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FFmpeg/libavutil/opt.h
Anton Khirnov fc706276c0 lavu/opt: distinguish between native and foreign access for AVOption fields 
Native access is from the code that declared the options, foreign access
is from code that is using the options. Forbid foreign access to
AVOption.offset/default_val, for which there is no good reason, and
which should allow us more freedom in extending their semantics in a
compatible way.
2024-03-08 07:24:50 +01:00

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/*
* AVOptions
* copyright (c) 2005 Michael Niedermayer <michaelni@gmx.at>
*
* This file is part of FFmpeg.
*
* FFmpeg is free software; you can redistribute it and/or
* modify it under the terms of the GNU Lesser General Public
* License as published by the Free Software Foundation; either
* version 2.1 of the License, or (at your option) any later version.
*
* FFmpeg is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
* Lesser General Public License for more details.
*
* You should have received a copy of the GNU Lesser General Public
* License along with FFmpeg; if not, write to the Free Software
* Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
*/
#ifndef AVUTIL_OPT_H
#define AVUTIL_OPT_H
/**
* @file
* AVOptions
*/
#include "rational.h"
#include "avutil.h"
#include "channel_layout.h"
#include "dict.h"
#include "log.h"
#include "pixfmt.h"
#include "samplefmt.h"
/**
* @defgroup avoptions AVOptions
* @ingroup lavu_data
* @{
* AVOptions provide a generic system to declare options on arbitrary structs
* ("objects"). An option can have a help text, a type and a range of possible
* values. Options may then be enumerated, read and written to.
*
* There are two modes of access to members of AVOption and its child structs.
* One is called 'native access', and refers to access from the code that
* declares the AVOption in question. The other is 'foreign access', and refers
* to access from other code.
*
* Certain struct members in this header are documented as 'native access only'
* or similar - it means that only the code that declared the AVOption in
* question is allowed to access the field. This allows us to extend the
* semantics of those fields without breaking API compatibility.
*
* @section avoptions_implement Implementing AVOptions
* This section describes how to add AVOptions capabilities to a struct.
*
* All AVOptions-related information is stored in an AVClass. Therefore
* the first member of the struct should be a pointer to an AVClass describing it.
* The option field of the AVClass must be set to a NULL-terminated static array
* of AVOptions. Each AVOption must have a non-empty name, a type, a default
* value and for number-type AVOptions also a range of allowed values. It must
* also declare an offset in bytes from the start of the struct, where the field
* associated with this AVOption is located. Other fields in the AVOption struct
* should also be set when applicable, but are not required.
*
* The following example illustrates an AVOptions-enabled struct:
* @code
* typedef struct test_struct {
* const AVClass *class;
* int int_opt;
* char *str_opt;
* uint8_t *bin_opt;
* int bin_len;
* } test_struct;
*
* static const AVOption test_options[] = {
* { "test_int", "This is a test option of int type.", offsetof(test_struct, int_opt),
* AV_OPT_TYPE_INT, { .i64 = -1 }, INT_MIN, INT_MAX },
* { "test_str", "This is a test option of string type.", offsetof(test_struct, str_opt),
* AV_OPT_TYPE_STRING },
* { "test_bin", "This is a test option of binary type.", offsetof(test_struct, bin_opt),
* AV_OPT_TYPE_BINARY },
* { NULL },
* };
*
* static const AVClass test_class = {
* .class_name = "test class",
* .item_name = av_default_item_name,
* .option = test_options,
* .version = LIBAVUTIL_VERSION_INT,
* };
* @endcode
*
* Next, when allocating your struct, you must ensure that the AVClass pointer
* is set to the correct value. Then, av_opt_set_defaults() can be called to
* initialize defaults. After that the struct is ready to be used with the
* AVOptions API.
*
* When cleaning up, you may use the av_opt_free() function to automatically
* free all the allocated string and binary options.
*
* Continuing with the above example:
*
* @code
* test_struct *alloc_test_struct(void)
* {
* test_struct *ret = av_mallocz(sizeof(*ret));
* ret->class = &test_class;
* av_opt_set_defaults(ret);
* return ret;
* }
* void free_test_struct(test_struct **foo)
* {
* av_opt_free(*foo);
* av_freep(foo);
* }
* @endcode
*
* @subsection avoptions_implement_nesting Nesting
* It may happen that an AVOptions-enabled struct contains another
* AVOptions-enabled struct as a member (e.g. AVCodecContext in
* libavcodec exports generic options, while its priv_data field exports
* codec-specific options). In such a case, it is possible to set up the
* parent struct to export a child's options. To do that, simply
* implement AVClass.child_next() and AVClass.child_class_iterate() in the
* parent struct's AVClass.
