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.
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.
Unless specified otherwise under a specific message, the driver should return an MMSYSERR_ or AUXERR_ error code.
The driver should return MMSYSERR_NOTSUPPORTED if it does not support the specified message.