NumberOfLines Property

Imports Leadtools
Imports Leadtools.Multimedia
Imports LeadtoolsMultimediaExamples.Fixtures

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 18\Media"
End Class