添加H.264代码

1. struct hdr_cmn { enum dir_t { DOWN= -1, NONE= 0, UP= 1 }; packet_t ptype_; // packet type (see above) int size_; // simulated packet size int uid_; // unique id int error_; // error flag int errbitcnt_; // # of corrupted bits jahn int fecsize_; double ts_; // timestamp: fo