2 * copyright (c) 2001 Fabrice Bellard
4 * This file is part of FFmpeg.
6 * FFmpeg is free software; you can redistribute it and/or
7 * modify it under the terms of the GNU Lesser General Public
8 * License as published by the Free Software Foundation; either
9 * version 2.1 of the License, or (at your option) any later version.
11 * FFmpeg is distributed in the hope that it will be useful,
12 * but WITHOUT ANY WARRANTY; without even the implied warranty of
13 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
14 * Lesser General Public License for more details.
16 * You should have received a copy of the GNU Lesser General Public
17 * License along with FFmpeg; if not, write to the Free Software
18 * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
20 #ifndef AVFORMAT_AVIO_H
21 #define AVFORMAT_AVIO_H
26 * Buffered I/O operations
31 #include "libavutil/common.h"
32 #include "libavutil/dict.h"
33 #include "libavutil/log.h"
35 #include "libavformat/version.h"
38 #define AVIO_SEEKABLE_NORMAL 0x0001 /**< Seeking works like for a local file */
41 * Callback for checking whether to abort blocking functions.
42 * AVERROR_EXIT is returned in this case by the interrupted
43 * function. During blocking operations, callback is called with
44 * opaque as parameter. If the callback returns 1, the
45 * blocking operation will be aborted.
47 * No members can be added to this struct without a major bump, if
48 * new elements have been added after this struct in AVFormatContext
51 typedef struct AVIOInterruptCB {
52 int (*callback)(void*);
57 * Bytestream IO Context.
58 * New fields can be added to the end with minor version bumps.
59 * Removal, reordering and changes to existing fields require a major
61 * sizeof(AVIOContext) must not be used outside libav*.
63 * @note None of the function pointers in AVIOContext should be called
64 * directly, they should only be set by the client application
65 * when implementing custom I/O. Normally these are set to the
66 * function pointers specified in avio_alloc_context()
68 typedef struct AVIOContext {
70 * A class for private options.
72 * If this AVIOContext is created by avio_open2(), av_class is set and
73 * passes the options down to protocols.
75 * If this AVIOContext is manually allocated, then av_class may be set by
78 * warning -- this field can be NULL, be sure to not pass this AVIOContext
79 * to any av_opt_* functions in that case.
81 const AVClass *av_class;
82 unsigned char *buffer; /**< Start of the buffer. */
83 int buffer_size; /**< Maximum buffer size */
84 unsigned char *buf_ptr; /**< Current position in the buffer */
85 unsigned char *buf_end; /**< End of the data, may be less than
86 buffer+buffer_size if the read function returned
87 less data than requested, e.g. for streams where
88 no more data has been received yet. */
89 void *opaque; /**< A private pointer, passed to the read/write/seek/...
91 int (*read_packet)(void *opaque, uint8_t *buf, int buf_size);
92 int (*write_packet)(void *opaque, uint8_t *buf, int buf_size);
93 int64_t (*seek)(void *opaque, int64_t offset, int whence);
94 int64_t pos; /**< position in the file of the current buffer */
95 int must_flush; /**< true if the next seek should flush */
96 int eof_reached; /**< true if eof reached */
97 int write_flag; /**< true if open for writing */
99 unsigned long checksum;
100 unsigned char *checksum_ptr;
101 unsigned long (*update_checksum)(unsigned long checksum, const uint8_t *buf, unsigned int size);
102 int error; /**< contains the error code or 0 if no error happened */
104 * Pause or resume playback for network streaming protocols - e.g. MMS.
106 int (*read_pause)(void *opaque, int pause);
108 * Seek to a given timestamp in stream with the specified stream_index.
109 * Needed for some network streaming protocols which don't support seeking
112 int64_t (*read_seek)(void *opaque, int stream_index,
113 int64_t timestamp, int flags);
115 * A combination of AVIO_SEEKABLE_ flags or 0 when the stream is not seekable.
120 * max filesize, used to limit allocations
121 * This field is internal to libavformat and access from outside is not allowed.
126 * avio_read and avio_write should if possible be satisfied directly
127 * instead of going through a buffer, and avio_seek will always
128 * call the underlying seek function directly.
