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
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 * There are two modes of access to members of AVOption and its child structs.
47 * One is called 'native access', and refers to access from the code that
48 * declares the AVOption in question. The other is 'foreign access', and refers
49 * to access from other code.
50 *
51 * Certain struct members in this header are documented as 'native access only'
52 * or similar - it means that only the code that declared the AVOption in
53 * question is allowed to access the field. This allows us to extend the
54 * semantics of those fields without breaking API compatibility.
55 *
56 * @section avoptions_scope Scope of AVOptions
57 *
58 * AVOptions is designed to support any set of multimedia configuration options
59 * that can be defined at compile-time. Although it is mainly used to expose
60 * FFmpeg options, you are welcome to adapt it to your own use case.
61 *
62 * No single approach can ever fully solve the problem of configuration,
63 * but please submit a patch if you believe you have found a problem
64 * that is best solved by extending AVOptions.
65 *
66 * @section avoptions_implement Implementing AVOptions
67 * This section describes how to add AVOptions capabilities to a struct.
68 *
69 * All AVOptions-related information is stored in an AVClass. Therefore
70 * the first member of the struct should be a pointer to an AVClass describing it.
71 * The option field of the AVClass must be set to a NULL-terminated static array
72 * of AVOptions. Each AVOption must have a non-empty name, a type, a default
73 * value and for number-type AVOptions also a range of allowed values. It must
74 * also declare an offset in bytes from the start of the struct, where the field
75 * associated with this AVOption is located. Other fields in the AVOption struct
76 * should also be set when applicable, but are not required.
77 *
78 * The following example illustrates an AVOptions-enabled struct:
79 * @code
80 * typedef struct test_struct {
81 * const AVClass *class;
82 * int int_opt;
83 * char *str_opt;
84 * uint8_t *bin_opt;
85 * int bin_len;
86 * } test_struct;
87 *
88 * static const AVOption test_options[] = {
89 * { "test_int", "This is a test option of int type.", offsetof(test_struct, int_opt),
90 * AV_OPT_TYPE_INT, { .i64 = -1 }, INT_MIN, INT_MAX },
91 * { "test_str", "This is a test option of string type.", offsetof(test_struct, str_opt),
92 * AV_OPT_TYPE_STRING },
93 * { "test_bin", "This is a test option of binary type.", offsetof(test_struct, bin_opt),
94 * AV_OPT_TYPE_BINARY },
95 * { NULL },
96 * };
97 *
98 * static const AVClass test_class = {
99 * .class_name = "test class",
100 * .item_name = av_default_item_name,
101 * .option = test_options,
102 * .version = LIBAVUTIL_VERSION_INT,
103 * };
104 * @endcode
105 *
106 * Next, when allocating your struct, you must ensure that the AVClass pointer
107 * is set to the correct value. Then, av_opt_set_defaults() can be called to
108 * initialize defaults. After that the struct is ready to be used with the
109 * AVOptions API.
110 *
111 * When cleaning up, you may use the av_opt_free() function to automatically
112 * free all the allocated string and binary options.
113 *
114 * Continuing with the above example:
115 *
116 * @code
117 * test_struct *alloc_test_struct(void)
118 * {
119 * test_struct *ret = av_mallocz(sizeof(*ret));
120 * ret->class = &test_class;
121 * av_opt_set_defaults(ret);
122 * return ret;
123 * }
124 * void free_test_struct(test_struct **foo)
125 * {
126 * av_opt_free(*foo);
127 * av_freep(foo);
128 * }
129 * @endcode
130 *
131 * @subsection avoptions_implement_nesting Nesting
132 * It may happen that an AVOptions-enabled struct contains another
133 * AVOptions-enabled struct as a member (e.g. AVCodecContext in
134 * libavcodec exports generic options, while its priv_data field exports
135 * codec-specific options). In such a case, it is possible to set up the
136 * parent struct to export a child's options. To do that, simply
137 * implement AVClass.child_next() and AVClass.child_class_iterate() in the
138 * parent struct's AVClass.
139 * Assuming that the test_struct from above now also contains a
140 * child_struct field:
141 *
142 * @code
143 * typedef struct child_struct {
144 * AVClass *class;
145 * int flags_opt;
146 * } child_struct;
147 * static const AVOption child_opts[] = {
148 * { "test_flags", "This is a test option of flags type.",
149 * offsetof(child_struct, flags_opt), AV_OPT_TYPE_FLAGS, { .i64 = 0 }, INT_MIN, INT_MAX },
150 * { NULL },
151 * };
152 * static const AVClass child_class = {
153 * .class_name = "child class",
154 * .item_name = av_default_item_name,
155 * .option = child_opts,
156 * .version = LIBAVUTIL_VERSION_INT,
157 * };
158 *
159 * void *child_next(void *obj, void *prev)
160 * {
161 * test_struct *t = obj;
162 * if (!prev && t->child_struct)
163 * return t->child_struct;
164 * return NULL
165 * }
166 * const AVClass child_class_iterate(void **iter)
167 * {
168 * const AVClass *c = *iter ? NULL : &child_class;
169 * *iter = (void*)(uintptr_t)c;
170 * return c;
171 * }
172 * @endcode
173 * Putting child_next() and child_class_iterate() as defined above into
174 * test_class will now make child_struct's options accessible through
175 * test_struct (again, proper setup as described above needs to be done on
176 * child_struct right after it is created).
