summaryrefslogtreecommitdiffstats
path: root/libavformat/avio.h
blob: 3360e8296e85b76dd1bdc48309ee4c3fc0c087e5 (plain)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
283
284
285
286
287
288
289
290
291
292
293
294
295
296
297
298
299
300
301
302
303
304
305
306
307
308
309
310
311
312
313
314
315
316
317
318
319
320
321
322
323
324
325
326
327
328
329
330
331
332
333
334
335
336
337
338
339
340
341
342
343
344
345
346
347
348
349
350
351
352
353
354
355
356
357
358
359
360
361
362
363
364
365
366
367
368
369
370
371
372
373
374
375
376
377
378
379
380
381
382
383
384
385
386
387
388
389
390
391
392
393
394
395
396
397
398
399
400
401
402
403
404
405
406
407
408
409
410
411
412
413
414
415
416
417
418
419
420
421
422
423
424
425
426
427
428
429
430
431
432
433
434
435
436
437
438
439
/*
 * copyright (c) 2001 Fabrice Bellard
 *
 * This file is part of Libav.
 *
 * Libav is free software; you can redistribute it and/or
 * modify it under the terms of the GNU Lesser General Public
 * License as published by the Free Software Foundation; either
 * version 2.1 of the License, or (at your option) any later version.
 *
 * Libav is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
 * Lesser General Public License for more details.
 *
 * You should have received a copy of the GNU Lesser General Public
 * License along with Libav; if not, write to the Free Software
 * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
 */
#ifndef AVFORMAT_AVIO_H
#define AVFORMAT_AVIO_H

/**
 * @file
 * @ingroup lavf_io
 * Buffered I/O operations
 */

#include <stdint.h>

#include "libavutil/common.h"
#include "libavutil/dict.h"
#include "libavutil/log.h"

#include "libavformat/version.h"


#define AVIO_SEEKABLE_NORMAL 0x0001 /**< Seeking works like for a local file */

/**
 * Callback for checking whether to abort blocking functions.
 * AVERROR_EXIT is returned in this case by the interrupted
 * function. During blocking operations, callback is called with
 * opaque as parameter. If the callback returns 1, the
 * blocking operation will be aborted.
 *
 * No members can be added to this struct without a major bump, if
 * new elements have been added after this struct in AVFormatContext
 * or AVIOContext.
 */
typedef struct AVIOInterruptCB {
    int (*callback)(void*);
    void *opaque;
} AVIOInterruptCB;

/**
 * Bytestream IO Context.
 * New fields can be added to the end with minor version bumps.
 * Removal, reordering and changes to existing fields require a major
 * version bump.
 * sizeof(AVIOContext) must not be used outside libav*.
 *
 * @note None of the function pointers in AVIOContext should be called
 *       directly, they should only be set by the client application
 *       when implementing custom I/O. Normally these are set to the
 *       function pointers specified in avio_alloc_context()
 */
typedef struct AVIOContext {
    /**
     * A class for private options.
     *
     * If this AVIOContext is created by avio_open2(), av_class is set and
     * passes the options down to protocols.
     *
     * If this AVIOContext is manually allocated, then av_class may be set by
     * the caller.
     *
     * warning -- this field can be NULL, be sure to not pass this AVIOContext
     * to any av_opt_* functions in that case.
     */
    const AVClass *av_class;
    unsigned char *buffer;  /**< Start of the buffer. */
    int buffer_size;        /**< Maximum buffer size */
    unsigned char *buf_ptr; /**< Current position in the buffer */
    unsigned char *buf_end; /**< End of the data, may be less than
                                 buffer+buffer_size if the read function returned
                                 less data than requested, e.g. for streams where
                                 no more data has been received yet. */
    void *opaque;           /**< A private pointer, passed to the read/write/seek/...
                                 functions. */
    int (*read_packet)(void *opaque, uint8_t *buf, int buf_size);
    int (*write_packet)(void *opaque, uint8_t *buf, int buf_size);
    int64_t (*seek)(void *opaque, int64_t offset, int whence);
    int64_t pos;            /**< position in the file of the current buffer */
    int must_flush;         /**< true if the next seek should flush */
    int eof_reached;        /**< true if eof reached */
    int write_flag;         /**< true if open for writing */
    int max_packet_size;
    unsigned long checksum;
    unsigned char *checksum_ptr;
    unsigned long (*update_checksum)(unsigned long checksum, const uint8_t *buf, unsigned int size);
    int error;              /**< contains the error code or 0 if no error happened */
    /**
     * Pause or resume playback for network streaming protocols - e.g. MMS.
     */
    int (*read_pause)(void *opaque, int pause);
    /**
     * Seek to a given timestamp in stream with the specified stream_index.
     * Needed for some network streaming protocols which don't support seeking
     * to byte position.
     */
    int64_t (*read_seek)(void *opaque, int stream_index,
                         int64_t timestamp, int flags);
    /**
     * A combination of AVIO_SEEKABLE_ flags or 0 when the stream is not seekable.
     */
    int seekable;
} AVIOContext;

