The basic command messages are summarized in the following list. MCI does not modify any of these messages or the data associated with them. MCI relays all information received from the calling application to your device driver.
Loads a device element from disk.
Suspends playing or recording.
Starts transmitting output data.
Starts recording data.
Resumes a paused device.
Saves the current file. Devices which modify files should not destroy the original copy until they receive the save message.
Seeks forward or backward.
Sets device information.
Returns status information from the device. MCI_STATUS as a basic command has additional flags not present for the required message.
Stops playing, with no video shown and no audio played.
The basic command messages use the lParam1 parameter for the flags applicable to the command message. They also use the lParam2 parameter for a pointer to a message-specific data structure. Your device driver might add flags and parameters to create extended commands. When you extend a command message, your device driver must still respond to the basic flags and parameters.