3 * copyright (c) 2005 Michael Niedermayer <michaelni@gmx.at>
5 * This file is part of FFmpeg.
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.
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.
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
35 #include "samplefmt.h"
39 * @defgroup avoptions AVOptions
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.
46 * @section avoptions_implement Implementing AVOptions
47 * This section describes how to add AVOptions capabilities to a struct.
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.
58 * The following example illustrates an AVOptions-enabled struct:
60 * typedef struct test_struct {
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 },
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,
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
91 * When cleaning up, you may use the av_opt_free() function to automatically
92 * free all the allocated string and binary options.
94 * Continuing with the above example:
97 * test_struct *alloc_test_struct(void)
99 * test_struct *ret = av_malloc(sizeof(*ret));
100 * ret->class = &test_class;
101 * av_opt_set_defaults(ret);
104 * void free_test_struct(test_struct **foo)
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_next() in the
118 * parent struct's AVClass.
119 * Assuming that the test_struct from above now also contains a
120 * child_struct field:
123 * typedef struct 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 },
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,
139 * void *child_next(void *obj, void *prev)
141 * test_struct *t = obj;
142 * if (!prev && t->child_struct)
143 * return t->child_struct;
146 * const AVClass child_class_next(const AVClass *prev)
148 * return prev ? NULL : &child_class;
151 * Putting child_next() and child_class_next() as defined above into
152 * test_class will now make child_struct's options accessible through
153 * test_struct (again, proper setup as described above needs to be done on
154 * child_struct right after it is created).
156 * From the above example it might not be clear why both child_next()
157 * and child_class_next() are needed. The distinction is that child_next()
158 * iterates over actually existing objects, while child_class_next()
159 * iterates over all possible child classes. E.g. if an AVCodecContext
160 * was initialized to use a codec which has private options, then its
161 * child_next() will return AVCodecContext.priv_data and finish
162 * iterating. OTOH child_class_next() on AVCodecContext.av_class will
163 * iterate over all available codecs with private options.
165 * @subsection avoptions_implement_named_constants Named constants
166 * It is possible to create named constants for options. Simply set the unit
167 * field of the option the constants should apply to a string and
168 * create the constants themselves as options of type AV_OPT_TYPE_CONST
169 * with their unit field set to the same string.
170 * Their default_val field should contain the value of the named
172 * For example, to add some named constants for the test_flags option
173 * above, put the following into the child_opts array:
175 * { "test_flags", "This is a test option of flags type.",
176 * offsetof(child_struct, flags_opt), AV_OPT_TYPE_FLAGS, { .i64 = 0 }, INT_MIN, INT_MAX, "test_unit" },
177 * { "flag1", "This is a flag with value 16", 0, AV_OPT_TYPE_CONST, { .i64 = 16 }, 0, 0, "test_unit" },
180 * @section avoptions_use Using AVOptions
181 * This section deals with accessing options in an AVOptions-enabled struct.
182 * Such structs in FFmpeg are e.g. AVCodecContext in libavcodec or
183 * AVFormatContext in libavformat.
185 * @subsection avoptions_use_examine Examining AVOptions
186 * The basic functions for examining options are av_opt_next(), which iterates
187 * over all options defined for one object, and av_opt_find(), which searches
188 * for an option with the given name.
190 * The situation is more complicated with nesting. An AVOptions-enabled struct
191 * may have AVOptions-enabled children. Passing the AV_OPT_SEARCH_CHILDREN flag
192 * to av_opt_find() will make the function search children recursively.
194 * For enumerating there are basically two cases. The first is when you want to
195 * get all options that may potentially exist on the struct and its children
196 * (e.g. when constructing documentation). In that case you should call
197 * av_opt_child_class_next() recursively on the parent struct's AVClass. The
198 * second case is when you have an already initialized struct with all its
199 * children and you want to get all options that can be actually written or read
200 * from it. In that case you should call av_opt_child_next() recursively (and
201 * av_opt_next() on each result).