* Assuming that the test_struct from above now also contains a
* child_struct field:
*
* @code
* typedef struct child_struct {
* AVClass *class;
* int flags_opt;
* } child_struct;
* static const AVOption child_opts[] = {
* { "test_flags", "This is a test option of flags type.",
* offsetof(child_struct, flags_opt), AV_OPT_TYPE_FLAGS, { .i64 = 0 }, INT_MIN, INT_MAX },
* { NULL },
* };
* static const AVClass child_class = {
* .class_name = "child class",
* .item_name = av_default_item_name,
* .option = child_opts,
* .version = LIBAVUTIL_VERSION_INT,
* };
*
* void *child_next(void *obj, void *prev)
* {
* test_struct *t = obj;
* if (!prev && t->child_struct)
* return t->child_struct;
* return NULL
* }
* const AVClass child_class_iterate(void **iter)
* {
* const AVClass *c = *iter ? NULL : &child_class;
* *iter = (void*)(uintptr_t)c;
* return c;
* }
* @endcode
* Putting child_next() and child_class_iterate() as defined above into
* test_class will now make child_struct's options accessible through
* test_struct (again, proper setup as described above needs to be done on
* child_struct right after it is created).
*
* From the above example it might not be clear why both child_next()
* and child_class_iterate() are needed. The distinction is that child_next()
* iterates over actually existing objects, while child_class_iterate()
* iterates over all possible child classes. E.g. if an AVCodecContext
* was initialized to use a codec which has private options, then its
* child_next() will return AVCodecContext.priv_data and finish
* iterating. OTOH child_class_iterate() on AVCodecContext.av_class will
* iterate over all available codecs with private options.
*
* @subsection avoptions_implement_named_constants Named constants
* It is possible to create named constants for options. Simply set the unit
* field of the option the constants should apply to a string and
* create the constants themselves as options of type AV_OPT_TYPE_CONST
* with their unit field set to the same string.
* Their default_val field should contain the value of the named
* constant.
* For example, to add some named constants for the test_flags option
* above, put the following into the child_opts array:
* @code
* { "test_flags", "This is a test option of flags type.",
* offsetof(child_struct, flags_opt), AV_OPT_TYPE_FLAGS, { .i64 = 0 }, INT_MIN, INT_MAX, "test_unit" },
* { "flag1", "This is a flag with value 16", 0, AV_OPT_TYPE_CONST, { .i64 = 16 }, 0, 0, "test_unit" },
* @endcode
*
* @section avoptions_use Using AVOptions
* This section deals with accessing options in an AVOptions-enabled struct.
* Such structs in FFmpeg are e.g. AVCodecContext in libavcodec or
* AVFormatContext in libavformat.
*
* @subsection avoptions_use_examine Examining AVOptions
* The basic functions for examining options are av_opt_next(), which iterates
* over all options defined for one object, and av_opt_find(), which searches
* for an option with the given name.
*
* The situation is more complicated with nesting. An AVOptions-enabled struct
* may have AVOptions-enabled children. Passing the AV_OPT_SEARCH_CHILDREN flag
* to av_opt_find() will make the function search children recursively.
*
* For enumerating there are basically two cases. The first is when you want to
* get all options that may potentially exist on the struct and its children
* (e.g. when constructing documentation). In that case you should call
* av_opt_child_class_iterate() recursively on the parent struct's AVClass. The
* second case is when you have an already initialized struct with all its
* children and you want to get all options that can be actually written or read
* from it. In that case you should call av_opt_child_next() recursively (and
* av_opt_next() on each result).
*
* @subsection avoptions_use_get_set Reading and writing AVOptions
* When setting options, you often have a string read directly from the
* user. In such a case, simply passing it to av_opt_set() is enough. For
* non-string type options, av_opt_set() will parse the string according to the
* option type.
*
* Similarly av_opt_get() will read any option type and convert it to a string
* which will be returned. Do not forget that the string is allocated, so you
* have to free it with av_free().