177 *
178 * From the above example it might not be clear why both child_next()
179 * and child_class_iterate() are needed. The distinction is that child_next()
180 * iterates over actually existing objects, while child_class_iterate()
181 * iterates over all possible child classes. E.g. if an AVCodecContext
182 * was initialized to use a codec which has private options, then its
183 * child_next() will return AVCodecContext.priv_data and finish
184 * iterating. OTOH child_class_iterate() on AVCodecContext.av_class will
185 * iterate over all available codecs with private options.
186 *
187 * @subsection avoptions_implement_named_constants Named constants
188 * It is possible to create named constants for options. Simply set the unit
189 * field of the option the constants should apply to a string and
190 * create the constants themselves as options of type AV_OPT_TYPE_CONST
191 * with their unit field set to the same string.
192 * Their default_val field should contain the value of the named
193 * constant.
194 * For example, to add some named constants for the test_flags option
195 * above, put the following into the child_opts array:
196 * @code
197 * { "test_flags", "This is a test option of flags type.",
198 * offsetof(child_struct, flags_opt), AV_OPT_TYPE_FLAGS, { .i64 = 0 }, INT_MIN, INT_MAX, "test_unit" },
199 * { "flag1", "This is a flag with value 16", 0, AV_OPT_TYPE_CONST, { .i64 = 16 }, 0, 0, "test_unit" },
200 * @endcode
201 *
202 * @section avoptions_use Using AVOptions
203 * This section deals with accessing options in an AVOptions-enabled struct.
204 * Such structs in FFmpeg are e.g. AVCodecContext in libavcodec or
205 * AVFormatContext in libavformat.
206 *
207 * @subsection avoptions_use_examine Examining AVOptions
208 * The basic functions for examining options are av_opt_next(), which iterates
209 * over all options defined for one object, and av_opt_find(), which searches
210 * for an option with the given name.
211 *
212 * The situation is more complicated with nesting. An AVOptions-enabled struct
213 * may have AVOptions-enabled children. Passing the AV_OPT_SEARCH_CHILDREN flag
214 * to av_opt_find() will make the function search children recursively.
215 *
216 * For enumerating there are basically two cases. The first is when you want to
217 * get all options that may potentially exist on the struct and its children
218 * (e.g. when constructing documentation). In that case you should call
219 * av_opt_child_class_iterate() recursively on the parent struct's AVClass. The
220 * second case is when you have an already initialized struct with all its
221 * children and you want to get all options that can be actually written or read
222 * from it. In that case you should call av_opt_child_next() recursively (and
223 * av_opt_next() on each result).
224 *
225 * @subsection avoptions_use_get_set Reading and writing AVOptions
226 * When setting options, you often have a string read directly from the
227 * user. In such a case, simply passing it to av_opt_set() is enough. For
228 * non-string type options, av_opt_set() will parse the string according to the
229 * option type.
230 *
231 * Similarly av_opt_get() will read any option type and convert it to a string
232 * which will be returned. Do not forget that the string is allocated, so you
233 * have to free it with av_free().
234 *
235 * In some cases it may be more convenient to put all options into an
236 * AVDictionary and call av_opt_set_dict() on it. A specific case of this
237 * are the format/codec open functions in lavf/lavc which take a dictionary
238 * filled with option as a parameter. This makes it possible to set some options
239 * that cannot be set otherwise, since e.g. the input file format is not known
240 * before the file is actually opened.
241 */
242
243 /**
244 * An option type determines:
245 * - for native access, the underlying C type of the field that an AVOption
246 * refers to;
247 * - for foreign access, the semantics of accessing the option through this API,
248 * e.g. which av_opt_get_*() and av_opt_set_*() functions can be called, or
249 * what format will av_opt_get()/av_opt_set() expect/produce.
250 */
252 /**
253 * Underlying C type is unsigned int.
254 */
256 /**
257 * Underlying C type is int.
258 */
260 /**
261 * Underlying C type is int64_t.
262 */
264 /**
265 * Underlying C type is double.
266 */
268 /**
269 * Underlying C type is float.
270 */
272 /**
273 * Underlying C type is a uint8_t* that is either NULL or points to a C
274 * string allocated with the av_malloc() family of functions.
275 */
277 /**
278 * Underlying C type is AVRational.
279 */
281 /**
282 * Underlying C type is a uint8_t* that is either NULL or points to an array
283 * allocated with the av_malloc() family of functions. The pointer is
284 * immediately followed by an int containing the array length in bytes.
285 */
287 /**
288 * Underlying C type is AVDictionary*.
289 */
291 /**
292 * Underlying C type is uint64_t.