203 * @subsection avoptions_use_get_set Reading and writing AVOptions
204 * When setting options, you often have a string read directly from the
205 * user. In such a case, simply passing it to av_opt_set() is enough. For
206 * non-string type options, av_opt_set() will parse the string according to the
209 * Similarly av_opt_get() will read any option type and convert it to a string
210 * which will be returned. Do not forget that the string is allocated, so you
211 * have to free it with av_free().
213 * In some cases it may be more convenient to put all options into an
214 * AVDictionary and call av_opt_set_dict() on it. A specific case of this
215 * are the format/codec open functions in lavf/lavc which take a dictionary
216 * filled with option as a parameter. This makes it possible to set some options
217 * that cannot be set otherwise, since e.g. the input file format is not known
218 * before the file is actually opened.
228 AV_OPT_TYPE_RATIONAL,
229 AV_OPT_TYPE_BINARY, ///< offset must point to a pointer immediately followed by an int for the length
231 AV_OPT_TYPE_CONST = 128,
232 AV_OPT_TYPE_IMAGE_SIZE = MKBETAG('S','I','Z','E'), ///< offset must point to two consecutive integers
233 AV_OPT_TYPE_PIXEL_FMT = MKBETAG('P','F','M','T'),
234 AV_OPT_TYPE_SAMPLE_FMT = MKBETAG('S','F','M','T'),
235 AV_OPT_TYPE_VIDEO_RATE = MKBETAG('V','R','A','T'), ///< offset must point to AVRational
236 AV_OPT_TYPE_DURATION = MKBETAG('D','U','R',' '),
237 AV_OPT_TYPE_COLOR = MKBETAG('C','O','L','R'),
238 AV_OPT_TYPE_CHANNEL_LAYOUT = MKBETAG('C','H','L','A'),
244 typedef struct AVOption {
248 * short English help text
249 * @todo What about other languages?
254 * The offset relative to the context structure where the option
255 * value is stored. It should be 0 for named constants.
258 enum AVOptionType type;
261 * the default value for scalar options
267 /* TODO those are unused now */
270 double min; ///< minimum valid value for the option
271 double max; ///< maximum valid value for the option
274 #define AV_OPT_FLAG_ENCODING_PARAM 1 ///< a generic parameter which can be set by the user for muxing or encoding
275 #define AV_OPT_FLAG_DECODING_PARAM 2 ///< a generic parameter which can be set by the user for demuxing or decoding
276 #if FF_API_OPT_TYPE_METADATA
277 #define AV_OPT_FLAG_METADATA 4 ///< some data extracted or inserted into the file like title, comment, ...
279 #define AV_OPT_FLAG_AUDIO_PARAM 8
280 #define AV_OPT_FLAG_VIDEO_PARAM 16
281 #define AV_OPT_FLAG_SUBTITLE_PARAM 32
283 * The option is inteded for exporting values to the caller.
285 #define AV_OPT_FLAG_EXPORT 64
287 * The option may not be set through the AVOptions API, only read.
288 * This flag only makes sense when AV_OPT_FLAG_EXPORT is also set.
290 #define AV_OPT_FLAG_READONLY 128
291 #define AV_OPT_FLAG_FILTERING_PARAM (1<<16) ///< a generic parameter which can be set by the user for filtering
292 //FIXME think about enc-audio, ... style flags
295 * The logical unit to which the option belongs. Non-constant
296 * options and corresponding named constants share the same
303 * A single allowed range of values, or a single allowed value.
305 typedef struct AVOptionRange {
309 * For string ranges this represents the min/max length.
310 * For dimensions this represents the min/max pixel count or width/height in multi-component case.
312 double value_min, value_max;
314 * Value's component range.
315 * For string this represents the unicode range for chars, 0-127 limits to ASCII.
317 double component_min, component_max;
320 * If set to 1 the struct encodes a range, if set to 0 a single value.
326 * List of AVOptionRange structs.
328 typedef struct AVOptionRanges {
330 * Array of option ranges.
332 * Most of option types use just one component.
333 * Following describes multi-component option types:
335 * AV_OPT_TYPE_IMAGE_SIZE:
336 * component index 0: range of pixel count (width * height).
337 * component index 1: range of width.
