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
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()
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.
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.
129 * Return AVIO_FLAG_* access flags corresponding to the access permissions
130 * of the resource in url, or a negative value corresponding to an
131 * AVERROR code in case of failure. The returned access flags are
132 * masked by the value in flags.
134 * @note This function is intrinsically unsafe, in the sense that the
135 * checked resource may change its existence or permission status from
136 * one call to another. Thus you should not trust the returned value,
137 * unless you are sure that no other processes are accessing the
140 int avio_check(const char *url, int flags);
143 * Allocate and initialize an AVIOContext for buffered I/O. It must be later
144 * freed with av_free().
146 * @param buffer Memory block for input/output operations via AVIOContext.
147 * The buffer must be allocated with av_malloc() and friends.
148 * @param buffer_size The buffer size is very important for performance.
149 * For protocols with fixed blocksize it should be set to this blocksize.
150 * For others a typical size is a cache page, e.g. 4kb.
151 * @param write_flag Set to 1 if the buffer should be writable, 0 otherwise.
152 * @param opaque An opaque pointer to user-specific data.
153 * @param read_packet A function for refilling the buffer, may be NULL.
154 * @param write_packet A function for writing the buffer contents, may be NULL.
155 * @param seek A function for seeking to specified byte position, may be NULL.
157 * @return Allocated AVIOContext or NULL on failure.
159 AVIOContext *avio_alloc_context(
160 unsigned char *buffer,
164 int (*read_packet)(void *opaque, uint8_t *buf, int buf_size),
165 int (*write_packet)(void *opaque, uint8_t *buf, int buf_size),
166 int64_t (*seek)(void *opaque, int64_t offset, int whence));
168 void avio_w8(AVIOContext *s, int b);
169 void avio_write(AVIOContext *s, const unsigned char *buf, int size);
170 void avio_wl64(AVIOContext *s, uint64_t val);
171 void avio_wb64(AVIOContext *s, uint64_t val);
172 void avio_wl32(AVIOContext *s, unsigned int val);
173 void avio_wb32(AVIOContext *s, unsigned int val);
174 void avio_wl24(AVIOContext *s, unsigned int val);
175 void avio_wb24(AVIOContext *s, unsigned int val);
176 void avio_wl16(AVIOContext *s, unsigned int val);
177 void avio_wb16(AVIOContext *s, unsigned int val);
180 * Write a NULL-terminated string.
181 * @return number of bytes written.
183 int avio_put_str(AVIOContext *s, const char *str);
186 * Convert an UTF-8 string to UTF-16LE and write it.
187 * @return number of bytes written.
189 int avio_put_str16le(AVIOContext *s, const char *str);
192 * Passing this as the "whence" parameter to a seek function causes it to
193 * return the filesize without seeking anywhere. Supporting this is optional.
194 * If it is not supported then the seek function will return <0.
196 #define AVSEEK_SIZE 0x10000
199 * Oring this flag as into the "whence" parameter to a seek function causes it to
200 * seek by any means (like reopening and linear reading) or other normally unreasonble
201 * means that can be extreemly slow.
202 * This may be ignored by the seek code.
204 #define AVSEEK_FORCE 0x20000
207 * fseek() equivalent for AVIOContext.
208 * @return new position or AVERROR.
210 int64_t avio_seek(AVIOContext *s, int64_t offset, int whence);
213 * Skip given number of bytes forward
214 * @return new position or AVERROR.
216 int64_t avio_skip(AVIOContext *s, int64_t offset);
219 * ftell() equivalent for AVIOContext.
220 * @return position or AVERROR.
222 static av_always_inline int64_t avio_tell(AVIOContext *s)
224 return avio_seek(s, 0, SEEK_CUR);
229 * @return filesize or AVERROR
231 int64_t avio_size(AVIOContext *s);
234 * feof() equivalent for AVIOContext.
235 * @return non zero if and only if end of file
237 int url_feof(AVIOContext *s);
239 /** @warning currently size is limited */
240 int avio_printf(AVIOContext *s, const char *fmt, ...) av_printf_format(2, 3);
242 void avio_flush(AVIOContext *s);
246 * Read size bytes from AVIOContext into buf.
247 * @return number of bytes read or AVERROR
249 int avio_read(AVIOContext *s, unsigned char *buf, int size);
252 * @name Functions for reading from AVIOContext
255 * @note return 0 if EOF, so you cannot use it if EOF handling is
258 int avio_r8 (AVIOContext *s);
259 unsigned int avio_rl16(AVIOContext *s);
260 unsigned int avio_rl24(AVIOContext *s);
261 unsigned int avio_rl32(AVIOContext *s);
262 uint64_t avio_rl64(AVIOContext *s);
263 unsigned int avio_rb16(AVIOContext *s);
264 unsigned int avio_rb24(AVIOContext *s);
265 unsigned int avio_rb32(AVIOContext *s);
266 uint64_t avio_rb64(AVIOContext *s);
272 * Read a string from pb into buf. The reading will terminate when either
273 * a NULL character was encountered, maxlen bytes have been read, or nothing
274 * more can be read from pb. The result is guaranteed to be NULL-terminated, it
275 * will be truncated if buf is too small.
276 * Note that the string is not interpreted or validated in any way, it
277 * might get truncated in the middle of a sequence for multi-byte encodings.
279 * @return number of bytes read (is always <= maxlen).
280 * If reading ends on EOF or error, the return value will be one more than
281 * bytes actually read.
