AUXDM_SETVOLUME

Sent to an auxiliary audio device driver to set the volume level for an 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.
MMSYSERR_NOTSUPPORTED	The driver does not support changes to volume level.

DWORD dwParam1

Specifies the new volume level. The high-order word contains the right channel setting and the low-order word contains the left channel setting. A value of 0 is silence, and a value of 0xFFFF is full volume. If the driver does not support both left and right channel volume changes, it uses the volume specified in the low-order word. The driver will probably not support the full 16 bits of volume control and should truncate the lower bits if necessary. However, the original value requested with AUXDM_SETVOLUME should be returned with AUXDM_GETVOLUME.

DWORD dwParam2

Unused.

Support for volume level changes is optional. Drivers must indicate whether they support volume level changes when they receive the AUXDM_GETDEVCAPS message.

If a driver supports changes to the volume level with the AUXDM_SETVOLUME message, it must support queries with the AUXDM_GETVOLUME message.