1/*
2 * AVOptions
3 * copyright (c) 2005 Michael Niedermayer <michaelni@gmx.at>
4 *
5 * This file is part of FFmpeg.
6 *
7 * FFmpeg is free software; you can redistribute it and/or
8 * modify it under the terms of the GNU Lesser General Public
9 * License as published by the Free Software Foundation; either
10 * version 2.1 of the License, or (at your option) any later version.
11 *
12 * FFmpeg is distributed in the hope that it will be useful,
13 * but WITHOUT ANY WARRANTY; without even the implied warranty of
14 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
15 * Lesser General Public License for more details.
16 *
17 * You should have received a copy of the GNU Lesser General Public
18 * License along with FFmpeg; if not, write to the Free Software
19 * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
20 */
21
22#ifndef AVUTIL_OPT_H
23#define AVUTIL_OPT_H
24
25/**
26 * @file
27 * AVOptions
28 */
29
30#include "rational.h"
31#include "avutil.h"
32#include "dict.h"
33#include "log.h"
34#include "pixfmt.h"
35#include "samplefmt.h"
36#include "version.h"
37
38/**
39 * @defgroup avoptions AVOptions
40 * @ingroup lavu_data
41 * @{
42 * AVOptions provide a generic system to declare options on arbitrary structs
43 * ("objects"). An option can have a help text, a type and a range of possible
44 * values. Options may then be enumerated, read and written to.
45 *
46 * @section avoptions_implement Implementing AVOptions
47 * This section describes how to add AVOptions capabilities to a struct.
48 *
49 * All AVOptions-related information is stored in an AVClass. Therefore
50 * the first member of the struct should be a pointer to an AVClass describing it.
51 * The option field of the AVClass must be set to a NULL-terminated static array
52 * of AVOptions. Each AVOption must have a non-empty name, a type, a default
53 * value and for number-type AVOptions also a range of allowed values. It must
54 * also declare an offset in bytes from the start of the struct, where the field
55 * associated with this AVOption is located. Other fields in the AVOption struct
56 * should also be set when applicable, but are not required.
57 *
58 * The following example illustrates an AVOptions-enabled struct:
59 * @code
60 * typedef struct test_struct {
61 * const AVClass *class;
62 * int int_opt;
63 * char *str_opt;
64 * uint8_t *bin_opt;
65 * int bin_len;
66 * } test_struct;
67 *
68 * static const AVOption test_options[] = {
69 * { "test_int", "This is a test option of int type.", offsetof(test_struct, int_opt),
70 * AV_OPT_TYPE_INT, { .i64 = -1 }, INT_MIN, INT_MAX },
71 * { "test_str", "This is a test option of string type.", offsetof(test_struct, str_opt),
72 * AV_OPT_TYPE_STRING },
73 * { "test_bin", "This is a test option of binary type.", offsetof(test_struct, bin_opt),
74 * AV_OPT_TYPE_BINARY },
75 * { NULL },
76 * };
77 *
78 * static const AVClass test_class = {
79 * .class_name = "test class",
80 * .item_name = av_default_item_name,
81 * .option = test_options,
82 * .version = LIBAVUTIL_VERSION_INT,
83 * };
84 * @endcode
85 *
86 * Next, when allocating your struct, you must ensure that the AVClass pointer
87 * is set to the correct value. Then, av_opt_set_defaults() can be called to
88 * initialize defaults. After that the struct is ready to be used with the
89 * AVOptions API.
90 *
91 * When cleaning up, you may use the av_opt_free() function to automatically
92 * free all the allocated string and binary options.
93 *
94 * Continuing with the above example:
95 *
96 * @code
97 * test_struct *alloc_test_struct(void)
98 * {
99 * test_struct *ret = av_mallocz(sizeof(*ret));
100 * ret->class = &test_class;
101 * av_opt_set_defaults(ret);
102 * return ret;
103 * }
104 * void free_test_struct(test_struct **foo)
105 * {
106 * av_opt_free(*foo);
107 * av_freep(foo);
108 * }
109 * @endcode
110 *
111 * @subsection avoptions_implement_nesting Nesting
112 * It may happen that an AVOptions-enabled struct contains another
113 * AVOptions-enabled struct as a member (e.g. AVCodecContext in
114 * libavcodec exports generic options, while its priv_data field exports
115 * codec-specific options). In such a case, it is possible to set up the
116 * parent struct to export a child's options. To do that, simply
117 * implement AVClass.child_next() and AVClass.child_class_iterate() in the
118 * parent struct's AVClass.