*
* In some cases it may be more convenient to put all options into an
* AVDictionary and call av_opt_set_dict() on it. A specific case of this
* are the format/codec open functions in lavf/lavc which take a dictionary
* filled with option as a parameter. This makes it possible to set some options
* that cannot be set otherwise, since e.g. the input file format is not known
* before the file is actually opened.
*/
enum AVOptionType{
AV_OPT_TYPE_FLAGS = 1,
AV_OPT_TYPE_INT,
AV_OPT_TYPE_INT64,
AV_OPT_TYPE_DOUBLE,
AV_OPT_TYPE_FLOAT,
AV_OPT_TYPE_STRING,
AV_OPT_TYPE_RATIONAL,
AV_OPT_TYPE_BINARY, ///< offset must point to a pointer immediately followed by an int for the length
AV_OPT_TYPE_DICT,
AV_OPT_TYPE_UINT64,
AV_OPT_TYPE_CONST,
AV_OPT_TYPE_IMAGE_SIZE, ///< offset must point to two consecutive integers
AV_OPT_TYPE_PIXEL_FMT,
AV_OPT_TYPE_SAMPLE_FMT,
AV_OPT_TYPE_VIDEO_RATE, ///< offset must point to AVRational
AV_OPT_TYPE_DURATION,
AV_OPT_TYPE_COLOR,
AV_OPT_TYPE_BOOL,
AV_OPT_TYPE_CHLAYOUT,
};
/**
* A generic parameter which can be set by the user for muxing or encoding.
*/
#define AV_OPT_FLAG_ENCODING_PARAM (1 << 0)
/**
* A generic parameter which can be set by the user for demuxing or decoding.
*/
#define AV_OPT_FLAG_DECODING_PARAM (1 << 1)
#define AV_OPT_FLAG_AUDIO_PARAM (1 << 3)
#define AV_OPT_FLAG_VIDEO_PARAM (1 << 4)
#define AV_OPT_FLAG_SUBTITLE_PARAM (1 << 5)
/**
* The option is intended for exporting values to the caller.
*/
#define AV_OPT_FLAG_EXPORT (1 << 6)
/**
* The option may not be set through the AVOptions API, only read.
* This flag only makes sense when AV_OPT_FLAG_EXPORT is also set.
*/
#define AV_OPT_FLAG_READONLY (1 << 7)
/**
* A generic parameter which can be set by the user for bit stream filtering.
*/
#define AV_OPT_FLAG_BSF_PARAM (1 << 8)
/**
* A generic parameter which can be set by the user at runtime.
*/
#define AV_OPT_FLAG_RUNTIME_PARAM (1 << 15)
/**
* A generic parameter which can be set by the user for filtering.
*/
#define AV_OPT_FLAG_FILTERING_PARAM (1 << 16)
/**
* Set if option is deprecated, users should refer to AVOption.help text for
* more information.
*/
#define AV_OPT_FLAG_DEPRECATED (1 << 17)
/**
* Set if option constants can also reside in child objects.
*/
#define AV_OPT_FLAG_CHILD_CONSTS (1 << 18)
/**
* AVOption
*/
typedef struct AVOption {
const char *name;
/**
* short English help text
* @todo What about other languages?
*/
const char *help;
/**
* Native access only.
*
* The offset relative to the context structure where the option
* value is stored. It should be 0 for named constants.
*/
int offset;
enum AVOptionType type;
/**
* Native access only.
*
* the default value for scalar options
*/
union {
int64_t i64;
double dbl;
const char *str;
/* TODO those are unused now */
AVRational q;
} default_val;
double min; ///< minimum valid value for the option
double max; ///< maximum valid value for the option
/**
* A combination of AV_OPT_FLAG_*.
*/
int flags;
/**
* The logical unit to which the option belongs. Non-constant
* options and corresponding named constants share the same
* unit. May be NULL.
*/
const char *unit;
} AVOption;
/**
* A single allowed range of values, or a single allowed value.
*/
typedef struct AVOptionRange {
const char *str;
/**
* Value range.
* For string ranges this represents the min/max length.
* For dimensions this represents the min/max pixel count or width/height in multi-component case.
*/
double value_min, value_max;
/**
* Value's component range.
* For string this represents the unicode range for chars, 0-127 limits to ASCII.
*/
double component_min, component_max;
/**
* Range flag.
* If set to 1 the struct encodes a range, if set to 0 a single value.
*/
int is_range;
} AVOptionRange;
/**
* List of AVOptionRange structs.