293 */
295 /**
296 * Special option type for declaring named constants. Does not correspond to
297 * an actual field in the object, offset must be 0.
298 */
300 /**
301 * Underlying C type is two consecutive integers.
302 */
304 /**
305 * Underlying C type is enum AVPixelFormat.
306 */
308 /**
309 * Underlying C type is enum AVSampleFormat.
310 */
312 /**
313 * Underlying C type is AVRational.
314 */
316 /**
317 * Underlying C type is int64_t.
318 */
320 /**
321 * Underlying C type is uint8_t[4].
322 */
324 /**
325 * Underlying C type is int.
326 */
328 /**
329 * Underlying C type is AVChannelLayout.
330 */
332 /**
333 * Underlying C type is unsigned int.
334 */
336
337 /**
338 * May be combined with another regular option type to declare an array
339 * option.
340 *
341 * For array options, @ref AVOption.offset should refer to a pointer
342 * corresponding to the option type. The pointer should be immediately
343 * followed by an unsigned int that will store the number of elements in the
344 * array.
345 */
347 };
348
349 /**
350 * A generic parameter which can be set by the user for muxing or encoding.
351 */
352 #define AV_OPT_FLAG_ENCODING_PARAM (1 << 0)
353 /**
354 * A generic parameter which can be set by the user for demuxing or decoding.
355 */
356 #define AV_OPT_FLAG_DECODING_PARAM (1 << 1)
357 #define AV_OPT_FLAG_AUDIO_PARAM (1 << 3)
358 #define AV_OPT_FLAG_VIDEO_PARAM (1 << 4)
359 #define AV_OPT_FLAG_SUBTITLE_PARAM (1 << 5)
360 /**
361 * The option is intended for exporting values to the caller.
362 */
363 #define AV_OPT_FLAG_EXPORT (1 << 6)
364 /**
365 * The option may not be set through the AVOptions API, only read.
366 * This flag only makes sense when AV_OPT_FLAG_EXPORT is also set.
367 */
368 #define AV_OPT_FLAG_READONLY (1 << 7)
369 /**
370 * A generic parameter which can be set by the user for bit stream filtering.
371 */
372 #define AV_OPT_FLAG_BSF_PARAM (1 << 8)
373
374 /**
375 * A generic parameter which can be set by the user at runtime.
376 */
377 #define AV_OPT_FLAG_RUNTIME_PARAM (1 << 15)
378 /**
379 * A generic parameter which can be set by the user for filtering.
380 */
381 #define AV_OPT_FLAG_FILTERING_PARAM (1 << 16)
382 /**
383 * Set if option is deprecated, users should refer to AVOption.help text for
384 * more information.
385 */
386 #define AV_OPT_FLAG_DEPRECATED (1 << 17)
387 /**
388 * Set if option constants can also reside in child objects.
389 */
390 #define AV_OPT_FLAG_CHILD_CONSTS (1 << 18)
391
392 /**
393 * May be set as default_val for AV_OPT_TYPE_FLAG_ARRAY options.
394 */
396 /**
397 * Native access only.
398 *
399 * Default value of the option, as would be serialized by av_opt_get() (i.e.
400 * using the value of sep as the separator).
401 */
403
404 /**
405 * Minimum number of elements in the array. When this field is non-zero, def
406 * must be non-NULL and contain at least this number of elements.
407 */
409 /**
410 * Maximum number of elements in the array, 0 when unlimited.
411 */
413
414 /**
415 * Separator between array elements in string representations of this
416 * option, used by av_opt_set() and av_opt_get(). It must be a printable
417 * ASCII character, excluding alphanumeric and the backslash. A comma is
418 * used when sep=0.
419 *
420 * The separator and the backslash must be backslash-escaped in order to
421 * appear in string representations of the option value.
422 */
425
426 /**
427 * AVOption
428 */
431
432 /**
433 * short English help text
434 * @todo What about other languages?
435 */
437
438 /**
439 * Native access only.
440 *
441 * The offset relative to the context structure where the option
442 * value is stored. It should be 0 for named constants.
443 */
446
447 /**
448 * Native access only, except when documented otherwise.
449 * the default value for scalar options
450 */
451 union {
455 /* TODO those are unused now */
457
458 /**
459 * Used for AV_OPT_TYPE_FLAG_ARRAY options. May be NULL.
460 *
461 * Foreign access to some members allowed, as noted in AVOptionArrayDef
462 * documentation.
463 */
466 double min;
///< minimum valid value for the option
467 double max;
///< maximum valid value for the option
468
469 /**
470 * A combination of AV_OPT_FLAG_*.
471 */
473
474 /**
475 * The logical unit to which the option belongs. Non-constant
476 * options and corresponding named constants share the same
477 * unit. May be NULL.
478 */
481
482 /**
483 * A single allowed range of values, or a single allowed value.
484 */
487 /**
488 * Value range.
489 * For string ranges this represents the min/max length.
490 * For dimensions this represents the min/max pixel count or width/height in multi-component case.