338 * component index 2: range of height.
340 * @note To obtain multi-component version of this structure, user must
341 * provide AV_OPT_MULTI_COMPONENT_RANGE to av_opt_query_ranges or
342 * av_opt_query_ranges_default function.
344 * Multi-component range can be read as in following example:
347 * int range_index, component_index;
348 * AVOptionRanges *ranges;
349 * AVOptionRange *range[3]; //may require more than 3 in the future.
350 * av_opt_query_ranges(&ranges, obj, key, AV_OPT_MULTI_COMPONENT_RANGE);
351 * for (range_index = 0; range_index < ranges->nb_ranges; range_index++) {
352 * for (component_index = 0; component_index < ranges->nb_components; component_index++)
353 * range[component_index] = ranges->range[ranges->nb_ranges * component_index + range_index];
354 * //do something with range here.
356 * av_opt_freep_ranges(&ranges);
359 AVOptionRange **range;
361 * Number of ranges per component.
365 * Number of componentes.
371 * Show the obj options.
373 * @param req_flags requested flags for the options to show. Show only the
374 * options for which it is opt->flags & req_flags.
375 * @param rej_flags rejected flags for the options to show. Show only the
376 * options for which it is !(opt->flags & req_flags).
377 * @param av_log_obj log context to use for showing the options
379 int av_opt_show2(void *obj, void *av_log_obj, int req_flags, int rej_flags);
382 * Set the values of all AVOption fields to their default values.
384 * @param s an AVOption-enabled struct (its first member must be a pointer to AVClass)
386 void av_opt_set_defaults(void *s);
389 * Set the values of all AVOption fields to their default values. Only these
390 * AVOption fields for which (opt->flags & mask) == flags will have their
391 * default applied to s.
393 * @param s an AVOption-enabled struct (its first member must be a pointer to AVClass)
394 * @param mask combination of AV_OPT_FLAG_*
395 * @param flags combination of AV_OPT_FLAG_*
397 void av_opt_set_defaults2(void *s, int mask, int flags);
400 * Parse the key/value pairs list in opts. For each key/value pair
401 * found, stores the value in the field in ctx that is named like the
402 * key. ctx must be an AVClass context, storing is done using
405 * @param opts options string to parse, may be NULL
406 * @param key_val_sep a 0-terminated list of characters used to
407 * separate key from value
408 * @param pairs_sep a 0-terminated list of characters used to separate
409 * two pairs from each other
410 * @return the number of successfully set key/value pairs, or a negative
411 * value corresponding to an AVERROR code in case of error:
412 * AVERROR(EINVAL) if opts cannot be parsed,
413 * the error code issued by av_opt_set() if a key/value pair
416 int av_set_options_string(void *ctx, const char *opts,
417 const char *key_val_sep, const char *pairs_sep);
420 * Parse the key-value pairs list in opts. For each key=value pair found,
421 * set the value of the corresponding option in ctx.
423 * @param ctx the AVClass object to set options on
424 * @param opts the options string, key-value pairs separated by a
426 * @param shorthand a NULL-terminated array of options names for shorthand
427 * notation: if the first field in opts has no key part,
428 * the key is taken from the first element of shorthand;
429 * then again for the second, etc., until either opts is
430 * finished, shorthand is finished or a named option is
431 * found; after that, all options must be named
432 * @param key_val_sep a 0-terminated list of characters used to separate
433 * key from value, for example '='
434 * @param pairs_sep a 0-terminated list of characters used to separate
435 * two pairs from each other, for example ':' or ','
436 * @return the number of successfully set key=value pairs, or a negative
437 * value corresponding to an AVERROR code in case of error:
438 * AVERROR(EINVAL) if opts cannot be parsed,
439 * the error code issued by av_set_string3() if a key/value pair
442 * Options names must use only the following characters: a-z A-Z 0-9 - . / _
443 * Separators must use characters distinct from option names and from each
446 int av_opt_set_from_string(void *ctx, const char *opts,
447 const char *const *shorthand,
448 const char *key_val_sep, const char *pairs_sep);
450 * Free all allocated objects in obj.