*/
typedef struct AVOptionRanges {
/**
* Array of option ranges.
*
* Most of option types use just one component.
* Following describes multi-component option types:
*
* AV_OPT_TYPE_IMAGE_SIZE:
* component index 0: range of pixel count (width * height).
* component index 1: range of width.
* component index 2: range of height.
*
* @note To obtain multi-component version of this structure, user must
* provide AV_OPT_MULTI_COMPONENT_RANGE to av_opt_query_ranges or
* av_opt_query_ranges_default function.
*
* Multi-component range can be read as in following example:
*
* @code
* int range_index, component_index;
* AVOptionRanges *ranges;
* AVOptionRange *range[3]; //may require more than 3 in the future.
* av_opt_query_ranges(&ranges, obj, key, AV_OPT_MULTI_COMPONENT_RANGE);
* for (range_index = 0; range_index < ranges->nb_ranges; range_index++) {
* for (component_index = 0; component_index < ranges->nb_components; component_index++)
* range[component_index] = ranges->range[ranges->nb_ranges * component_index + range_index];
* //do something with range here.
* }
* av_opt_freep_ranges(&ranges);
* @endcode
*/
AVOptionRange **range;
/**
* Number of ranges per component.
*/
int nb_ranges;
/**
* Number of componentes.
*/
int nb_components;
} AVOptionRanges;
/**
* @defgroup opt_mng AVOption (un)initialization and inspection.
* @{
*/
/**
* Set the values of all AVOption fields to their default values.
*
* @param s an AVOption-enabled struct (its first member must be a pointer to AVClass)
*/
void av_opt_set_defaults(void *s);
/**
* Set the values of all AVOption fields to their default values. Only these
* AVOption fields for which (opt->flags & mask) == flags will have their
* default applied to s.
*
* @param s an AVOption-enabled struct (its first member must be a pointer to AVClass)
* @param mask combination of AV_OPT_FLAG_*
* @param flags combination of AV_OPT_FLAG_*
*/
void av_opt_set_defaults2(void *s, int mask, int flags);
/**
* Free all allocated objects in obj.
*/
void av_opt_free(void *obj);
/**
* Iterate over all AVOptions belonging to obj.
*
* @param obj an AVOptions-enabled struct or a double pointer to an
* AVClass describing it.
* @param prev result of the previous call to av_opt_next() on this object
* or NULL
* @return next AVOption or NULL
*/
const AVOption *av_opt_next(const void *obj, const AVOption *prev);
/**
* Iterate over AVOptions-enabled children of obj.
*
* @param prev result of a previous call to this function or NULL
* @return next AVOptions-enabled child or NULL
*/
void *av_opt_child_next(void *obj, void *prev);
/**
* Iterate over potential AVOptions-enabled children of parent.
*
* @param iter a pointer where iteration state is stored.
* @return AVClass corresponding to next potential child or NULL
*/
const AVClass *av_opt_child_class_iterate(const AVClass *parent, void **iter);
#define AV_OPT_SEARCH_CHILDREN (1 << 0) /**< Search in possible children of the
given object first. */
/**
* The obj passed to av_opt_find() is fake -- only a double pointer to AVClass
* instead of a required pointer to a struct containing AVClass. This is
* useful for searching for options without needing to allocate the corresponding
* object.
*/
#define AV_OPT_SEARCH_FAKE_OBJ (1 << 1)
/**
* In av_opt_get, return NULL if the option has a pointer type and is set to NULL,
* rather than returning an empty string.
*/
#define AV_OPT_ALLOW_NULL (1 << 2)
/**
* Allows av_opt_query_ranges and av_opt_query_ranges_default to return more than
* one component for certain option types.
* @see AVOptionRanges for details.
*/
#define AV_OPT_MULTI_COMPONENT_RANGE (1 << 12)
/**
* Look for an option in an object. Consider only options which
* have all the specified flags set.
*
* @param[in] obj A pointer to a struct whose first element is a
* pointer to an AVClass.
* Alternatively a double pointer to an AVClass, if
* AV_OPT_SEARCH_FAKE_OBJ search flag is set.
* @param[in] name The name of the option to look for.
* @param[in] unit When searching for named constants, name of the unit
* it belongs to.
* @param opt_flags Find only options with all the specified flags set (AV_OPT_FLAG).
