Good morning Kerno
No, you don't need need to check any references, but you do need all the additional code that comes before the actual function. Thiis states all the constants that are required and cals the APIs to find them. Here, with all due credit to KeepITCool, is the code from this thread :
http://www.pcreview.co.uk/forums/thread-1008148.php
Option Explicit
Const MMSYSERR_NOERROR = 0
Const MAXPNAMELEN = 32
Const MIXER_LONG_NAME_CHARS = 64
Const MIXER_SHORT_NAME_CHARS = 16
Const MIXER_OBJECTF_HANDLE As Long = &H80000000
Const MIXER_OBJECTF_MIXER As Long = &H0&
Const MIXER_OBJECTF_HMIXER As Long = ( _
MIXER_OBJECTF_HANDLE Or MIXER_OBJECTF_MIXER)
Const MIXER_GETLINEINFOF_COMPONENTTYPE = &H3&
Const MIXER_GETCONTROLDETAILSF_VALUE = &H0&
Const MIXER_GETLINECONTROLSF_ONEBYTYPE = &H2&
Const MIXERLINE_COMPONENTTYPE_DST_FIRST = &H0&
Const MIXERLINE_COMPONENTTYPE_DST_SPEAKERS = ( _
MIXERLINE_COMPONENTTYPE_DST_FIRST + 4)
Const MIXERCONTROL_CT_CLASS_SWITCH As Long = &H20000000
Const MIXERCONTROL_CT_SC_SWITCH_BOOLEAN As Long = &H0&
Const MIXERCONTROL_CT_UNITS_BOOLEAN As Long = &H10000
Const MIXERCONTROL_CONTROLTYPE_BOOLEAN As Long = ( _
MIXERCONTROL_CT_CLASS_SWITCH Or _
MIXERCONTROL_CT_SC_SWITCH_BOOLEAN Or _
MIXERCONTROL_CT_UNITS_BOOLEAN)
Const MIXERCONTROL_CONTROLTYPE_MUTE As Long = ( _
MIXERCONTROL_CONTROLTYPE_BOOLEAN + 2)
Declare Function mixerClose Lib "winmm.dll" ( _
ByVal hmx As Long) As Long
Declare Function mixerOpen Lib "winmm.dll" (phmx As Long, _
ByVal uMxId As Long, ByVal dwCallback As Long, _
ByVal dwInstance As Long, ByVal fdwOpen As Long) As Long
Declare Function mixerGetControlDetails Lib "winmm.dll" _
Alias "mixerGetControlDetailsA" (ByVal hmxobj As Long, _
pmxcd As MIXERCONTROLDETAILS, _
ByVal fdwDetails As Long) As Long
Declare Function mixerGetLineControls Lib "winmm.dll" Alias _
"mixerGetLineControlsA" (ByVal hmxobj As Long, _
pmxlc As MIXERLINECONTROLS, _
ByVal fdwControls As Long) As Long
Declare Function mixerGetLineInfo Lib "winmm.dll" Alias _
"mixerGetLineInfoA" (ByVal hmxobj As Long, _
pmxl As MIXERLINE, ByVal fdwInfo As Long) As Long
Declare Function GlobalAlloc Lib "kernel32" ( _
ByVal wFlags As Long, ByVal dwBytes As Long) As Long
Declare Function GlobalLock Lib "kernel32" ( _
ByVal hMem As Long) As Long
Declare Function GlobalFree Lib "kernel32" ( _
ByVal hMem As Long) As Long
Declare Sub CopyStructFromPtr Lib "kernel32" Alias _
"RtlMoveMemory" (struct As Any, ByVal ptr As Long, _
ByVal cb As Long)
Declare Sub CopyPtrFromStruct Lib "kernel32" Alias _
"RtlMoveMemory" (ByVal ptr As Long, struct As Any, _
ByVal cb As Long)
Type MIXERCONTROL
cbStruct As Long
dwControlID As Long
dwControlType As Long
fdwControl As Long
cMultipleItems As Long
szShortName As String * MIXER_SHORT_NAME_CHARS
szName As String * MIXER_LONG_NAME_CHARS
lMinimum As Long
lMaximum As Long
reserved(10) As Long
End Type
Type MIXERCONTROLDETAILS
cbStruct As Long