119 * Assuming that the test_struct from above now also contains a
120 * child_struct field:
121 *
122 * @code
123 * typedef struct child_struct {
124 * AVClass *class;
125 * int flags_opt;
126 * } child_struct;
127 * static const AVOption child_opts[] = {
128 * { "test_flags", "This is a test option of flags type.",
129 * offsetof(child_struct, flags_opt), AV_OPT_TYPE_FLAGS, { .i64 = 0 }, INT_MIN, INT_MAX },
130 * { NULL },
131 * };
132 * static const AVClass child_class = {
133 * .class_name = "child class",
134 * .item_name = av_default_item_name,
135 * .option = child_opts,
136 * .version = LIBAVUTIL_VERSION_INT,
137 * };
138 *
139 * void *child_next(void *obj, void *prev)
140 * {
141 * test_struct *t = obj;
142 * if (!prev && t->child_struct)
143 * return t->child_struct;
144 * return NULL
145 * }
146 * const AVClass child_class_iterate(void **iter)
147 * {
148 * const AVClass *c = *iter ? NULL : &child_class;
149 * *iter = (void*)(uintptr_t)c;
150 * return c;
151 * }
152 * @endcode
153 * Putting child_next() and child_class_iterate() as defined above into
154 * test_class will now make child_struct's options accessible through
155 * test_struct (again, proper setup as described above needs to be done on
156 * child_struct right after it is created).
157 *
158 * From the above example it might not be clear why both child_next()
159 * and child_class_iterate() are needed. The distinction is that child_next()
160 * iterates over actually existing objects, while child_class_iterate()
161 * iterates over all possible child classes. E.g. if an AVCodecContext
162 * was initialized to use a codec which has private options, then its
163 * child_next() will return AVCodecContext.priv_data and finish
164 * iterating. OTOH child_class_iterate() on AVCodecContext.av_class will
165 * iterate over all available codecs with private options.
166 *
167 * @subsection avoptions_implement_named_constants Named constants
168 * It is possible to create named constants for options. Simply set the unit
169 * field of the option the constants should apply to a string and
170 * create the constants themselves as options of type AV_OPT_TYPE_CONST
171 * with their unit field set to the same string.
172 * Their default_val field should contain the value of the named
173 * constant.
174 * For example, to add some named constants for the test_flags option
175 * above, put the following into the child_opts array:
176 * @code
177 * { "test_flags", "This is a test option of flags type.",
178 * offsetof(child_struct, flags_opt), AV_OPT_TYPE_FLAGS, { .i64 = 0 }, INT_MIN, INT_MAX, "test_unit" },
179 * { "flag1", "This is a flag with value 16", 0, AV_OPT_TYPE_CONST, { .i64 = 16 }, 0, 0, "test_unit" },
180 * @endcode
181 *
182 * @section avoptions_use Using AVOptions
183 * This section deals with accessing options in an AVOptions-enabled struct.
184 * Such structs in FFmpeg are e.g. AVCodecContext in libavcodec or
185 * AVFormatContext in libavformat.
186 *
187 * @subsection avoptions_use_examine Examining AVOptions
188 * The basic functions for examining options are av_opt_next(), which iterates
189 * over all options defined for one object, and av_opt_find(), which searches
190 * for an option with the given name.
191 *
192 * The situation is more complicated with nesting. An AVOptions-enabled struct
193 * may have AVOptions-enabled children. Passing the AV_OPT_SEARCH_CHILDREN flag
194 * to av_opt_find() will make the function search children recursively.
195 *
196 * For enumerating there are basically two cases. The first is when you want to
197 * get all options that may potentially exist on the struct and its children
198 * (e.g. when constructing documentation). In that case you should call
199 * av_opt_child_class_iterate() recursively on the parent struct's AVClass. The
200 * second case is when you have an already initialized struct with all its
201 * children and you want to get all options that can be actually written or read
202 * from it. In that case you should call av_opt_child_next() recursively (and
203 * av_opt_next() on each result).
204 *
205 * @subsection avoptions_use_get_set Reading and writing AVOptions
206 * When setting options, you often have a string read directly from the
207 * user. In such a case, simply passing it to av_opt_set() is enough. For
208 * non-string type options, av_opt_set() will parse the string according to the
209 * option type.
210 *
211 * Similarly av_opt_get() will read any option type and convert it to a string
212 * which will be returned. Do not forget that the string is allocated, so you
213 * have to free it with av_free().
214 *
215 * In some cases it may be more convenient to put all options into an
216 * AVDictionary and call av_opt_set_dict() on it. A specific case of this
217 * are the format/codec open functions in lavf/lavc which take a dictionary
218 * filled with option as a parameter. This makes it possible to set some options
219 * that cannot be set otherwise, since e.g. the input file format is not known
220 * before the file is actually opened.