452 void av_opt_free(void *obj);
455 * Check whether a particular flag is set in a flags field.
457 * @param field_name the name of the flag field option
458 * @param flag_name the name of the flag to check
459 * @return non-zero if the flag is set, zero if the flag isn't set,
460 * isn't of the right type, or the flags field doesn't exist.
462 int av_opt_flag_is_set(void *obj, const char *field_name, const char *flag_name);
465 * Set all the options from a given dictionary on an object.
467 * @param obj a struct whose first element is a pointer to AVClass
468 * @param options options to process. This dictionary will be freed and replaced
469 * by a new one containing all options not found in obj.
470 * Of course this new dictionary needs to be freed by caller
471 * with av_dict_free().
473 * @return 0 on success, a negative AVERROR if some option was found in obj,
474 * but could not be set.
476 * @see av_dict_copy()
478 int av_opt_set_dict(void *obj, struct AVDictionary **options);
482 * Set all the options from a given dictionary on an object.
484 * @param obj a struct whose first element is a pointer to AVClass
485 * @param options options to process. This dictionary will be freed and replaced
486 * by a new one containing all options not found in obj.
487 * Of course this new dictionary needs to be freed by caller
488 * with av_dict_free().
489 * @param search_flags A combination of AV_OPT_SEARCH_*.
491 * @return 0 on success, a negative AVERROR if some option was found in obj,
492 * but could not be set.
494 * @see av_dict_copy()
496 int av_opt_set_dict2(void *obj, struct AVDictionary **options, int search_flags);
499 * Extract a key-value pair from the beginning of a string.
501 * @param ropts pointer to the options string, will be updated to
502 * point to the rest of the string (one of the pairs_sep
504 * @param key_val_sep a 0-terminated list of characters used to separate
505 * key from value, for example '='
506 * @param pairs_sep a 0-terminated list of characters used to separate
507 * two pairs from each other, for example ':' or ','
508 * @param flags flags; see the AV_OPT_FLAG_* values below
509 * @param rkey parsed key; must be freed using av_free()
510 * @param rval parsed value; must be freed using av_free()
512 * @return >=0 for success, or a negative value corresponding to an
513 * AVERROR code in case of error; in particular:
514 * AVERROR(EINVAL) if no key is present
517 int av_opt_get_key_value(const char **ropts,
518 const char *key_val_sep, const char *pairs_sep,
520 char **rkey, char **rval);
525 * Accept to parse a value without a key; the key will then be returned
528 AV_OPT_FLAG_IMPLICIT_KEY = 1,
532 * @defgroup opt_eval_funcs Evaluating option strings
534 * This group of functions can be used to evaluate option strings
535 * and get numbers out of them. They do the same thing as av_opt_set(),
536 * except the result is written into the caller-supplied pointer.
538 * @param obj a struct whose first element is a pointer to AVClass.
539 * @param o an option for which the string is to be evaluated.
540 * @param val string to be evaluated.
541 * @param *_out value of the string will be written here.
543 * @return 0 on success, a negative number on failure.
545 int av_opt_eval_flags (void *obj, const AVOption *o, const char *val, int *flags_out);
546 int av_opt_eval_int (void *obj, const AVOption *o, const char *val, int *int_out);
547 int av_opt_eval_int64 (void *obj, const AVOption *o, const char *val, int64_t *int64_out);
548 int av_opt_eval_float (void *obj, const AVOption *o, const char *val, float *float_out);
549 int av_opt_eval_double(void *obj, const AVOption *o, const char *val, double *double_out);
550 int av_opt_eval_q (void *obj, const AVOption *o, const char *val, AVRational *q_out);
555 #define AV_OPT_SEARCH_CHILDREN 0x0001 /**< Search in possible children of the
556 given object first. */
558 * The obj passed to av_opt_find() is fake -- only a double pointer to AVClass
559 * instead of a required pointer to a struct containing AVClass. This is
560 * useful for searching for options without needing to allocate the corresponding
563 #define AV_OPT_SEARCH_FAKE_OBJ 0x0002
566 * Allows av_opt_query_ranges and av_opt_query_ranges_default to return more than
567 * one component for certain option types.