/* unbuffered I/O */

/**
 * Return AVIO_FLAG_* access flags corresponding to the access permissions
 * of the resource in url, or a negative value corresponding to an
 * AVERROR code in case of failure. The returned access flags are
 * masked by the value in flags.
 *
 * @note This function is intrinsically unsafe, in the sense that the
 * checked resource may change its existence or permission status from
 * one call to another. Thus you should not trust the returned value,
 * unless you are sure that no other processes are accessing the
 * checked resource.
 */
int avio_check(const char *url, int flags);

/**
 * Allocate and initialize an AVIOContext for buffered I/O. It must be later
 * freed with av_free().
 *
 * @param buffer Memory block for input/output operations via AVIOContext.
 *        The buffer must be allocated with av_malloc() and friends.
 * @param buffer_size The buffer size is very important for performance.
 *        For protocols with fixed blocksize it should be set to this blocksize.
 *        For others a typical size is a cache page, e.g. 4kb.
 * @param write_flag Set to 1 if the buffer should be writable, 0 otherwise.
 * @param opaque An opaque pointer to user-specific data.
 * @param read_packet  A function for refilling the buffer, may be NULL.
 * @param write_packet A function for writing the buffer contents, may be NULL.
 * @param seek A function for seeking to specified byte position, may be NULL.
 *
 * @return Allocated AVIOContext or NULL on failure.
 */
AVIOContext *avio_alloc_context(
                  unsigned char *buffer,
                  int buffer_size,
                  int write_flag,
                  void *opaque,
                  int (*read_packet)(void *opaque, uint8_t *buf, int buf_size),
                  int (*write_packet)(void *opaque, uint8_t *buf, int buf_size),
                  int64_t (*seek)(void *opaque, int64_t offset, int whence));

void avio_w8(AVIOContext *s, int b);
void avio_write(AVIOContext *s, const unsigned char *buf, int size);
void avio_wl64(AVIOContext *s, uint64_t val);
void avio_wb64(AVIOContext *s, uint64_t val);
void avio_wl32(AVIOContext *s, unsigned int val);
void avio_wb32(AVIOContext *s, unsigned int val);
void avio_wl24(AVIOContext *s, unsigned int val);
void avio_wb24(AVIOContext *s, unsigned int val);
void avio_wl16(AVIOContext *s, unsigned int val);
void avio_wb16(AVIOContext *s, unsigned int val);

/**
 * Write a NULL-terminated string.
 * @return number of bytes written.
 */
int avio_put_str(AVIOContext *s, const char *str);

/**
 * Convert an UTF-8 string to UTF-16LE and write it.
 * @return number of bytes written.
 */
int avio_put_str16le(AVIOContext *s, const char *str);

/**
 * Passing this as the "whence" parameter to a seek function causes it to
 * return the filesize without seeking anywhere. Supporting this is optional.
 * If it is not supported then the seek function will return <0.
 */
#define AVSEEK_SIZE 0x10000

/**
 * Oring this flag as into the "whence" parameter to a seek function causes it to
 * seek by any means (like reopening and linear reading) or other normally unreasonble
 * means that can be extreemly slow.
 * This may be ignored by the seek code.
 */
#define AVSEEK_FORCE 0x20000

/**
 * fseek() equivalent for AVIOContext.
 * @return new position or AVERROR.
 */
int64_t avio_seek(AVIOContext *s, int64_t offset, int whence);