221 */
222
223enum AVOptionType{
224 AV_OPT_TYPE_FLAGS,
225 AV_OPT_TYPE_INT,
226 AV_OPT_TYPE_INT64,
227 AV_OPT_TYPE_DOUBLE,
228 AV_OPT_TYPE_FLOAT,
229 AV_OPT_TYPE_STRING,
230 AV_OPT_TYPE_RATIONAL,
231 AV_OPT_TYPE_BINARY, ///< offset must point to a pointer immediately followed by an int for the length
232 AV_OPT_TYPE_DICT,
233 AV_OPT_TYPE_UINT64,
234 AV_OPT_TYPE_CONST,
235 AV_OPT_TYPE_IMAGE_SIZE, ///< offset must point to two consecutive integers
236 AV_OPT_TYPE_PIXEL_FMT,
237 AV_OPT_TYPE_SAMPLE_FMT,
238 AV_OPT_TYPE_VIDEO_RATE, ///< offset must point to AVRational
239 AV_OPT_TYPE_DURATION,
240 AV_OPT_TYPE_COLOR,
241 AV_OPT_TYPE_CHANNEL_LAYOUT,
242 AV_OPT_TYPE_BOOL,
243};
244
245/**
246 * AVOption
247 */
248typedef struct AVOption {
249 const char *name;
250
251 /**
252 * short English help text
253 * @todo What about other languages?
254 */
255 const char *help;
256
257 /**
258 * The offset relative to the context structure where the option
259 * value is stored. It should be 0 for named constants.
260 */
261 int offset;
262 enum AVOptionType type;
263
264 /**
265 * the default value for scalar options
266 */
267 union {
268 int64_t i64;
269 double dbl;
270 const char *str;
271 /* TODO those are unused now */
272 AVRational q;
273 } default_val;
274 double min; ///< minimum valid value for the option
275 double max; ///< maximum valid value for the option
276
277 int flags;
278#define AV_OPT_FLAG_ENCODING_PARAM 1 ///< a generic parameter which can be set by the user for muxing or encoding
279#define AV_OPT_FLAG_DECODING_PARAM 2 ///< a generic parameter which can be set by the user for demuxing or decoding
280#define AV_OPT_FLAG_AUDIO_PARAM 8
281#define AV_OPT_FLAG_VIDEO_PARAM 16
282#define AV_OPT_FLAG_SUBTITLE_PARAM 32
283/**
284 * The option is intended for exporting values to the caller.
285 */
286#define AV_OPT_FLAG_EXPORT 64
287/**
288 * The option may not be set through the AVOptions API, only read.
289 * This flag only makes sense when AV_OPT_FLAG_EXPORT is also set.
290 */
291#define AV_OPT_FLAG_READONLY 128
292#define AV_OPT_FLAG_BSF_PARAM (1<<8) ///< a generic parameter which can be set by the user for bit stream filtering
293#define AV_OPT_FLAG_RUNTIME_PARAM (1<<15) ///< a generic parameter which can be set by the user at runtime
294#define AV_OPT_FLAG_FILTERING_PARAM (1<<16) ///< a generic parameter which can be set by the user for filtering
295#define AV_OPT_FLAG_DEPRECATED (1<<17) ///< set if option is deprecated, users should refer to AVOption.help text for more information
296#define AV_OPT_FLAG_CHILD_CONSTS (1<<18) ///< set if option constants can also reside in child objects
297//FIXME think about enc-audio, ... style flags
298
299 /**
300 * The logical unit to which the option belongs. Non-constant
301 * options and corresponding named constants share the same
302 * unit. May be NULL.
303 */
304 const char *unit;
305} AVOption;
306
307/**
308 * A single allowed range of values, or a single allowed value.
309 */
310typedef struct AVOptionRange {
311 const char *str;
312 /**
313 * Value range.
314 * For string ranges this represents the min/max length.
315 * For dimensions this represents the min/max pixel count or width/height in multi-component case.
316 */
317 double value_min, value_max;
318 /**
319 * Value's component range.
320 * For string this represents the unicode range for chars, 0-127 limits to ASCII.
321 */
322 double component_min, component_max;
323 /**
324 * Range flag.
325 * If set to 1 the struct encodes a range, if set to 0 a single value.
326 */
327 int is_range;
328} AVOptionRange;
329
330/**
331 * List of AVOptionRange structs.
332 */
333typedef struct AVOptionRanges {
334 /**
335 * Array of option ranges.
336 *
337 * Most of option types use just one component.
338 * Following describes multi-component option types:
339 *
340 * AV_OPT_TYPE_IMAGE_SIZE:
341 * component index 0: range of pixel count (width * height).
342 * component index 1: range of width.
343 * component index 2: range of height.
