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Volume.exe: Set volume control levels using Visual Basic

This article has been archived. It is offered "as is" and will no longer be updated.
Volume.exe is a self-extracting compressed file that contains a sample project demonstrating how to set the volume and microphone levels using Visual Basic.
More information
After downloading and running the self-extracting file, the following files are copied to the Volume Level Project directory on your hard drive:
  Form1.frm    - the main form in the project  Module1.bas  - the module containing the function and type declarations.  Project1.vbp - the project file  Project1.vbw - the project workspace file  Readme.txt   - you are currently reading this file.
To set these microphone and volume levels from Visual Basic, use the following Windows API functions:
  • GlobalAlloc - allocates the specified number of bytes from the heap.
  • GlobalLock - locks a global memory object and returns a pointer to the first byte of the object's memory block. The memory block associated with a locked memory object cannot be moved or discarded.
  • GlobalFree - frees the specified global memory object and invalidates its handle.
  • mixerClose - closes the specified mixer device.
  • mixerGetControlDetails - retrieves details about a single control associated with an audio line.
  • mixerGetDevCaps - queries a specified mixer device to determine its capabilities.
  • mixerGetID - retrieves the device identifier for a mixer device associated with a specified device handle.
  • mixerGetLineControls - retrieves one or more controls associated with an audio line.
  • mixerGetLineInfo - retrieves information about a specific line of a mixer device.
  • mixerGetNumDevs - retrieves the number of mixer devices present in the system.
  • mixerMessage - sends a custom mixer driver message directly to a mixer driver.
  • mixerOpen - opens a specified mixer device and ensures that the device will not be removed until the application closes the handle.
  • mixerSetControlDetails - sets properties of a single control associated with an audio line.
The next section shows how to create a sample project that uses these functions to set the volume and microphone levels.