/**
 * Skip given number of bytes forward
 * @return new position or AVERROR.
 */
static av_always_inline int64_t avio_skip(AVIOContext *s, int64_t offset)
{
    return avio_seek(s, offset, SEEK_CUR);
}

/**
 * ftell() equivalent for AVIOContext.
 * @return position or AVERROR.
 */
static av_always_inline int64_t avio_tell(AVIOContext *s)
{
    return avio_seek(s, 0, SEEK_CUR);
}

/**
 * Get the filesize.
 * @return filesize or AVERROR
 */
int64_t avio_size(AVIOContext *s);

/** @warning currently size is limited */
int avio_printf(AVIOContext *s, const char *fmt, ...) av_printf_format(2, 3);

void avio_flush(AVIOContext *s);


/**
 * Read size bytes from AVIOContext into buf.
 * @return number of bytes read or AVERROR
 */
int avio_read(AVIOContext *s, unsigned char *buf, int size);

/**
 * @name Functions for reading from AVIOContext
 * @{
 *
 * @note return 0 if EOF, so you cannot use it if EOF handling is
 *       necessary
 */
int          avio_r8  (AVIOContext *s);
unsigned int avio_rl16(AVIOContext *s);
unsigned int avio_rl24(AVIOContext *s);
unsigned int avio_rl32(AVIOContext *s);
uint64_t     avio_rl64(AVIOContext *s);
unsigned int avio_rb16(AVIOContext *s);
unsigned int avio_rb24(AVIOContext *s);
unsigned int avio_rb32(AVIOContext *s);
uint64_t     avio_rb64(AVIOContext *s);
/**
 * @}
 */

/**
 * Read a string from pb into buf. The reading will terminate when either
 * a NULL character was encountered, maxlen bytes have been read, or nothing
 * more can be read from pb. The result is guaranteed to be NULL-terminated, it
 * will be truncated if buf is too small.
 * Note that the string is not interpreted or validated in any way, it
 * might get truncated in the middle of a sequence for multi-byte encodings.
 *
 * @return number of bytes read (is always <= maxlen).
 * If reading ends on EOF or error, the return value will be one more than
 * bytes actually read.
 */
int avio_get_str(AVIOContext *pb, int maxlen, char *buf, int buflen);

/**
 * Read a UTF-16 string from pb and convert it to UTF-8.
 * The reading will terminate when either a null or invalid character was
 * encountered or maxlen bytes have been read.
 * @return number of bytes read (is always <= maxlen)
 */
int avio_get_str16le(AVIOContext *pb, int maxlen, char *buf, int buflen);
int avio_get_str16be(AVIOContext *pb, int maxlen, char *buf, int buflen);


/**
 * @name URL open modes
 * The flags argument to avio_open must be one of the following
 * constants, optionally ORed with other flags.
 * @{
 */
#define AVIO_FLAG_READ  1                                      /**< read-only */
#define AVIO_FLAG_WRITE 2                                      /**< write-only */
#define AVIO_FLAG_READ_WRITE (AVIO_FLAG_READ|AVIO_FLAG_WRITE)  /**< read-write pseudo flag */
/**
 * @}
 */

/**
 * Use non-blocking mode.
 * If this flag is set, operations on the context will return
 * AVERROR(EAGAIN) if they can not be performed immediately.
 * If this flag is not set, operations on the context will never return
 * AVERROR(EAGAIN).
 * Note that this flag does not affect the opening/connecting of the
 * context. Connecting a protocol will always block if necessary (e.g. on
 * network protocols) but never hang (e.g. on busy devices).
 * Warning: non-blocking protocols is work-in-progress; this flag may be
 * silently ignored.
 */
#define AVIO_FLAG_NONBLOCK 8

/**
 * Create and initialize a AVIOContext for accessing the
 * resource indicated by url.
 * @note When the resource indicated by url has been opened in
 * read+write mode, the AVIOContext can be used only for writing.
 *
 * @param s Used to return the pointer to the created AVIOContext.
 * In case of failure the pointed to value is set to NULL.
 * @param url resource to access
 * @param flags flags which control how the resource indicated by url
 * is to be opened
 * @return 0 in case of success, a negative value corresponding to an
 * AVERROR code in case of failure
 */
int avio_open(AVIOContext **s, const char *url, int flags);

