AUXDM_GETDEVCAPS

Sent to an auxiliary audio device driver to request the capabilities of a specific auxiliary audio device.

The return value is an error code, or zero (MMSYSERR_NOERROR) if the operation is successful. Possible error codes are:

MMSYSERR_NOTENABLED

The driver failed to load or initialize.

DWORD dwParam1: For Plug and Play drivers, specifies a pointer to an MDEVICECAPSEX structure. The driver fills this structure with the capabilities of the device.
For non-Plug and Play drivers, specifies a far pointer to an AUXCAPS data structure. The driver fills this structure with the capabilities of the device.
DWORD dwParam2: For Plug and Play drivers, specifies a device node.
For non-Plug and Play drivers, specifies the size of the AUXCAPS structure, in bytes.

For non-Plug and Play drivers, the driver should only write dwParam2 or less bytes to the location pointed to by dwParam1. If dwParam2 is 0, write nothing and return MMSYSERR_NOERROR.