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 * It may be freed and replaced with a new buffer by libavformat.
190 * AVIOContext.buffer holds the buffer currently in use,
191 * which must be later freed with av_free().
192 * @param buffer_size The buffer size is very important for performance.
193 * For protocols with fixed blocksize it should be set to this blocksize.
194 * For others a typical size is a cache page, e.g. 4kb.
195 * @param write_flag Set to 1 if the buffer should be writable, 0 otherwise.
196 * @param opaque An opaque pointer to user-specific data.
197 * @param read_packet A function for refilling the buffer, may be NULL.
198 * @param write_packet A function for writing the buffer contents, may be NULL.
199 * The function may not change the input buffers content.
200 * @param seek A function for seeking to specified byte position, may be NULL.
202 * @return Allocated AVIOContext or NULL on failure.
204 AVIOContext
*avio_alloc_context(
205 unsigned char *buffer
,
209 int (*read_packet
)(void *opaque
, uint8_t *buf
, int buf_size
),
210 int (*write_packet
)(void *opaque
, uint8_t *buf
, int buf_size
),
211 int64_t (*seek
)(void *opaque
, int64_t offset
, int whence
));
213 void avio_w8(AVIOContext
*s
, int b
);
214 void avio_write(AVIOContext
*s
, const unsigned char *buf
, int size
);
215 void avio_wl64(AVIOContext
*s
, uint64_t val
);
216 void avio_wb64(AVIOContext
*s
, uint64_t val
);
217 void avio_wl32(AVIOContext
*s
, unsigned int val
);
218 void avio_wb32(AVIOContext
*s
, unsigned int val
);
219 void avio_wl24(AVIOContext
*s
, unsigned int val
);
220 void avio_wb24(AVIOContext
*s
, unsigned int val
);
221 void avio_wl16(AVIOContext
*s
, unsigned int val
);
222 void avio_wb16(AVIOContext
*s
, unsigned int val
);
225 * Write a NULL-terminated string.
226 * @return number of bytes written.
228 int avio_put_str(AVIOContext
*s
, const char *str
);
231 * Convert an UTF-8 string to UTF-16LE and write it.
232 * @return number of bytes written.
234 int avio_put_str16le(AVIOContext
*s
, const char *str
);
237 * Passing this as the "whence" parameter to a seek function causes it to
238 * return the filesize without seeking anywhere. Supporting this is optional.
239 * If it is not supported then the seek function will return <0.
241 #define AVSEEK_SIZE 0x10000
244 * Oring this flag as into the "whence" parameter to a seek function causes it to
245 * seek by any means (like reopening and linear reading) or other normally unreasonable
246 * means that can be extremely slow.
247 * This may be ignored by the seek code.
249 #define AVSEEK_FORCE 0x20000
252 * fseek() equivalent for AVIOContext.
253 * @return new position or AVERROR.
255 int64_t avio_seek(AVIOContext
*s
, int64_t offset
, int whence
);
258 * Skip given number of bytes forward
259 * @return new position or AVERROR.
261 int64_t avio_skip(AVIOContext
*s
, int64_t offset
);
264 * ftell() equivalent for AVIOContext.
265 * @return position or AVERROR.
267 static av_always_inline
int64_t avio_tell(AVIOContext
*s
)
269 return avio_seek(s
, 0, SEEK_CUR
);
274 * @return filesize or AVERROR
276 int64_t avio_size(AVIOContext
*s
);
279 * feof() equivalent for AVIOContext.
280 * @return non zero if and only if end of file
282 int avio_feof(AVIOContext
*s
);
285 * @deprecated use avio_feof()
288 int url_feof(AVIOContext
*s
);
291 /** @warning currently size is limited */
292 int avio_printf(AVIOContext
*s
, const char *fmt
, ...) av_printf_format(2, 3);
295 * Force flushing of buffered data.
297 * For write streams, force the buffered data to be immediately written to the output,
298 * without to wait to fill the internal buffer.
300 * For read streams, discard all currently buffered data, and advance the
301 * reported file position to that of the underlying stream. This does not
302 * read new data, and does not perform any seeks.
