ffmpeg的AVDictionary模块介绍

字典用来存储键-值对。

相关结构体定义：

typedef struct AVDictionaryEntry {
    char *key;
    char *value;
} AVDictionaryEntry;

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

1、创建一个字典

AVDictionary *d = NULL; // "create" an empty dictionary

NULL可以作为一个空字典，在任何需要指向AVDictionary指针的地方使用。

2、添加一个键-值对

av_dict_set(&d, "foo", "bar", 0); // add an entry

3、遍历字典

AVDictionaryEntry *t = NULL;
while ((t = av_dict_iterate(d, t))) {
   <....>                        // iterate over all entries in d
}

4、获取某个键-值对

AVDictionaryEntry *t = av_dict_get(d, "foo", NULL, AV_DICT_MATCH_CASE);

5、释放字典以及包含的内容

av_dict_free(&d);

6、例子

#include 
#include 

int main()
{
    AVDictionary *d = NULL;
    av_dict_set(&d, "name", "clark", 0);
    av_dict_set(&d, "age", "18", 0);
    av_dict_set(&d, "sex", "man", 0);
    av_dict_set(&d, "job", "engineer", 0);

    const AVDictionaryEntry *t = NULL;
    while ((t = av_dict_iterate(d, t))) {
        printf("%s -> %s
", t->key, t->value);
    }

    t = av_dict_get(d, "job", NULL, AV_DICT_MATCH_CASE);

    av_dict_free(&d);
    return 0;
}

输出：

演示例子打印