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4/8/2010

This function sets the volume of a waveform output device.

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 dwVolumespecifies the volume level, and the high-order word is ignored.

Return Value

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 waveOutSetVolumecall 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 dwSupportmember of the WAVEOUTCAPSstructure (filled by the waveOutGetDevCapsfunction). 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 waveOutGetVolumefunction 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.

Requirements

Header mmsystem.h
Library coredll.lib
Windows Embedded CE Windows CE 2.0 and later
Windows Mobile Windows Mobile Version 5.0 and later

See Also