Capturing Using a TV Tuner

Take the following steps to create and run a multimedia TV tuner capture application using the LEADTOOLS Media Foundation CaptureCtrl control.

1. Start Visual Studio.

2. Choose File->New->Project... from the menu.

3. In the New Project dialog box, choose either "Visual C# Projects" or "VB Projects" in the Projects Type List, and choose "Windows Application " in the Templates List.

4. Type the project name as "Multimedia TV Tuner Capture" in the Project Name field, and then choose OK. If desired, type a new location for your project or select a directory using the Browse button, and then choose OK.

5. In the "Solution Explorer" window, right-click on the "References" folder, and select "Add Reference..." from the context menu. In the "Add Reference" dialog box, select the ".NET" tab and select Leadtools.MediaFoundation and click OK.

6. Make sure Form1 is in design view. Go to the toolbox (View->Toolbox) and drag and drop a CaptureCtrl control on the form. NOTE: If you do not have CaptureCtrl in your toolbox, select Tools->Choose Toolbox Items from the menu. Click Browse and then select Leadtools.MediaFoundation.dll from "<LEADTOOLS_INSTALLDIR>\Bin\Dotnet4\Win32" and then click Open and then click OK. After adding it to the form, set the following properties on the capture control:

   Property	Value
   Name	_capturectrl
   Anchor	Top, Bottom, Left, Right

7. Go to the toolbox (View->Toolbox) and drag and drop a ProgressBar control (to be used to display capture progress) on the form (below the capture control) and set the following properties:

   Property	Value
   Name	_progress
   Anchor	Bottom, Left, Right

8. Go to the toolbox (View->Toolbox) and drag and drop 4 Button controls on the bottom of the form (for Capture, Channel Up and Channel Down) and set the following properties:

   Property	Value
   Name	_buttonCapture
   Text	Capture
   Anchor	Bottom, Right
   Name	_buttonChannelUp
   Text	Up
   Anchor	Bottom, Right
   Name	_buttonChannelDown
   Text	Down
   Anchor	Bottom, Right

9. Go to the toolbox (View->Toolbox) and drag and drop a Label control, a Text control, another Label control and a ProgressBar control on the bottom left of the form (for a "Channel:" label, a channel text box, a "Signal:" label and a signal strength meter) and set the following properties:

   Property	Value
   Name	label1
   Text	Channel:
   Anchor	Bottom, Left
   Name	_textChannel
   Anchor	Bottom, Left
   Locked	True
   ReadOnly	True
   TextAlign	Center
   Name	label2
   Text	Signal:
   Anchor	Bottom, Left
   Name	_signal
   Anchor	Bottom, Left

10. Switch Form1 to code view (right-click Form1 in the solution explorer then select View Code) and add the following lines at the beginning of the file:

    C#

    using System.Runtime.InteropServices; 
    using Leadtools.MediaFoundation; 

    VB

    Imports System.Runtime.InteropServices 
    Imports Leadtools.MediaFoundation 

11. Declare the following private variables:

    C#

    private string _targetFile; 
    private int _captureTime; 

    VB

    Private _targetFile As String 
    Private _captureTime As Integer 

12. Add an event handler to the Form1 Load event and code it as follows:

    C#

    private void Form1_Load(object sender, EventArgs e) 
    { 
       if (_capturectrl.VideoDevices.Count == 0) 
          throw new Exception("No capture devices available"); 
       if (_capturectrl.VideoDevices["Analog"] == null) 
          throw new Exception("No Analog TV capture devices available"); 
       _capturectrl.VideoDevices["Analog"].Selected = true; 
       _capturectrl.UseVideoDeviceAudio = true; 
                        
       _capturectrl..TargetFormats.Selection = TargetFormatType.MP4; 
                        
       _targetFile = @"capture.mp4"; 
       _captureTime = 30; 
       _capturectrl.PreviewSource = CapturePreview.Video; 
       _capturectrl.Preview = true; 
       DisplayChannelAndSignal(); 
    } 

    VB

    Private Sub Form1_Load(ByVal sender As Object, ByVal e As EventArgs) Handles MyBase.Load 
       If _capturectrl.VideoDevices.Count = 0 Then 
          Throw New Exception("No capture devices available") 
       End If 
       If _capturectrl.VideoDevices("Analog") Is Nothing Then 
          Throw New Exception("No Analog TV capture devices available") 
       End If 
       _capturectrl.VideoDevices("Analog").Selected = True 
                        
       _capturectrl..TargetFormats.Selection = TargetFormatType.MP4 
                        
       _targetFile = "capture.mp4" 
       _captureTime = 30 
       _capturectrl.PreviewSource = CapturePreview.Video 
       _capturectrl.Preview = True 
       DisplayChannelAndSignal() 
    End Sub 

13. Add the following helper methods as follows:

    C#

    private void DisplayChannelAndSignal() 
    { 
       if (_capturectrl.TVTuner != null) 
       { 
          int currChannel = _capturectrl.TVTuner.Channel; 
          _textChannel.Text = currChannel.ToString(); 
          TunerSignalStrength signal = _capturectrl.TVTuner.SignalPresent; 
          switch (signal) 
          { 
             case TunerSignalStrength.NoSignal: 
                _signal.Value = 0; 
                break; 
             case TunerSignalStrength.HasNoSignalStrength: 
                _signal.Value = 10; 
                break; 
             case TunerSignalStrength.SignalPresent: 
                _signal.Value = 100; 
                break; 
          } 
       } 
    } 
    private void ChangeChannel(bool up) 
    { 
       int chanMin = _capturectrl.TVTuner.ChannelMin; 
       int chanMax = _capturectrl.TVTuner.ChannelMax; 
       int currChannel = _capturectrl.TVTuner.Channel; 
       int currVideoChannel = _capturectrl.TVTuner.VideoSubChannel; 
       if (up) 
       { 
          if (currChannel == chanMax) 
             currChannel = chanMin; 
          else 
             currChannel++; 
       } 
       else 
       { 
          if (currChannel == chanMin) 
             currChannel = chanMax; 
          else 
             currChannel--; 
       } 
       _capturectrl.TVTuner.SetChannel(currChannel, -1, -1); 
       DisplayChannelAndSignal(); 
    } 