Create the Sample Project

  1. Start a new Standard EXE project in Visual Basic. Form1 is created by default.
  2. Add two command buttons, two text boxes, and two labels to Form1.
  3. Add a Module to the project by completing the following steps:
    1. From the Project menu, click Add module. The Add Module dialog box appears.
    2. From the New tab, choose Module and click OK. A new module is added to your project.
  4. Copy the following code to the Code window of Module1:
          Option Explicit      Public Const MMSYSERR_NOERROR = 0      Public Const MAXPNAMELEN = 32      Public Const MIXER_LONG_NAME_CHARS = 64      Public Const MIXER_SHORT_NAME_CHARS = 16      Public Const MIXER_GETLINEINFOF_COMPONENTTYPE = &H3&      Public Const MIXER_GETCONTROLDETAILSF_VALUE = &H0&      Public Const MIXER_GETLINECONTROLSF_ONEBYTYPE = &H2&      Public Const MIXERLINE_COMPONENTTYPE_DST_FIRST = &H0&      Public Const MIXERLINE_COMPONENTTYPE_SRC_FIRST = &H1000&      Public Const MIXERLINE_COMPONENTTYPE_DST_SPEAKERS = _                     (MIXERLINE_COMPONENTTYPE_DST_FIRST + 4)      Public Const MIXERLINE_COMPONENTTYPE_SRC_MICROPHONE = _                     (MIXERLINE_COMPONENTTYPE_SRC_FIRST + 3)      Public Const MIXERLINE_COMPONENTTYPE_SRC_LINE = _                     (MIXERLINE_COMPONENTTYPE_SRC_FIRST + 2)      Public Const MIXERCONTROL_CT_CLASS_FADER = &H50000000      Public Const MIXERCONTROL_CT_UNITS_UNSIGNED = &H30000      Public Const MIXERCONTROL_CONTROLTYPE_FADER = _                     (MIXERCONTROL_CT_CLASS_FADER Or _                     MIXERCONTROL_CT_UNITS_UNSIGNED)      Public Const MIXERCONTROL_CONTROLTYPE_VOLUME = _                     (MIXERCONTROL_CONTROLTYPE_FADER + 1)      Declare Function mixerClose Lib "winmm.dll" _                     (ByVal hmx 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 mixerGetDevCaps Lib "winmm.dll" _                     Alias "mixerGetDevCapsA" _                     (ByVal uMxId As Long, _                     ByVal pmxcaps As MIXERCAPS, _                     ByVal cbmxcaps As Long) As Long      Declare Function mixerGetID Lib "winmm.dll" _                     (ByVal hmxobj As Long, _                     pumxID As Long, _                     ByVal fdwId 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 mixerGetNumDevs Lib "winmm.dll" () As Long      Declare Function mixerMessage Lib "winmm.dll" _                     (ByVal hmx As Long, _                     ByVal uMsg As Long, _                     ByVal dwParam1 As Long, _                     ByVal dwParam2 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 mixerSetControlDetails Lib "winmm.dll" _                     (ByVal hmxobj As Long, _                     pmxcd As MIXERCONTROLDETAILS, _                     ByVal fdwDetails 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)      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      Type MIXERCAPS         wMid As Integer                   '  manufacturer id         wPid As Integer                   '  product id         vDriverVersion As Long            '  version of the driver         szPname As String * MAXPNAMELEN   '  product name         fdwSupport As Long                '  misc. support bits         cDestinations As Long             '  count of destinations      End Type      Type MIXERCONTROL         cbStruct As Long           '  size in Byte of MIXERCONTROL         dwControlID As Long        '  unique control id for mixer device         dwControlType As Long      '  MIXERCONTROL_CONTROLTYPE_xxx         fdwControl As Long         '  MIXERCONTROL_CONTROLF_xxx         cMultipleItems As Long     '  if MIXERCONTROL_CONTROLF_MULTIPLE                                    '  set         szShortName As String * MIXER_SHORT_NAME_CHARS  ' short name of                                                         ' control         szName As String * MIXER_LONG_NAME_CHARS        ' long name of                                                         ' control         lMinimum As Long           '  Minimum value         lMaximum As Long           '  Maximum value         reserved(10) As Long       '  reserved structure space         End Type      Type MIXERCONTROLDETAILS         cbStruct As Long       '  size in Byte of MIXERCONTROLDETAILS         dwControlID As Long    '  control id to get/set details on         cChannels As Long      '  number of channels in paDetails array         item As Long           '  hwndOwner or cMultipleItems         cbDetails As Long      '  size of _one_ details_XX struct         paDetails As Long      '  pointer to array of details_XX structs      End Type      Type MIXERCONTROLDETAILS_UNSIGNED         dwValue As Long        '  value of the control      End Type      Type MIXERLINE         cbStruct As Long               '  size of MIXERLINE structure         dwDestination As Long          '  zero based destination index         dwSource As Long               '  zero based source index (if                                        '  source)         dwLineID As Long               '  unique line id for mixer device         fdwLine As Long                '  state/information about line         dwUser As Long                 '  driver specific information         dwComponentType As Long        '  component type line connects to         cChannels As Long              '  number of channels line supports         cConnections As Long           '  number of connections (possible)         cControls As Long              '  number of controls at this line         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       '  size in Byte of MIXERLINECONTROLS         dwLineID As Long       '  line id (from MIXERLINE.dwLineID)                                '  MIXER_GETLINECONTROLSF_ONEBYID or         dwControl As Long      '  MIXER_GETLINECONTROLSF_ONEBYTYPE         cControls As Long      '  count of controls pmxctrl points to         cbmxctrl As Long       '  size in Byte of _one_ MIXERCONTROL         pamxctrl As Long       '  pointer to first MIXERCONTROL array      End Type      Function GetVolumeControl(ByVal hmixer As Long, _                              ByVal componentType As Long, _                              ByVal ctrlType As Long, _                              ByRef mxc As MIXERCONTROL) As Boolean      ' This function attempts to obtain a mixer control.      ' Returns True if successful.         Dim mxlc As MIXERLINECONTROLS         Dim mxl As MIXERLINE         Dim hmem As Long         Dim rc As Long         mxl.cbStruct = Len(mxl)         mxl.dwComponentType = componentType         ' Obtain a line corresponding to the component type         rc = mixerGetLineInfo(hmixer, _                               mxl, _                               MIXER_GETLINEINFOF_COMPONENTTYPE)         If (MMSYSERR_NOERROR = rc) Then             mxlc.cbStruct = Len(mxlc)             mxlc.dwLineID = mxl.dwLineID             mxlc.dwControl = ctrlType             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                 GetVolumeControl = True                 ' Copy the control into the destination structure                 CopyStructFromPtr mxc, mxlc.pamxctrl, Len(mxc)             Else                 GetVolumeControl = False             End If             GlobalFree (hmem)             Exit Function         End If         GetVolumeControl = False      End Function      Function SetVolumeControl(ByVal hmixer As Long, _                              mxc As MIXERCONTROL, _                              ByVal volume As Long) As Boolean      ' This function sets the value for a volume control.      ' Returns True if successful         Dim mxcd As MIXERCONTROLDETAILS         Dim vol As MIXERCONTROLDETAILS_UNSIGNED         mxcd.item = 0         mxcd.dwControlID = mxc.dwControlID         mxcd.cbStruct = Len(mxcd)         mxcd.cbDetails = Len(vol)         ' Allocate a buffer for the control value buffer         hmem = GlobalAlloc(&H40, Len(vol))         mxcd.paDetails = GlobalLock(hmem)         mxcd.cChannels = 1         vol.dwValue = volume         ' Copy the data into the control value buffer         CopyPtrFromStruct mxcd.paDetails, vol, Len(vol)         ' Set the control value         rc = mixerSetControlDetails(hmixer, _                                    mxcd, _                                    MIXER_SETCONTROLDETAILSF_VALUE)         GlobalFree (hmem)         If (MMSYSERR_NOERROR = rc) Then             SetVolumeControl = True         Else             SetVolumeControl = False         End If      End Function
  5. Copy the following code to the Code window of Form1:
          Option Explicit      Dim hmixer As Long          ' mixer handle      Dim volCtrl As MIXERCONTROL ' waveout volume control      Dim micCtrl As MIXERCONTROL ' microphone volume control      Dim rc As Long              ' return code      Dim ok As Boolean           ' boolean return code      Dim vol As Long             ' volume        Private Sub Form_Load()      ' Open the mixer with deviceID 0.         rc = mixerOpen(hmixer, 0, 0, 0, 0)         If ((MMSYSERR_NOERROR <> rc)) Then             MsgBox "Couldn't open the mixer."             Exit Sub             End If         ' Get the waveout volume control         ok = GetVolumeControl(hmixer, _                              MIXERLINE_COMPONENTTYPE_DST_SPEAKERS, _                              MIXERCONTROL_CONTROLTYPE_VOLUME, _                              volCtrl)         If (ok = True) Then             ' If the function successfully gets the volume control,             ' the maximum and minimum values are specified by             ' lMaximum and lMinimum             Label1.Caption = volCtrl.lMinimum _                              & " to " _                              & volCtrl.lMaximum             End If         ' Get the microphone volume control         ok = GetVolumeControl(hmixer, _                              MIXERLINE_COMPONENTTYPE_SRC_MICROPHONE, _                              MIXERCONTROL_CONTROLTYPE_VOLUME, _                              micCtrl)         If (ok = True) Then             Label2.Caption = micCtrl.lMinimum _                              & " to " _                              & micCtrl.lMaximum             End If      End Sub      Private Sub Command1_Click()         vol = CLng(Text1.Text)         SetVolumeControl hmixer, volCtrl, vol      End Sub      Private Sub Command2_Click()         vol = CLng(Text2.Text)         SetVolumeControl hmixer, micCtrl, vol      End Sub
  6. On the Run menu, click Start or press the F5 key to start the program. Minimize the Visual Basic IDE so all that appears on your display is Form1. Maximize the Volume Level program in the Task bar. Arrange Form1 and the Volume Level program so both programs are visible.
  7. Enter a value between the minimum and maximum values shown in one or both text boxes and click one of the command buttons in Form1. Note that the corresponding slider in the Volume Level program is adjusted to your specified level.
(c) Microsoft Corporation 1997, All Rights Reserved.
Contributions by Arsenio Locsin, Microsoft Corporation

Article ID: 178456 - Last Review: 12/05/2015 08:14:55 - Revision: 6.0

Microsoft Visual Basic 5.0 Learning Edition, Microsoft Visual Basic 5.0 Professional Edition, Microsoft Visual Basic 5.0 Enterprise Edition, Microsoft Visual Basic 6.0 Professional Edition

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