/**
 * Create and initialize a AVIOContext for accessing the
 * resource indicated by url.
 * @note When the resource indicated by url has been opened in
 * read+write mode, the AVIOContext can be used only for writing.
 *
 * @param s Used to return the pointer to the created AVIOContext.
 * In case of failure the pointed to value is set to NULL.
 * @param url resource to access
 * @param flags flags which control how the resource indicated by url
 * is to be opened
 * @param int_cb an interrupt callback to be used at the protocols level
 * @param options  A dictionary filled with protocol-private options. On return
 * this parameter will be destroyed and replaced with a dict containing options
 * that were not found. May be NULL.
 * @return 0 in case of success, a negative value corresponding to an
 * AVERROR code in case of failure
 */
int avio_open2(AVIOContext **s, const char *url, int flags,
               const AVIOInterruptCB *int_cb, AVDictionary **options);

/**
 * Close the resource accessed by the AVIOContext s and free it.
 * This function can only be used if s was opened by avio_open().
 *
 * The internal buffer is automatically flushed before closing the
 * resource.
 *
 * @return 0 on success, an AVERROR < 0 on error.
 * @see avio_closep
 */
int avio_close(AVIOContext *s);

/**
 * Close the resource accessed by the AVIOContext *s, free it
 * and set the pointer pointing to it to NULL.
 * This function can only be used if s was opened by avio_open().
 *
 * The internal buffer is automatically flushed before closing the
 * resource.
 *
 * @return 0 on success, an AVERROR < 0 on error.
 * @see avio_close
 */
int avio_closep(AVIOContext **s);


/**
 * Open a write only memory stream.
 *
 * @param s new IO context
 * @return zero if no error.
 */
int avio_open_dyn_buf(AVIOContext **s);

/**
 * Return the written size and a pointer to the buffer. The buffer
 * must be freed with av_free().
 * Padding of FF_INPUT_BUFFER_PADDING_SIZE is added to the buffer.
 *
 * @param s IO context
 * @param pbuffer pointer to a byte buffer
 * @return the length of the byte buffer
 */
int avio_close_dyn_buf(AVIOContext *s, uint8_t **pbuffer);

/**
 * Iterate through names of available protocols.
 *
 * @param opaque A private pointer representing current protocol.
 *        It must be a pointer to NULL on first iteration and will
 *        be updated by successive calls to avio_enum_protocols.
 * @param output If set to 1, iterate over output protocols,
 *               otherwise over input protocols.
 *
 * @return A static string containing the name of current protocol or NULL
 */
const char *avio_enum_protocols(void **opaque, int output);

/**
 * Pause and resume playing - only meaningful if using a network streaming
 * protocol (e.g. MMS).
 *
 * @param h     IO context from which to call the read_pause function pointer
 * @param pause 1 for pause, 0 for resume
 */
int     avio_pause(AVIOContext *h, int pause);

/**
 * Seek to a given timestamp relative to some component stream.
 * Only meaningful if using a network streaming protocol (e.g. MMS.).
 *
 * @param h IO context from which to call the seek function pointers
 * @param stream_index The stream index that the timestamp is relative to.
 *        If stream_index is (-1) the timestamp should be in AV_TIME_BASE
 *        units from the beginning of the presentation.
 *        If a stream_index >= 0 is used and the protocol does not support
 *        seeking based on component streams, the call will fail with ENOTSUP.
 * @param timestamp timestamp in AVStream.time_base units
 *        or if there is no stream specified then in AV_TIME_BASE units.
 * @param flags Optional combination of AVSEEK_FLAG_BACKWARD, AVSEEK_FLAG_BYTE
 *        and AVSEEK_FLAG_ANY. The protocol may silently ignore
 *        AVSEEK_FLAG_BACKWARD and AVSEEK_FLAG_ANY, but AVSEEK_FLAG_BYTE will
 *        fail with ENOTSUP if used and not supported.
 * @return >= 0 on success
 * @see AVInputFormat::read_seek
 */
int64_t avio_seek_time(AVIOContext *h, int stream_index,
                       int64_t timestamp, int flags);

#endif /* AVFORMAT_AVIO_H */
OpenPOWER on IntegriCloud