2 * copyright (c) 2001 Fabrice Bellard
4 * This file is part of Libav.
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.
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.
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
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 * Different data types that can be returned via the AVIO
58 * write_data_type callback.
60 enum AVIODataMarkerType {
62 * Header data; this needs to be present for the stream to be decodeable.
64 AVIO_DATA_MARKER_HEADER,
66 * A point in the output bytestream where a decoder can start decoding
67 * (i.e. a keyframe). A demuxer/decoder given the data flagged with
68 * AVIO_DATA_MARKER_HEADER, followed by any AVIO_DATA_MARKER_SYNC_POINT,
69 * should give decodeable results.
71 AVIO_DATA_MARKER_SYNC_POINT,
73 * A point in the output bytestream where a demuxer can start parsing
74 * (for non self synchronizing bytestream formats). That is, any
75 * non-keyframe packet start point.
77 AVIO_DATA_MARKER_BOUNDARY_POINT,
79 * This is any, unlabelled data. It can either be a muxer not marking
80 * any positions at all, it can be an actual boundary/sync point
81 * that the muxer chooses not to mark, or a later part of a packet/fragment
82 * that is cut into multiple write callbacks due to limited IO buffer size.
84 AVIO_DATA_MARKER_UNKNOWN,
86 * Trailer data, which doesn't contain actual content, but only for
87 * finalizing the output file.
89 AVIO_DATA_MARKER_TRAILER
93 * Bytestream IO Context.
94 * New fields can be added to the end with minor version bumps.
95 * Removal, reordering and changes to existing fields require a major
97 * sizeof(AVIOContext) must not be used outside libav*.
99 * @note None of the function pointers in AVIOContext should be called
100 * directly, they should only be set by the client application
101 * when implementing custom I/O. Normally these are set to the
102 * function pointers specified in avio_alloc_context()
104 typedef struct AVIOContext {
106 * A class for private options.
108 * If this AVIOContext is created by avio_open2(), av_class is set and
109 * passes the options down to protocols.
111 * If this AVIOContext is manually allocated, then av_class may be set by
114 * warning -- this field can be NULL, be sure to not pass this AVIOContext
115 * to any av_opt_* functions in that case.
117 const AVClass *av_class;
118 unsigned char *buffer; /**< Start of the buffer. */
119 int buffer_size; /**< Maximum buffer size */
120 unsigned char *buf_ptr; /**< Current position in the buffer */
121 unsigned char *buf_end; /**< End of the data, may be less than
122 buffer+buffer_size if the read function returned
123 less data than requested, e.g. for streams where
124 no more data has been received yet. */
125 void *opaque; /**< A private pointer, passed to the read/write/seek/...
127 int (*read_packet)(void *opaque, uint8_t *buf, int buf_size);
128 int (*write_packet)(void *opaque, uint8_t *buf, int buf_size);
129 int64_t (*seek)(void *opaque, int64_t offset, int whence);
130 int64_t pos; /**< position in the file of the current buffer */
131 int must_flush; /**< true if the next seek should flush */
132 int eof_reached; /**< true if eof reached */
133 int write_flag; /**< true if open for writing */
135 unsigned long checksum;
136 unsigned char *checksum_ptr;
137 unsigned long (*update_checksum)(unsigned long checksum, const uint8_t *buf, unsigned int size);
138 int error; /**< contains the error code or 0 if no error happened */
140 * Pause or resume playback for network streaming protocols - e.g. MMS.
142 int (*read_pause)(void *opaque, int pause);
144 * Seek to a given timestamp in stream with the specified stream_index.
145 * Needed for some network streaming protocols which don't support seeking
148 int64_t (*read_seek)(void *opaque, int stream_index,
149 int64_t timestamp, int flags);
151 * A combination of AVIO_SEEKABLE_ flags or 0 when the stream is not seekable.
156 * A callback that is used instead of write_packet.
158 int (*write_data_type)(void *opaque, uint8_t *buf, int buf_size,
159 enum AVIODataMarkerType type, int64_t time);
161 * If set, don't call write_data_type separately for AVIO_DATA_MARKER_BOUNDARY_POINT,
162 * but ignore them and treat them as AVIO_DATA_MARKER_UNKNOWN (to avoid needlessly
163 * small chunks of data returned from the callback).
