The midi/in device class consists of MIDI sequencers that are used for input. You access these devices by using the MIDI functions, which are described in the Platform Software Development Kit (SDK).
DWORD DeviceId; // identifier of MIDI device
The DeviceId member is the identifier of a closed MIDI device. You use this identifier in a call to the midiInOpen function to open the device for input. You can use the resulting device handle to record MIDI data from the line or phone device.
For more information about the MIDI functions, see Multimedia Functions.