UseFilterCache Property

Imports Leadtools
Imports Leadtools.Multimedia
Imports LeadtoolsMultimediaExamples.Fixtures

Public _result As Boolean = False
Public _form As CaptureCtrlForm = New CaptureCtrlForm()
Public _pMpgMux As LMMpg2MxTLib.LMMpg2MxT
' This example will show you the correct way to set up a muxer's properties during capture
' Normally, the muxer is added only after the capture graph has been build with ReadyCapture or StartCapture
' But at this point, the graph is in running mode, so some muxer operations might fail
' If you need to make changes to the muxer in stopped state (like adding KLV data stream, for example),
' then you need to change the muxer before the graph is fully built. You can do so by instructing the toolkit
' to cache the target filters by setting the the TargetFormat.UseFilterCache property to true
' In this situation, the filters used to implement a certain target format are created and used whenever 
' you set that target format.

' This example will show you how to add KLV data to a MPEG-2 Transport Stream in a capture situation.

Public Sub UseFilterCacheExample()
   ' reference the capture control
   Dim capturectrl As CaptureCtrl = _form.CaptureCtrl
   Dim outFile As String = Path.Combine(LEAD_VARS.MediaDir, "CaptureKLV.mpg")

   Try
      ' select the capture device
      capturectrl.VideoDevices.Selection = 0 ' Use a different video device if you want 

      ' capturectrl.Preview = true; -- enable this if you want 


      ' set the video compressor (only if the capture device is not already capturing compressed video)

      capturectrl.VideoCompressors.Mpeg2.Selected = True

      ' set the target output file
      capturectrl.TargetFile = outFile

      ' subscribe to the compete event
      AddHandler capturectrl.Started, AddressOf CaptureCtrl_Started

      ' just 10 seconds of capture time
      capturectrl.TimeLimit = 10
      capturectrl.UseTimeLimit = True

      ' subscribe to the compete event
      AddHandler capturectrl.Complete, AddressOf CaptureCtrl_Complete

      ' IN a capture situation 
      'in order to get the mux in a capture situation, set the UseFilterCache property for the target format to TRUE
      '      This tells the toolkit to create a Mux object and keep it around when building or rebuilding graphs
      capturectrl.TargetFormats(Leadtools.Multimedia.TargetFormatType.MPEG2Transport).UseFilterCache = True
      capturectrl.TargetFormat = Leadtools.Multimedia.TargetFormatType.MPEG2Transport

      _pMpgMux = DirectCast(capturectrl.TargetFormats(Leadtools.Multimedia.TargetFormatType.MPEG2Transport).GetCacheObject(TargetFormatObject.Mux), LMMpg2MxTLib.LMMpg2MxT)
      If _pMpgMux IsNot Nothing Then
         _pMpgMux.PrivateDataPID = &H70
         _pMpgMux.PrivateDataFormatID = &H41564C4B
         _pMpgMux.EnablePrivateData = True
      End If

      ' start capture
      capturectrl.StartCapture(Leadtools.Multimedia.CaptureMode.Video)
      _result = True
   Catch generatedExceptionName As Exception
      _result = False
   End Try
End Sub

Private Sub WriteKLVData(ByVal pMpgMux As LMMpg2MxTLib.LMMpg2MxT)
   ' get the current time since Jan 1, 1970
   Dim basetime As TimeSpan = DateTime.UtcNow - New DateTime(1970, 1, 1, 0, 0, 0)
   ' get the number of microseconds since Jan 1, 1970
   Dim timestamp As Int64 = CLng(basetime.TotalSeconds) * 1000000
   ' don't really need to do this, since I am writing only one item
   pMpgMux.KlvBuilder.Clear()
   ' write the UDS timestamp (number of microseconds since Jan 1, 1970)
   pMpgMux.KlvBuilder.InsertUInt64(-1, "06 0E 2B 34 01 01 01 03 07 02 01 01 01 05 00 00", CULng(timestamp))
   ' write one KLV data at the beginning
   pMpgMux.WritePrivateData(CInt(LMMpg2MxTLib.Mpg2MxT_WriteFlags.Mpg2MxT_WriteFlag_PTSValid) _
                            Or CInt(LMMpg2MxTLib.Mpg2MxT_WriteFlags.Mpg2MxT_WriteFlag_PTSInSeconds), _
                            0.0, pMpgMux.KlvBuilder.GetData(), -1)
   ' close the stream
   pMpgMux.ClosePrivateData()
End Sub

Public Sub CaptureCtrl_Started(ByVal sender As Object, ByVal e As EventArgs)
   WriteKLVData(_pMpgMux)
End Sub

Public Sub CaptureCtrl_Complete(ByVal sender As Object, ByVal e As EventArgs)
   ' set result
   _result = True
End Sub

Public NotInheritable Class LEAD_VARS
Public Const MediaDir As String = "C:\Program Files (x86)\LEAD Technologies\LEADTOOLS 19\Media"
End Class