304 void avio_flush(AVIOContext
*s
);
307 * Read size bytes from AVIOContext into buf.
308 * @return number of bytes read or AVERROR
310 int avio_read(AVIOContext
*s
, unsigned char *buf
, int size
);
313 * @name Functions for reading from AVIOContext
316 * @note return 0 if EOF, so you cannot use it if EOF handling is
319 int avio_r8 (AVIOContext
*s
);
320 unsigned int avio_rl16(AVIOContext
*s
);
321 unsigned int avio_rl24(AVIOContext
*s
);
322 unsigned int avio_rl32(AVIOContext
*s
);
323 uint64_t avio_rl64(AVIOContext
*s
);
324 unsigned int avio_rb16(AVIOContext
*s
);
325 unsigned int avio_rb24(AVIOContext
*s
);
326 unsigned int avio_rb32(AVIOContext
*s
);
327 uint64_t avio_rb64(AVIOContext
*s
);
333 * Read a string from pb into buf. The reading will terminate when either
334 * a NULL character was encountered, maxlen bytes have been read, or nothing
335 * more can be read from pb. The result is guaranteed to be NULL-terminated, it
336 * will be truncated if buf is too small.
337 * Note that the string is not interpreted or validated in any way, it
338 * might get truncated in the middle of a sequence for multi-byte encodings.
340 * @return number of bytes read (is always <= maxlen).
341 * If reading ends on EOF or error, the return value will be one more than
342 * bytes actually read.
344 int avio_get_str(AVIOContext
*pb
, int maxlen
, char *buf
, int buflen
);
347 * Read a UTF-16 string from pb and convert it to UTF-8.
348 * The reading will terminate when either a null or invalid character was
349 * encountered or maxlen bytes have been read.
350 * @return number of bytes read (is always <= maxlen)
352 int avio_get_str16le(AVIOContext
*pb
, int maxlen
, char *buf
, int buflen
);
353 int avio_get_str16be(AVIOContext
*pb
, int maxlen
, char *buf
, int buflen
);
357 * @name URL open modes
358 * The flags argument to avio_open must be one of the following
359 * constants, optionally ORed with other flags.
362 #define AVIO_FLAG_READ 1 /**< read-only */
363 #define AVIO_FLAG_WRITE 2 /**< write-only */
364 #define AVIO_FLAG_READ_WRITE (AVIO_FLAG_READ|AVIO_FLAG_WRITE) /**< read-write pseudo flag */
370 * Use non-blocking mode.
371 * If this flag is set, operations on the context will return
372 * AVERROR(EAGAIN) if they can not be performed immediately.
373 * If this flag is not set, operations on the context will never return
375 * Note that this flag does not affect the opening/connecting of the
376 * context. Connecting a protocol will always block if necessary (e.g. on
377 * network protocols) but never hang (e.g. on busy devices).
378 * Warning: non-blocking protocols is work-in-progress; this flag may be
381 #define AVIO_FLAG_NONBLOCK 8
385 * avio_read and avio_write should if possible be satisfied directly
386 * instead of going through a buffer, and avio_seek will always
387 * call the underlying seek function directly.
389 #define AVIO_FLAG_DIRECT 0x8000
392 * Create and initialize a AVIOContext for accessing the
393 * resource indicated by url.
394 * @note When the resource indicated by url has been opened in
395 * read+write mode, the AVIOContext can be used only for writing.
397 * @param s Used to return the pointer to the created AVIOContext.
398 * In case of failure the pointed to value is set to NULL.
399 * @param url resource to access
400 * @param flags flags which control how the resource indicated by url
402 * @return >= 0 in case of success, a negative value corresponding to an
403 * AVERROR code in case of failure
405 int avio_open(AVIOContext
**s
, const char *url
, int flags
);
408 * Create and initialize a AVIOContext for accessing the
409 * resource indicated by url.
410 * @note When the resource indicated by url has been opened in
411 * read+write mode, the AVIOContext can be used only for writing.
413 * @param s Used to return the pointer to the created AVIOContext.
414 * In case of failure the pointed to value is set to NULL.
