Clone a fec_parameter_t with fec changed only

fec_manager.h

@@ -190,7 +190,14 @@ struct fec_parameter_t
 		return 0;
 	}
 
+	int clone_fec(fec_parameter_t & other)
+	{
+		assert(other.rs_cnt>=1);
+		rs_cnt=other.rs_cnt;
+		memcpy(rs_par,other.rs_par,sizeof(rs_parameter_t)*rs_cnt);
 
+		return 0;
+	}
 };
 
 extern fec_parameter_t g_fec_par;