MIDM_START

Sent to a MIDI input driver to begin MIDI input.

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.

DWORD dwParam1: Unused.
DWORD dwParam2: Unused.

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.