The MIM_LONGERROR callback message notifies a client that a user-mode driver has received an invalid MIDI system-exclusive (long) message.
Parameters
dwMsg
MIM_LONGERROR
dwParam1
Address of a MIDIHDR structure identifying a buffer containing the invalid long message. (MIDIHDR is defined in the Win32 SDK.)
dwParam2
Time stamp. Number of milliseconds since MIDM_START was received.
Comments
A user-mode MIDI input driver sends a MIM_LONGERROR message to its client, by means of a callback, when the driver has received an invalid MIDI system-exclusive (long) message. The driver sends the message to the client by calling DriverCallback, passing the specified parameters.
The driver sends the MIM_LONGERROR message only if the client has previously specified a notification target with a MIDM_OPEN message.
When a driver detects an invalid message long message, it should send MIM_LONGERROR instead of MIM_LONGDATA.
Win32 SDK documentation states that clients receive a MM_MIM_LONGERROR message if the notification target is a window handle. MIM_LONGERROR and MM_MIM_LONGERROR are equivalent.
For additional information, see Notifying Clients from Audio Drivers and Transferring MIDI Input Data.