344 *
345 * @note To obtain multi-component version of this structure, user must
346 * provide AV_OPT_MULTI_COMPONENT_RANGE to av_opt_query_ranges or
347 * av_opt_query_ranges_default function.
348 *
349 * Multi-component range can be read as in following example:
350 *
351 * @code
352 * int range_index, component_index;
353 * AVOptionRanges *ranges;
354 * AVOptionRange *range[3]; //may require more than 3 in the future.
355 * av_opt_query_ranges(&ranges, obj, key, AV_OPT_MULTI_COMPONENT_RANGE);
356 * for (range_index = 0; range_index < ranges->nb_ranges; range_index++) {
357 * for (component_index = 0; component_index < ranges->nb_components; component_index++)
358 * range[component_index] = ranges->range[ranges->nb_ranges * component_index + range_index];
359 * //do something with range here.
360 * }
361 * av_opt_freep_ranges(&ranges);
362 * @endcode
363 */
364 AVOptionRange **range;
365 /**
366 * Number of ranges per component.
367 */
368 int nb_ranges;
369 /**
370 * Number of componentes.
371 */
372 int nb_components;
373} AVOptionRanges;
374
375/**
376 * Show the obj options.
377 *
378 * @param req_flags requested flags for the options to show. Show only the
379 * options for which it is opt->flags & req_flags.
380 * @param rej_flags rejected flags for the options to show. Show only the
381 * options for which it is !(opt->flags & req_flags).
382 * @param av_log_obj log context to use for showing the options
383 */
384int av_opt_show2(void *obj, void *av_log_obj, int req_flags, int rej_flags);
385
386/**
387 * Set the values of all AVOption fields to their default values.
388 *
389 * @param s an AVOption-enabled struct (its first member must be a pointer to AVClass)
390 */
391void av_opt_set_defaults(void *s);
392
393/**
394 * Set the values of all AVOption fields to their default values. Only these
395 * AVOption fields for which (opt->flags & mask) == flags will have their
396 * default applied to s.
397 *
398 * @param s an AVOption-enabled struct (its first member must be a pointer to AVClass)
399 * @param mask combination of AV_OPT_FLAG_*
400 * @param flags combination of AV_OPT_FLAG_*
401 */
402void av_opt_set_defaults2(void *s, int mask, int flags);
403
404/**
405 * Parse the key/value pairs list in opts. For each key/value pair
406 * found, stores the value in the field in ctx that is named like the
407 * key. ctx must be an AVClass context, storing is done using
408 * AVOptions.
409 *
410 * @param opts options string to parse, may be NULL
411 * @param key_val_sep a 0-terminated list of characters used to
412 * separate key from value
413 * @param pairs_sep a 0-terminated list of characters used to separate
414 * two pairs from each other
415 * @return the number of successfully set key/value pairs, or a negative
416 * value corresponding to an AVERROR code in case of error:
417 * AVERROR(EINVAL) if opts cannot be parsed,
418 * the error code issued by av_opt_set() if a key/value pair
419 * cannot be set
420 */
421int av_set_options_string(void *ctx, const char *opts,
422 const char *key_val_sep, const char *pairs_sep);
423
424/**
425 * Parse the key-value pairs list in opts. For each key=value pair found,
426 * set the value of the corresponding option in ctx.
427 *
428 * @param ctx the AVClass object to set options on
429 * @param opts the options string, key-value pairs separated by a
430 * delimiter
431 * @param shorthand a NULL-terminated array of options names for shorthand
432 * notation: if the first field in opts has no key part,
433 * the key is taken from the first element of shorthand;
434 * then again for the second, etc., until either opts is
435 * finished, shorthand is finished or a named option is
436 * found; after that, all options must be named
437 * @param key_val_sep a 0-terminated list of characters used to separate
438 * key from value, for example '='
439 * @param pairs_sep a 0-terminated list of characters used to separate
440 * two pairs from each other, for example ':' or ','
441 * @return the number of successfully set key=value pairs, or a negative
442 * value corresponding to an AVERROR code in case of error:
443 * AVERROR(EINVAL) if opts cannot be parsed,
444 * the error code issued by av_set_string3() if a key/value pair
445 * cannot be set
446 *
447 * Options names must use only the following characters: a-z A-Z 0-9 - . / _
448 * Separators must use characters distinct from option names and from each
449 * other.
450 */
451int av_opt_set_from_string(void *ctx, const char *opts,
452 const char *const *shorthand,
453 const char *key_val_sep, const char *pairs_sep);
454/**
455 * Free all allocated objects in obj.
456 */
457void av_opt_free(void *obj);
458
459/**
460 * Check whether a particular flag is set in a flags field.
461 *
462 * @param field_name the name of the flag field option
463 * @param flag_name the name of the flag to check
464 * @return non-zero if the flag is set, zero if the flag isn't set,
465 * isn't of the right type, or the flags field doesn't exist.
