This message is sent to a MIDI input driver to begin MIDI input.
DWORD dwParam1
Unused.
DWORD dwParam2
Unused.
The return value is an error code, or zero (MMSYSERR_NOERROR) if the operation is successful. Possible error codes are:
MMSYSERR_NOTENABLED
The driver failed to load or initialize.
This message should reset the time stamp to zero. If this message is received after input has been started, the driver should just return MMSYSERR_NOERROR.