The MIM_DATA callback message notifies a client that a user-mode driver has received a MIDI short message.
Parameters
dwMsg
MIM_DATA
dwParam1
MIDI short message contents (one to three bytes).
dwParam2
Time stamp. Number of milliseconds since MIDM_START was received.
Comments
A user-mode MIDI input driver sends a MIM_DATA message to its client, by means of a callback, when the driver has received a MIDI short message. The driver sends the message to the client by calling DriverCallback, passing the specified parameters.
The driver sends the MIM_DATA message only if the client has previously specified a notification target with a MIDM_OPEN message.
If the driver detects that the message is invalid, it should send MIM_ERROR instead of MIM_DATA.
Win32 SDK documentation states that clients receive an MM_MIM_DATA message if the notification target is a window handle. MIM_DATA and MM_MIM_DATA are equivalent.
For additional information, see Notifying Clients from Audio Drivers and Transferring MIDI Input Data.