Simple key:value store. More...

Data Structures
struct	AVDictionaryEntry

Macros
#define	AV_DICT_MATCH_CASE 1
	Only get an entry with exact-case key match. More...

#define	AV_DICT_IGNORE_SUFFIX 2
	Return first entry in a dictionary whose first part corresponds to the search key, ignoring the suffix of the found key string. More...

#define	AV_DICT_DONT_STRDUP_KEY 4
	Take ownership of a key that's been allocated with av_malloc() or another memory allocation function. More...

#define	AV_DICT_DONT_STRDUP_VAL 8
	Take ownership of a value that's been allocated with av_malloc() or another memory allocation function. More...

#define	AV_DICT_DONT_OVERWRITE 16
	Don't overwrite existing entries. More...

#define	AV_DICT_APPEND 32
	If the entry already exists, append to it. More...

#define	AV_DICT_MULTIKEY 64
	Allow to store several equal keys in the dictionary. More...

Typedefs
typedef struct AVDictionary	AVDictionary

Functions
AVDictionaryEntry *	av_dict_get (const AVDictionary m, const char key, const AVDictionaryEntry *prev, int flags)
	Get a dictionary entry with matching key. More...

int	av_dict_count (const AVDictionary *m)
	Get number of entries in dictionary. More...

int	av_dict_set (AVDictionary *pm, const char key, const char *value, int flags)
	Set the given entry in *pm, overwriting an existing entry. More...

int	av_dict_set_int (AVDictionary *pm, const char key, int64_t value, int flags)
	Convenience wrapper for av_dict_set that converts the value to a string and stores it. More...

int	av_dict_parse_string (AVDictionary *pm, const char str, const char key_val_sep, const char pairs_sep, int flags)
	Parse the key/value pairs list and add the parsed entries to a dictionary. More...

int	av_dict_copy (AVDictionary *dst, const AVDictionary src, int flags)
	Copy entries from one AVDictionary struct into another. More...

void	av_dict_free (AVDictionary **m)
	Free all the memory allocated for an AVDictionary struct and all keys and values. More...

int	av_dict_get_string (const AVDictionary m, char *buffer, const char key_val_sep, const char pairs_sep)
	Get dictionary entries as a string. More...

Detailed Description

Simple key:value store.

Dictionaries are used for storing key:value pairs. To create an AVDictionary, simply pass an address of a NULL pointer to av_dict_set(). NULL can be used as an empty dictionary wherever a pointer to an AVDictionary is required. Use av_dict_get() to retrieve an entry or iterate over all entries and finally av_dict_free() to free the dictionary and all its contents.

AVDictionary *d = NULL;           // "create" an empty dictionary
AVDictionaryEntry *t = NULL;
 
av_dict_set(&d, "foo", "bar", 0); // add an entry
 
char *k = av_strdup("key");       // if your strings are already allocated,
char *v = av_strdup("value");     // you can avoid copying them like this
av_dict_set(&d, k, v, AV_DICT_DONT_STRDUP_KEY | AV_DICT_DONT_STRDUP_VAL);
 
while (t = av_dict_get(d, "", t, AV_DICT_IGNORE_SUFFIX)) {
    <....>                             // iterate over all entries in d
}
av_dict_free(&d);

Macro Definition Documentation

◆ AV_DICT_MATCH_CASE

#define AV_DICT_MATCH_CASE 1

Only get an entry with exact-case key match.

Only relevant in av_dict_get().

Definition at line 67 of file dict.h.

◆ AV_DICT_IGNORE_SUFFIX

#define AV_DICT_IGNORE_SUFFIX 2

Return first entry in a dictionary whose first part corresponds to the search key, ignoring the suffix of the found key string.

Only relevant in av_dict_get().

Examples: metadata.c.

Definition at line 69 of file dict.h.

◆ AV_DICT_DONT_STRDUP_KEY

#define AV_DICT_DONT_STRDUP_KEY 4

Take ownership of a key that's been allocated with av_malloc() or another memory allocation function.

Definition at line 71 of file dict.h.

◆ AV_DICT_DONT_STRDUP_VAL

#define AV_DICT_DONT_STRDUP_VAL 8

Take ownership of a value that's been allocated with av_malloc() or another memory allocation function.

Definition at line 73 of file dict.h.

◆ AV_DICT_DONT_OVERWRITE

#define AV_DICT_DONT_OVERWRITE 16

Don't overwrite existing entries.

Definition at line 74 of file dict.h.

◆ AV_DICT_APPEND

#define AV_DICT_APPEND 32

If the entry already exists, append to it.

Note that no delimiter is added, the strings are simply concatenated.

Definition at line 76 of file dict.h.

◆ AV_DICT_MULTIKEY

#define AV_DICT_MULTIKEY 64

Allow to store several equal keys in the dictionary.

Definition at line 77 of file dict.h.

Typedef Documentation

◆ AVDictionary

typedef struct AVDictionary AVDictionary

Definition at line 84 of file dict.h.

Function Documentation

◆ av_dict_get()

AVDictionaryEntry * av_dict_get	(	const AVDictionary *	m,
		const char *	key,
		const AVDictionaryEntry *	prev,
		int	flags
	)

Get a dictionary entry with matching key.

