const char *name;
220 int (*url_open)(URLContext *h, const char *url, int flags);
221 int (*url_read)(URLContext *h, unsigned char *buf, int size);
222 int (*url_write)(URLContext *h, unsigned char *buf, int size);
223 int64_t (*url_seek)(URLContext *h, int64_t pos, int whence);
224 int (*url_close)(URLContext *h);
225 struct URLProtocol *next;
226 int (*url_read_pause)(URLContext *h, int pause);
227 int64_t (*url_read_seek)(URLContext *h, int stream_index,
228 int64_t timestamp, int flags);
229 int (*url_get_file_handle)(URLContext *h);
230 } URLProtocol;
231
232 #if LIBAVFORMAT_VERSION_MAJOR < 53
233 extern URLProtocol *first_protocol;
234 #endif
235
236 extern URLInterruptCB *url_interrupt_cb;
237
238 /**
239 * If protocol is NULL, returns the first registered protocol,
240 * if protocol is non-NULL, returns the next registered protocol after protocol,
241 * or NULL if protocol is the last one.
242 */
243 URLProtocol *av_protocol_next(URLProtocol *p);
244
245 #if LIBAVFORMAT_VERSION_MAJOR < 53
246 /**
247 * @deprecated Use av_register_protocol() instead.
248 */
249 attribute_deprecated int register_protocol(URLProtocol *protocol);
250 #endif
251
252 /**
253 * Registers the URLProtocol protocol.
254 */
255 int av_register_protocol(URLProtocol *protocol);
256
257 /**
258 * Bytestream IO Context.
259 * New fields can be added to the end with minor version bumps.
260 * Removal, reordering and changes to existing fields require a major
261 * version bump.
262 * sizeof(ByteIOContext) must not be used outside libav*.
263 */
264 typedef struct {
265 unsigned char *buffer;
266 int buffer_size;
267 unsigned char *buf_ptr, *buf_end;
268 void *opaque;
269 int (*read_packet)(void *opaque, uint8_t *buf, int buf_size);
270 int (*write_packet)(void *opaque, uint8_t *buf, int buf_size);
271 int64_t (*seek)(void *opaque, int64_t offset, int whence);
272 int64_t pos; /**< position in the file of the current buffer */
273 int must_flush; /**< true if the next seek should flush */
274 int eof_reached; /**< true if eof reached */
275 int write_flag; /**< true if open for writing */
276 int is_streamed;
277 int max_packet_size;
278 unsigned long checksum;
279 unsigned char *checksum_ptr;
280 unsigned long (*update_checksum)(unsigned long checksum, const uint8_t *buf, unsigned int size);
281 int error; ///< contains the error code or 0 if no error happened
282 int (*read_pause)(void *opaque, int pause);
283 int64_t (*read_seek)(void *opaque, int stream_index,
284 int64_t timestamp, int flags);
285 } ByteIOContext;
286
287 int init_put_byte(ByteIOContext *s,
288 unsigned char *buffer,
289 int buffer_size,
290 int write_flag,
291 void *opaque,
292 int (*read_packet)(void *opaque, uint8_t *buf, int buf_size),
293 int (*write_packet)(void *opaque, uint8_t *buf, int buf_size),
294 int64_t (*seek)(void *opaque, int64_t offset, int whence));
295 ByteIOContext *av_alloc_put_byte(
296 unsigned char *buffer,
297 int buffer_size,
298 int write_flag,
299 void *opaque,
300 int (*read_packet)(void *opaque, uint8_t *buf, int buf_size),
301 int (*write_packet)(void *opaque, uint8_t *buf, int buf_size),
302 int64_t (*seek)(void *opaque, int64_t offset, int whence));
303
304 void put_byte(ByteIOContext *s, int b);
305 void put_buffer(ByteIOContext *s, const unsigned char *buf, int size);
306 void put_le64(ByteIOContext *s, uint64_t val);
307 void put_be64(ByteIOContext *s, uint64_t val);
308 void put_le32(ByteIOContext *s, unsigned int val);
309 void put_be32(ByteIOContext *s, unsigned int val);
310 void put_le24(ByteIOContext *s, unsigned int val);
311 void put_be24(ByteIOContext *s, unsigned int val);
312 void put_le16(ByteIOContext *s, unsigned int val);
313 void put_be16(ByteIOContext *s, unsigned int val);
314 void put_tag(ByteIOContext *s, const char *tag);
315
316 void put_strz(ByteIOContext *s, const char *buf);
317
318 /**
319 * fseek() equivalent for ByteIOContext.