491 */
493 /**
494 * Value's component range.
495 * For string this represents the unicode range for chars, 0-127 limits to ASCII.
496 */
498 /**
499 * Range flag.
500 * If set to 1 the struct encodes a range, if set to 0 a single value.
501 */
504
505 /**
506 * List of AVOptionRange structs.
507 */
509 /**
510 * Array of option ranges.
511 *
512 * Most of option types use just one component.
513 * Following describes multi-component option types:
514 *
515 * AV_OPT_TYPE_IMAGE_SIZE:
516 * component index 0: range of pixel count (width * height).
517 * component index 1: range of width.
518 * component index 2: range of height.
519 *
520 * @note To obtain multi-component version of this structure, user must
521 * provide AV_OPT_MULTI_COMPONENT_RANGE to av_opt_query_ranges or
522 * av_opt_query_ranges_default function.
523 *
524 * Multi-component range can be read as in following example:
525 *
526 * @code
527 * int range_index, component_index;
528 * AVOptionRanges *ranges;
529 * AVOptionRange *range[3]; //may require more than 3 in the future.
530 * av_opt_query_ranges(&ranges, obj, key, AV_OPT_MULTI_COMPONENT_RANGE);
531 * for (range_index = 0; range_index < ranges->nb_ranges; range_index++) {
532 * for (component_index = 0; component_index < ranges->nb_components; component_index++)
533 * range[component_index] = ranges->range[ranges->nb_ranges * component_index + range_index];
534 * //do something with range here.
535 * }
536 * av_opt_freep_ranges(&ranges);
537 * @endcode
538 */
540 /**
541 * Number of ranges per component.
542 */
544 /**
545 * Number of components.
546 */
549
550 /**
551 * @defgroup opt_mng AVOption (un)initialization and inspection.
552 * @{
553 */
554
555 /**
556 * Set the values of all AVOption fields to their default values.
557 *
558 * @param s an AVOption-enabled struct (its first member must be a pointer to AVClass)
559 */
561
562 /**
563 * Set the values of all AVOption fields to their default values. Only these
564 * AVOption fields for which (opt->flags & mask) == flags will have their
565 * default applied to s.
566 *
567 * @param s an AVOption-enabled struct (its first member must be a pointer to AVClass)
568 * @param mask combination of AV_OPT_FLAG_*
569 * @param flags combination of AV_OPT_FLAG_*
570 */
572
573 /**
574 * Free all allocated objects in obj.
575 */
577
578 /**
579 * Iterate over all AVOptions belonging to obj.
580 *
581 * @param obj an AVOptions-enabled struct or a double pointer to an
582 * AVClass describing it.
583 * @param prev result of the previous call to av_opt_next() on this object
584 * or NULL
585 * @return next AVOption or NULL
586 */
588
589 /**
590 * Iterate over AVOptions-enabled children of obj.
591 *
592 * @param prev result of a previous call to this function or NULL
593 * @return next AVOptions-enabled child or NULL
594 */
596
597 /**
598 * Iterate over potential AVOptions-enabled children of parent.
599 *
600 * @param iter a pointer where iteration state is stored.
601 * @return AVClass corresponding to next potential child or NULL
602 */
604
605 #define AV_OPT_SEARCH_CHILDREN (1 << 0) /**< Search in possible children of the
606 given object first. */
607 /**
608 * The obj passed to av_opt_find() is fake -- only a double pointer to AVClass
609 * instead of a required pointer to a struct containing AVClass. This is
610 * useful for searching for options without needing to allocate the corresponding
611 * object.
612 */
613 #define AV_OPT_SEARCH_FAKE_OBJ (1 << 1)
614
615 /**
616 * In av_opt_get, return NULL if the option has a pointer type and is set to NULL,
617 * rather than returning an empty string.
618 */
619 #define AV_OPT_ALLOW_NULL (1 << 2)
620
621 /**
622 * May be used with av_opt_set_array() to signal that new elements should
623 * replace the existing ones in the indicated range.
624 */
625 #define AV_OPT_ARRAY_REPLACE (1 << 3)
626
627 /**
628 * Allows av_opt_query_ranges and av_opt_query_ranges_default to return more than
629 * one component for certain option types.
630 * @see AVOptionRanges for details.
631 */
632 #define AV_OPT_MULTI_COMPONENT_RANGE (1 << 12)
633
634 /**
635 * Look for an option in an object. Consider only options which
636 * have all the specified flags set.
637 *
638 * @param[in] obj A pointer to a struct whose first element is a
639 * pointer to an AVClass.
640 * Alternatively a double pointer to an AVClass, if
641 * AV_OPT_SEARCH_FAKE_OBJ search flag is set.
642 * @param[in] name The name of the option to look for.
643 * @param[in] unit When searching for named constants, name of the unit
644 * it belongs to.
645 * @param opt_flags Find only options with all the specified flags set (AV_OPT_FLAG).
646 * @param search_flags A combination of AV_OPT_SEARCH_*.
