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* 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
* 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
* @file
* Public dictionary API.
* @deprecated
* AVDictionary is provided for compatibility with libav. It is both in
* implementation as well as API inefficient. It does not scale and is
* extremely slow with large dictionaries.
* It is recommended that new code uses our tree container from tree.c/h
* where applicable, which uses AVL trees to achieve O(log n) performance.
#include <stdint.h>
#include "version.h"
* @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_MATCH_CASE 1 /**< Only get an entry with exact-case key match. Only relevant in av_dict_get(). */
#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(). */
#define AV_DICT_DONT_STRDUP_KEY 4 /**< Take ownership of a key that's been
allocated with av_malloc() or another memory allocation function. */
#define AV_DICT_DONT_STRDUP_VAL 8 /**< Take ownership of a value that's been
allocated with av_malloc() or another memory allocation function. */
#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. */
#define AV_DICT_MULTIKEY 64 /**< Allow to store several equal keys in the dictionary */
typedef struct AVDictionaryEntry {
char *key;
char *value;
} AVDictionaryEntry;
typedef struct AVDictionary AVDictionary;
* 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.
* @param prev Set to the previous matching element to find the next.
* If set to NULL the first matching element is returned.
* @param key matching key
* @param flags a collection of AV_DICT_* flags controlling how the entry is retrieved
* @return found entry or NULL in case no matching entry was found in the dictionary
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.
* 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.
* @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 either be av_strduped or added as a new key depending on flags)
* @param 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.
* @return >= 0 on success otherwise an error code <0
int av_dict_set(AVDictionary **pm, const char *key, const char *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.
int av_dict_set_int(AVDictionary **pm, const char *key, int64_t value, 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.
* @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
* @return 0 on success, negative AVERROR code on failure. If dst was allocated
* by this function, callers should free the associated memory.
int 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);
* 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 ('\').
* @param[in] m dictionary
* @param[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.
* @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_dict_get_string(const AVDictionary *m, char **buffer,
const char key_val_sep, const char pairs_sep);
* @}
#endif /* AVUTIL_DICT_H */