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* This file is part of Libav.
* Libav 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.
* Libav is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* Lesser General Public License for more details.
* You should have received a copy of the GNU Lesser General Public
* License along with Libav; if not, write to the Free Software
* Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
* @file
* Public dictionary API.
* @addtogroup lavu_dict AVDictionary
* @ingroup lavu_data
* @brief 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
while (t = av_dict_get(d, "", t, AV_DICT_IGNORE_SUFFIX)) {
<....> // iterate over all entries in d
#define AV_DICT_DONT_STRDUP_KEY 4 /**< Take ownership of a key that's been
allocated with av_malloc() and children. */
#define AV_DICT_DONT_STRDUP_VAL 8 /**< Take ownership of a value that's been
allocated with av_malloc() and chilren. */
#define AV_DICT_DONT_OVERWRITE 16 ///< Don't overwrite existing entries.
#define AV_DICT_APPEND 32 /**< If the entry already exists, append to it. Note that no
delimiter is added, the strings are simply concatenated. */
typedef struct AVDictionaryEntry {
char *key;
char *value;
} AVDictionaryEntry;
typedef struct AVDictionary AVDictionary;
* Get a dictionary entry with matching key.
* @param prev Set to the previous matching element to find the next.
* If set to NULL the first matching element is returned.
* @param flags Allows case as well as suffix-insensitive comparisons.
* @return Found entry or NULL, changing key or value leads to undefined behavior.
AVDictionaryEntry *av_dict_get(const AVDictionary *m, const char *key,
const AVDictionaryEntry *prev, int flags);
* Get number of entries in dictionary.
* @param m dictionary
* @return number of entries in dictionary
int av_dict_count(const AVDictionary *m);
* Set the given entry in *pm, overwriting an existing entry.
* @param pm pointer to a pointer to a dictionary struct. If *pm is NULL
* a dictionary struct is allocated and put in *pm.
* @param key entry key to add to *pm (will be av_strduped depending on flags)
* @param value entry value to add to *pm (will be av_strduped depending on flags).
* Passing a NULL value will cause an existing entry to be deleted.
* @return >= 0 on success otherwise an error code <0
int av_dict_set(AVDictionary **pm, const char *key, const char *value, int flags);
* Parse the key/value pairs list and add to a dictionary.
* @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
* @param flags flags to use when adding to dictionary.
* are ignored since the key/value tokens will always
* be duplicated.
* @return 0 on success, negative AVERROR code on failure
int av_dict_parse_string(AVDictionary **pm, const char *str,
const char *key_val_sep, const char *pairs_sep,
int flags);
* Copy entries from one AVDictionary struct into another.
* @param 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
* @param src pointer to source AVDictionary struct
* @param flags flags to use when setting entries in *dst
* @note metadata is read using the AV_DICT_IGNORE_SUFFIX flag
void av_dict_copy(AVDictionary **dst, const AVDictionary *src, int flags);
* Free all the memory allocated for an AVDictionary struct
* and all keys and values.
void av_dict_free(AVDictionary **m);
* @}
#endif /* AVUTIL_DICT_H */