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)
    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 18\Media"
End Class