165 int ignore_boundary_point;
168 * Internal, not meant to be used from outside of AVIOContext.
170 enum AVIODataMarkerType current_type;
175 * Return AVIO_FLAG_* access flags corresponding to the access permissions
176 * of the resource in url, or a negative value corresponding to an
177 * AVERROR code in case of failure. The returned access flags are
178 * masked by the value in flags.
180 * @note This function is intrinsically unsafe, in the sense that the
181 * checked resource may change its existence or permission status from
182 * one call to another. Thus you should not trust the returned value,
183 * unless you are sure that no other processes are accessing the
186 int avio_check(const char *url, int flags);
189 * Allocate and initialize an AVIOContext for buffered I/O. It must be later
190 * freed with av_free().
192 * @param buffer Memory block for input/output operations via AVIOContext.
193 * The buffer must be allocated with av_malloc() and friends.
194 * @param buffer_size The buffer size is very important for performance.
195 * For protocols with fixed blocksize it should be set to this blocksize.
196 * For others a typical size is a cache page, e.g. 4kb.
197 * @param write_flag Set to 1 if the buffer should be writable, 0 otherwise.
198 * @param opaque An opaque pointer to user-specific data.
199 * @param read_packet A function for refilling the buffer, may be NULL.
200 * @param write_packet A function for writing the buffer contents, may be NULL.
201 * @param seek A function for seeking to specified byte position, may be NULL.
203 * @return Allocated AVIOContext or NULL on failure.
205 AVIOContext *avio_alloc_context(
206 unsigned char *buffer,
210 int (*read_packet)(void *opaque, uint8_t *buf, int buf_size),
211 int (*write_packet)(void *opaque, uint8_t *buf, int buf_size),
212 int64_t (*seek)(void *opaque, int64_t offset, int whence));
214 void avio_w8(AVIOContext *s, int b);
215 void avio_write(AVIOContext *s, const unsigned char *buf, int size);
216 void avio_wl64(AVIOContext *s, uint64_t val);
217 void avio_wb64(AVIOContext *s, uint64_t val);
218 void avio_wl32(AVIOContext *s, unsigned int val);
219 void avio_wb32(AVIOContext *s, unsigned int val);
220 void avio_wl24(AVIOContext *s, unsigned int val);
221 void avio_wb24(AVIOContext *s, unsigned int val);
222 void avio_wl16(AVIOContext *s, unsigned int val);
223 void avio_wb16(AVIOContext *s, unsigned int val);
226 * Write a NULL-terminated string.
227 * @return number of bytes written.
229 int avio_put_str(AVIOContext *s, const char *str);
232 * Convert an UTF-8 string to UTF-16LE and write it.
233 * @param s the AVIOContext
234 * @param str NULL-terminated UTF-8 string
236 * @return number of bytes written.
238 int avio_put_str16le(AVIOContext *s, const char *str);
241 * Convert an UTF-8 string to UTF-16BE and write it.
242 * @param s the AVIOContext
243 * @param str NULL-terminated UTF-8 string
245 * @return number of bytes written.
247 int avio_put_str16be(AVIOContext *s, const char *str);
250 * Mark the written bytestream as a specific type.
252 * Zero-length ranges are omitted from the output.
254 * @param time the stream time the current bytestream pos corresponds to
255 * (in AV_TIME_BASE units), or AV_NOPTS_VALUE if unknown or not
257 * @param type the kind of data written starting at the current pos
259 void avio_write_marker(AVIOContext *s, int64_t time, enum AVIODataMarkerType type);
262 * ORing this as the "whence" parameter to a seek function causes it to
263 * return the filesize without seeking anywhere. Supporting this is optional.
264 * If it is not supported then the seek function will return <0.
266 #define AVSEEK_SIZE 0x10000
269 * Passing this flag as the "whence" parameter to a seek function causes it to
270 * seek by any means (like reopening and linear reading) or other normally unreasonable
271 * means that can be extremely slow.
272 * This may be ignored by the seek code.