* @param search_flags A combination of AV_OPT_SEARCH_*.
*
* @return A pointer to the option found, or NULL if no option
* was found.
*
* @note Options found with AV_OPT_SEARCH_CHILDREN flag may not be settable
* directly with av_opt_set(). Use special calls which take an options
* AVDictionary (e.g. avformat_open_input()) to set options found with this
* flag.
*/
const AVOption *av_opt_find(void *obj, const char *name, const char *unit,
int opt_flags, int search_flags);
/**
* Look for an option in an object. Consider only options which
* have all the specified flags set.
*
* @param[in] obj A pointer to a struct whose first element is a
* pointer to an AVClass.
* Alternatively a double pointer to an AVClass, if
* AV_OPT_SEARCH_FAKE_OBJ search flag is set.
* @param[in] name The name of the option to look for.
* @param[in] unit When searching for named constants, name of the unit
* it belongs to.
* @param opt_flags Find only options with all the specified flags set (AV_OPT_FLAG).
* @param search_flags A combination of AV_OPT_SEARCH_*.
* @param[out] target_obj if non-NULL, an object to which the option belongs will be
* written here. It may be different from obj if AV_OPT_SEARCH_CHILDREN is present
* in search_flags. This parameter is ignored if search_flags contain
* AV_OPT_SEARCH_FAKE_OBJ.
*
* @return A pointer to the option found, or NULL if no option
* was found.
*/
const AVOption *av_opt_find2(void *obj, const char *name, const char *unit,
int opt_flags, int search_flags, void **target_obj);
/**
* Show the obj options.
*
* @param req_flags requested flags for the options to show. Show only the
* options for which it is opt->flags & req_flags.
* @param rej_flags rejected flags for the options to show. Show only the
* options for which it is !(opt->flags & req_flags).
* @param av_log_obj log context to use for showing the options
*/
int av_opt_show2(void *obj, void *av_log_obj, int req_flags, int rej_flags);
/**
* Extract a key-value pair from the beginning of a string.
*
* @param ropts pointer to the options string, will be updated to
* point to the rest of the string (one of the pairs_sep
* or the final NUL)
* @param key_val_sep a 0-terminated list of characters used to separate
* key from value, for example '='
* @param pairs_sep a 0-terminated list of characters used to separate
* two pairs from each other, for example ':' or ','
* @param flags flags; see the AV_OPT_FLAG_* values below
* @param rkey parsed key; must be freed using av_free()
* @param rval parsed value; must be freed using av_free()
*
* @return >=0 for success, or a negative value corresponding to an
* AVERROR code in case of error; in particular:
* AVERROR(EINVAL) if no key is present
*
*/
int av_opt_get_key_value(const char **ropts,
const char *key_val_sep, const char *pairs_sep,
unsigned flags,
char **rkey, char **rval);
enum {
/**
* Accept to parse a value without a key; the key will then be returned
* as NULL.
*/
AV_OPT_FLAG_IMPLICIT_KEY = 1,
};
/**
* @}
*/
/**
* @defgroup opt_write Setting and modifying option values
* @{
*/
/**
* Parse the key/value pairs list in opts. For each key/value pair
* found, stores the value in the field in ctx that is named like the
* key. ctx must be an AVClass context, storing is done using
* AVOptions.
*
* @param opts options string to parse, may be NULL
* @param key_val_sep a 0-terminated list of characters used to
* separate key from value
* @param pairs_sep a 0-terminated list of characters used to separate
* two pairs from each other
* @return the number of successfully set key/value pairs, or a negative
* value corresponding to an AVERROR code in case of error:
* AVERROR(EINVAL) if opts cannot be parsed,
* the error code issued by av_opt_set() if a key/value pair
* cannot be set
*/
int av_set_options_string(void *ctx, const char *opts,
const char *key_val_sep, const char *pairs_sep);
/**
* Parse the key-value pairs list in opts. For each key=value pair found,
* set the value of the corresponding option in ctx.
