242 lines
9.2 KiB
C
242 lines
9.2 KiB
C
/*
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* This file is part of FFmpeg.
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*
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* FFmpeg is free software; you can redistribute it and/or
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* modify it under the terms of the GNU Lesser General Public
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* License as published by the Free Software Foundation; either
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* version 2.1 of the License, or (at your option) any later version.
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*
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* FFmpeg is distributed in the hope that it will be useful,
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* but WITHOUT ANY WARRANTY; without even the implied warranty of
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
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* Lesser General Public License for more details.
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*
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* You should have received a copy of the GNU Lesser General Public
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* License along with FFmpeg; if not, write to the Free Software
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* Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
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*/
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/**
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* @file
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* Public dictionary API.
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* @deprecated
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* AVDictionary is provided for compatibility with libav. It is both in
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* implementation as well as API inefficient. It does not scale and is
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* extremely slow with large dictionaries.
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* It is recommended that new code uses our tree container from tree.c/h
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* where applicable, which uses AVL trees to achieve O(log n) performance.
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*/
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#ifndef AVUTIL_DICT_H
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#define AVUTIL_DICT_H
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#include <stdint.h>
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/**
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* @addtogroup lavu_dict AVDictionary
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* @ingroup lavu_data
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*
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* @brief Simple key:value store
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*
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* @{
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* Dictionaries are used for storing key-value pairs.
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*
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* - To **create an AVDictionary**, simply pass an address of a NULL
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* pointer to av_dict_set(). NULL can be used as an empty dictionary
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* wherever a pointer to an AVDictionary is required.
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* - To **insert an entry**, use av_dict_set().
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* - Use av_dict_get() to **retrieve an entry**.
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* - To **iterate over all entries**, use av_dict_iterate().
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* - In order to **free the dictionary and all its contents**, use av_dict_free().
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*
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@code
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AVDictionary *d = NULL; // "create" an empty dictionary
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AVDictionaryEntry *t = NULL;
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av_dict_set(&d, "foo", "bar", 0); // add an entry
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char *k = av_strdup("key"); // if your strings are already allocated,
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char *v = av_strdup("value"); // you can avoid copying them like this
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av_dict_set(&d, k, v, AV_DICT_DONT_STRDUP_KEY | AV_DICT_DONT_STRDUP_VAL);
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while ((t = av_dict_iterate(d, t))) {
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<....> // iterate over all entries in d
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}
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av_dict_free(&d);
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@endcode
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*/
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/**
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* @name AVDictionary Flags
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* Flags that influence behavior of the matching of keys or insertion to the dictionary.
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* @{
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*/
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#define AV_DICT_MATCH_CASE 1 /**< Only get an entry with exact-case key match. Only relevant in av_dict_get(). */
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#define AV_DICT_IGNORE_SUFFIX 2 /**< Return first entry in a dictionary whose first part corresponds to the search key,
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ignoring the suffix of the found key string. Only relevant in av_dict_get(). */
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#define AV_DICT_DONT_STRDUP_KEY 4 /**< Take ownership of a key that's been
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allocated with av_malloc() or another memory allocation function. */
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#define AV_DICT_DONT_STRDUP_VAL 8 /**< Take ownership of a value that's been
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allocated with av_malloc() or another memory allocation function. */
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#define AV_DICT_DONT_OVERWRITE 16 /**< Don't overwrite existing entries. */
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#define AV_DICT_APPEND 32 /**< If the entry already exists, append to it. Note that no
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delimiter is added, the strings are simply concatenated. */
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#define AV_DICT_MULTIKEY 64 /**< Allow to store several equal keys in the dictionary */
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/**
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* @}
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*/
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typedef struct AVDictionaryEntry {
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char *key;
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char *value;
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} AVDictionaryEntry;
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typedef struct AVDictionary AVDictionary;
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/**
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* Get a dictionary entry with matching key.
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*
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* The returned entry key or value must not be changed, or it will
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* cause undefined behavior.
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*
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* @param prev Set to the previous matching element to find the next.
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* If set to NULL the first matching element is returned.
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* @param key Matching key
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* @param flags A collection of AV_DICT_* flags controlling how the
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* entry is retrieved
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*
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* @return Found entry or NULL in case no matching entry was found in the dictionary
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*/
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AVDictionaryEntry *av_dict_get(const AVDictionary *m, const char *key,
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const AVDictionaryEntry *prev, int flags);
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/**
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* Iterate over a dictionary
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*
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* Iterates through all entries in the dictionary.
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*
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* @warning The returned AVDictionaryEntry key/value must not be changed.