415 * @param url resource to access
416 * @param flags flags which control how the resource indicated by url
418 * @param int_cb an interrupt callback to be used at the protocols level
419 * @param options A dictionary filled with protocol-private options. On return
420 * this parameter will be destroyed and replaced with a dict containing options
421 * that were not found. May be NULL.
422 * @return >= 0 in case of success, a negative value corresponding to an
423 * AVERROR code in case of failure
425 int avio_open2(AVIOContext
**s
, const char *url
, int flags
,
426 const AVIOInterruptCB
*int_cb
, AVDictionary
**options
);
429 * Close the resource accessed by the AVIOContext s and free it.
430 * This function can only be used if s was opened by avio_open().
432 * The internal buffer is automatically flushed before closing the
435 * @return 0 on success, an AVERROR < 0 on error.
438 int avio_close(AVIOContext
*s
);
441 * Close the resource accessed by the AVIOContext *s, free it
442 * and set the pointer pointing to it to NULL.
443 * This function can only be used if s was opened by avio_open().
445 * The internal buffer is automatically flushed before closing the
448 * @return 0 on success, an AVERROR < 0 on error.
451 int avio_closep(AVIOContext
**s
);
455 * Open a write only memory stream.
457 * @param s new IO context
458 * @return zero if no error.
460 int avio_open_dyn_buf(AVIOContext
**s
);
463 * Return the written size and a pointer to the buffer. The buffer
464 * must be freed with av_free().
465 * Padding of FF_INPUT_BUFFER_PADDING_SIZE is added to the buffer.
467 * @param s IO context
468 * @param pbuffer pointer to a byte buffer
469 * @return the length of the byte buffer
471 int avio_close_dyn_buf(AVIOContext
*s
, uint8_t **pbuffer
);
474 * Iterate through names of available protocols.
476 * @param opaque A private pointer representing current protocol.
477 * It must be a pointer to NULL on first iteration and will
478 * be updated by successive calls to avio_enum_protocols.
479 * @param output If set to 1, iterate over output protocols,
480 * otherwise over input protocols.
482 * @return A static string containing the name of current protocol or NULL
484 const char *avio_enum_protocols(void **opaque
, int output
);
487 * Pause and resume playing - only meaningful if using a network streaming
488 * protocol (e.g. MMS).
490 * @param h IO context from which to call the read_pause function pointer
491 * @param pause 1 for pause, 0 for resume
493 int avio_pause(AVIOContext
*h
, int pause
);
496 * Seek to a given timestamp relative to some component stream.
497 * Only meaningful if using a network streaming protocol (e.g. MMS.).
499 * @param h IO context from which to call the seek function pointers
500 * @param stream_index The stream index that the timestamp is relative to.
501 * If stream_index is (-1) the timestamp should be in AV_TIME_BASE
502 * units from the beginning of the presentation.
503 * If a stream_index >= 0 is used and the protocol does not support
504 * seeking based on component streams, the call will fail.
505 * @param timestamp timestamp in AVStream.time_base units
506 * or if there is no stream specified then in AV_TIME_BASE units.
507 * @param flags Optional combination of AVSEEK_FLAG_BACKWARD, AVSEEK_FLAG_BYTE
508 * and AVSEEK_FLAG_ANY. The protocol may silently ignore
509 * AVSEEK_FLAG_BACKWARD and AVSEEK_FLAG_ANY, but AVSEEK_FLAG_BYTE will
510 * fail if used and not supported.
511 * @return >= 0 on success
512 * @see AVInputFormat::read_seek
514 int64_t avio_seek_time(AVIOContext
*h
, int stream_index
,
515 int64_t timestamp
, int flags
);
517 /* Avoid a warning. The header can not be included because it breaks c++. */
521 * Read contents of h into print buffer, up to max_size bytes, or up to EOF.
523 * @return 0 for success (max_size bytes read or EOF reached), negative error
526 int avio_read_to_bprint(AVIOContext
*h
, struct AVBPrint
*pb
, size_t max_size
);
528 #endif /* AVFORMAT_AVIO_H */