320 * @return new position or AVERROR.
321 */
322 int64_t url_fseek(ByteIOContext *s, int64_t offset, int whence);
323
324 /**
325 * Skip given number of bytes forward.
326 * @param offset number of bytes
327 */
328 void url_fskip(ByteIOContext *s, int64_t offset);
329
330 /**
331 * ftell() equivalent for ByteIOContext.
332 * @return position or AVERROR.
333 */
334 int64_t url_ftell(ByteIOContext *s);
335
336 /**
337 * Gets the filesize.
338 * @return filesize or AVERROR
339 */
340 int64_t url_fsize(ByteIOContext *s);
341
342 /**
343 * feof() equivalent for ByteIOContext.
344 * @return non zero if and only if end of file
345 */
346 int url_feof(ByteIOContext *s);
347
348 int url_ferror(ByteIOContext *s);
349
350 int av_url_read_fpause(ByteIOContext *h, int pause);
351 int64_t av_url_read_fseek(ByteIOContext *h, int stream_index,
352 int64_t timestamp, int flags);
353
354 #define URL_EOF (-1)
355 /** @note return URL_EOF (-1) if EOF */
356 int url_fgetc(ByteIOContext *s);
357
358 /** @warning currently size is limited */
359 #ifdef __GNUC__
360 int url_fprintf(ByteIOContext *s, const char *fmt, ...) __attribute__ ((__format__ (__printf__, 2, 3)));
361 #else
362 int url_fprintf(ByteIOContext *s, const char *fmt, ...);
363 #endif
364
365 /** @note unlike fgets, the EOL character is not returned and a whole
366 line is parsed. return NULL if first char read was EOF */
367 char *url_fgets(ByteIOContext *s, char *buf, int buf_size);
368
369 void put_flush_packet(ByteIOContext *s);
370
371
372 /**
373 * Reads size bytes from ByteIOContext into buf.
374 * @returns number of bytes read or AVERROR
375 */
376 int get_buffer(ByteIOContext *s, unsigned char *buf, int size);
377
378 /**
379 * Reads size bytes from ByteIOContext into buf.
380 * This reads at most 1 packet. If that is not enough fewer bytes will be
381 * returned.
382 * @returns number of bytes read or AVERROR
383 */
384 int get_partial_buffer(ByteIOContext *s, unsigned char *buf, int size);
385
386 /** @note return 0 if EOF, so you cannot use it if EOF handling is
387 necessary */
388 int get_byte(ByteIOContext *s);
389 unsigned int get_le24(ByteIOContext *s);
390 unsigned int get_le32(ByteIOContext *s);
391 uint64_t get_le64(ByteIOContext *s);
392 unsigned int get_le16(ByteIOContext *s);
393
394 char *get_strz(ByteIOContext *s, char *buf, int maxlen);
395 unsigned int get_be16(ByteIOContext *s);
396 unsigned int get_be24(ByteIOContext *s);
397 unsigned int get_be32(ByteIOContext *s);
398 uint64_t get_be64(ByteIOContext *s);
399
400 uint64_t ff_get_v(ByteIOContext *bc);
401
402 static inline int url_is_streamed(ByteIOContext *s)
403 {
404 return s->is_streamed;
405 }
406
407 /**
408 * Creates and initializes a ByteIOContext for accessing the
409 * resource referenced by the URLContext h.