466 */
467int av_opt_flag_is_set(void *obj, const char *field_name, const char *flag_name);
468
469/**
470 * Set all the options from a given dictionary on an object.
471 *
472 * @param obj a struct whose first element is a pointer to AVClass
473 * @param options options to process. This dictionary will be freed and replaced
474 * by a new one containing all options not found in obj.
475 * Of course this new dictionary needs to be freed by caller
476 * with av_dict_free().
477 *
478 * @return 0 on success, a negative AVERROR if some option was found in obj,
479 * but could not be set.
480 *
481 * @see av_dict_copy()
482 */
483int av_opt_set_dict(void *obj, struct AVDictionary **options);
484
485
486/**
487 * Set all the options from a given dictionary on an object.
488 *
489 * @param obj a struct whose first element is a pointer to AVClass
490 * @param options options to process. This dictionary will be freed and replaced
491 * by a new one containing all options not found in obj.
492 * Of course this new dictionary needs to be freed by caller
493 * with av_dict_free().
494 * @param search_flags A combination of AV_OPT_SEARCH_*.
495 *
496 * @return 0 on success, a negative AVERROR if some option was found in obj,
497 * but could not be set.
498 *
499 * @see av_dict_copy()
500 */
501int av_opt_set_dict2(void *obj, struct AVDictionary **options, int search_flags);
502
503/**
504 * Extract a key-value pair from the beginning of a string.
505 *
506 * @param ropts pointer to the options string, will be updated to
507 * point to the rest of the string (one of the pairs_sep
508 * or the final NUL)
509 * @param key_val_sep a 0-terminated list of characters used to separate
510 * key from value, for example '='
511 * @param pairs_sep a 0-terminated list of characters used to separate
512 * two pairs from each other, for example ':' or ','
513 * @param flags flags; see the AV_OPT_FLAG_* values below
514 * @param rkey parsed key; must be freed using av_free()
515 * @param rval parsed value; must be freed using av_free()
516 *
517 * @return >=0 for success, or a negative value corresponding to an
518 * AVERROR code in case of error; in particular:
519 * AVERROR(EINVAL) if no key is present
520 *
521 */
522int av_opt_get_key_value(const char **ropts,
523 const char *key_val_sep, const char *pairs_sep,
524 unsigned flags,
525 char **rkey, char **rval);
526
527enum {
528
529 /**
530 * Accept to parse a value without a key; the key will then be returned
531 * as NULL.
532 */
533 AV_OPT_FLAG_IMPLICIT_KEY = 1,
534};
535
536/**
537 * @defgroup opt_eval_funcs Evaluating option strings
538 * @{
539 * This group of functions can be used to evaluate option strings
540 * and get numbers out of them. They do the same thing as av_opt_set(),
541 * except the result is written into the caller-supplied pointer.
542 *
543 * @param obj a struct whose first element is a pointer to AVClass.
544 * @param o an option for which the string is to be evaluated.
545 * @param val string to be evaluated.
546 * @param *_out value of the string will be written here.
547 *
548 * @return 0 on success, a negative number on failure.
549 */
550int av_opt_eval_flags (void *obj, const AVOption *o, const char *val, int *flags_out);
551int av_opt_eval_int (void *obj, const AVOption *o, const char *val, int *int_out);
552int av_opt_eval_int64 (void *obj, const AVOption *o, const char *val, int64_t *int64_out);
553int av_opt_eval_float (void *obj, const AVOption *o, const char *val, float *float_out);
554int av_opt_eval_double(void *obj, const AVOption *o, const char *val, double *double_out);
555int av_opt_eval_q (void *obj, const AVOption *o, const char *val, AVRational *q_out);
556/**
557 * @}
558 */
559
560#define AV_OPT_SEARCH_CHILDREN (1 << 0) /**< Search in possible children of the
561 given object first. */
562/**
563 * The obj passed to av_opt_find() is fake -- only a double pointer to AVClass
564 * instead of a required pointer to a struct containing AVClass. This is
565 * useful for searching for options without needing to allocate the corresponding
566 * object.
567 */
568#define AV_OPT_SEARCH_FAKE_OBJ (1 << 1)
569
570/**
571 * In av_opt_get, return NULL if the option has a pointer type and is set to NULL,
572 * rather than returning an empty string.
573 */
574#define AV_OPT_ALLOW_NULL (1 << 2)
575
576/**
577 * Allows av_opt_query_ranges and av_opt_query_ranges_default to return more than
578 * one component for certain option types.
579 * @see AVOptionRanges for details.
580 */
581#define AV_OPT_MULTI_COMPONENT_RANGE (1 << 12)
582
583/**
584 * Look for an option in an object. Consider only options which
585 * have all the specified flags set.