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*
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* @warning As av_dict_set() invalidates all previous entries returned
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* by this function, it must not be called while iterating over the dict.
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*
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* Typical usage:
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* @code
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* const AVDictionaryEntry *e = NULL;
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* while ((e = av_dict_iterate(m, e))) {
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* // ...
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* }
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* @endcode
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*
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* @param m The dictionary to iterate over
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* @param prev Pointer to the previous AVDictionaryEntry, NULL initially
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*
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* @retval AVDictionaryEntry* The next element in the dictionary
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* @retval NULL No more elements in the dictionary
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*/
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const AVDictionaryEntry *av_dict_iterate(const AVDictionary *m,
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const AVDictionaryEntry *prev);
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/**
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* Get number of entries in dictionary.
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*
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* @param m dictionary
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* @return number of entries in dictionary
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*/
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int av_dict_count(const AVDictionary *m);
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/**
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* Set the given entry in *pm, overwriting an existing entry.
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*
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* Note: If AV_DICT_DONT_STRDUP_KEY or AV_DICT_DONT_STRDUP_VAL is set,
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* these arguments will be freed on error.
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*
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* @warning Adding a new entry to a dictionary invalidates all existing entries
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* previously returned with av_dict_get() or av_dict_iterate().
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*
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* @param pm Pointer to a pointer to a dictionary struct. If *pm is NULL
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* a dictionary struct is allocated and put in *pm.
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* @param key Entry key to add to *pm (will either be av_strduped or added as a new key depending on flags)
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* @param value Entry value to add to *pm (will be av_strduped or added as a new key depending on flags).
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* Passing a NULL value will cause an existing entry to be deleted.
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*
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* @return >= 0 on success otherwise an error code <0
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*/
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int av_dict_set(AVDictionary **pm, const char *key, const char *value, int flags);
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/**
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* Convenience wrapper for av_dict_set() that converts the value to a string
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* and stores it.
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*
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* Note: If ::AV_DICT_DONT_STRDUP_KEY is set, key will be freed on error.
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*/
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int av_dict_set_int(AVDictionary **pm, const char *key, int64_t value, int flags);
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/**
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* Parse the key/value pairs list and add the parsed entries to a dictionary.
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*
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* In case of failure, all the successfully set entries are stored in
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* *pm. You may need to manually free the created dictionary.
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*
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* @param key_val_sep A 0-terminated list of characters used to separate
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* key from value
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* @param pairs_sep A 0-terminated list of characters used to separate
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* two pairs from each other
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* @param flags Flags to use when adding to the dictionary.
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* ::AV_DICT_DONT_STRDUP_KEY and ::AV_DICT_DONT_STRDUP_VAL
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* are ignored since the key/value tokens will always
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* be duplicated.
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*
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* @return 0 on success, negative AVERROR code on failure
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*/
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int av_dict_parse_string(AVDictionary **pm, const char *str,
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const char *key_val_sep, const char *pairs_sep,
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int flags);
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/**
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* Copy entries from one AVDictionary struct into another.
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*
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* @note Metadata is read using the ::AV_DICT_IGNORE_SUFFIX flag
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*
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* @param dst Pointer to a pointer to a AVDictionary struct to copy into. If *dst is NULL,
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* this function will allocate a struct for you and put it in *dst
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* @param src Pointer to the source AVDictionary struct to copy items from.
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* @param flags Flags to use when setting entries in *dst
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*
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* @return 0 on success, negative AVERROR code on failure. If dst was allocated
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* by this function, callers should free the associated memory.
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*/
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int av_dict_copy(AVDictionary **dst, const AVDictionary *src, int flags);
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/**
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* Free all the memory allocated for an AVDictionary struct
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* and all keys and values.
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*/
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void av_dict_free(AVDictionary **m);
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/**
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* Get dictionary entries as a string.
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*
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* Create a string containing dictionary's entries.
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* Such string may be passed back to av_dict_parse_string().
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* @note String is escaped with backslashes ('\').
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*
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* @warning Separators cannot be neither '\\' nor '\0'. They also cannot be the same.
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*
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* @param[in] m The dictionary
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* @param[out] buffer Pointer to buffer that will be allocated with string containg entries.
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* Buffer must be freed by the caller when is no longer needed.
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* @param[in] key_val_sep Character used to separate key from value
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* @param[in] pairs_sep Character used to separate two pairs from each other
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*
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* @return >= 0 on success, negative on error
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*/
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int av_dict_get_string(const AVDictionary *m, char **buffer,
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const char key_val_sep, const char pairs_sep);
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/**
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* @}
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*/
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#endif /* AVUTIL_DICT_H */
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