NumberOfLines Property

'Declaration
 
Public ReadOnly Property NumberOfLines As Integer

Public _result As Boolean = False
      Public _form As CaptureCtrlForm = New CaptureCtrlForm()
      Public Sub AvailableTVFormatsExample()
         Try
            ' reference the forms capture control
            Dim capturectrl As CaptureCtrl = _form.CaptureCtrl

            Dim outFile As String = Path.Combine(LEAD_VARS.MediaDir, "AnalogVideoDecoder_AvailableTVFormatsExample.avi")
            Dim lines As Integer = 0
            Dim allResults As Boolean = True

            ' select the first device with analog in it's name
            ' Replace "Analog" with your tuner device name
            If capturectrl.VideoDevices("Analog") Is Nothing Then
               Throw New Exception("No analog video capture device available")
            End If

            capturectrl.VideoDevices("Analog").Selected = True

            Dim analogvideodecoder As AnalogVideoDecoder = capturectrl.AnalogVideoDecoder
            Dim availableFormats As AnalogVideoStandard = analogvideodecoder.AvailableTVFormats
            Dim tvFormat As AnalogVideoStandard = analogvideodecoder.TVFormat

            ' Check if format is NTSC and set it if not
                 If tvFormat <> AnalogVideoStandard.NTSC_M_J AndAlso (availableFormats And _
                                                                      AnalogVideoStandard.NTSC_M_J) = _
                                                                      AnalogVideoStandard.NTSC_M_J Then
                     ' set the analog video decoder TV format
                     analogvideodecoder.TVFormat = AnalogVideoStandard.NTSC_M_J

                     ' check the changed format
                     allResults = allResults And (analogvideodecoder.TVFormat = AnalogVideoStandard.NTSC_M_J)
                 End If

            ' Check if Horizontal Locked is enabled
            Dim vLocked As Boolean = capturectrl.AnalogVideoDecoder.HorizontalLocked

            ' Some video device's Analog Decoder implementations do not
            ' support the following properties, so we wrap these property 
            ' accesses with a special try block to catch possible exceptions
            Try
               ' Check if VCR Horizontal Sync locking is enabled and set if not
               Dim vcrLocked As Boolean = capturectrl.AnalogVideoDecoder.VCRHorizontalLocking
               If (Not vcrLocked) Then
                  ' set VCR horzontal sync locking
                  capturectrl.AnalogVideoDecoder.VCRHorizontalLocking = True

                  ' include this as one of our checks
                  allResults = allResults And capturectrl.AnalogVideoDecoder.VCRHorizontalLocking
               End If

               ' Check if output enabled is set and set if not
               Dim outputEnabled As Boolean = capturectrl.AnalogVideoDecoder.OutputEnable
               If (Not outputEnabled) Then
                  ' enable output
                  capturectrl.AnalogVideoDecoder.OutputEnable = True

                  ' include this as one of our checks
                  allResults = allResults And capturectrl.AnalogVideoDecoder.OutputEnable
               End If
            Catch cex As COMException
               ' if the device does not support the properties above
               ' skip it and dont fail
               If cex.ErrorCode <> CInt(ErrorCode.E_PROP_ID_UNSUPPORTED) AndAlso cex.ErrorCode <> CInt(ErrorCode.E_PROP_SET_UNSUPPORTED) Then
                  Throw cex
               End If
            End Try

            Dim tries As Integer = 0

            ' check scan line count a few times 
            ' initial frames may differ from format spec, until frame data 
            ' has propogated through the capture graph
            Do While lines <> 525 AndAlso tries < 10
               ' get the number of scan lines in the output format
               lines = capturectrl.AnalogVideoDecoder.NumberOfLines
               System.Diagnostics.Debug.WriteLine("TV Format: " & analogvideodecoder.TVFormat.ToString() & ", Scan Lines: " & lines.ToString())
               tries += 1
            Loop

            ' include the line count check
            allResults = allResults And (lines = 525 AndAlso tries < 10)
            System.Diagnostics.Debug.WriteLine("Tries: " & tries.ToString())

            ' test results
            _result = allResults
         Catch e1 As Exception
            _result = False
         End Try
      End Sub

Public NotInheritable Class LEAD_VARS
   Public Const MediaDir As String = "C:\Program Files (x86)\LEAD Technologies\LEADTOOLS 175\Media";
End Class