586 *
587 * @param[in] obj A pointer to a struct whose first element is a
588 * pointer to an AVClass.
589 * Alternatively a double pointer to an AVClass, if
590 * AV_OPT_SEARCH_FAKE_OBJ search flag is set.
591 * @param[in] name The name of the option to look for.
592 * @param[in] unit When searching for named constants, name of the unit
593 * it belongs to.
594 * @param opt_flags Find only options with all the specified flags set (AV_OPT_FLAG).
595 * @param search_flags A combination of AV_OPT_SEARCH_*.
596 *
597 * @return A pointer to the option found, or NULL if no option
598 * was found.
599 *
600 * @note Options found with AV_OPT_SEARCH_CHILDREN flag may not be settable
601 * directly with av_opt_set(). Use special calls which take an options
602 * AVDictionary (e.g. avformat_open_input()) to set options found with this
603 * flag.
604 */
605const AVOption *av_opt_find(void *obj, const char *name, const char *unit,
606 int opt_flags, int search_flags);
607
608/**
609 * Look for an option in an object. Consider only options which
610 * have all the specified flags set.
611 *
612 * @param[in] obj A pointer to a struct whose first element is a
613 * pointer to an AVClass.
614 * Alternatively a double pointer to an AVClass, if
615 * AV_OPT_SEARCH_FAKE_OBJ search flag is set.
616 * @param[in] name The name of the option to look for.
617 * @param[in] unit When searching for named constants, name of the unit
618 * it belongs to.
619 * @param opt_flags Find only options with all the specified flags set (AV_OPT_FLAG).
620 * @param search_flags A combination of AV_OPT_SEARCH_*.
621 * @param[out] target_obj if non-NULL, an object to which the option belongs will be
622 * written here. It may be different from obj if AV_OPT_SEARCH_CHILDREN is present
623 * in search_flags. This parameter is ignored if search_flags contain
624 * AV_OPT_SEARCH_FAKE_OBJ.
625 *
626 * @return A pointer to the option found, or NULL if no option
627 * was found.
628 */
629const AVOption *av_opt_find2(void *obj, const char *name, const char *unit,
630 int opt_flags, int search_flags, void **target_obj);
631
632/**
633 * Iterate over all AVOptions belonging to obj.
634 *
635 * @param obj an AVOptions-enabled struct or a double pointer to an
636 * AVClass describing it.
637 * @param prev result of the previous call to av_opt_next() on this object
638 * or NULL
639 * @return next AVOption or NULL
640 */
641const AVOption *av_opt_next(const void *obj, const AVOption *prev);
642
643/**
644 * Iterate over AVOptions-enabled children of obj.
645 *
646 * @param prev result of a previous call to this function or NULL
647 * @return next AVOptions-enabled child or NULL
648 */
649void *av_opt_child_next(void *obj, void *prev);
650
651#if FF_API_CHILD_CLASS_NEXT
652/**
653 * Iterate over potential AVOptions-enabled children of parent.
654 *
655 * @param prev result of a previous call to this function or NULL
656 * @return AVClass corresponding to next potential child or NULL
657 *
658 * @deprecated use av_opt_child_class_iterate
659 */
660attribute_deprecated
661const AVClass *av_opt_child_class_next(const AVClass *parent, const AVClass *prev);
662#endif
663
664/**
665 * Iterate over potential AVOptions-enabled children of parent.
666 *
667 * @param iter a pointer where iteration state is stored.
668 * @return AVClass corresponding to next potential child or NULL
669 */
670const AVClass *av_opt_child_class_iterate(const AVClass *parent, void **iter);
671
672/**
673 * @defgroup opt_set_funcs Option setting functions
674 * @{
675 * Those functions set the field of obj with the given name to value.
676 *
677 * @param[in] obj A struct whose first element is a pointer to an AVClass.
678 * @param[in] name the name of the field to set
679 * @param[in] val The value to set. In case of av_opt_set() if the field is not
680 * of a string type, then the given string is parsed.
681 * SI postfixes and some named scalars are supported.
682 * If the field is of a numeric type, it has to be a numeric or named
683 * scalar. Behavior with more than one scalar and +- infix operators
684 * is undefined.
685 * If the field is of a flags type, it has to be a sequence of numeric
686 * scalars or named flags separated by '+' or '-'. Prefixing a flag
687 * with '+' causes it to be set without affecting the other flags;
688 * similarly, '-' unsets a flag.
689 * If the field is of a dictionary type, it has to be a ':' separated list of
690 * key=value parameters. Values containing ':' special characters must be
691 * escaped.