274 #define AVSEEK_FORCE 0x20000
277 * fseek() equivalent for AVIOContext.
278 * @return new position or AVERROR.
280 int64_t avio_seek(AVIOContext *s, int64_t offset, int whence);
283 * Skip given number of bytes forward
284 * @return new position or AVERROR.
286 static av_always_inline int64_t avio_skip(AVIOContext *s, int64_t offset)
288 return avio_seek(s, offset, SEEK_CUR);
292 * ftell() equivalent for AVIOContext.
293 * @return position or AVERROR.
295 static av_always_inline int64_t avio_tell(AVIOContext *s)
297 return avio_seek(s, 0, SEEK_CUR);
302 * @return filesize or AVERROR
304 int64_t avio_size(AVIOContext *s);
306 /** @warning currently size is limited */
307 int avio_printf(AVIOContext *s, const char *fmt, ...) av_printf_format(2, 3);
309 void avio_flush(AVIOContext *s);
313 * Read size bytes from AVIOContext into buf.
314 * @return number of bytes read or AVERROR
316 int avio_read(AVIOContext *s, unsigned char *buf, int size);
319 * @name Functions for reading from AVIOContext
322 * @note return 0 if EOF, so you cannot use it if EOF handling is
325 int avio_r8 (AVIOContext *s);
326 unsigned int avio_rl16(AVIOContext *s);
327 unsigned int avio_rl24(AVIOContext *s);
328 unsigned int avio_rl32(AVIOContext *s);
329 uint64_t avio_rl64(AVIOContext *s);
330 unsigned int avio_rb16(AVIOContext *s);
331 unsigned int avio_rb24(AVIOContext *s);
332 unsigned int avio_rb32(AVIOContext *s);
333 uint64_t avio_rb64(AVIOContext *s);
339 * Read a string from pb into buf. The reading will terminate when either
340 * a NULL character was encountered, maxlen bytes have been read, or nothing
341 * more can be read from pb. The result is guaranteed to be NULL-terminated, it
342 * will be truncated if buf is too small.
343 * Note that the string is not interpreted or validated in any way, it
344 * might get truncated in the middle of a sequence for multi-byte encodings.
346 * @return number of bytes read (is always <= maxlen).
347 * If reading ends on EOF or error, the return value will be one more than
348 * bytes actually read.
350 int avio_get_str(AVIOContext *pb, int maxlen, char *buf, int buflen);
353 * Read a UTF-16 string from pb and convert it to UTF-8.
354 * The reading will terminate when either a null or invalid character was
355 * encountered or maxlen bytes have been read.
356 * @return number of bytes read (is always <= maxlen)
358 int avio_get_str16le(AVIOContext *pb, int maxlen, char *buf, int buflen);
359 int avio_get_str16be(AVIOContext *pb, int maxlen, char *buf, int buflen);
363 * @name URL open modes
364 * The flags argument to avio_open must be one of the following
365 * constants, optionally ORed with other flags.
368 #define AVIO_FLAG_READ 1 /**< read-only */
369 #define AVIO_FLAG_WRITE 2 /**< write-only */
370 #define AVIO_FLAG_READ_WRITE (AVIO_FLAG_READ|AVIO_FLAG_WRITE) /**< read-write pseudo flag */
376 * Use non-blocking mode.
377 * If this flag is set, operations on the context will return
378 * AVERROR(EAGAIN) if they can not be performed immediately.
379 * If this flag is not set, operations on the context will never return
381 * Note that this flag does not affect the opening/connecting of the
382 * context. Connecting a protocol will always block if necessary (e.g. on
383 * network protocols) but never hang (e.g. on busy devices).
384 * Warning: non-blocking protocols is work-in-progress; this flag may be
387 #define AVIO_FLAG_NONBLOCK 8
390 * Create and initialize a AVIOContext for accessing the
391 * resource indicated by url.
392 * @note When the resource indicated by url has been opened in
393 * read+write mode, the AVIOContext can be used only for writing.
395 * @param s Used to return the pointer to the created AVIOContext.
396 * In case of failure the pointed to value is set to NULL.
