The AUXDM_GETVOLUME message requests a user-mode driver to return the current volume level setting for the specified auxiliary audio device.
Parameters
uDeviceId
Device identifier (0, 1, 2, and so on) for the target device.
uMsg
AUXDM_GETVOLUME
dwUser
Not used.
dwParam1
Pointer to a DWORD location to receive the volume setting.
dwParam2
Not used.
Return Value
The driver should return MMSYSERR_NOERROR if the operation succeeds. Otherwise it should return one of the MMSYSERR error codes defined in mmsystem.h.
Comments
A client sends the AUXDM_GETVOLUME message by calling the user-mode driver’s auxMessage entry point, passing the specified parameters.
Support for this message by user-mode drivers is optional. If the driver supports AUXDM_SETVOLUME, it must support AUXDM_GETVOLUME.
The volume value is returned in the DWORD pointed to by dwParam1 as follows:
| Channel | Portion of dwParam1 Used |
| Left channel | Low word |
| Right channel | High word |
| Single channel | Low word |
A value of zero is silence, and a value of 0xFFFF is full volume.
Typically, the user-mode driver calls DeviceIoControl to send the kernel-mode driver an IOCTL_AUX_GET_VOLUME control code.