133 * Bytes read statistic
134 * This field is internal to libavformat and access from outside is not allowed.
140 * This field is internal to libavformat and access from outside is not allowed.
146 * This field is internal to libavformat and access from outside is not allowed.
151 * Original buffer size
152 * used internally after probing and ensure seekback to reset the buffer size
153 * This field is internal to libavformat and access from outside is not allowed.
155 int orig_buffer_size;
161 * Return the name of the protocol that will handle the passed URL.
163 * NULL is returned if no protocol could be found for the given URL.
165 * @return Name of the protocol or NULL.
167 const char *avio_find_protocol_name(const char *url);
170 * Return AVIO_FLAG_* access flags corresponding to the access permissions
171 * of the resource in url, or a negative value corresponding to an
172 * AVERROR code in case of failure. The returned access flags are
173 * masked by the value in flags.
175 * @note This function is intrinsically unsafe, in the sense that the
176 * checked resource may change its existence or permission status from
177 * one call to another. Thus you should not trust the returned value,
178 * unless you are sure that no other processes are accessing the
181 int avio_check(const char *url, int flags);
184 * Allocate and initialize an AVIOContext for buffered I/O. It must be later
185 * freed with av_free().
187 * @param buffer Memory block for input/output operations via AVIOContext.
188 * The buffer must be allocated with av_malloc() and friends.
189 * @param buffer_size The buffer size is very important for performance.
190 * For protocols with fixed blocksize it should be set to this blocksize.
191 * For others a typical size is a cache page, e.g. 4kb.
192 * @param write_flag Set to 1 if the buffer should be writable, 0 otherwise.
193 * @param opaque An opaque pointer to user-specific data.
194 * @param read_packet A function for refilling the buffer, may be NULL.
195 * @param write_packet A function for writing the buffer contents, may be NULL.
196 * The function may not change the input buffers content.
197 * @param seek A function for seeking to specified byte position, may be NULL.
199 * @return Allocated AVIOContext or NULL on failure.
201 AVIOContext *avio_alloc_context(
202 unsigned char *buffer,
206 int (*read_packet)(void *opaque, uint8_t *buf, int buf_size),
207 int (*write_packet)(void *opaque, uint8_t *buf, int buf_size),
208 int64_t (*seek)(void *opaque, int64_t offset, int whence));
210 void avio_w8(AVIOContext *s, int b);
211 void avio_write(AVIOContext *s, const unsigned char *buf, int size);
212 void avio_wl64(AVIOContext *s, uint64_t val);
213 void avio_wb64(AVIOContext *s, uint64_t val);
214 void avio_wl32(AVIOContext *s, unsigned int val);
215 void avio_wb32(AVIOContext *s, unsigned int val);
216 void avio_wl24(AVIOContext *s, unsigned int val);
217 void avio_wb24(AVIOContext *s, unsigned int val);
218 void avio_wl16(AVIOContext *s, unsigned int val);
219 void avio_wb16(AVIOContext *s, unsigned int val);
222 * Write a NULL-terminated string.
223 * @return number of bytes written.
225 int avio_put_str(AVIOContext *s, const char *str);
228 * Convert an UTF-8 string to UTF-16LE and write it.
229 * @return number of bytes written.
231 int avio_put_str16le(AVIOContext *s, const char *str);
234 * Passing this as the "whence" parameter to a seek function causes it to
235 * return the filesize without seeking anywhere. Supporting this is optional.
236 * If it is not supported then the seek function will return <0.
238 #define AVSEEK_SIZE 0x10000
241 * Oring this flag as into the "whence" parameter to a seek function causes it to
242 * seek by any means (like reopening and linear reading) or other normally unreasonable
243 * means that can be extremely slow.
244 * This may be ignored by the seek code.
246 #define AVSEEK_FORCE 0x20000
249 * fseek() equivalent for AVIOContext.
250 * @return new position or AVERROR.
252 int64_t avio_seek(AVIOContext *s, int64_t offset, int whence);
255 * Skip given number of bytes forward
256 * @return new position or AVERROR.
258 int64_t avio_skip(AVIOContext *s, int64_t offset);
261 * ftell() equivalent for AVIOContext.
