How switch on/off sound?

[r_maier]

Hi all,

I wish to switch on/off the sound programmatically. How can I do this?

Best regards

Robert

[WizBang]

One way might be to set the master volume to 0. Just remember to save the original setting so you can restore the level to where it was before. There are API calls you can use for this.

[r_maier]

Thanks for the reply.
I haven't done this before. Could you give me a hint, what API's to use?

Regards

Robert

[Cimperiali]

From MSDN:
'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.
'Value Description
'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.
'Requirements
' Windows NT/2000/XP: Included in Windows NT 3.1 and later.
' Windows 95/98/Me: Included in Windows 95 and later.
' Header: Declared in Mmsystem.h; include Windows
'Example from Api -Guide---------------------------

Option Explicit
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()
    'KPD-Team 2000
    'URL: http://www.allapi.net/
    'E-Mail: KPDTeam@Allapi.net
    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

[r_maier]

Thanks for the code, I haven't tried out it yet.
However, to be more precise, I want to only control the volume of the PC sound. How can I identify the corresponding device?

Thanks

Robert

[Cimperiali]

...I have no soundcard here, thus cannot tell you. But I found these at planet source code. Have a look:
http://planet-source-code.com/vb/scr...42946&lngWId=1
http://planet-source-code.com/vb/scr...38589&lngWId=1