ffmpeg数据结构之AVDictionary

一：AVDictionary的定义：

struct AVDictionary {
int count;
AVDictionaryEntry *elems;
};


AVDictionaryEntry的定义：
typedef struct AVDictionaryEntry {
char *key;
char *value;
} AVDictionaryEntry;


作用：简单的键值对存储。
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);