WMPlayer无法启动

Question

我正在尝试使用Windows Media Player控件从视频中获取大量帧。它被放置在Panel控件上。

Public Class Form1
    Private b As New System.Drawing.Bitmap(160, 120)
    Private rct As New Rectangle(0, 0, 160, 120)
    Private pb As PictureBox

    Private Sub Button1_Click(sender As Object, e As EventArgs) Handles Button1.Click
        wm.URL = TextBox1.Text
        wm.Ctlcontrols.play()
    End Sub

    Private Sub wm_OpenStateChange(sender As Object, e As AxWMPLib._WMPOCXEvents_OpenStateChangeEvent) Handles wm.OpenStateChange
        If e.newState = 13 And wm.playState = 3 Then
            Dim g As Graphics = Graphics.FromImage(b)
            g.CopyFromScreen(PointToScreen(Panel1.Location), New Drawing.Point(0, 0), b.Size, CopyPixelOperation.SourceCopy)
            pb = New PictureBox With {.Width = 160, .Height = 120, .Image = b}
            FlowLayoutPanel1.Controls.Add(pb)
            Try
                While True
                    wm.Ctlcontrols.currentPosition += 20
                    Application.DoEvents()
                    If wm.Ctlcontrols.currentPosition > wm.currentMedia.duration - 20 Then
                        Exit Sub
                    End If
                    b = New Bitmap(160, 120)
                    g = Graphics.FromImage(b)
                    g.CopyFromScreen(PointToScreen(Panel1.Location), New Drawing.Point(0, 0), b.Size, CopyPixelOperation.SourceCopy)
                    pb = New PictureBox With {.Width = 160, .Height = 120, .Image = b}
                    FlowLayoutPanel1.Controls.Add(pb)
                End While
            Catch ex As Exception
            End Try
        End If
    End Sub
End Class

因此我希望在FlowLayoutPanel Control中获得许多帧。但是有一些“黑匣子”（重复第一帧）。有什么想法？..如何让WMP更新它的位置和布局？我的想象已经结束了。