typedef NTSTATUS (* PMIXER_DD_GET_SET_DATA)(struct _MIXER_INFO * MixerInfo, ULONG ID, ULONG Length, PVOID Data);
PMIXER_DD_GET_SET_DATA is a type definition for functions that set or retrieve information for mixer lines and controls.
Drivers using soundlib.lib define functions modeled on this type and place their addresses in the HwGetLineData, HwGetControlData, HwGetCombinedControlData, and HwSetControlData members of a MIXER_INFO structure.