This message is sent to a MIDI output device driver to output a single MIDI event.
DWORD dwParam1
Specifies the MIDI event. The low-order byte is the first byte of the event.
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.
MIDIERR_NOTREADY
The MIDI hardware is busy with other data.
This message is used to output all MIDI events, except system-exclusive events. System-exclusive events are output with the MODM_LONGDATA message. MIDI events output with MODM_DATA can be either one, two, or three bytes long. The driver must parse the event to determine how many bytes to output. Unused bytes are not guaranteed to be zero.
The driver can choose not to return until the message has been sent to the output device, or the driver can return immediately and output the MIDI data in the background.