262 * @return position or AVERROR.
264 static av_always_inline int64_t avio_tell(AVIOContext *s)
266 return avio_seek(s, 0, SEEK_CUR);
271 * @return filesize or AVERROR
273 int64_t avio_size(AVIOContext *s);
276 * feof() equivalent for AVIOContext.
277 * @return non zero if and only if end of file
279 int url_feof(AVIOContext *s);
281 /** @warning currently size is limited */
282 int avio_printf(AVIOContext *s, const char *fmt, ...) av_printf_format(2, 3);
285 * Force flushing of buffered data to the output s.
287 * Force the buffered data to be immediately written to the output,
288 * without to wait to fill the internal buffer.
290 void avio_flush(AVIOContext *s);
293 * Read size bytes from AVIOContext into buf.
294 * @return number of bytes read or AVERROR
296 int avio_read(AVIOContext *s, unsigned char *buf, int size);
299 * @name Functions for reading from AVIOContext
302 * @note return 0 if EOF, so you cannot use it if EOF handling is
305 int avio_r8 (AVIOContext *s);
306 unsigned int avio_rl16(AVIOContext *s);
307 unsigned int avio_rl24(AVIOContext *s);
308 unsigned int avio_rl32(AVIOContext *s);
309 uint64_t avio_rl64(AVIOContext *s);
310 unsigned int avio_rb16(AVIOContext *s);
311 unsigned int avio_rb24(AVIOContext *s);
312 unsigned int avio_rb32(AVIOContext *s);
313 uint64_t avio_rb64(AVIOContext *s);
319 * Read a string from pb into buf. The reading will terminate when either
320 * a NULL character was encountered, maxlen bytes have been read, or nothing
321 * more can be read from pb. The result is guaranteed to be NULL-terminated, it
322 * will be truncated if buf is too small.
323 * Note that the string is not interpreted or validated in any way, it
324 * might get truncated in the middle of a sequence for multi-byte encodings.
326 * @return number of bytes read (is always <= maxlen).
327 * If reading ends on EOF or error, the return value will be one more than
328 * bytes actually read.
330 int avio_get_str(AVIOContext *pb, int maxlen, char *buf, int buflen);
333 * Read a UTF-16 string from pb and convert it to UTF-8.
334 * The reading will terminate when either a null or invalid character was
335 * encountered or maxlen bytes have been read.
336 * @return number of bytes read (is always <= maxlen)
338 int avio_get_str16le(AVIOContext *pb, int maxlen, char *buf, int buflen);
339 int avio_get_str16be(AVIOContext *pb, int maxlen, char *buf, int buflen);
343 * @name URL open modes
344 * The flags argument to avio_open must be one of the following
345 * constants, optionally ORed with other flags.
348 #define AVIO_FLAG_READ 1 /**< read-only */
349 #define AVIO_FLAG_WRITE 2 /**< write-only */
350 #define AVIO_FLAG_READ_WRITE (AVIO_FLAG_READ|AVIO_FLAG_WRITE) /**< read-write pseudo flag */
356 * Use non-blocking mode.
357 * If this flag is set, operations on the context will return
358 * AVERROR(EAGAIN) if they can not be performed immediately.
359 * If this flag is not set, operations on the context will never return
361 * Note that this flag does not affect the opening/connecting of the
362 * context. Connecting a protocol will always block if necessary (e.g. on
363 * network protocols) but never hang (e.g. on busy devices).
364 * Warning: non-blocking protocols is work-in-progress; this flag may be
367 #define AVIO_FLAG_NONBLOCK 8
371 * avio_read and avio_write should if possible be satisfied directly
372 * instead of going through a buffer, and avio_seek will always
373 * call the underlying seek function directly.
375 #define AVIO_FLAG_DIRECT 0x8000
378 * Create and initialize a AVIOContext for accessing the
379 * resource indicated by url.
380 * @note When the resource indicated by url has been opened in
381 * read+write mode, the AVIOContext can be used only for writing.
383 * @param s Used to return the pointer to the created AVIOContext.
384 * In case of failure the pointed to value is set to NULL.
