Fade volume of background media on specific slide in PowerPoint using VBA

问题

I have a PowerPoint which begins with a a media file automatically playing. The first slide is programmed to transition after 20 seconds, all the while the music keeps playing. I would like for it to keep playing for the duration of the slideshow, but fade to a lower volume once the second slide appears and remain that way for the rest of the presentation. I've looked at this Powerpoint change sound effect volume in macro but it doesn't seem to satisfy my needs.

I tried this:

Sub fadeVolSlideChange(ByVal ShowPos As SlideShowWindow)
    Dim ShowPos As Integer
    Dim bkgMusic As Shape
    Dim Step As Long
    
    ShowPos = ShowPos.View.CurrentShowPosition
    Set bkgMusic = ActiveWindow.Selection.ShapeRange(1)

    If ShowPos = 2 Then
        Set Step = 0.05
        For i = 1 To 0.5
            With bkgMusic.MediaFormat
                .Volume = i
                .Muted = False
            End With
            i = i - Step
            Application.Wait (Now + 0.0000025)
        Next i
    End If

End Sub

With no luck. Thoughts?

Here's the latest edit (still no luck getting it to work):

Sub OnSlideShowPageChange()
    Dim i As Integer
    Dim bkgMusic As Shape
    Dim bkgVol As Long
    Dim inc As Long
    i = ActivePresentation.SlideShowWindow.View.CurrentShowPosition
    Set bkgMusic = ActivePresentation.Slides(1).Shapes("Opening Theme")
    
    If i = 1 Then
        'Do nothing
    ElseIf i <> 1 Then
        inc = 0.05
        For bkgVol = 1 To 0.1
            With bkgMusic.MediaFormat
                .Volume = bkgVol
                .Muted = False
            End With
            bkgVol = bkgVol - inc
            Application.Wait (Now + TimeValue("0:00:01"))
        Next bkgVol
    End If
    
End Sub

回答1:

This almost works, but PPT shoots us down in the end. After it runs, the volume of the sound file has been reduced, but it doesn't change during the slideshow.

Sub OnSlideShowPageChange()
    Dim i As Integer
    Dim bkgMusic As Shape
    ' This needs to be single, not Long
    Dim bkgVol As Single
    Dim inc As Long
    Dim lCounter As Long
    
    i = ActivePresentation.SlideShowWindow.View.CurrentShowPosition

    Set bkgMusic = ActivePresentation.Slides(1).Shapes("Opening Theme")
    
    If i = 2 Then
        inc = 0.05
        ' Changing the value by fractions so must be a single, not a long, and
        ' decreasing the value requires Step and a negative number:
        For bkgVol = 1 To 0.1 Step -0.1
            With bkgMusic.MediaFormat
                .Volume = bkgVol
                .Muted = False
            End With
            'bkgVol = bkgVol - inc
            ' Application.Wait is not supported in PPT
            'Application.Wait (Now + TimeValue("0:00:01"))
            WaitForIt
            SlideShowWindows(1).View.GotoSlide (2)
        Next bkgVol
    End If
    
End Sub


Sub WaitForIt()

Dim x As Long

For x = 1 To 1000000
    DoEvents
Next
    'MsgBox "Done waiting"
End Sub

来源：https://stackoverflow.com/questions/64916028/fade-volume-of-background-media-on-specific-slide-in-powerpoint-using-vba

标签

vba

powerpoint