410 * @note When the URLContext h has been opened in read+write mode, the
411 * ByteIOContext can be used only for writing.
412 *
413 * @param s Used to return the pointer to the created ByteIOContext.
414 * In case of failure the pointed to value is set to NULL.
415 * @return 0 in case of success, a negative value corresponding to an
416 * AVERROR code in case of failure
417 */
418 int url_fdopen(ByteIOContext **s, URLContext *h);
419
420 /** @warning must be called before any I/O */
421 int url_setbufsize(ByteIOContext *s, int buf_size);
422 #if LIBAVFORMAT_VERSION_MAJOR < 53
423 /** Reset the buffer for reading or writing.
424 * @note Will drop any data currently in the buffer without transmitting it.
425 * @param flags URL_RDONLY to set up the buffer for reading, or URL_WRONLY
426 * to set up the buffer for writing. */
427 int url_resetbuf(ByteIOContext *s, int flags);
428 #endif
429
430 /**
431 * Creates and initializes a ByteIOContext for accessing the
432 * resource indicated by url.
433 * @note When the resource indicated by url has been opened in
434 * read+write mode, the ByteIOContext can be used only for writing.
435 *
436 * @param s Used to return the pointer to the created ByteIOContext.
437 * In case of failure the pointed to value is set to NULL.
438 * @param flags flags which control how the resource indicated by url
439 * is to be opened
440 * @return 0 in case of success, a negative value corresponding to an
441 * AVERROR code in case of failure
442 */
443 int url_fopen(ByteIOContext **s, const char *url, int flags);
444
445 int url_fclose(ByteIOContext *s);
446 URLContext *url_fileno(ByteIOContext *s);
447
448 /**
449 * Return the maximum packet size associated to packetized buffered file
450 * handle. If the file is not packetized (stream like http or file on
451 * disk), then 0 is returned.
452 *
453 * @param s buffered file handle
454 * @return maximum packet size in bytes
455 */
456 int url_fget_max_packet_size(ByteIOContext *s);
457
458 int url_open_buf(ByteIOContext **s, uint8_t *buf, int buf_size, int flags);
459
460 /** return the written or read size */
461 int url_close_buf(ByteIOContext *s);
462
463 /**
464 * Open a write only memory stream.
465 *
466 * @param s new IO context
467 * @return zero if no error.
468 */
469 int url_open_dyn_buf(ByteIOContext **s);
470
471 /**
472 * Open a write only packetized memory stream with a maximum packet
473 * size of 'max_packet_size'. The stream is stored in a memory buffer
474 * with a big endian 4 byte header giving the packet size in bytes.
475 *
476 * @param s new IO context
477 * @param max_packet_size maximum packet size (must be > 0)
478 * @return zero if no error.
479 */
480 int url_open_dyn_packet_buf(ByteIOContext **s, int max_packet_size);
481
482 /**
483 * Return the written size and a pointer to the buffer. The buffer
484 * must be freed with av_free().
485 * @param s IO context
486 * @param pbuffer pointer to a byte buffer
487 * @return the length of the byte buffer
488 */
489 int url_close_dyn_buf(ByteIOContext *s, uint8_t **pbuffer);
490
491 unsigned long ff_crc04C11DB7_update(unsigned long checksum, const uint8_t *buf,
492 unsigned int len);
493 unsigned long get_checksum(ByteIOContext *s);
494 void init_checksum(ByteIOContext *s,
495 unsigned long (*update_checksum)(unsigned long c, const uint8_t *p, unsigned int len),
496 unsigned long checksum);
497
498 /* udp.c */
499 int udp_set_remote_url(URLContext *h, const char *uri);
500 int udp_get_local_port(URLContext *h);
501 #if (LIBAVFORMAT_VERSION_MAJOR <= 52)
502 int udp_get_file_handle(URLContext *h);
503 #endif
504
505 #endif /* AVFORMAT_AVIO_H */