This message is sent to an auxiliary audio device driver to set the volume level for an auxiliary audio device.
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.
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.
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.