auxSetVolume
The auxSetVolume
function sets the volume of the specified auxiliary output device.
MMRESULT auxSetVolume(
|
UINT uDeviceID, |
|
|
DWORD dwVolume |
|
|
); |
|
Parameters
uDeviceID
Identifier of
the auxiliary output device to be queried. Device identifiers are determined
implicitly from the number of devices present in the system. Device identifier
values range from zero to one less than the number of devices present. Use the auxGetNumDevs function to determine the
number of auxiliary devices in the system.
dwVolume
Specifies the
new volume setting. The low-order word specifies the left-channel volume
setting, and the high-order word specifies the right-channel setting. A value of
0xFFFF represents full volume, and a value of 0x0000 is silence.
If a device
does not support both left and right volume control, the low-order word of dwVolume
specifies the volume level, and the high-order word is ignored.
Return Values
Returns MMSYSERR_NOERROR
if successful or an error otherwise. Possible error values include the
following:
|
MMSYSERR_BADDEVICEID |
Specified
device identifier is out of range. |
Remarks
Not all
devices support volume control. To determine whether the device supports volume
control, use the AUXCAPS_VOLUME flag to test the dwSupport member of the
AUXCAPS
structure (filled by the auxGetDevCaps function).
To determine
whether the device supports volume control on both the left and right channels,
use the AUXCAPS_LRVOLUME flag to test the dwSupport member of the AUXCAPS
structure (filled by auxGetDevCaps).
Most devices
do not support the full 16 bits of volume-level control and will use only the
high-order bits of the requested volume setting. For example, for a device that
supports 4 bits of volume control, requested volume level values of 0x4000,
0x4FFF, and 0x43BE will produce the same physical volume setting, 0x4000. The auxGetVolume
function will return the full 16-bit setting set with auxSetVolume.
Volume
settings are interpreted logarithmically. This means the perceived volume
increase is the same when increasing the volume level from 0x5000 to 0x6000 as
it is from 0x4000 to 0x5000.
See Also