397 * @param url resource to access
398 * @param flags flags which control how the resource indicated by url
400 * @return 0 in case of success, a negative value corresponding to an
401 * AVERROR code in case of failure
403 int avio_open(AVIOContext **s, const char *url, int flags);
406 * Create and initialize a AVIOContext for accessing the
407 * resource indicated by url.
408 * @note When the resource indicated by url has been opened in
409 * read+write mode, the AVIOContext can be used only for writing.
411 * @param s Used to return the pointer to the created AVIOContext.
412 * In case of failure the pointed to value is set to NULL.
413 * @param url resource to access
414 * @param flags flags which control how the resource indicated by url
416 * @param int_cb an interrupt callback to be used at the protocols level
417 * @param options A dictionary filled with protocol-private options. On return
418 * this parameter will be destroyed and replaced with a dict containing options
419 * that were not found. May be NULL.
420 * @return 0 in case of success, a negative value corresponding to an
421 * AVERROR code in case of failure
423 int avio_open2(AVIOContext **s, const char *url, int flags,
424 const AVIOInterruptCB *int_cb, AVDictionary **options);
427 * Close the resource accessed by the AVIOContext s and free it.
428 * This function can only be used if s was opened by avio_open().
430 * The internal buffer is automatically flushed before closing the
433 * @return 0 on success, an AVERROR < 0 on error.
436 int avio_close(AVIOContext *s);
439 * Close the resource accessed by the AVIOContext *s, free it
440 * and set the pointer pointing to it to NULL.
441 * This function can only be used if s was opened by avio_open().
443 * The internal buffer is automatically flushed before closing the
446 * @return 0 on success, an AVERROR < 0 on error.
449 int avio_closep(AVIOContext **s);
453 * Open a write only memory stream.
455 * @param s new IO context
456 * @return zero if no error.
458 int avio_open_dyn_buf(AVIOContext **s);
461 * Return the written size and a pointer to the buffer. The buffer
462 * must be freed with av_free().
463 * Padding of AV_INPUT_BUFFER_PADDING_SIZE is added to the buffer.
465 * @param s IO context
466 * @param pbuffer pointer to a byte buffer
467 * @return the length of the byte buffer
469 int avio_close_dyn_buf(AVIOContext *s, uint8_t **pbuffer);
472 * Iterate through names of available protocols.
474 * @param opaque A private pointer representing current protocol.
475 * It must be a pointer to NULL on first iteration and will
476 * be updated by successive calls to avio_enum_protocols.
477 * @param output If set to 1, iterate over output protocols,
478 * otherwise over input protocols.
480 * @return A static string containing the name of current protocol or NULL
482 const char *avio_enum_protocols(void **opaque, int output);
485 * Pause and resume playing - only meaningful if using a network streaming
486 * protocol (e.g. MMS).
488 * @param h IO context from which to call the read_pause function pointer
489 * @param pause 1 for pause, 0 for resume
491 int avio_pause(AVIOContext *h, int pause);
494 * Seek to a given timestamp relative to some component stream.
495 * Only meaningful if using a network streaming protocol (e.g. MMS.).
497 * @param h IO context from which to call the seek function pointers
498 * @param stream_index The stream index that the timestamp is relative to.
499 * If stream_index is (-1) the timestamp should be in AV_TIME_BASE
500 * units from the beginning of the presentation.
501 * If a stream_index >= 0 is used and the protocol does not support
502 * seeking based on component streams, the call will fail with ENOTSUP.
503 * @param timestamp timestamp in AVStream.time_base units
504 * or if there is no stream specified then in AV_TIME_BASE units.
505 * @param flags Optional combination of AVSEEK_FLAG_BACKWARD, AVSEEK_FLAG_BYTE
506 * and AVSEEK_FLAG_ANY. The protocol may silently ignore
507 * AVSEEK_FLAG_BACKWARD and AVSEEK_FLAG_ANY, but AVSEEK_FLAG_BYTE will
508 * fail with ENOTSUP if used and not supported.
509 * @return >= 0 on success
510 * @see AVInputFormat::read_seek
512 int64_t avio_seek_time(AVIOContext *h, int stream_index,
513 int64_t timestamp, int flags);
515 #endif /* AVFORMAT_AVIO_H */