692 * @param search_flags flags passed to av_opt_find2. I.e. if AV_OPT_SEARCH_CHILDREN
693 * is passed here, then the option may be set on a child of obj.
694 *
695 * @return 0 if the value has been set, or an AVERROR code in case of
696 * error:
697 * AVERROR_OPTION_NOT_FOUND if no matching option exists
698 * AVERROR(ERANGE) if the value is out of range
699 * AVERROR(EINVAL) if the value is not valid
700 */
701int av_opt_set (void *obj, const char *name, const char *val, int search_flags);
702int av_opt_set_int (void *obj, const char *name, int64_t val, int search_flags);
703int av_opt_set_double (void *obj, const char *name, double val, int search_flags);
704int av_opt_set_q (void *obj, const char *name, AVRational val, int search_flags);
705int av_opt_set_bin (void *obj, const char *name, const uint8_t *val, int size, int search_flags);
706int av_opt_set_image_size(void *obj, const char *name, int w, int h, int search_flags);
707int av_opt_set_pixel_fmt (void *obj, const char *name, enum AVPixelFormat fmt, int search_flags);
708int av_opt_set_sample_fmt(void *obj, const char *name, enum AVSampleFormat fmt, int search_flags);
709int av_opt_set_video_rate(void *obj, const char *name, AVRational val, int search_flags);
710int av_opt_set_channel_layout(void *obj, const char *name, int64_t ch_layout, int search_flags);
711/**
712 * @note Any old dictionary present is discarded and replaced with a copy of the new one. The
713 * caller still owns val is and responsible for freeing it.
714 */
715int av_opt_set_dict_val(void *obj, const char *name, const AVDictionary *val, int search_flags);
716
717/**
718 * Set a binary option to an integer list.
719 *
720 * @param obj AVClass object to set options on
721 * @param name name of the binary option
722 * @param val pointer to an integer list (must have the correct type with
723 * regard to the contents of the list)
724 * @param term list terminator (usually 0 or -1)
725 * @param flags search flags
726 */
727#define av_opt_set_int_list(obj, name, val, term, flags) \
728 (av_int_list_length(val, term) > INT_MAX / sizeof(*(val)) ? \
729 AVERROR(EINVAL) : \
730 av_opt_set_bin(obj, name, (const uint8_t *)(val), \
731 av_int_list_length(val, term) * sizeof(*(val)), flags))
732
733/**
734 * @}
735 */
736
737/**
738 * @defgroup opt_get_funcs Option getting functions
739 * @{
740 * Those functions get a value of the option with the given name from an object.
741 *
742 * @param[in] obj a struct whose first element is a pointer to an AVClass.
743 * @param[in] name name of the option to get.
744 * @param[in] search_flags flags passed to av_opt_find2. I.e. if AV_OPT_SEARCH_CHILDREN
745 * is passed here, then the option may be found in a child of obj.
746 * @param[out] out_val value of the option will be written here
747 * @return >=0 on success, a negative error code otherwise
748 */
749/**
750 * @note the returned string will be av_malloc()ed and must be av_free()ed by the caller
751 *
752 * @note if AV_OPT_ALLOW_NULL is set in search_flags in av_opt_get, and the
753 * option is of type AV_OPT_TYPE_STRING, AV_OPT_TYPE_BINARY or AV_OPT_TYPE_DICT
754 * and is set to NULL, *out_val will be set to NULL instead of an allocated
755 * empty string.
756 */
757int av_opt_get (void *obj, const char *name, int search_flags, uint8_t **out_val);
758int av_opt_get_int (void *obj, const char *name, int search_flags, int64_t *out_val);
759int av_opt_get_double (void *obj, const char *name, int search_flags, double *out_val);
760int av_opt_get_q (void *obj, const char *name, int search_flags, AVRational *out_val);
761int av_opt_get_image_size(void *obj, const char *name, int search_flags, int *w_out, int *h_out);
762int av_opt_get_pixel_fmt (void *obj, const char *name, int search_flags, enum AVPixelFormat *out_fmt);
763int av_opt_get_sample_fmt(void *obj, const char *name, int search_flags, enum AVSampleFormat *out_fmt);
764int av_opt_get_video_rate(void *obj, const char *name, int search_flags, AVRational *out_val);
765int av_opt_get_channel_layout(void *obj, const char *name, int search_flags, int64_t *ch_layout);
766/**
767 * @param[out] out_val The returned dictionary is a copy of the actual value and must
768 * be freed with av_dict_free() by the caller
769 */
770int av_opt_get_dict_val(void *obj, const char *name, int search_flags, AVDictionary **out_val);
771/**
772 * @}
773 */
774/**
775 * Gets a pointer to the requested field in a struct.