385 * @param url resource to access
386 * @param flags flags which control how the resource indicated by url
388 * @return >= 0 in case of success, a negative value corresponding to an
389 * AVERROR code in case of failure
391 int avio_open(AVIOContext **s, const char *url, int flags);
394 * Create and initialize a AVIOContext for accessing the
395 * resource indicated by url.
396 * @note When the resource indicated by url has been opened in
397 * read+write mode, the AVIOContext can be used only for writing.
399 * @param s Used to return the pointer to the created AVIOContext.
400 * In case of failure the pointed to value is set to NULL.
401 * @param url resource to access
402 * @param flags flags which control how the resource indicated by url
404 * @param int_cb an interrupt callback to be used at the protocols level
405 * @param options A dictionary filled with protocol-private options. On return
406 * this parameter will be destroyed and replaced with a dict containing options
407 * that were not found. May be NULL.
408 * @return >= 0 in case of success, a negative value corresponding to an
409 * AVERROR code in case of failure
411 int avio_open2(AVIOContext **s, const char *url, int flags,
412 const AVIOInterruptCB *int_cb, AVDictionary **options);
415 * Close the resource accessed by the AVIOContext s and free it.
416 * This function can only be used if s was opened by avio_open().
418 * The internal buffer is automatically flushed before closing the
421 * @return 0 on success, an AVERROR < 0 on error.
424 int avio_close(AVIOContext *s);
427 * Close the resource accessed by the AVIOContext *s, free it
428 * and set the pointer pointing to it to NULL.
429 * This function can only be used if s was opened by avio_open().
431 * The internal buffer is automatically flushed before closing the
434 * @return 0 on success, an AVERROR < 0 on error.
437 int avio_closep(AVIOContext **s);
441 * Open a write only memory stream.
443 * @param s new IO context
444 * @return zero if no error.
446 int avio_open_dyn_buf(AVIOContext **s);
449 * Return the written size and a pointer to the buffer. The buffer
450 * must be freed with av_free().
451 * Padding of FF_INPUT_BUFFER_PADDING_SIZE is added to the buffer.
453 * @param s IO context
454 * @param pbuffer pointer to a byte buffer
455 * @return the length of the byte buffer
457 int avio_close_dyn_buf(AVIOContext *s, uint8_t **pbuffer);
460 * Iterate through names of available protocols.
462 * @param opaque A private pointer representing current protocol.
463 * It must be a pointer to NULL on first iteration and will
464 * be updated by successive calls to avio_enum_protocols.
465 * @param output If set to 1, iterate over output protocols,
466 * otherwise over input protocols.
468 * @return A static string containing the name of current protocol or NULL
470 const char *avio_enum_protocols(void **opaque, int output);
473 * Pause and resume playing - only meaningful if using a network streaming
474 * protocol (e.g. MMS).
476 * @param h IO context from which to call the read_pause function pointer
477 * @param pause 1 for pause, 0 for resume
479 int avio_pause(AVIOContext *h, int pause);
482 * Seek to a given timestamp relative to some component stream.
483 * Only meaningful if using a network streaming protocol (e.g. MMS.).
485 * @param h IO context from which to call the seek function pointers
486 * @param stream_index The stream index that the timestamp is relative to.
487 * If stream_index is (-1) the timestamp should be in AV_TIME_BASE
488 * units from the beginning of the presentation.
489 * If a stream_index >= 0 is used and the protocol does not support
490 * seeking based on component streams, the call will fail.
491 * @param timestamp timestamp in AVStream.time_base units
492 * or if there is no stream specified then in AV_TIME_BASE units.
493 * @param flags Optional combination of AVSEEK_FLAG_BACKWARD, AVSEEK_FLAG_BYTE
494 * and AVSEEK_FLAG_ANY. The protocol may silently ignore
495 * AVSEEK_FLAG_BACKWARD and AVSEEK_FLAG_ANY, but AVSEEK_FLAG_BYTE will
496 * fail if used and not supported.
497 * @return >= 0 on success
498 * @see AVInputFormat::read_seek
500 int64_t avio_seek_time(AVIOContext *h, int stream_index,
501 int64_t timestamp, int flags);
503 #endif /* AVFORMAT_AVIO_H */