The DRV_CLOSE message requests a user-mode multimedia driver to close the specified driver instance.
The driver should return a nonzero value if the operation succeeds. Otherwise it should return zero.
The DRV_CLOSE message is one of the standard driver messages. A client sends the message by calling the driver’s DriverProc entry point, passing the specified parameter values.
When a driver receives a DRV_CLOSE message, it should close the specified driver instance. Other driver instances might still be open.