구조체 초기화 멤버 접근방식

typedef struct OptionDef {
    const char *name;
    int flags;
     union {
        void *dst_ptr;
        int (*func_arg)(void *, const char *, const char *);
        size_t off;
    } u;
    const char *help;
    const char *argname;
} OptionDef;

const OptionDef options[] = {
{ "vcodec",			OPT_VIDEO,	{ .func_arg = opt_video_codec },	"force video codec ('copy' to copy stream)", "codec"	},
...
};