647 *
648 * @return A pointer to the option found, or NULL if no option
649 * was found.
650 *
651 * @note Options found with AV_OPT_SEARCH_CHILDREN flag may not be settable
652 * directly with av_opt_set(). Use special calls which take an options
653 * AVDictionary (e.g. avformat_open_input()) to set options found with this
654 * flag.
655 */
657 int opt_flags, int search_flags);
658
659 /**
660 * Look for an option in an object. Consider only options which
661 * have all the specified flags set.
662 *
663 * @param[in] obj A pointer to a struct whose first element is a
664 * pointer to an AVClass.
665 * Alternatively a double pointer to an AVClass, if
666 * AV_OPT_SEARCH_FAKE_OBJ search flag is set.
667 * @param[in] name The name of the option to look for.
668 * @param[in] unit When searching for named constants, name of the unit
669 * it belongs to.
670 * @param opt_flags Find only options with all the specified flags set (AV_OPT_FLAG).
671 * @param search_flags A combination of AV_OPT_SEARCH_*.
672 * @param[out] target_obj if non-NULL, an object to which the option belongs will be
673 * written here. It may be different from obj if AV_OPT_SEARCH_CHILDREN is present
674 * in search_flags. This parameter is ignored if search_flags contain
675 * AV_OPT_SEARCH_FAKE_OBJ.
676 *
677 * @return A pointer to the option found, or NULL if no option
678 * was found.
679 */
681 int opt_flags, int search_flags, void **target_obj);
682
683 /**
684 * Show the obj options.
685 *
686 * @param req_flags requested flags for the options to show. Show only the
687 * options for which it is opt->flags & req_flags.
688 * @param rej_flags rejected flags for the options to show. Show only the
689 * options for which it is !(opt->flags & req_flags).
690 * @param av_log_obj log context to use for showing the options
691 */
692 int av_opt_show2(
void *obj,
void *av_log_obj,
int req_flags,
int rej_flags);
693
694 /**
695 * Extract a key-value pair from the beginning of a string.
696 *
697 * @param ropts pointer to the options string, will be updated to
698 * point to the rest of the string (one of the pairs_sep
699 * or the final NUL)
700 * @param key_val_sep a 0-terminated list of characters used to separate
701 * key from value, for example '='
702 * @param pairs_sep a 0-terminated list of characters used to separate
703 * two pairs from each other, for example ':' or ','
704 * @param flags flags; see the AV_OPT_FLAG_* values below
705 * @param rkey parsed key; must be freed using av_free()
706 * @param rval parsed value; must be freed using av_free()
707 *
708 * @return >=0 for success, or a negative value corresponding to an
709 * AVERROR code in case of error; in particular:
710 * AVERROR(EINVAL) if no key is present
711 *
712 */
714 const char *key_val_sep, const char *pairs_sep,
716 char **rkey, char **rval);
717
718 enum {
719
720 /**
721 * Accept to parse a value without a key; the key will then be returned
722 * as NULL.
723 */
725 };
726
727 /**
728 * @}
729 */
730
731 /**
732 * @defgroup opt_write Setting and modifying option values
733 * @{
734 */
735
736 /**
737 * Parse the key/value pairs list in opts. For each key/value pair
738 * found, stores the value in the field in ctx that is named like the
739 * key. ctx must be an AVClass context, storing is done using
740 * AVOptions.
741 *
742 * @param opts options string to parse, may be NULL
743 * @param key_val_sep a 0-terminated list of characters used to
744 * separate key from value
745 * @param pairs_sep a 0-terminated list of characters used to separate
746 * two pairs from each other
747 * @return the number of successfully set key/value pairs, or a negative
748 * value corresponding to an AVERROR code in case of error:
749 * AVERROR(EINVAL) if opts cannot be parsed,
750 * the error code issued by av_opt_set() if a key/value pair
751 * cannot be set
752 */
754 const char *key_val_sep, const char *pairs_sep);
755
756 /**
757 * Parse the key-value pairs list in opts. For each key=value pair found,
758 * set the value of the corresponding option in ctx.
759 *
760 * @param ctx the AVClass object to set options on
761 * @param opts the options string, key-value pairs separated by a
762 * delimiter
763 * @param shorthand a NULL-terminated array of options names for shorthand
764 * notation: if the first field in opts has no key part,
765 * the key is taken from the first element of shorthand;
766 * then again for the second, etc., until either opts is
767 * finished, shorthand is finished or a named option is
768 * found; after that, all options must be named
769 * @param key_val_sep a 0-terminated list of characters used to separate
770 * key from value, for example '='
771 * @param pairs_sep a 0-terminated list of characters used to separate
772 * two pairs from each other, for example ':' or ','
773 * @return the number of successfully set key=value pairs, or a negative
774 * value corresponding to an AVERROR code in case of error:
775 * AVERROR(EINVAL) if opts cannot be parsed,
776 * the error code issued by av_set_string3() if a key/value pair
777 * cannot be set
778 *
779 * Options names must use only the following characters: a-z A-Z 0-9 - . / _
780 * Separators must use characters distinct from option names and from each
781 * other.
