AVOption (un)initialization and inspection.

Macros
#define	AV_OPT_SEARCH_CHILDREN   (1 << 0)
	Search in possible children of the given object first.
#define	AV_OPT_SEARCH_FAKE_OBJ   (1 << 1)
	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.
#define	AV_OPT_ALLOW_NULL   (1 << 2)
	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_ARRAY_REPLACE   (1 << 3)
	May be used with av_opt_set_array() to signal that new elements should replace the existing ones in the indicated range.
#define	AV_OPT_MULTI_COMPONENT_RANGE   (1 << 12)
	Allows av_opt_query_ranges and av_opt_query_ranges_default to return more than one component for certain option types.

Enumerations
enum	{ AV_OPT_FLAG_IMPLICIT_KEY = 1 }

Functions
void	av_opt_set_defaults (void *s)
	Set the values of all AVOption fields to their default values.
void	av_opt_set_defaults2 (void *s, int mask, int flags)
	Set the values of all AVOption fields to their default values.
void	av_opt_free (void *obj)
	Free all allocated objects in obj.
const AVOption *	av_opt_next (const void *obj, const AVOption *prev)
	Iterate over all AVOptions belonging to obj.
void *	av_opt_child_next (void *obj, void *prev)
	Iterate over AVOptions-enabled children of obj.
const AVClass *	av_opt_child_class_iterate (const AVClass *parent, void **iter)
	Iterate over potential AVOptions-enabled children of parent.
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.
const AVOption *	av_opt_find2 (void *obj, const char *name, const char *unit, int opt_flags, int search_flags, void **target_obj)
	Look for an option in an object.
int	av_opt_show2 (void *obj, void *av_log_obj, int req_flags, int rej_flags)
	Show the obj options.
int	av_opt_get_key_value (const char **ropts, const char *key_val_sep, const char *pairs_sep, unsigned flags, char **rkey, char **rval)
	Extract a key-value pair from the beginning of a string.

Detailed Description

Macro Definition Documentation

AV_OPT_SEARCH_CHILDREN

#define AV_OPT_SEARCH_CHILDREN   (1 << 0)

Search in possible children of the given object first.

Examples

decode_filter_audio.c, decode_filter_video.c, filter_audio.c, and transcode.c.

Definition at line 606 of file opt.h.

AV_OPT_SEARCH_FAKE_OBJ

#define AV_OPT_SEARCH_FAKE_OBJ   (1 << 1)

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.

Definition at line 613 of file opt.h.

AV_OPT_ALLOW_NULL

#define AV_OPT_ALLOW_NULL   (1 << 2)

In av_opt_get, return NULL if the option has a pointer type and is set to NULL, rather than returning an empty string.

Definition at line 619 of file opt.h.

AV_OPT_ARRAY_REPLACE

#define AV_OPT_ARRAY_REPLACE   (1 << 3)

May be used with av_opt_set_array() to signal that new elements should replace the existing ones in the indicated range.

Definition at line 625 of file opt.h.

AV_OPT_MULTI_COMPONENT_RANGE

#define AV_OPT_MULTI_COMPONENT_RANGE   (1 << 12)

Allows av_opt_query_ranges and av_opt_query_ranges_default to return more than one component for certain option types.

See also

AVOptionRanges for details.

Definition at line 632 of file opt.h.

Enumeration Type Documentation

anonymous enum

anonymous enum

Enumerator
AV_OPT_FLAG_IMPLICIT_KEY	Accept to parse a value without a key; the key will then be returned as NULL.

Definition at line 718 of file opt.h.

Function Documentation

av_opt_set_defaults()

void av_opt_set_defaults

(

void *

s

)

Set the values of all AVOption fields to their default values.

Parameters

s	an AVOption-enabled struct (its first member must be a pointer to AVClass)

av_opt_set_defaults2()

void av_opt_set_defaults2	(	void *	s,
		int	mask,
		int	flags
	)

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.

Parameters

s	an AVOption-enabled struct (its first member must be a pointer to AVClass)
mask	combination of AV_OPT_FLAG_*
flags	combination of AV_OPT_FLAG_*

av_opt_free()

void av_opt_free

(

void *

obj

)

Free all allocated objects in obj.

av_opt_next()

const AVOption * av_opt_next	(	const void *	obj,
		const AVOption *	prev
	)

Iterate over all AVOptions belonging to obj.

Parameters

obj	an AVOptions-enabled struct or a double pointer to an AVClass describing it.
prev	result of the previous call to av_opt_next() on this object or NULL

Returns

next AVOption or NULL

av_opt_child_next()

void * av_opt_child_next	(	void *	obj,
		void *	prev
	)

Iterate over AVOptions-enabled children of obj.

Parameters

prev	result of a previous call to this function or NULL

Returns

next AVOptions-enabled child or NULL

av_opt_child_class_iterate()

const AVClass * av_opt_child_class_iterate	(	const AVClass *	parent,
		void **	iter
	)

Iterate over potential AVOptions-enabled children of parent.

Parameters

iter	a pointer where iteration state is stored.

Returns

AVClass corresponding to next potential child or NULL

av_opt_find()

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.

Parameters

[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.
[in]	name	The name of the option to look for.
[in]	unit	When searching for named constants, name of the unit it belongs to.
	opt_flags	Find only options with all the specified flags set (AV_OPT_FLAG).
	search_flags	A combination of AV_OPT_SEARCH_*.

Returns

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.

av_opt_find2()

const AVOption * av_opt_find2	(	void *	obj,
		const char *	name,
		const char *	unit,
		int	opt_flags,
		int	search_flags,
		void **	target_obj
	)

Look for an option in an object.

Consider only options which have all the specified flags set.

Parameters

[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.
[in]	name	The name of the option to look for.
[in]	unit	When searching for named constants, name of the unit it belongs to.
	opt_flags	Find only options with all the specified flags set (AV_OPT_FLAG).
	search_flags	A combination of AV_OPT_SEARCH_*.
[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.

Returns

A pointer to the option found, or NULL if no option was found.

av_opt_show2()

int av_opt_show2	(	void *	obj,
		void *	av_log_obj,
		int	req_flags,
		int	rej_flags
	)

Show the obj options.

Parameters

req_flags	requested flags for the options to show. Show only the options for which it is opt->flags & req_flags.
rej_flags	rejected flags for the options to show. Show only the options for which it is !(opt->flags & req_flags).
av_log_obj	log context to use for showing the options

av_opt_get_key_value()

int av_opt_get_key_value	(	const char **	ropts,
		const char *	key_val_sep,
		const char *	pairs_sep,
		unsigned	flags,
		char **	rkey,
		char **	rval
	)

Extract a key-value pair from the beginning of a string.

Parameters

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)
key_val_sep	a 0-terminated list of characters used to separate key from value, for example '='
pairs_sep	a 0-terminated list of characters used to separate two pairs from each other, for example ':' or ','
flags	flags; see the AV_OPT_FLAG_* values below
rkey	parsed key; must be freed using av_free()
rval	parsed value; must be freed using av_free()

Returns

>=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