This function sets the volume of a waveform output device.
At a Glance
| Header file: | Mmsystem.h |
| Windows CE versions: | 2.0 and later |
Syntax
MMRESULT waveOutSetVolume(HWAVEOUT hwo, DWORD dwVolume);
Parameters
hwo
Handle to an open waveform-audio output device. This parameter can also be a device identifier.
dwVolume
Specifies a new volume setting. The low-order word contains the left-channel volume setting, and the high-order word contains 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
One of the values described in the following table is returned.
| Value | Description |
| MMSYSERR_NOERROR | Success. |
| MMSYSERR_INVALHANDLE | Specified device handle is invalid. |
| MMSYSERR_NODRIVER | No device driver is present. |
| MMSYSERR_NOMEM | Unable to allocate or lock memory. |
| MMSYSERR_NOTSUPPORTED | Function is not supported. |
Remarks
If a device identifier is used, then the result of the waveOutSetVolume call applies to all instances of the device. If a device handle is used, then the result applies only to the instance of the device referenced by the device handle.
Not all devices support volume changes. To determine whether the device supports volume control, use the WAVECAPS_VOLUME flag to test the dwSupport member of the WAVEOUTCAPS structure (filled by the waveOutGetDevCaps function). To determine whether the device supports volume control on both the left and right channels, use the WAVECAPS_LRVOLUME flag.
Most devices do not support the full 16 bits of volume-level control and will not use 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 all produce the same physical volume setting: 0x4000. The waveOutGetVolume function returns the full 16-bit setting set with waveOutSetVolume.
Volume settings are interpreted logarithmically. This means the perceived increase in volume is the same when increasing the volume level from 0x5000 to 0x6000 as it is from 0x4000 to 0x5000.