NumberOfLines Property

Summary

Gets the number of scan lines in the video signal.

Syntax
C#
VB
C++
public int NumberOfLines { get; } 
Public ReadOnly Property NumberOfLines As Integer 
public: 
property int NumberOfLines { 
   int get(); 
} 

Property Value

A value indicating the number of scan lines.

Remarks

This property is updated with the number of scan lines in the video signal. The retrieved value is generally 525 lines for NTSC and 625 lines for PAL or SECAM.

For more detailed information, refer to the Microsoft documentation for IAMAnalogVideoDecoder.get_NumberOfLines.

Example
C#
VB
using Leadtools; 
using Leadtools.Multimedia; 
using LeadtoolsMultimediaExamples.Fixtures; 
 
public bool _result = false; 
public CaptureCtrlForm _form = new CaptureCtrlForm(); 
 
public void AvailableTVFormatsExample() 
{ 
   try 
   { 
      // reference the forms capture control 
      CaptureCtrl capturectrl = _form.CaptureCtrl; 
 
      string outFile = Path.Combine(LEAD_VARS.MediaDir, "AnalogVideoDecoder_AvailableTVFormatsExample.avi"); 
      int lines = 0; 
      bool allResults = true; 
 
      // select the first device with the word "analog" in its name 
      // Replace "Analog" with the name of your tuner device 
      if (capturectrl.VideoDevices["Analog"] == null) 
         throw new Exception("No analog video capture device available"); 
 
      capturectrl.VideoDevices["Analog"].Selected = true; 
 
      AnalogVideoDecoder analogvideodecoder = capturectrl.AnalogVideoDecoder; 
      AnalogVideoStandard availableFormats = analogvideodecoder.AvailableTVFormats; 
      AnalogVideoStandard tvFormat = analogvideodecoder.TVFormat; 
 
      // check whether the format is NTSC and set it if not 
      if (tvFormat != AnalogVideoStandard.NTSC_M_J 
         && (availableFormats & AnalogVideoStandard.NTSC_M_J) == AnalogVideoStandard.NTSC_M_J) 
      { 
         // set the analog video decoder TV format 
         analogvideodecoder.TVFormat = AnalogVideoStandard.NTSC_M_J; 
 
         // check the changed format 
         allResults &= (analogvideodecoder.TVFormat == AnalogVideoStandard.NTSC_M_J); 
      } 
 
      // check whether Horizontal Locked is enabled 
      bool vLocked = 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 whether VCR Horizontal Sync locking is enabled and set it if not 
         bool vcrLocked = capturectrl.AnalogVideoDecoder.VCRHorizontalLocking; 
         if (!vcrLocked) 
         { 
            // set VCR horzontal sync locking 
            capturectrl.AnalogVideoDecoder.VCRHorizontalLocking = true; 
 
            // include this as one of our checks 
            allResults &= capturectrl.AnalogVideoDecoder.VCRHorizontalLocking; 
         } 
 
         // check whether output enabled is set and set it if not 
         bool outputEnabled = capturectrl.AnalogVideoDecoder.OutputEnable; 
         if (!outputEnabled) 
         { 
            // enable output 
            capturectrl.AnalogVideoDecoder.OutputEnable = true; 
 
            // include this as one of our checks 
            allResults &= capturectrl.AnalogVideoDecoder.OutputEnable; 
         } 
      } 
      catch (COMException cex) 
      { 
         // if the device does not support the properties above 
         // skip it and do not fail 
         if (cex.ErrorCode != (int)ErrorCode.E_PROP_ID_UNSUPPORTED 
            && cex.ErrorCode != (int)ErrorCode.E_PROP_SET_UNSUPPORTED) 
            throw cex; 
      } 
 
      int tries = 0; 
 
      // check scan line count a few times  
      // initial frames may differ from format spec, until frame data  
      // has propogated through the capture graph 
      while (lines != 525 && 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()); 
      } 
 
      // include the line count check 
      allResults &= (lines == 525 && tries < 10); 
      System.Diagnostics.Debug.WriteLine("Tries: " + tries.ToString()); 
 
      // test results 
      _result = allResults; 
   } 
   catch (Exception) 
   { 
      _result = false; 
   } 
} 
 
static class LEAD_VARS 
{ 
   public const string MediaDir = @"C:\Program Files (x86)\LEAD Technologies\LEADTOOLS 20\Media"; 
} 
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 20\Media" 
End Class 
Requirements

Target Platforms

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Leadtools.Multimedia Assembly