*
* @param ctx the AVClass object to set options on
* @param opts the options string, key-value pairs separated by a
* delimiter
* @param shorthand a NULL-terminated array of options names for shorthand
* notation: if the first field in opts has no key part,
* the key is taken from the first element of shorthand;
* then again for the second, etc., until either opts is
* finished, shorthand is finished or a named option is
* found; after that, all options must be named
* @param key_val_sep a 0-terminated list of characters used to separate
* key from value, for example '='
* @param pairs_sep a 0-terminated list of characters used to separate
* two pairs from each other, for example ':' or ','
* @return the number of successfully set key=value pairs, or a negative
* value corresponding to an AVERROR code in case of error:
* AVERROR(EINVAL) if opts cannot be parsed,
* the error code issued by av_set_string3() if a key/value pair
* cannot be set
*
* Options names must use only the following characters: a-z A-Z 0-9 - . / _
* Separators must use characters distinct from option names and from each
* other.
*/
int av_opt_set_from_string(void *ctx, const char *opts,
const char *const *shorthand,
const char *key_val_sep, const char *pairs_sep);
/**
* Set all the options from a given dictionary on an object.
*
* @param obj a struct whose first element is a pointer to AVClass
* @param options options to process. This dictionary will be freed and replaced
* by a new one containing all options not found in obj.
* Of course this new dictionary needs to be freed by caller
* with av_dict_free().
*
* @return 0 on success, a negative AVERROR if some option was found in obj,
* but could not be set.
*
* @see av_dict_copy()
*/
int av_opt_set_dict(void *obj, struct AVDictionary **options);
/**
* Set all the options from a given dictionary on an object.
*
* @param obj a struct whose first element is a pointer to AVClass
* @param options options to process. This dictionary will be freed and replaced
* by a new one containing all options not found in obj.
* Of course this new dictionary needs to be freed by caller
* with av_dict_free().
* @param search_flags A combination of AV_OPT_SEARCH_*.
*
* @return 0 on success, a negative AVERROR if some option was found in obj,
* but could not be set.
*
* @see av_dict_copy()
*/
int av_opt_set_dict2(void *obj, struct AVDictionary **options, int search_flags);
/**
* Copy options from src object into dest object.
*
* The underlying AVClass of both src and dest must coincide. The guarantee
* below does not apply if this is not fulfilled.
*
* Options that require memory allocation (e.g. string or binary) are malloc'ed in dest object.
* Original memory allocated for such options is freed unless both src and dest options points to the same memory.
*
* Even on error it is guaranteed that allocated options from src and dest
* no longer alias each other afterwards; in particular calling av_opt_free()
* on both src and dest is safe afterwards if dest has been memdup'ed from src.
*
* @param dest Object to copy from
* @param src Object to copy into
* @return 0 on success, negative on error
*/
int av_opt_copy(void *dest, const void *src);
/**
* @defgroup opt_set_funcs Option setting functions
* @{
* Those functions set the field of obj with the given name to value.
*
* @param[in] obj A struct whose first element is a pointer to an AVClass.
* @param[in] name the name of the field to set
* @param[in] val The value to set. In case of av_opt_set() if the field is not
* of a string type, then the given string is parsed.
* SI postfixes and some named scalars are supported.
* If the field is of a numeric type, it has to be a numeric or named
* scalar. Behavior with more than one scalar and +- infix operators
* is undefined.
* If the field is of a flags type, it has to be a sequence of numeric
* scalars or named flags separated by '+' or '-'. Prefixing a flag
* with '+' causes it to be set without affecting the other flags;
* similarly, '-' unsets a flag.
* If the field is of a dictionary type, it has to be a ':' separated list of
* key=value parameters. Values containing ':' special characters must be
* escaped.
* @param search_flags flags passed to av_opt_find2. I.e. if AV_OPT_SEARCH_CHILDREN
* is passed here, then the option may be set on a child of obj.
*
* @return 0 if the value has been set, or an AVERROR code in case of
* error:
* AVERROR_OPTION_NOT_FOUND if no matching option exists
* AVERROR(ERANGE) if the value is out of range
* AVERROR(EINVAL) if the value is not valid
*/
int av_opt_set (void *obj, const char *name, const char *val, int search_flags);
int av_opt_set_int (void *obj, const char *name, int64_t val, int search_flags);
int av_opt_set_double (void *obj, const char *name, double val, int search_flags);
int av_opt_set_q (void *obj, const char *name, AVRational val, int search_flags);
int av_opt_set_bin (void *obj, const char *name, const uint8_t *val, int size, int search_flags);
int av_opt_set_image_size(void *obj, const char *name, int w, int h, int search_flags);
int av_opt_set_pixel_fmt (void *obj, const char *name, enum AVPixelFormat fmt, int search_flags);
int av_opt_set_sample_fmt(void *obj, const char *name, enum AVSampleFormat fmt, int search_flags);
int av_opt_set_video_rate(void *obj, const char *name, AVRational val, int search_flags);
int av_opt_set_chlayout(void *obj, const char *name, const AVChannelLayout *layout, int search_flags);
/**
* @note Any old dictionary present is discarded and replaced with a copy of the new one. The
* caller still owns val is and responsible for freeing it.