782 */
784 const char *const *shorthand,
785 const char *key_val_sep, const char *pairs_sep);
786
787 /**
788 * Set all the options from a given dictionary on an object.
789 *
790 * @param obj a struct whose first element is a pointer to AVClass
791 * @param options options to process. This dictionary will be freed and replaced
792 * by a new one containing all options not found in obj.
793 * Of course this new dictionary needs to be freed by caller
794 * with av_dict_free().
795 *
796 * @return 0 on success, a negative AVERROR if some option was found in obj,
797 * but could not be set.
798 *
799 * @see av_dict_copy()
800 */
802
803
804 /**
805 * Set all the options from a given dictionary on an object.
806 *
807 * @param obj a struct whose first element is a pointer to AVClass
808 * @param options options to process. This dictionary will be freed and replaced
809 * by a new one containing all options not found in obj.
810 * Of course this new dictionary needs to be freed by caller
811 * with av_dict_free().
812 * @param search_flags A combination of AV_OPT_SEARCH_*.
813 *
814 * @return 0 on success, a negative AVERROR if some option was found in obj,
815 * but could not be set.
816 *
817 * @see av_dict_copy()
818 */
820
821 /**
822 * Copy options from src object into dest object.
823 *
824 * The underlying AVClass of both src and dest must coincide. The guarantee
825 * below does not apply if this is not fulfilled.
826 *
827 * Options that require memory allocation (e.g. string or binary) are malloc'ed in dest object.
828 * Original memory allocated for such options is freed unless both src and dest options points to the same memory.
829 *
830 * Even on error it is guaranteed that allocated options from src and dest
831 * no longer alias each other afterwards; in particular calling av_opt_free()
832 * on both src and dest is safe afterwards if dest has been memdup'ed from src.
833 *
834 * @param dest Object to copy from
835 * @param src Object to copy into
836 * @return 0 on success, negative on error
837 */
839
840 /**
841 * @defgroup opt_set_funcs Option setting functions
842 * @{
843 * Those functions set the field of obj with the given name to value.
844 *
845 * @param[in] obj A struct whose first element is a pointer to an AVClass.
846 * @param[in] name the name of the field to set
847 * @param[in] val The value to set. In case of av_opt_set() if the field is not
848 * of a string type, then the given string is parsed.
849 * SI postfixes and some named scalars are supported.
850 * If the field is of a numeric type, it has to be a numeric or named
851 * scalar. Behavior with more than one scalar and +- infix operators
852 * is undefined.
853 * If the field is of a flags type, it has to be a sequence of numeric
854 * scalars or named flags separated by '+' or '-'. Prefixing a flag
855 * with '+' causes it to be set without affecting the other flags;
856 * similarly, '-' unsets a flag.
857 * If the field is of a dictionary type, it has to be a ':' separated list of
858 * key=value parameters. Values containing ':' special characters must be
859 * escaped.
860 * @param search_flags flags passed to av_opt_find2. I.e. if AV_OPT_SEARCH_CHILDREN
861 * is passed here, then the option may be set on a child of obj.
862 *
863 * @return 0 if the value has been set, or an AVERROR code in case of
864 * error:
865 * AVERROR_OPTION_NOT_FOUND if no matching option exists
866 * AVERROR(ERANGE) if the value is out of range
867 * AVERROR(EINVAL) if the value is not valid
868 */
878 /**
879 * @note Any old chlayout present is discarded and replaced with a copy of the new one. The
880 * caller still owns layout and is responsible for uninitializing it.
881 */
883 /**
884 * @note Any old dictionary present is discarded and replaced with a copy of the new one. The
885 * caller still owns val is and responsible for freeing it.
886 */
888
889 #if FF_API_OPT_INT_LIST
890 /**
891 * Set a binary option to an integer list.
892 *
893 * @param obj AVClass object to set options on
894 * @param name name of the binary option
895 * @param val pointer to an integer list (must have the correct type with
896 * regard to the contents of the list)
897 * @param term list terminator (usually 0 or -1)
898 * @param flags search flags
899 */
900 #define av_opt_set_int_list(obj, name, val, term, flags) \
901 (av_int_list_length(val, term) > INT_MAX / sizeof(*(val)) ? \
902 AVERROR(EINVAL) : \
903 av_opt_set_bin(obj, name, (const uint8_t *)(val), \
904 av_int_list_length(val, term) * sizeof(*(val)), flags))
905 #endif
906
907 /**
908 * Add, replace, or remove elements for an array option. Which of these
909 * operations is performed depends on the values of val and search_flags.
910 *
911 * @param start_elem Index of the first array element to modify; must not be
912 * larger than array size as returned by
913 * av_opt_get_array_size().
914 * @param nb_elems number of array elements to modify; when val is NULL,
915 * start_elem+nb_elems must not be larger than array size as
916 * returned by av_opt_get_array_size()
917 *
918 * @param val_type Option type corresponding to the type of val, ignored when val is
919 * NULL.
