KS Mediums
A Medium defines a type of communication bus. The minidriver indicates which mediums a pin supports by providing a pointer to an array of KSPIN_MEDIUM structures in the relevant KSPIN_DESCRIPTOR structure. A KSPIN_MEDIUM identifies a specific connection on a communication bus.
Clients specify the medium to use for a connection by setting the Medium member in the KSPIN_CONNECT structure that they provide in a call to KsCreatePin.
Clients request a list of mediums supported by a filter or pin by using the KSPROPERTY_PIN_MEDIUMS property.