sFile = Left$(sBuffer, InStr(sBuffer, vbNullChar) - 1)

Public Function MP3_Play(ByVal sFile As String, _
  ByVal sAlias As String) As Boolean
 
        Dim bResult As Boolean
 
        ' Dateinamen in DOS 8.3 Format, da z.B. Sonderzeichen
        ' wie Leerzeichen Probleme machen
        Dim sBuffer As String
        Dim lResult As Long
 
        sBuffer = Space$(255)
        lResult = GetShortPathName(sFile, sBuffer, Len(sBuffer))
 
        If lResult <> 0 Then
            sFile = Left$(sBuffer, InStr(sBuffer, vbNullChar) - 1)
 
            ' MCI öffnen
            lResult = mciSendString("open " & sFile & _
              " type MPEGVideo alias " & sAlias, 0, 0, 0)
 
            If lResult = 0 Then
                ' MP3 abspielen
                If mciSendString("play " & sAlias & _
                  " from 0", 0, 0, 0) = 0 Then
                    bResult = True
                End If
            End If
        End If
 
        MP3_Play = bResult
    End Function

        If lied1 = "leer" Then
            GoTo ml1
        End If
        MP3_Play(lied1), "MyAlias"
ml1:
        If lied2 = "leer" Then
            GoTo ml2
        End If
        MP3_Play(lied2),  "MyAlias"
ml2:
        If lied3 = "leer" Then
            GoTo ml3
        End If
        MP3_Play(lied3),  "MyAlias"
ml3:
        If lied4 = "leer" Then
            GoTo ml4
        End If
        MP3_Play(lied4), "MyAlias"
ml4:

Dim lied1 As String = TextBox1.Text
        Dim lied2 As String = TextBox2.Text
        Dim lied3 As String = TextBox3.Text
        Dim lied4 As String = TextBox4.Text

_________________________
Professionelle Entwicklerkomponenten
www.tools4vb.de

Dim WithEvents Playback As New AudioPlayback

"WithEvents" ist bei der Deklaration von lokalen Variablen ungültig.

Imports Microsoft.DirectX
Public Class AudioPlayback
    ' Musik ist zu Ende Event
    Public Event AudioEnd(ByVal sender As Object, ByVal e As EventArgs)
 
    ' DirectX9 Audio
    Public WithEvents m_Audio As AudioVideoPlayback.Audio = Nothing
 
    ' Variable : Läuft die Musik noch ?
    Private m_AudioPlaying As Boolean = False
    ''' <summary>
    ''' Lädt die angegebene Audio-Datei
    ''' </summary>
    ''' <param name="Filename">Dateiname der Audio-Datei</param>
    Public Sub Load(ByVal Filename As String)
        m_Audio = New AudioVideoPlayback.Audio(Filename)
    End Sub
    ''' <summary>
    ''' Spielt die Audio-Datei ab
    ''' </summary>
    Public Sub Play()
        Try
            m_Audio.Play()
            m_AudioPlaying = True
        Catch
            m_AudioPlaying = False
        End Try
    End Sub
    ''' <summary>
    ''' Abspielvorgang stoppen
    ''' </summary>
    Public Sub [Stop]()
        m_Audio.Stop()
        m_AudioPlaying = False
    End Sub
    ''' <summary>
    ''' Pause-Funktion für den Abspielvorgang
    ''' </summary>
    Public Sub Pause()
        m_Audio.Pause()
    End Sub
    ' Gibt die Ressourcen frei
    Private Sub Dispose()
        m_Audio.Dispose()
    End Sub
    ''' <summary>
    ''' Beendet die Wiedergabe und gibt die Ressourcen frei
    ''' </summary>
    Public Sub Beenden()
        [Stop]()
        Dispose()
    End Sub
    ''' <summary>
    ''' Legt die Lautstärke fest oder gibt diese zurück
    ''' </summary>
    Public Property Volume() As Integer
        Get
            Return m_Audio.Volume
        End Get
        Set(ByVal value As Integer)
            m_Audio.Volume = value
        End Set
    End Property
    ''' <summary>
    ''' Gibt zurück, ob aktuell ein Abspielvorgang läuft
    ''' </summary>
    Public ReadOnly Property IsPlaying() As Boolean
        Get
            Return m_AudioPlaying
        End Get
    End Property
    ' Löst ein Event aus, wenn der Abspielvorgang beendet ist
    Private Sub Ending(ByVal sender As Object, _
      ByVal e As EventArgs) Handles m_Audio.Ending
 
        m_AudioPlaying = False
 
        ' Event auslösen
        RaiseEvent AudioEnd(sender, e)
    End Sub
End Class

Zitat:

... Fügen Sie Ihrem Projekt zunächst den Verweis "Microsoft.DirectX.AudioVideoPlayback" hinzu. ...

_________________________
Professionelle Entwicklerkomponenten
www.tools4vb.de

Public Class Form1
    Dim WithEvents Playback As New AudioPlayback
    Microsoft.DirectX.AudioVideoPlayback()
    Private Sub Button1_Click(ByVal sender As System.Object, ByVal e As _
      System.EventArgs) Handles Button1.Click
 
        Dim lied1 As String = TextBox1.Text
        Dim lied2 As String = TextBox2.Text
        Dim lied3 As String = TextBox3.Text
        Dim lied4 As String = TextBox4.Text
        If RadioButton1.Checked = True Then
            GoTo wav
        End If
        If RadioButton2.Checked = True Then
            GoTo mp
        End If
wav:
        If lied1 = "leer" Then
            GoTo l1
 
        End If
        Playback.Load(lied1)

Microsoft.DirectX.AudioVideoPlayback()