920 *
921 * The effect of this function will will be as if av_opt_setX()
922 * was called for each element, where X is specified by type.
923 * E.g. AV_OPT_TYPE_STRING corresponds to av_opt_set().
924 *
925 * Typically this should be the same as the scalarized type of
926 * the AVOption being set, but certain conversions are also
927 * possible - the same as those done by the corresponding
928 * av_opt_set*() function. E.g. any option type can be set from
929 * a string, numeric types can be set from int64, double, or
930 * rational, etc.
931 *
932 * @param val Array with nb_elems elements or NULL.
933 *
934 * When NULL, nb_elems array elements starting at start_elem are
935 * removed from the array. Any array elements remaining at the end
936 * are shifted by nb_elems towards the first element in order to keep
937 * the array contiguous.
938 *
939 * Otherwise (val is non-NULL), the type of val must match the
940 * underlying C type as documented for val_type.
941 *
942 * When AV_OPT_ARRAY_REPLACE is not set in search_flags, the array is
943 * enlarged by nb_elems, and the contents of val are inserted at
944 * start_elem. Previously existing array elements from start_elem
945 * onwards (if present) are shifted by nb_elems away from the first
946 * element in order to make space for the new elements.
947 *
948 * When AV_OPT_ARRAY_REPLACE is set in search_flags, the contents
949 * of val replace existing array elements from start_elem to
950 * start_elem+nb_elems (if present). New array size is
951 * max(start_elem + nb_elems, old array size).
952 */
954 unsigned int start_elem, unsigned int nb_elems,
956
957 /**
958 * @}
959 * @}
960 */
961
962 /**
963 * @defgroup opt_read Reading option values
964 * @{
965 */
966
967 /**
968 * @defgroup opt_get_funcs Option getting functions
969 * @{
970 * Those functions get a value of the option with the given name from an object.
971 *
972 * @param[in] obj a struct whose first element is a pointer to an AVClass.
973 * @param[in] name name of the option to get.
974 * @param[in] search_flags flags passed to av_opt_find2. I.e. if AV_OPT_SEARCH_CHILDREN
975 * is passed here, then the option may be found in a child of obj.
976 * @param[out] out_val value of the option will be written here
977 * @return >=0 on success, a negative error code otherwise
978 */
979 /**
980 * @note the returned string will be av_malloc()ed and must be av_free()ed by the caller
981 *
982 * @note if AV_OPT_ALLOW_NULL is set in search_flags in av_opt_get, and the
983 * option is of type AV_OPT_TYPE_STRING, AV_OPT_TYPE_BINARY or AV_OPT_TYPE_DICT
984 * and is set to NULL, *out_val will be set to NULL instead of an allocated
985 * empty string.
986 */
987 int av_opt_get (
void *obj,
const char *
name,
int search_flags, uint8_t **out_val);
995 /**
996 * @param[out] layout The returned layout is a copy of the actual value and must
997 * be freed with av_channel_layout_uninit() by the caller
998 */
1000 /**
1001 * @param[out] out_val The returned dictionary is a copy of the actual value and must
1002 * be freed with av_dict_free() by the caller
1003 */
1005
1006 /**
1007 * For an array-type option, get the number of elements in the array.
1008 */
1010 unsigned int *out_val);
1011
1012 /**
1013 * For an array-type option, retrieve the values of one or more array elements.
1014 *
1015 * @param start_elem index of the first array element to retrieve
1016 * @param nb_elems number of array elements to retrieve; start_elem+nb_elems
1017 * must not be larger than array size as returned by
1018 * av_opt_get_array_size()
1019 *
1020 * @param out_type Option type corresponding to the desired output.
1021 *
1022 * The array elements produced by this function will
1023 * will be as if av_opt_getX() was called for each element,
1024 * where X is specified by out_type. E.g. AV_OPT_TYPE_STRING
1025 * corresponds to av_opt_get().
1026 *
1027 * Typically this should be the same as the scalarized type of
1028 * the AVOption being retrieved, but certain conversions are
1029 * also possible - the same as those done by the corresponding
1030 * av_opt_get*() function. E.g. any option type can be retrieved
1031 * as a string, numeric types can be retrieved as int64, double,
1032 * or rational, etc.
1033 *
1034 * @param out_val Array with nb_elems members into which the output will be
1035 * written. The array type must match the underlying C type as
1036 * documented for out_type, and be zeroed on entry to this
1037 * function.
1038 *
1039 * For dynamically allocated types (strings, binary, dicts,
1040 * etc.), the result is owned and freed by the caller.
1041 */
1043 unsigned int start_elem, unsigned int nb_elems,
1045 /**
1046 * @}
1047 */
1048
1049 /**
1050 * @defgroup opt_eval_funcs Evaluating option strings
1051 * @{
1052 * This group of functions can be used to evaluate option strings
1053 * and get numbers out of them. They do the same thing as av_opt_set(),
1054 * except the result is written into the caller-supplied pointer.
1055 *
1056 * @param obj a struct whose first element is a pointer to AVClass.
