Media won't play if called via invoke delegate

carled · Postby **carled** » 13 Jul 2009 11:06

Hi all. Just started doing a vb.net prog.

Very simple concept, the player sits there listening for events on the serial port, once received, it starts playing that media.

If I put a drop down box on the page and select the media file, it successfully plays the media like this:

Code: Select all

(in "play" button pressed sub)
playMedia(combobox1.selectedItem)

Private Sub playMedia()
        Dim vlc As AxAXVLC.AxVLCPlugin2 = AxVLCPlugin21
        If (vlc.playlist.items.count > 0) Then
            If (vlc.playlist.isPlaying) Then
                vlc.playlist.stop()
            End If
            vlc.playlist.items.clear()
        End If
        Dim item As Integer = vlc.playlist.add("c:\media\" + mediaString) 'mediastring is global variable
        vlc.playlist.playItem(item)
        mediaString = ""
End Sub

Now as the windows form is on a different thread to the event listener, if I try and access the vlc control via that thread, I get a "cross-thread exception" and rightly so. I therefore used a delegate:

Code: Select all

    Public Delegate Sub myVLCDelegate()

(and in my "event received" subroutine:)

Private Sub DataReceived( _
       ByVal sender As Object, _
       ByVal e As System.IO.Ports.SerialDataReceivedEventArgs) _
       Handles serialPort.DataReceived
        Dim x As String = serialPort.ReadExisting
        mediaString += x
        If x = Chr(13) Then
            'playMedia(mediaString) '(can't do this - cross thread exception)
            If InvokeRequired Then '(this always comes up with "true")
                Invoke(New myVLCDelegate(AddressOf playMedia), New Object() {})
            End If
        End If
    End Sub

Now in debug, I can see I no longer get the cross-thread exception, yahoo! However, directly after the "vlc.playlist.playItem(item)" in the playMedia sub, I check on "playlist.isPlaying" and it changes immediately to "false"...

Any ideas where I'm going wrong please? Seems simple, should work...?

carled · Postby **carled** » 14 Jul 2009 11:21

Update: it was me. I'd cracked the problem using the delegate. The new problem only became visible when I was looking at the log messages and it was saying, "can't open file". I realised that I was passing a carriage return in the filename too. Works a charm when that is stripped off!

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Media won't play if called via invoke delegate

Media won't play if called via invoke delegate

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