    VB

    Private Sub DisplayChannelAndSignal() 
       If Not _capturectrl.TVTuner Is Nothing Then 
          Dim currChannel As Integer = _capturectrl.TVTuner.Channel 
          _textChannel.Text = currChannel.ToString() 
          Dim signal As TunerSignalStrength = _capturectrl.TVTuner.SignalPresent 
          Select Case signal 
             Case TunerSignalStrength.NoSignal 
                _signal.Value = 0 
             Case TunerSignalStrength.HasNoSignalStrength 
                _signal.Value = 10 
             Case TunerSignalStrength.SignalPresent 
                _signal.Value = 100 
          End Select 
       End If 
    End Sub 
    Private Sub ChangeChannel(ByVal up As Boolean) 
       Dim chanMin As Integer = _capturectrl.TVTuner.ChannelMin 
       Dim chanMax As Integer = _capturectrl.TVTuner.ChannelMax 
       Dim currChannel As Integer = _capturectrl.TVTuner.Channel 
       Dim currVideoChannel As Integer = _capturectrl.TVTuner.VideoSubChannel 
       If up Then 
          If currChannel = chanMax Then 
             currChannel = chanMin 
          Else 
             currChannel += 1 
          End If 
       Else 
          If currChannel = chanMin Then 
             currChannel = chanMax 
          Else 
             currChannel -= 1 
          End If 
       End If 
       _capturectrl.TVTuner.SetChannel(currChannel, -1, -1) 
       DisplayChannelAndSignal() 
    End Sub 

14. Add an event handler to the _capturectrl Progress event and code it as follows:

    C#

    private void _capturectrl_Progress(object sender, ProgressEventArgs e) 
    { 
       _progress.Value = (int)((_progress.Maximum * e.time) / (_captureTime * 1000)); 
    } 

    VB

    Private Sub _capturectrl_Progress(ByVal sender As System.Object, ByVal e As ProgressEventArgs) Handles _capturectrl.Progress 
       _progress.Value = CInt((_progress.Maximum * e.time) / (_captureTime * 1000)) 
    End Sub 

15. Add an event handler to the _capturectrl Complete event and code it as follows:

    C#

    private void _capturectrl_Complete(object sender, EventArgs e) 
    { 
       MessageBox.Show("Capture Complete"); 
       _buttonCapture.Enabled = true; 
    } 

    VB

    Private Sub _capturectrl_Complete(ByVal sender As System.Object, ByVal e As EventArgs) Handles _capturectrl.Complete 
       MessageBox.Show("Capture Complete") 
       _buttonCapture.Enabled = True 
    End Sub 

16. Add an event handler to the _buttonChannelUp Click event and code it as follows:

    C#

    private void _buttonChannelUp_Click(object sender, EventArgs e) 
    { 
       if (_capturectrl.TVTuner != null) 
       { 
          ChangeChannel(true); 
       } 
    } 

    VB

    Private Sub _buttonChannelUp_Click(ByVal sender As Object, ByVal e As EventArgs) Handles _buttonChannelUp.Click 
       If Not _capturectrl.TVTuner Is Nothing Then 
          ChangeChannel(True) 
       End If 
    End Sub 

17. Add an event handler to the _buttonChannelDown Click event and code it as follows:

    C#

    private void _buttonChannelDown_Click(object sender, EventArgs e) 
    { 
       if (_capturectrl.TVTuner != null) 
       { 
          ChangeChannel(false); 
       } 
    } 

    VB

    Private Sub _buttonChannelDown_Click(ByVal sender As Object, ByVal e As EventArgs) Handles _buttonChannelDown.Click 
       If Not _capturectrl.TVTuner Is Nothing Then 
          ChangeChannel(False) 
       End If 
    End Sub 

18. Add an event handler to the _buttonCapture Click event and code it as follows:

    C#

    private void _buttonCapture_Click(object sender, System.EventArgs e) 
    { 
       try 
       { 
          _capturectrl.Preview = true; 
          _capturectrl.TargetFile = _targetFile; 
          _capturectrl.UseTimeLimit = true; 
          _capturectrl.TimeLimit = _captureTime; 
                           
          _capturectrl.StartCapture(CaptureMode.Video); 
          _buttonCapture.Enabled = false; 
       } 
       catch (Exception ex) 
       { 
          MessageBox.Show(ex.Message); 
       } 
    } 

    VB

    Private Sub _buttonCapture_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles _buttonCapture.Click 
       Try 
          _capturectrl.Preview = True 
          _capturectrl.TargetFile = _targetFile 
          _capturectrl.UseTimeLimit = True 
          _capturectrl.TimeLimit = _captureTime 
                           
          _capturectrl.StartCapture(CaptureMode.Video) 
          _buttonCapture.Enabled = False 
       Catch ex As Exception 
          MessageBox.Show(ex.Message) 
       End Try 
    End Sub    

19. Build, and Run the program to test it.