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.
@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
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.
@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