568 * @see AVOptionRanges for details.
570 #define AV_OPT_MULTI_COMPONENT_RANGE 0x1000
573 * Look for an option in an object. Consider only options which
574 * have all the specified flags set.
576 * @param[in] obj A pointer to a struct whose first element is a
577 * pointer to an AVClass.
578 * Alternatively a double pointer to an AVClass, if
579 * AV_OPT_SEARCH_FAKE_OBJ search flag is set.
580 * @param[in] name The name of the option to look for.
581 * @param[in] unit When searching for named constants, name of the unit
583 * @param opt_flags Find only options with all the specified flags set (AV_OPT_FLAG).
584 * @param search_flags A combination of AV_OPT_SEARCH_*.
586 * @return A pointer to the option found, or NULL if no option
589 * @note Options found with AV_OPT_SEARCH_CHILDREN flag may not be settable
590 * directly with av_opt_set(). Use special calls which take an options
591 * AVDictionary (e.g. avformat_open_input()) to set options found with this
594 const AVOption *av_opt_find(void *obj, const char *name, const char *unit,
595 int opt_flags, int search_flags);
598 * Look for an option in an object. Consider only options which
599 * have all the specified flags set.
601 * @param[in] obj A pointer to a struct whose first element is a
602 * pointer to an AVClass.
603 * Alternatively a double pointer to an AVClass, if
604 * AV_OPT_SEARCH_FAKE_OBJ search flag is set.
605 * @param[in] name The name of the option to look for.
606 * @param[in] unit When searching for named constants, name of the unit
608 * @param opt_flags Find only options with all the specified flags set (AV_OPT_FLAG).
609 * @param search_flags A combination of AV_OPT_SEARCH_*.
610 * @param[out] target_obj if non-NULL, an object to which the option belongs will be
611 * written here. It may be different from obj if AV_OPT_SEARCH_CHILDREN is present
612 * in search_flags. This parameter is ignored if search_flags contain
613 * AV_OPT_SEARCH_FAKE_OBJ.
615 * @return A pointer to the option found, or NULL if no option
618 const AVOption *av_opt_find2(void *obj, const char *name, const char *unit,
619 int opt_flags, int search_flags, void **target_obj);
622 * Iterate over all AVOptions belonging to obj.
624 * @param obj an AVOptions-enabled struct or a double pointer to an
625 * AVClass describing it.
626 * @param prev result of the previous call to av_opt_next() on this object
628 * @return next AVOption or NULL
630 const AVOption *av_opt_next(const void *obj, const AVOption *prev);
633 * Iterate over AVOptions-enabled children of obj.
635 * @param prev result of a previous call to this function or NULL
636 * @return next AVOptions-enabled child or NULL
638 void *av_opt_child_next(void *obj, void *prev);
641 * Iterate over potential AVOptions-enabled children of parent.
643 * @param prev result of a previous call to this function or NULL
644 * @return AVClass corresponding to next potential child or NULL
646 const AVClass *av_opt_child_class_next(const AVClass *parent, const AVClass *prev);
649 * @defgroup opt_set_funcs Option setting functions
651 * Those functions set the field of obj with the given name to value.
653 * @param[in] obj A struct whose first element is a pointer to an AVClass.
654 * @param[in] name the name of the field to set
655 * @param[in] val The value to set. In case of av_opt_set() if the field is not
656 * of a string type, then the given string is parsed.
657 * SI postfixes and some named scalars are supported.
658 * If the field is of a numeric type, it has to be a numeric or named
659 * scalar. Behavior with more than one scalar and +- infix operators
661 * If the field is of a flags type, it has to be a sequence of numeric
662 * scalars or named flags separated by '+' or '-'. Prefixing a flag
663 * with '+' causes it to be set without affecting the other flags;
664 * similarly, '-' unsets a flag.
665 * @param search_flags flags passed to av_opt_find2. I.e. if AV_OPT_SEARCH_CHILDREN
666 * is passed here, then the option may be set on a child of obj.
