MCI drivers are installable, user-mode device drivers that process MCI commands. Like all other user-mode drivers under Windows NT, MCI drivers are DLLs. For more information about user-mode drivers under Windows NT, see Introduction to Multimedia Drivers.
MCI drivers can initiate hardware operations by either of two methods:
1.They can call kernel-mode drivers using Win32 API functions such as CreateFile, ReadFile, and WriteFile, as described in Introduction to Multimedia Drivers.
2.They can call other user-mode drivers, using Win32 multimedia functions described in the Win32 SDK. For example, a driver implementing an MCI interface for MIDI sequencers can call the Win32 MIDI functions, causing a user-mode audio driver to be accessed.
Like all other types of installable drivers, MCI drivers must define a DriverProc function. This function must handle the standard driver messages. Additionally, it must handle MCI messages. For more information, see DriverProc in MCI Drivers.
The following topics provide more introductory information about MCI drivers: