DWORD auxMessage(uDevice, uMsg, dwUser, dwParam1, dwParam2)
This function is the entry point for an auxiliary audio device driver.
UINT uDevice
Specifies the ID of the target device. Device IDs are sequential, starting at zero and ending at a value equal to one less than the number of devices the driver supports.
UINT uMsg
Specifies the message being sent to the driver.
DWORD dwUser
Not used.
DWORD dwParam1
Specifies a message-dependent parameter.
DWORD dwParam2
Specifies a message-dependent parameter.
The driver should return MMSYSERR_NOTSUPPORTED if it does not support the specified message.