The returned entry key or value must not be changed, or it will cause undefined behavior.

To iterate through all the dictionary entries, you can set the matching key to the null string "" and set the AV_DICT_IGNORE_SUFFIX flag.

Parameters

prev	Set to the previous matching element to find the next. If set to NULL the first matching element is returned.
key	matching key
flags	a collection of AV_DICT_* flags controlling how the entry is retrieved

Returns: found entry or NULL in case no matching entry was found in the dictionary

Examples: metadata.c.

Referenced by main().

◆ av_dict_count()

int av_dict_count ( const AVDictionary * m )

Get number of entries in dictionary.

Parameters

m	dictionary

Returns: number of entries in dictionary

◆ av_dict_set()

int av_dict_set	(	AVDictionary **	pm,
		const char *	key,
		const char *	value,
		int	flags
	)

Set the given entry in *pm, overwriting an existing entry.

Note: If AV_DICT_DONT_STRDUP_KEY or AV_DICT_DONT_STRDUP_VAL is set, these arguments will be freed on error.

Warning: Adding a new entry to a dictionary invalidates all existing entries previously returned with av_dict_get.

Parameters

pm	pointer to a pointer to a dictionary struct. If pm is NULL a dictionary struct is allocated and put in pm.
key	entry key to add to *pm (will either be av_strduped or added as a new key depending on flags)
value	entry value to add to *pm (will be av_strduped or added as a new key depending on flags). Passing a NULL value will cause an existing entry to be deleted.

Returns: >= 0 on success otherwise an error code <0

Examples: filter_audio.c, http_multiclient.c, and muxing.c.

Referenced by init_filter_graph(), main(), and open_codec_context().

◆ av_dict_set_int()

int av_dict_set_int	(	AVDictionary **	pm,
		const char *	key,
		int64_t	value,
		int	flags
	)

Convenience wrapper for av_dict_set that converts the value to a string and stores it.

Note: If AV_DICT_DONT_STRDUP_KEY is set, key will be freed on error.

◆ av_dict_parse_string()

int av_dict_parse_string	(	AVDictionary **	pm,
		const char *	str,
		const char *	key_val_sep,
		const char *	pairs_sep,
		int	flags
	)

Parse the key/value pairs list and add the parsed entries to a dictionary.

In case of failure, all the successfully set entries are stored in *pm. You may need to manually free the created dictionary.

Parameters

key_val_sep	a 0-terminated list of characters used to separate key from value
pairs_sep	a 0-terminated list of characters used to separate two pairs from each other
flags	flags to use when adding to dictionary. AV_DICT_DONT_STRDUP_KEY and AV_DICT_DONT_STRDUP_VAL are ignored since the key/value tokens will always be duplicated.

Returns: 0 on success, negative AVERROR code on failure

◆ av_dict_copy()

int av_dict_copy	(	AVDictionary **	dst,
		const AVDictionary *	src,
		int	flags
	)

Copy entries from one AVDictionary struct into another.

Parameters

dst	pointer to a pointer to a AVDictionary struct. If dst is NULL, this function will allocate a struct for you and put it in dst
src	pointer to source AVDictionary struct
flags	flags to use when setting entries in *dst

Note: metadata is read using the AV_DICT_IGNORE_SUFFIX flag

Returns: 0 on success, negative AVERROR code on failure. If dst was allocated by this function, callers should free the associated memory.

Examples: muxing.c.

Referenced by open_audio(), and open_video().

◆ av_dict_free()

void av_dict_free ( AVDictionary ** m )

Free all the memory allocated for an AVDictionary struct and all keys and values.

Examples: filter_audio.c, and muxing.c.

Referenced by init_filter_graph(), open_audio(), open_codec_context(), and open_video().

◆ av_dict_get_string()

int av_dict_get_string	(	const AVDictionary *	m,
		char **	buffer,
		const char	key_val_sep,
		const char	pairs_sep
	)

Get dictionary entries as a string.

Create a string containing dictionary's entries. Such string may be passed back to av_dict_parse_string().

Note: String is escaped with backslashes ('\').

Parameters

[in]	m	dictionary
[out]	buffer	Pointer to buffer that will be allocated with string containg entries. Buffer must be freed by the caller when is no longer needed.
[in]	key_val_sep	character used to separate key from value
[in]	pairs_sep	character used to separate two pairs from each other

Returns: >= 0 on success, negative on error

Warning: Separators cannot be neither '\' nor '\0'. They also cannot be the same.

Data Structures

Macros

Typedefs

Functions

Detailed Description

Macro Definition Documentation

◆ AV_DICT_MATCH_CASE

◆ AV_DICT_IGNORE_SUFFIX

◆ AV_DICT_DONT_STRDUP_KEY

◆ AV_DICT_DONT_STRDUP_VAL

◆ AV_DICT_DONT_OVERWRITE

◆ AV_DICT_APPEND

◆ AV_DICT_MULTIKEY

Typedef Documentation

◆ AVDictionary

Function Documentation

◆ av_dict_get()

◆ av_dict_count()

◆ av_dict_set()

◆ av_dict_set_int()

◆ av_dict_parse_string()

◆ av_dict_copy()

◆ av_dict_free()

◆ av_dict_get_string()