*/
int av_opt_set_dict_val(void *obj, const char *name, const AVDictionary *val, int search_flags);
/**
* Set a binary option to an integer list.
*
* @param obj AVClass object to set options on
* @param name name of the binary option
* @param val pointer to an integer list (must have the correct type with
* regard to the contents of the list)
* @param term list terminator (usually 0 or -1)
* @param flags search flags
*/
#define av_opt_set_int_list(obj, name, val, term, flags) \
(av_int_list_length(val, term) > INT_MAX / sizeof(*(val)) ? \
AVERROR(EINVAL) : \
av_opt_set_bin(obj, name, (const uint8_t *)(val), \
av_int_list_length(val, term) * sizeof(*(val)), flags))
/**
* @}
* @}
*/
/**
* @defgroup opt_read Reading option values
* @{
*/
/**
* @defgroup opt_get_funcs Option getting functions
* @{
* Those functions get a value of the option with the given name from an object.
*
* @param[in] obj a struct whose first element is a pointer to an AVClass.
* @param[in] name name of the option to get.
* @param[in] search_flags flags passed to av_opt_find2. I.e. if AV_OPT_SEARCH_CHILDREN
* is passed here, then the option may be found in a child of obj.
* @param[out] out_val value of the option will be written here
* @return >=0 on success, a negative error code otherwise
*/
/**
* @note the returned string will be av_malloc()ed and must be av_free()ed by the caller
*
* @note if AV_OPT_ALLOW_NULL is set in search_flags in av_opt_get, and the
* option is of type AV_OPT_TYPE_STRING, AV_OPT_TYPE_BINARY or AV_OPT_TYPE_DICT
* and is set to NULL, *out_val will be set to NULL instead of an allocated
* empty string.
*/
int av_opt_get (void *obj, const char *name, int search_flags, uint8_t **out_val);
int av_opt_get_int (void *obj, const char *name, int search_flags, int64_t *out_val);
int av_opt_get_double (void *obj, const char *name, int search_flags, double *out_val);
int av_opt_get_q (void *obj, const char *name, int search_flags, AVRational *out_val);
int av_opt_get_image_size(void *obj, const char *name, int search_flags, int *w_out, int *h_out);
int av_opt_get_pixel_fmt (void *obj, const char *name, int search_flags, enum AVPixelFormat *out_fmt);
int av_opt_get_sample_fmt(void *obj, const char *name, int search_flags, enum AVSampleFormat *out_fmt);
int av_opt_get_video_rate(void *obj, const char *name, int search_flags, AVRational *out_val);
int av_opt_get_chlayout(void *obj, const char *name, int search_flags, AVChannelLayout *layout);
/**
* @param[out] out_val The returned dictionary is a copy of the actual value and must
* be freed with av_dict_free() by the caller
*/
int av_opt_get_dict_val(void *obj, const char *name, int search_flags, AVDictionary **out_val);
/**
* @}
*/
/**
* @defgroup opt_eval_funcs Evaluating option strings
* @{
* This group of functions can be used to evaluate option strings
* and get numbers out of them. They do the same thing as av_opt_set(),
* except the result is written into the caller-supplied pointer.
*
* @param obj a struct whose first element is a pointer to AVClass.
* @param o an option for which the string is to be evaluated.
* @param val string to be evaluated.
* @param *_out value of the string will be written here.
*
* @return 0 on success, a negative number on failure.
*/
int av_opt_eval_flags (void *obj, const AVOption *o, const char *val, int *flags_out);
int av_opt_eval_int (void *obj, const AVOption *o, const char *val, int *int_out);
int av_opt_eval_int64 (void *obj, const AVOption *o, const char *val, int64_t *int64_out);
int av_opt_eval_float (void *obj, const AVOption *o, const char *val, float *float_out);
int av_opt_eval_double(void *obj, const AVOption *o, const char *val, double *double_out);
int av_opt_eval_q (void *obj, const AVOption *o, const char *val, AVRational *q_out);
/**
* @}
*/
/**
* Gets a pointer to the requested field in a struct.