776 * This function allows accessing a struct even when its fields are moved or
777 * renamed since the application making the access has been compiled,
778 *
779 * @returns a pointer to the field, it can be cast to the correct type and read
780 * or written to.
781 */
782void *av_opt_ptr(const AVClass *avclass, void *obj, const char *name);
783
784/**
785 * Free an AVOptionRanges struct and set it to NULL.
786 */
787void av_opt_freep_ranges(AVOptionRanges **ranges);
788
789/**
790 * Get a list of allowed ranges for the given option.
791 *
792 * The returned list may depend on other fields in obj like for example profile.
793 *
794 * @param flags is a bitmask of flags, undefined flags should not be set and should be ignored
795 * AV_OPT_SEARCH_FAKE_OBJ indicates that the obj is a double pointer to a AVClass instead of a full instance
796 * AV_OPT_MULTI_COMPONENT_RANGE indicates that function may return more than one component, @see AVOptionRanges
797 *
798 * The result must be freed with av_opt_freep_ranges.
799 *
800 * @return number of compontents returned on success, a negative errro code otherwise
801 */
802int av_opt_query_ranges(AVOptionRanges **, void *obj, const char *key, int flags);
803
804/**
805 * Copy options from src object into dest object.
806 *
807 * Options that require memory allocation (e.g. string or binary) are malloc'ed in dest object.
808 * Original memory allocated for such options is freed unless both src and dest options points to the same memory.
809 *
810 * @param dest Object to copy from
811 * @param src Object to copy into
812 * @return 0 on success, negative on error
813 */
814int av_opt_copy(void *dest, const void *src);
815
816/**
817 * Get a default list of allowed ranges for the given option.
818 *
819 * This list is constructed without using the AVClass.query_ranges() callback
820 * and can be used as fallback from within the callback.
821 *
822 * @param flags is a bitmask of flags, undefined flags should not be set and should be ignored
823 * AV_OPT_SEARCH_FAKE_OBJ indicates that the obj is a double pointer to a AVClass instead of a full instance
824 * AV_OPT_MULTI_COMPONENT_RANGE indicates that function may return more than one component, @see AVOptionRanges
825 *
826 * The result must be freed with av_opt_free_ranges.
827 *
828 * @return number of compontents returned on success, a negative errro code otherwise
829 */
830int av_opt_query_ranges_default(AVOptionRanges **, void *obj, const char *key, int flags);
831
832/**
833 * Check if given option is set to its default value.
834 *
835 * Options o must belong to the obj. This function must not be called to check child's options state.
836 * @see av_opt_is_set_to_default_by_name().
837 *
838 * @param obj AVClass object to check option on
839 * @param o option to be checked
840 * @return >0 when option is set to its default,
841 * 0 when option is not set its default,
842 * <0 on error
843 */
844int av_opt_is_set_to_default(void *obj, const AVOption *o);
845
846/**
847 * Check if given option is set to its default value.
848 *
849 * @param obj AVClass object to check option on
850 * @param name option name
851 * @param search_flags combination of AV_OPT_SEARCH_*
852 * @return >0 when option is set to its default,
853 * 0 when option is not set its default,
854 * <0 on error
855 */
856int av_opt_is_set_to_default_by_name(void *obj, const char *name, int search_flags);
857
858
859#define AV_OPT_SERIALIZE_SKIP_DEFAULTS 0x00000001 ///< Serialize options that are not set to default values only.
860#define AV_OPT_SERIALIZE_OPT_FLAGS_EXACT 0x00000002 ///< Serialize options that exactly match opt_flags only.
861
862/**
863 * Serialize object's options.
864 *
865 * Create a string containing object's serialized options.
866 * Such string may be passed back to av_opt_set_from_string() in order to restore option values.
867 * A key/value or pairs separator occurring in the serialized value or
868 * name string are escaped through the av_escape() function.
869 *
870 * @param[in] obj AVClass object to serialize
871 * @param[in] opt_flags serialize options with all the specified flags set (AV_OPT_FLAG)
872 * @param[in] flags combination of AV_OPT_SERIALIZE_* flags
873 * @param[out] buffer Pointer to buffer that will be allocated with string containg serialized options.
874 * Buffer must be freed by the caller when is no longer needed.
875 * @param[in] key_val_sep character used to separate key from value
876 * @param[in] pairs_sep character used to separate two pairs from each other
877 * @return >= 0 on success, negative on error
878 * @warning Separators cannot be neither '\\' nor '\0'. They also cannot be the same.
879 */
880int av_opt_serialize(void *obj, int opt_flags, int flags, char **buffer,
881 const char key_val_sep, const char pairs_sep);
882/**
883 * @}
884 */
885
886#endif /* AVUTIL_OPT_H */
887

source code of include/x86_64-linux-gnu/libavutil/opt.h