[VB6, Vista+] Core Audio Basics

[fafalone]

Core Audio Demos

A few days ago I released the latest version of my oleexp typelib containing all of the Core Audio interfaces. Here's a demo of some of the basic features.

All of the functions shown in the above screenshot work, and additionally the 'Mute Default Multimedia Device' button also demonstrates how to set a callback for that device-- if any other app, like the volume mixer, then unmutes or does something else with that device, your app will be notified of the change. Note that all interfaces used for the callback must be module-level and not released while the callback is active, otherwise your app will freeze.

Requirements
-Windows Vista or higher
-oleexp v4.0 (released 24 Nov 2016): Add oleexp.tlb as a reference-- for IDE only, does not need to be redistributed with compiled app.
-oleexp addons: mCoreAudio.bas, mIID.bas, and mPKEY.bas (all of which are now included in main oleexp download).

Code Example: Muting all active capture devices (e.g. microphones)

Dim sOut As String
Dim i As Long
Dim lp As Long
Dim s1 As String
Dim sName As String

Dim pDvEnum As MMDeviceEnumerator
Set pDvEnum = New MMDeviceEnumerator

Dim pDvCol As IMMDeviceCollection

pDvEnum.EnumAudioEndpoints eCapture, DEVICE_STATE_ACTIVE, pDvCol

If (pDvCol Is Nothing) = False Then
    Dim nCount As Long
    Dim pDevice As IMMDevice
    If pDvCol.GetCount(nCount) = S_OK Then
        If nCount > 0 Then
            For i = 0 To (nCount - 1)
                sName = GetDeviceName(pDvCol, i)
                sOut = sOut & "Muting Device(" & i & ", Name=" & sName & ")..." & vbCrLf
                pDvCol.Item i, pDevice
                If (pDevice Is Nothing) = False Then
                    Dim pAEV As IAudioEndpointVolume
                    pDevice.Activate IID_IAudioEndpointVolume, CLSCTX_INPROC_SERVER, CVar(0), pAEV
                    If (pAEV Is Nothing) = False Then
                        If pAEV.SetMute(1, UUID_NULL) = S_OK Then
                            sOut = sOut & "...Device successfully muted!" & vbCrLf
                        Else
                            sOut = sOut & "...Failed to mute device " & i & " (" & sName & "). Already muted?" & vbCrLf
                        End If
                    Else
                        Debug.Print "Failed to set pAEV"
                        sOut = sOut & "...An error occured accessing the volume control." & vbCrLf
                    End If
                Else
                    Debug.Print "Failed to set pDevice"
                    sOut = sOut & "...Failed to get pointer to device." & vbCrLf
                End If
            Next
        Else
            sOut = "No active devices found." & vbCrLf
        End If
    Else
        Debug.Print "Failed to get device count."
        sOut = sOut & "An error occured getting the device count." & vbCrLf
    End If
Else
    Debug.Print "Failed to set pDvCol"
    sOut = "Failed to get device collection (no active devices or an error occured)"
End If
Text1.Text = sOut

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twinBASIC 64bit-compatible version can be found at: https://github.com/fafalone/CoreAudioDemos