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auxSetVolume
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API Explanation
The auxSetVolume function sets the volume of the specified auxiliary output device.
Parameter Information
Declare Function auxSetVolume Lib "winmm.dll" Alias "auxSetVolume" (ByVal uDeviceID As Long, ByVal dwVolume As Long) As Long
· 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.
Returns MMSYSERR_NOERROR if successful or an error otherwise. Possible error values include the following: MMSYSERR_BADDEVICEID
Specified device identifier is out of range.
The auxSetVolume function sets the volume of the specified auxiliary output device.
Parameter Information
Declare Function auxSetVolume Lib "winmm.dll" Alias "auxSetVolume" (ByVal uDeviceID As Long, ByVal dwVolume As Long) As Long
· 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.
Returns MMSYSERR_NOERROR if successful or an error otherwise. Possible error values include the following: MMSYSERR_BADDEVICEID
Specified device identifier is out of range.
Code
Private Const HIGHEST_VOLUME_SETTING = 100 '%
Private Const AUX_MAPPER = -1&
Private Const MAXPNAMELEN = 32
Private Const AUXCAPS_CDAUDIO = 1 ' audio from internal CD-ROM drive
Private Const AUXCAPS_AUXIN = 2 ' audio from auxiliary input jacks
Private Const AUXCAPS_VOLUME = &H1 ' supports volume control
Private Const AUXCAPS_LRVOLUME = &H2 ' separate left-right volume control
Private Const MMSYSERR_NOERROR = 0
Private Const MMSYSERR_BASE = 0
Private Const MMSYSERR_BADDEVICEID = (MMSYSERR_BASE + 2)
Private Type AUXCAPS
wMid As Integer
wPid As Integer
vDriverVersion As Long
szPname As String * MAXPNAMELEN
wTechnology As Integer
dwSupport As Long
End Type
Private Type VolumeSetting
LeftVol As Integer
RightVol As Integer
End Type
Private Declare Function auxGetNumDevs Lib "winmm.dll" () As Long
Private Declare Function auxGetDevCaps Lib "winmm.dll" Alias "auxGetDevCapsA" (ByVal uDeviceID As _
Long, lpCaps As AUXCAPS, ByVal uSize As Long) As Long
Private Declare Function auxSetVolume Lib "winmm.dll" (ByVal uDeviceID As Long, ByVal dwVolume As _
Long) As Long
Private Declare Function auxGetVolume Lib "winmm.dll" (ByVal uDeviceID As Long, ByRef lpdwVolume _
As VolumeSetting) As Long
Private Declare Sub CopyMemory Lib "kernel32" Alias "RtlMoveMemory" (hpvDest As Any, hpvSource As _
Any, ByVal cbCopy As Long)
Private Function nSigned(ByVal lUnsignedInt As Long) As Integer
Dim nReturnVal As Integer ' Return value from Function
If lUnsignedInt > 65535 Or lUnsignedInt < 0 Then
MsgBox "Error in conversion from Unsigned to nSigned Integer"
nSignedInt = 0
Exit Function
End If
If lUnsignedInt > 32767 Then
nReturnVal = lUnsignedInt - 65536
Else
nReturnVal = lUnsignedInt
End If
nSigned = nReturnVal
End Function
Private Function lUnsigned(ByVal nSignedInt As Integer) As Long
Dim lReturnVal As Long ' Return value from Function
If nSignedInt < 0 Then
lReturnVal = nSignedInt + 65536
Else
lReturnVal = nSignedInt
End If
If lReturnVal > 65535 Or lReturnVal < 0 Then
MsgBox "Error in conversion from nSigned to Unsigned Integer"
lReturnVal = 0
End If
lUnsigned = lReturnVal
End Function
Private Function lSetVolume(ByRef lLeftVol As Long, ByRef lRightVol As Long, lDeviceID As Long) As Long
Dim Volume As VolumeSetting, lBothVolumes As Long
Volume.LeftVol = nSigned(lLeftVol * 65535 / HIGHEST_VOLUME_SETTING)
Volume.RightVol = nSigned(lRightVol * 65535 / HIGHEST_VOLUME_SETTING)
'copy our Volume-variable to a long
CopyMemory lBothVolumes, Volume.LeftVol, Len(Volume)
'call the SetVolume-function
lSetVolume = auxSetVolume(lDeviceID, lBothVolumes)
End Function
Private Sub Form_Load()
Dim Volume As VolumeSetting, Cnt As Long, AC As AUXCAPS
'set the output to a persistent graphic
Me.AutoRedraw = True
'loop through all the devices
For Cnt = 0 To auxGetNumDevs - 1 'auxGetNumDevs is zero-based
'get the volume
auxGetVolume Cnt, Volume