dwControlID As Long
cChannels As Long
item As Long
cbDetails As Long
paDetails As Long
End Type
Type MIXERCONTROLDETAILS_BOOLEAN
dwValue As Long
End Type
Type MIXERLINE
cbStruct As Long
dwDestination As Long
dwSource As Long
dwLineID As Long
fdwLine As Long
dwUser As Long
dwComponentType As Long
cChannels As Long
cConnections As Long
cControls As Long
szShortName As String * MIXER_SHORT_NAME_CHARS
szName As String * MIXER_LONG_NAME_CHARS
dwType As Long
dwDeviceID As Long
wMid As Integer
wPid As Integer
vDriverVersion As Long
szPname As String * MAXPNAMELEN
End Type
Type MIXERLINECONTROLS
cbStruct As Long
dwLineID As Long
dwControl As Long
cControls As Long
cbmxctrl As Long
pamxctrl As Long
End Type
Function GetMasterMuteState() As Boolean
' This function reads the state of the masterMute control
Dim hMixer As Long ' mixer handle
Dim mxc As MIXERCONTROL
Dim mxl As MIXERLINE
Dim mxlc As MIXERLINECONTROLS
Dim mxcd As MIXERCONTROLDETAILS
Dim mxcdMute As MIXERCONTROLDETAILS_BOOLEAN
Dim hMem As Long
Dim rc As Long
Dim iErr As Integer
' Open the mixer with deviceID 0.
rc = mixerOpen(hMixer, 0, 0, 0, 0)
If ((MMSYSERR_NOERROR <> rc)) Then iErr = 1: GoTo theExit
mxl.cbStruct = Len(mxl)
mxl.dwComponentType = MIXERLINE_COMPONENTTYPE_DST_SPEAKERS
' Obtain a line corresponding to the component type
rc = mixerGetLineInfo(hMixer, mxl, _
MIXER_GETLINEINFOF_COMPONENTTYPE)
If (MMSYSERR_NOERROR <> rc) Then iErr = 2: GoTo theExit
mxlc.cbStruct = Len(mxlc)
mxlc.dwLineID = mxl.dwLineID
mxlc.dwControl = MIXERCONTROL_CONTROLTYPE_MUTE
mxlc.cControls = 1
mxlc.cbmxctrl = Len(mxc)
' Allocate a buffer for the control
hMem = GlobalAlloc(&H40, Len(mxc))
mxlc.pamxctrl = GlobalLock(hMem)
mxc.cbStruct = Len(mxc)
' Get the control
rc = mixerGetLineControls(hMixer, mxlc, _
MIXER_GETLINECONTROLSF_ONEBYTYPE)
If (MMSYSERR_NOERROR <> rc) Then iErr = 3: GoTo theExit
'Copy into mxc structure
CopyStructFromPtr mxc, mxlc.pamxctrl, Len(mxc)
GlobalFree (hMem)
hMem = 0
'Get the controldetails
mxcd.cbStruct = Len(mxcd)
mxcd.dwControlID = mxc.dwControlID
mxcd.cChannels = 1
mxcd.item = 0
mxcd.cbDetails = Len(mxcdMute)
' Allocate a buffer for the controldetails
hMem = GlobalAlloc(&H40, Len(mxcdMute))
mxcd.paDetails = GlobalLock(hMem)
'Get the controldetailvalue
rc = mixerGetControlDetails(hMixer, mxcd, _
MIXER_OBJECTF_HMIXER Or MIXER_GETCONTROLDETAILSF_VALUE)
If (MMSYSERR_NOERROR <> rc) Then iErr = 4: GoTo theExit
' Copy into mxcdMute structure
CopyStructFromPtr mxcdMute, mxcd.paDetails, Len(mxcdMute)
theExit:
If hMem Then GlobalFree (hMem)
If hMixer Then mixerClose (hMixer)
If iErr <> 0 Then
MsgBox "Couldn't read the Master Mute Control"
Else
GetMasterMuteState = CBool(mxcdMute.dwValue)
End If
End Function
Use this to call it from VBA, which will return the boolean value of TRUE / FALSE.
Sub test()
MsgBox GetMasterMuteState()
End Sub
HTH
DominicB
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