668 * @return 0 if the value has been set, or an AVERROR code in case of
670 * AVERROR_OPTION_NOT_FOUND if no matching option exists
671 * AVERROR(ERANGE) if the value is out of range
672 * AVERROR(EINVAL) if the value is not valid
674 int av_opt_set (void *obj, const char *name, const char *val, int search_flags);
675 int av_opt_set_int (void *obj, const char *name, int64_t val, int search_flags);
676 int av_opt_set_double (void *obj, const char *name, double val, int search_flags);
677 int av_opt_set_q (void *obj, const char *name, AVRational val, int search_flags);
678 int av_opt_set_bin (void *obj, const char *name, const uint8_t *val, int size, int search_flags);
679 int av_opt_set_image_size(void *obj, const char *name, int w, int h, int search_flags);
680 int av_opt_set_pixel_fmt (void *obj, const char *name, enum AVPixelFormat fmt, int search_flags);
681 int av_opt_set_sample_fmt(void *obj, const char *name, enum AVSampleFormat fmt, int search_flags);
682 int av_opt_set_video_rate(void *obj, const char *name, AVRational val, int search_flags);
683 int av_opt_set_channel_layout(void *obj, const char *name, int64_t ch_layout, int search_flags);
685 * @note Any old dictionary present is discarded and replaced with a copy of the new one. The
686 * caller still owns val is and responsible for freeing it.
688 int av_opt_set_dict_val(void *obj, const char *name, const AVDictionary *val, int search_flags);
691 * Set a binary option to an integer list.
693 * @param obj AVClass object to set options on
694 * @param name name of the binary option
695 * @param val pointer to an integer list (must have the correct type with
696 * regard to the contents of the list)
697 * @param term list terminator (usually 0 or -1)
698 * @param flags search flags
700 #define av_opt_set_int_list(obj, name, val, term, flags) \
701 (av_int_list_length(val, term) > INT_MAX / sizeof(*(val)) ? \
703 av_opt_set_bin(obj, name, (const uint8_t *)(val), \
704 av_int_list_length(val, term) * sizeof(*(val)), flags))
711 * @defgroup opt_get_funcs Option getting functions
713 * Those functions get a value of the option with the given name from an object.
715 * @param[in] obj a struct whose first element is a pointer to an AVClass.
716 * @param[in] name name of the option to get.
717 * @param[in] search_flags flags passed to av_opt_find2. I.e. if AV_OPT_SEARCH_CHILDREN
718 * is passed here, then the option may be found in a child of obj.
719 * @param[out] out_val value of the option will be written here
720 * @return >=0 on success, a negative error code otherwise
723 * @note the returned string will be av_malloc()ed and must be av_free()ed by the caller
725 int av_opt_get (void *obj, const char *name, int search_flags, uint8_t **out_val);
726 int av_opt_get_int (void *obj, const char *name, int search_flags, int64_t *out_val);
727 int av_opt_get_double (void *obj, const char *name, int search_flags, double *out_val);
728 int av_opt_get_q (void *obj, const char *name, int search_flags, AVRational *out_val);
729 int av_opt_get_image_size(void *obj, const char *name, int search_flags, int *w_out, int *h_out);
730 int av_opt_get_pixel_fmt (void *obj, const char *name, int search_flags, enum AVPixelFormat *out_fmt);
731 int av_opt_get_sample_fmt(void *obj, const char *name, int search_flags, enum AVSampleFormat *out_fmt);
732 int av_opt_get_video_rate(void *obj, const char *name, int search_flags, AVRational *out_val);
733 int av_opt_get_channel_layout(void *obj, const char *name, int search_flags, int64_t *ch_layout);
735 * @param[out] out_val The returned dictionary is a copy of the actual value and must
736 * be freed with av_dict_free() by the caller
738 int av_opt_get_dict_val(void *obj, const char *name, int search_flags, AVDictionary **out_val);
743 * Gets a pointer to the requested field in a struct.
744 * This function allows accessing a struct even when its fields are moved or
745 * renamed since the application making the access has been compiled,
747 * @returns a pointer to the field, it can be cast to the correct type and read
750 void *av_opt_ptr(const AVClass *avclass, void *obj, const char *name);
753 * Free an AVOptionRanges struct and set it to NULL.