* This function allows accessing a struct even when its fields are moved or
* renamed since the application making the access has been compiled,
*
* @returns a pointer to the field, it can be cast to the correct type and read
* or written to.
*/
void *av_opt_ptr(const AVClass *avclass, void *obj, const char *name);
/**
* Check if given option is set to its default value.
*
* Options o must belong to the obj. This function must not be called to check child's options state.
* @see av_opt_is_set_to_default_by_name().
*
* @param obj AVClass object to check option on
* @param o option to be checked
* @return >0 when option is set to its default,
* 0 when option is not set its default,
* <0 on error
*/
int av_opt_is_set_to_default(void *obj, const AVOption *o);
/**
* Check if given option is set to its default value.
*
* @param obj AVClass object to check option on
* @param name option name
* @param search_flags combination of AV_OPT_SEARCH_*
* @return >0 when option is set to its default,
* 0 when option is not set its default,
* <0 on error
*/
int av_opt_is_set_to_default_by_name(void *obj, const char *name, int search_flags);
/**
* Check whether a particular flag is set in a flags field.
*
* @param field_name the name of the flag field option
* @param flag_name the name of the flag to check
* @return non-zero if the flag is set, zero if the flag isn't set,
* isn't of the right type, or the flags field doesn't exist.
*/
int av_opt_flag_is_set(void *obj, const char *field_name, const char *flag_name);
#define AV_OPT_SERIALIZE_SKIP_DEFAULTS 0x00000001 ///< Serialize options that are not set to default values only.
#define AV_OPT_SERIALIZE_OPT_FLAGS_EXACT 0x00000002 ///< Serialize options that exactly match opt_flags only.
/**
* Serialize object's options.
*
* Create a string containing object's serialized options.
* Such string may be passed back to av_opt_set_from_string() in order to restore option values.
* A key/value or pairs separator occurring in the serialized value or
* name string are escaped through the av_escape() function.
*
* @param[in] obj AVClass object to serialize
* @param[in] opt_flags serialize options with all the specified flags set (AV_OPT_FLAG)
* @param[in] flags combination of AV_OPT_SERIALIZE_* flags
* @param[out] buffer Pointer to buffer that will be allocated with string containg serialized options.
* Buffer must be freed by the caller when is no longer needed.
* @param[in] key_val_sep character used to separate key from value
* @param[in] pairs_sep character used to separate two pairs from each other
* @return >= 0 on success, negative on error
* @warning Separators cannot be neither '\\' nor '\0'. They also cannot be the same.
*/
int av_opt_serialize(void *obj, int opt_flags, int flags, char **buffer,
const char key_val_sep, const char pairs_sep);
/**
* @}
*/
/**
* Free an AVOptionRanges struct and set it to NULL.
*/
void av_opt_freep_ranges(AVOptionRanges **ranges);
/**
* Get a list of allowed ranges for the given option.
*
* The returned list may depend on other fields in obj like for example profile.
*
* @param flags is a bitmask of flags, undefined flags should not be set and should be ignored
* AV_OPT_SEARCH_FAKE_OBJ indicates that the obj is a double pointer to a AVClass instead of a full instance
* AV_OPT_MULTI_COMPONENT_RANGE indicates that function may return more than one component, @see AVOptionRanges
*
* The result must be freed with av_opt_freep_ranges.
*
* @return number of compontents returned on success, a negative errro code otherwise
*/
int av_opt_query_ranges(AVOptionRanges **, void *obj, const char *key, int flags);
/**
* Get a default list of allowed ranges for the given option.
*
* This list is constructed without using the AVClass.query_ranges() callback
* and can be used as fallback from within the callback.
*
* @param flags is a bitmask of flags, undefined flags should not be set and should be ignored
* AV_OPT_SEARCH_FAKE_OBJ indicates that the obj is a double pointer to a AVClass instead of a full instance
* AV_OPT_MULTI_COMPONENT_RANGE indicates that function may return more than one component, @see AVOptionRanges
*
* The result must be freed with av_opt_free_ranges.
*
* @return number of compontents returned on success, a negative errro code otherwise
*/
int av_opt_query_ranges_default(AVOptionRanges **, void *obj, const char *key, int flags);
/**
* @}
*/
#endif /* AVUTIL_OPT_H */
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