'get the device capabilities
auxGetDevCaps Cnt, AC, Len(AC)
'print the name on the form
Me.Print "Device #" + Str$(Cnt + 1) + ": " + Left(AC.szPname, InStr(AC.szPname, vbNullChar) - 1)
'print the left- and right volume on the form
Me.Print "Left volume:" + Str$(HIGHEST_VOLUME_SETTING * lUnsigned(Volume.LeftVol) / 65535)
Me.Print "Right volume:" + Str$(HIGHEST_VOLUME_SETTING * lUnsigned(Volume.RightVol) / 65535)
'set the left- and right-volume to 50%
lSetVolume 50, 50, Cnt
Me.Print "Both volumes now set to 50%"
'empty line
Me.Print
Next
End Sub
Private Const AUX_MAPPER = -1&
Private Const MAXPNAMELEN = 32
Private Const AUXCAPS_CDAUDIO = 1 ' audio from internal CD-ROM drive
Private Const AUXCAPS_AUXIN = 2 ' audio from auxiliary input jacks
Private Const AUXCAPS_VOLUME = &H1 ' supports volume control
Private Const AUXCAPS_LRVOLUME = &H2 ' separate left-right volume control
Private Const MMSYSERR_NOERROR = 0
Private Const MMSYSERR_BASE = 0
Private Const MMSYSERR_BADDEVICEID = (MMSYSERR_BASE + 2)
Private Type AUXCAPS
wMid As Integer
wPid As Integer
vDriverVersion As Long
szPname As String * MAXPNAMELEN
wTechnology As Integer
dwSupport As Long
End Type
Private Type VolumeSetting
LeftVol As Integer
RightVol As Integer
End Type
Private Declare Function auxGetNumDevs Lib "winmm.dll" () As Long
Private Declare Function auxGetDevCaps Lib "winmm.dll" Alias "auxGetDevCapsA" (ByVal uDeviceID As _
Long, lpCaps As AUXCAPS, ByVal uSize As Long) As Long
Private Declare Function auxSetVolume Lib "winmm.dll" (ByVal uDeviceID As Long, ByVal dwVolume As _
Long) As Long
Private Declare Function auxGetVolume Lib "winmm.dll" (ByVal uDeviceID As Long, ByRef lpdwVolume _
As VolumeSetting) As Long
Private Declare Sub CopyMemory Lib "kernel32" Alias "RtlMoveMemory" (hpvDest As Any, hpvSource As _
Any, ByVal cbCopy As Long)
Private Function nSigned(ByVal lUnsignedInt As Long) As Integer
Dim nReturnVal As Integer ' Return value from Function
If lUnsignedInt > 65535 Or lUnsignedInt < 0 Then
MsgBox "Error in conversion from Unsigned to nSigned Integer"
nSignedInt = 0
Exit Function
End If
If lUnsignedInt > 32767 Then
nReturnVal = lUnsignedInt - 65536
Else
nReturnVal = lUnsignedInt
End If
nSigned = nReturnVal
End Function
Private Function lUnsigned(ByVal nSignedInt As Integer) As Long
Dim lReturnVal As Long ' Return value from Function
If nSignedInt < 0 Then
lReturnVal = nSignedInt + 65536
Else
lReturnVal = nSignedInt
End If
If lReturnVal > 65535 Or lReturnVal < 0 Then
MsgBox "Error in conversion from nSigned to Unsigned Integer"
lReturnVal = 0
End If
lUnsigned = lReturnVal
End Function
Private Function lSetVolume(ByRef lLeftVol As Long, ByRef lRightVol As Long, lDeviceID As Long) As Long
Dim Volume As VolumeSetting, lBothVolumes As Long
Volume.LeftVol = nSigned(lLeftVol * 65535 / HIGHEST_VOLUME_SETTING)
Volume.RightVol = nSigned(lRightVol * 65535 / HIGHEST_VOLUME_SETTING)
'copy our Volume-variable to a long
CopyMemory lBothVolumes, Volume.LeftVol, Len(Volume)
'call the SetVolume-function
lSetVolume = auxSetVolume(lDeviceID, lBothVolumes)
End Function
Private Sub Form_Load()
Dim Volume As VolumeSetting, Cnt As Long, AC As AUXCAPS
'set the output to a persistent graphic
Me.AutoRedraw = True
'loop through all the devices
For Cnt = 0 To auxGetNumDevs - 1 'auxGetNumDevs is zero-based
'get the volume
auxGetVolume Cnt, Volume
'get the device capabilities
auxGetDevCaps Cnt, AC, Len(AC)
'print the name on the form
Me.Print "Device #" + Str$(Cnt + 1) + ": " + Left(AC.szPname, InStr(AC.szPname, vbNullChar) - 1)
'print the left- and right volume on the form
Me.Print "Left volume:" + Str$(HIGHEST_VOLUME_SETTING * lUnsigned(Volume.LeftVol) / 65535)
Me.Print "Right volume:" + Str$(HIGHEST_VOLUME_SETTING * lUnsigned(Volume.RightVol) / 65535)
'set the left- and right-volume to 50%
lSetVolume 50, 50, Cnt
Me.Print "Both volumes now set to 50%"
'empty line
Me.Print
Next
End Sub