Describe the class of an AVClass context structure. More...

#include <libavutil/log.h>

Data Fields
const char *	class_name
	The name of the class; usually it is the same name as the context structure type to which the AVClass is associated.

const char (	item_name )(void *ctx)
	A pointer to a function which returns the name of a context instance ctx associated with the class.

const struct AVOption *	option
	a pointer to the first option specified in the class if any or NULL

int	version
	LIBAVUTIL_VERSION with which this structure was created.

int	log_level_offset_offset
	Offset in the structure where log_level_offset is stored.

int	parent_log_context_offset
	Offset in the structure where a pointer to the parent context for logging is stored.

AVClassCategory	category
	Category used for visualization (like color) This is only set if the category is equal for all objects using this class.

AVClassCategory(*	get_category )(void *ctx)
	Callback to return the category.

int(*	query_ranges )(struct AVOptionRanges *, void obj, const char *key, int flags)
	Callback to return the supported/allowed ranges.

void (	child_next )(void obj, void prev)
	Return next AVOptions-enabled child or NULL.

const struct AVClass (	child_class_iterate )(void **iter)
	Iterate over the AVClasses corresponding to potential AVOptions-enabled children.

Detailed Description

Describe the class of an AVClass context structure.

That is an arbitrary struct of which the first field is a pointer to an AVClass struct (e.g. AVCodecContext, AVFormatContext etc.).

Definition at line 66 of file log.h.

Field Documentation

◆ class_name

const char* AVClass::class_name

The name of the class; usually it is the same name as the context structure type to which the AVClass is associated.

Definition at line 71 of file log.h.

◆ item_name

const char *(* AVClass::item_name) (void *ctx)

A pointer to a function which returns the name of a context instance ctx associated with the class.

Definition at line 77 of file log.h.

◆ option

const struct AVOption* AVClass::option

a pointer to the first option specified in the class if any or NULL

See also: av_set_default_options()

Definition at line 84 of file log.h.

◆ version

int AVClass::version

LIBAVUTIL_VERSION with which this structure was created.

This is used to allow fields to be added without requiring major version bumps everywhere.

Definition at line 92 of file log.h.

◆ log_level_offset_offset

int AVClass::log_level_offset_offset

Offset in the structure where log_level_offset is stored.

0 means there is no such variable

Definition at line 98 of file log.h.

◆ parent_log_context_offset

int AVClass::parent_log_context_offset

Offset in the structure where a pointer to the parent context for logging is stored.

For example a decoder could pass its AVCodecContext to eval as such a parent context, which an av_log() implementation could then leverage to display the parent context. The offset can be NULL.

Definition at line 107 of file log.h.

◆ category

AVClassCategory AVClass::category

Category used for visualization (like color) This is only set if the category is equal for all objects using this class.

available since version (51 << 16 | 56 << 8 | 100)

Definition at line 114 of file log.h.

◆ get_category

AVClassCategory(* AVClass::get_category) (void *ctx)

Callback to return the category.

available since version (51 << 16 | 59 << 8 | 100)

Definition at line 120 of file log.h.

◆ query_ranges

int(* AVClass::query_ranges) (struct AVOptionRanges **, void *obj, const char *key, int flags)

Callback to return the supported/allowed ranges.

available since version (52.12)

Definition at line 126 of file log.h.

◆ child_next

void *(* AVClass::child_next) (void *obj, void *prev)

Return next AVOptions-enabled child or NULL.

Definition at line 131 of file log.h.

◆ child_class_iterate

const struct AVClass *(* AVClass::child_class_iterate) (void **iter)

Iterate over the AVClasses corresponding to potential AVOptions-enabled children.

Parameters

iter	pointer to opaque iteration state. The caller must initialize *iter to NULL before the first call.

Returns: AVClass for the next AVOptions-enabled child or NULL if there are no more such children.

Note: The difference between child_next and this is that child_next iterates over already existing objects, while child_class_iterate iterates over all possible children.