755 void av_opt_freep_ranges(AVOptionRanges **ranges);
758 * Get a list of allowed ranges for the given option.
760 * The returned list may depend on other fields in obj like for example profile.
762 * @param flags is a bitmask of flags, undefined flags should not be set and should be ignored
763 * AV_OPT_SEARCH_FAKE_OBJ indicates that the obj is a double pointer to a AVClass instead of a full instance
764 * AV_OPT_MULTI_COMPONENT_RANGE indicates that function may return more than one component, @see AVOptionRanges
766 * The result must be freed with av_opt_freep_ranges.
768 * @return number of compontents returned on success, a negative errro code otherwise
770 int av_opt_query_ranges(AVOptionRanges **, void *obj, const char *key, int flags);
773 * Copy options from src object into dest object.
775 * Options that require memory allocation (e.g. string or binary) are malloc'ed in dest object.
776 * Original memory allocated for such options is freed unless both src and dest options points to the same memory.
778 * @param dest Object to copy from
779 * @param src Object to copy into
780 * @return 0 on success, negative on error
782 int av_opt_copy(void *dest, const void *src);
785 * Get a default list of allowed ranges for the given option.
787 * This list is constructed without using the AVClass.query_ranges() callback
788 * and can be used as fallback from within the callback.
790 * @param flags is a bitmask of flags, undefined flags should not be set and should be ignored
791 * AV_OPT_SEARCH_FAKE_OBJ indicates that the obj is a double pointer to a AVClass instead of a full instance
792 * AV_OPT_MULTI_COMPONENT_RANGE indicates that function may return more than one component, @see AVOptionRanges
794 * The result must be freed with av_opt_free_ranges.
796 * @return number of compontents returned on success, a negative errro code otherwise
798 int av_opt_query_ranges_default(AVOptionRanges **, void *obj, const char *key, int flags);
801 * Check if given option is set to its default value.
803 * Options o must belong to the obj. This function must not be called to check child's options state.
804 * @see av_opt_is_set_to_default_by_name().
806 * @param obj AVClass object to check option on
807 * @param o option to be checked
808 * @return >0 when option is set to its default,
809 * 0 when option is not set its default,
812 int av_opt_is_set_to_default(void *obj, const AVOption *o);
815 * Check if given option is set to its default value.
817 * @param obj AVClass object to check option on
818 * @param name option name
819 * @param search_flags combination of AV_OPT_SEARCH_*
820 * @return >0 when option is set to its default,
821 * 0 when option is not set its default,
824 int av_opt_is_set_to_default_by_name(void *obj, const char *name, int search_flags);
827 #define AV_OPT_SERIALIZE_SKIP_DEFAULTS 0x00000001 ///< Serialize options that are not set to default values only.
828 #define AV_OPT_SERIALIZE_OPT_FLAGS_EXACT 0x00000002 ///< Serialize options that exactly match opt_flags only.
831 * Serialize object's options.
833 * Create a string containing object's serialized options.
834 * Such string may be passed back to av_opt_set_from_string() in order to restore option values.
835 * A key/value or pairs separator occurring in the serialized value or
836 * name string are escaped through the av_escape() function.
838 * @param[in] obj AVClass object to serialize
839 * @param[in] opt_flags serialize options with all the specified flags set (AV_OPT_FLAG)
840 * @param[in] flags combination of AV_OPT_SERIALIZE_* flags
841 * @param[out] buffer Pointer to buffer that will be allocated with string containg serialized options.
842 * Buffer must be freed by the caller when is no longer needed.
843 * @param[in] key_val_sep character used to separate key from value
844 * @param[in] pairs_sep character used to separate two pairs from each other
845 * @return >= 0 on success, negative on error
846 * @warning Separators cannot be neither '\\' nor '\0'. They also cannot be the same.
848 int av_opt_serialize(void *obj, int opt_flags, int flags, char **buffer,
849 const char key_val_sep, const char pairs_sep);
854 #endif /* AVUTIL_OPT_H */