283 int avio_get_str(AVIOContext *pb, int maxlen, char *buf, int buflen);
286 * Read a UTF-16 string from pb and convert it to UTF-8.
287 * The reading will terminate when either a null or invalid character was
288 * encountered or maxlen bytes have been read.
289 * @return number of bytes read (is always <= maxlen)
291 int avio_get_str16le(AVIOContext *pb, int maxlen, char *buf, int buflen);
292 int avio_get_str16be(AVIOContext *pb, int maxlen, char *buf, int buflen);
296 * @name URL open modes
297 * The flags argument to avio_open must be one of the following
298 * constants, optionally ORed with other flags.
301 #define AVIO_FLAG_READ 1 /**< read-only */
302 #define AVIO_FLAG_WRITE 2 /**< write-only */
303 #define AVIO_FLAG_READ_WRITE (AVIO_FLAG_READ|AVIO_FLAG_WRITE) /**< read-write pseudo flag */
309 * Use non-blocking mode.
310 * If this flag is set, operations on the context will return
311 * AVERROR(EAGAIN) if they can not be performed immediately.
312 * If this flag is not set, operations on the context will never return
314 * Note that this flag does not affect the opening/connecting of the
315 * context. Connecting a protocol will always block if necessary (e.g. on
316 * network protocols) but never hang (e.g. on busy devices).
317 * Warning: non-blocking protocols is work-in-progress; this flag may be
320 #define AVIO_FLAG_NONBLOCK 8
323 * Create and initialize a AVIOContext for accessing the
324 * resource indicated by url.
325 * @note When the resource indicated by url has been opened in
326 * read+write mode, the AVIOContext can be used only for writing.
328 * @param s Used to return the pointer to the created AVIOContext.
329 * In case of failure the pointed to value is set to NULL.
330 * @param flags flags which control how the resource indicated by url
332 * @return 0 in case of success, a negative value corresponding to an
333 * AVERROR code in case of failure
335 int avio_open(AVIOContext **s, const char *url, int flags);
338 * Create and initialize a AVIOContext for accessing the
339 * resource indicated by url.
340 * @note When the resource indicated by url has been opened in
341 * read+write mode, the AVIOContext can be used only for writing.
343 * @param s Used to return the pointer to the created AVIOContext.
344 * In case of failure the pointed to value is set to NULL.
345 * @param flags flags which control how the resource indicated by url
347 * @param int_cb an interrupt callback to be used at the protocols level
348 * @param options A dictionary filled with protocol-private options. On return
349 * this parameter will be destroyed and replaced with a dict containing options
350 * that were not found. May be NULL.
351 * @return 0 in case of success, a negative value corresponding to an
352 * AVERROR code in case of failure
354 int avio_open2(AVIOContext **s, const char *url, int flags,
355 const AVIOInterruptCB *int_cb, AVDictionary **options);
358 * Close the resource accessed by the AVIOContext s and free it.
359 * This function can only be used if s was opened by avio_open().
361 * @return 0 on success, an AVERROR < 0 on error.
363 int avio_close(AVIOContext *s);
366 * Open a write only memory stream.
368 * @param s new IO context
369 * @return zero if no error.
371 int avio_open_dyn_buf(AVIOContext **s);
374 * Return the written size and a pointer to the buffer. The buffer
375 * must be freed with av_free().
376 * Padding of FF_INPUT_BUFFER_PADDING_SIZE is added to the buffer.
378 * @param s IO context
379 * @param pbuffer pointer to a byte buffer
380 * @return the length of the byte buffer
382 int avio_close_dyn_buf(AVIOContext *s, uint8_t **pbuffer);
385 * Iterate through names of available protocols.
386 * @note it is recommanded to use av_protocol_next() instead of this
388 * @param opaque A private pointer representing current protocol.
389 * It must be a pointer to NULL on first iteration and will
390 * be updated by successive calls to avio_enum_protocols.
391 * @param output If set to 1, iterate over output protocols,
392 * otherwise over input protocols.
394 * @return A static string containing the name of current protocol or NULL
396 const char *avio_enum_protocols(void **opaque, int output);
399 * Pause and resume playing - only meaningful if using a network streaming
400 * protocol (e.g. MMS).
401 * @param pause 1 for pause, 0 for resume
403 int avio_pause(AVIOContext *h, int pause);
406 * Seek to a given timestamp relative to some component stream.
407 * Only meaningful if using a network streaming protocol (e.g. MMS.).
408 * @param stream_index The stream index that the timestamp is relative to.
409 * If stream_index is (-1) the timestamp should be in AV_TIME_BASE
410 * units from the beginning of the presentation.
411 * If a stream_index >= 0 is used and the protocol does not support
412 * seeking based on component streams, the call will fail.
413 * @param timestamp timestamp in AVStream.time_base units
414 * or if there is no stream specified then in AV_TIME_BASE units.
415 * @param flags Optional combination of AVSEEK_FLAG_BACKWARD, AVSEEK_FLAG_BYTE
416 * and AVSEEK_FLAG_ANY. The protocol may silently ignore
417 * AVSEEK_FLAG_BACKWARD and AVSEEK_FLAG_ANY, but AVSEEK_FLAG_BYTE will
418 * fail if used and not supported.
419 * @return >= 0 on success
420 * @see AVInputFormat::read_seek
422 int64_t avio_seek_time(AVIOContext *h, int stream_index,
423 int64_t timestamp, int flags);
425 #endif /* AVFORMAT_AVIO_H */