1057 * @param o an option for which the string is to be evaluated.
1058 * @param val string to be evaluated.
1059 * @param *_out value of the string will be written here.
1060 *
1061 * @return 0 on success, a negative number on failure.
1062 */
1070 /**
1071 * @}
1072 */
1073
1074 #if FF_API_OPT_PTR
1075 /**
1076 * Gets a pointer to the requested field in a struct.
1077 * This function allows accessing a struct even when its fields are moved or
1078 * renamed since the application making the access has been compiled,
1079 *
1080 * @returns a pointer to the field, it can be cast to the correct type and read
1081 * or written to.
1082 *
1083 * @deprecated direct access to AVOption-exported fields is not supported
1084 */
1087 #endif
1088
1089 /**
1090 * Check if given option is set to its default value.
1091 *
1092 * Options o must belong to the obj. This function must not be called to check child's options state.
1093 * @see av_opt_is_set_to_default_by_name().
1094 *
1095 * @param obj AVClass object to check option on
1096 * @param o option to be checked
1097 * @return >0 when option is set to its default,
1098 * 0 when option is not set its default,
1099 * <0 on error
1100 */
1102
1103 /**
1104 * Check if given option is set to its default value.
1105 *
1106 * @param obj AVClass object to check option on
1107 * @param name option name
1108 * @param search_flags combination of AV_OPT_SEARCH_*
1109 * @return >0 when option is set to its default,
1110 * 0 when option is not set its default,
1111 * <0 on error
1112 */
1114
1115 /**
1116 * Check whether a particular flag is set in a flags field.
1117 *
1118 * @param field_name the name of the flag field option
1119 * @param flag_name the name of the flag to check
1120 * @return non-zero if the flag is set, zero if the flag isn't set,
1121 * isn't of the right type, or the flags field doesn't exist.
1122 */
1124
1125 #define AV_OPT_SERIALIZE_SKIP_DEFAULTS 0x00000001 ///< Serialize options that are not set to default values only.
1126 #define AV_OPT_SERIALIZE_OPT_FLAGS_EXACT 0x00000002
///< Serialize options that exactly match opt_flags only.
1127 #define AV_OPT_SERIALIZE_SEARCH_CHILDREN 0x00000004
///< Serialize options in possible children of the given object.
1128
1129 /**
1130 * Serialize object's options.
1131 *
1132 * Create a string containing object's serialized options.
1133 * Such string may be passed back to av_opt_set_from_string() in order to restore option values.
1134 * A key/value or pairs separator occurring in the serialized value or
1135 * name string are escaped through the av_escape() function.
1136 *
1137 * @param[in] obj AVClass object to serialize
1138 * @param[in] opt_flags serialize options with all the specified flags set (AV_OPT_FLAG)
1139 * @param[in] flags combination of AV_OPT_SERIALIZE_* flags
1140 * @param[out] buffer Pointer to buffer that will be allocated with string containing serialized options.
1141 * Buffer must be freed by the caller when is no longer needed.
1142 * @param[in] key_val_sep character used to separate key from value
1143 * @param[in] pairs_sep character used to separate two pairs from each other
1144 * @return >= 0 on success, negative on error
1145 * @warning Separators cannot be neither '\\' nor '0円'. They also cannot be the same.
1146 */
1148 const char key_val_sep, const char pairs_sep);
1149
1150 /**
1151 * @}
1152 */
1153
1154 /**
1155 * Free an AVOptionRanges struct and set it to NULL.
1156 */
1158
1159 /**
1160 * Get a list of allowed ranges for the given option.
1161 *
1162 * The returned list may depend on other fields in obj like for example profile.
1163 *
1164 * @param flags is a bitmask of flags, undefined flags should not be set and should be ignored
1165 * AV_OPT_SEARCH_FAKE_OBJ indicates that the obj is a double pointer to a AVClass instead of a full instance
1166 * AV_OPT_MULTI_COMPONENT_RANGE indicates that function may return more than one component, @see AVOptionRanges
1167 *
1168 * The result must be freed with av_opt_freep_ranges.
1169 *
1170 * @return number of components returned on success, a negative error code otherwise
1171 */
1173
1174 /**
1175 * Get a default list of allowed ranges for the given option.
1176 *
1177 * This list is constructed without using the AVClass.query_ranges() callback
1178 * and can be used as fallback from within the callback.
1179 *
1180 * @param flags is a bitmask of flags, undefined flags should not be set and should be ignored
1181 * AV_OPT_SEARCH_FAKE_OBJ indicates that the obj is a double pointer to a AVClass instead of a full instance
1182 * AV_OPT_MULTI_COMPONENT_RANGE indicates that function may return more than one component, @see AVOptionRanges
1183 *
1184 * The result must be freed with av_opt_free_ranges.
1185 *
1186 * @return number of components returned on success, a negative error code otherwise
1187 */
1189
1190 /**
1191 * @}
1192 */
1193
1194 #endif /* AVUTIL_OPT_H */