Question Capturing screen and webcam video simultaneously?

sspears2020 · Nov 12, 2010

Hey guys,

I'm working on a screen capture and webcam capture program that will record both at the same time. I currently have a button that starts the screen cap (while opening a ppt) and a keyboard hook that stops it when I hit F12. I also have a button that starts webcam recording, and a button that stops the recording.

So they are both working individually, but when I try to do both at the same time (calling both actions when I hit the start capture button) it sort of freezes up both processes. I'm thinking maybe they need to be run on different threads but I've tried doing so and I think I'm either doing it wrong or its just not making any difference?

Also on a side note - when I am capturing video from the webcam the keyboard hook no longer works :/

Here is the code for my form, if you want the keyboard hook let me know:

VB.NET:

Imports Microsoft.Expression.Encoder.ScreenCapture
Imports Microsoft.Office.Interop
Imports Microsoft.Office.Interop.PowerPoint
Imports Microsoft.Expression.Encoder.Devices
Imports System.Runtime.InteropServices
Imports System.Windows.Forms
Imports System.Threading

Public Class VideoRecorder
    Inherits System.Windows.Forms.Form

    Dim ScreenCap As New ScreenCaptureJob
    Dim appPowerpoint As PowerPoint.Application = New PowerPoint.Application
    Dim ShutDownAll As Boolean = False
    Dim shortName As String

    ' Create constant using attend in function of DLL file.

    Const WM_CAP As Short = &H400S
    Const WM_CAP_DRIVER_CONNECT As Integer = WM_CAP + 10
    Const WM_CAP_DRIVER_DISCONNECT As Integer = WM_CAP + 11
    Const WM_CAP_EDIT_COPY As Integer = WM_CAP + 30
    Const WM_CAP_SET_PREVIEW As Integer = WM_CAP + 50
    Const WM_CAP_SET_PREVIEWRATE As Integer = WM_CAP + 52
    Const WM_CAP_SET_SCALE As Integer = WM_CAP + 53
    Const WS_CHILD As Integer = &H40000000
    Const WS_VISIBLE As Integer = &H10000000
    Const SWP_NOMOVE As Short = &H2S
    Const SWP_NOSIZE As Short = 1
    Const SWP_NOZORDER As Short = &H4S
    Const HWND_BOTTOM As Short = 1
    Const WM_CAP_FILE_SAVEAS As Integer = WM_CAP + 23
    Const WM_CAP_SEQUENCE As Integer = WM_CAP + 62

    Dim iDevice As Integer = 0  ' Normal device ID 
    Dim hHwnd As Integer  ' Handle value to preview window

    ' Declare function from AVI capture DLL.

    Declare Function SendMessage Lib "user32" Alias "SendMessageA" _
        (ByVal hwnd As IntPtr, ByVal wMsg As Integer, ByVal wParam As Integer, _
         ByVal lParam As String) As Integer

    Declare Function SetWindowPos Lib "user32" Alias "SetWindowPos" (ByVal hwnd As Integer, _
        ByVal hWndInsertAfter As Integer, ByVal x As Integer, ByVal y As Integer, _
        ByVal cx As Integer, ByVal cy As Integer, ByVal wFlags As Integer) As Integer

    Declare Function DestroyWindow Lib "user32" (ByVal hndw As Integer) As Boolean

    Declare Function capCreateCaptureWindowA Lib "avicap32.dll" _
        (ByVal lpszWindowName As String, ByVal dwStyle As Integer, _
        ByVal x As Integer, ByVal y As Integer, ByVal nWidth As Integer, _
        ByVal nHeight As Short, ByVal hWndParent As Integer, _
        ByVal nID As Integer) As Integer

    Declare Function capGetDriverDescriptionA Lib "avicap32.dll" (ByVal wDriver As Short, _
        ByVal lpszName As String, ByVal cbName As Integer, ByVal lpszVer As String, _
        ByVal cbVer As Integer) As Boolean

    Dim WithEvents K As New Keyboard

    Private Sub VideoRecorder_Load1(ByVal sender As Object, ByVal e As System.EventArgs) Handles Me.Load
        K.CreateHook()
        OpenPreviewWindow()

    End Sub

    Private Sub VideoRecorder_FormClosing(ByVal sender As Object, ByVal e As System.Windows.Forms.FormClosingEventArgs) Handles Me.FormClosing
        K.DiposeHook()
        ClosePreviewWindow()
    End Sub

    Private Sub K_Down(ByVal Key As String) Handles K.Down
        If Key.ToString = "<F12>" Then
            Label1.Text = Key.ToString
            ShutDownAll = True
            Timer2.Enabled = True
        End If
    End Sub

    Private Sub Timer2_Tick(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles Timer2.Tick
        If ShutDownAll = True Then
            'StopVideoCap()
            ScreenCap.Stop()
            ScreenCap.Dispose()
            appPowerpoint.ActivePresentation.Close()
            appPowerpoint.Quit()
            Me.Close()
        End If
    End Sub

    Private Sub btnChooseFile_Click_1(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles btnChooseFile.Click
        ChooseFileDialog.ShowDialog()
        txtChooseFile.Text = ChooseFileDialog.FileName
        Dim less As Integer
        If txtChooseFile.Text.Contains(".ppt") Then
            less = 4
            If txtChooseFile.Text.Contains(".pptx") Then
                less = 5
            End If
        End If
        shortName = txtChooseFile.Text.Substring(0, txtChooseFile.Text.Length - less)
    End Sub

    Private Sub btnStart_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles btnStart.Click
        If txtChooseFile.Text = "" Then
            MsgBox("Please choose a PowerPoint file.")
            Exit Sub
        End If

        'open powerpoint slideshow
        Try
            Process.Start(txtChooseFile.Text)
        Catch ex As Exception
            MsgBox(ex.Message)
        End Try

        appPowerpoint.Activate()

        'capture settings
        ScreenCap.CaptureMouseCursor = False
        ScreenCap.CaptureRectangle = Screen.PrimaryScreen.Bounds
        ScreenCap.ShowCountdown = True
        ScreenCap.OutputScreenCaptureFileName = shortName + "_scr" + ".wmv"
        ScreenCap.ScreenCaptureVideoProfile.FrameRate = 60
        ScreenCap.Start()

        Timer1.Start()
    End Sub

    Private Sub Timer1_Tick(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles Timer1.Tick
        If appPowerpoint.Presentations.Count = 1 Then
            StartShow()
            Timer1.Enabled = False
        End If
    End Sub

    Private Sub StartShow()
        appPowerpoint.ActivePresentation.SlideShowSettings.Run()
        'StartVideoCap()
    End Sub


    '***************** VIDEO CAPTURE ************************
    Private Sub OpenPreviewWindow()
        Dim iHeight As Integer = picCapture.Height
        Dim iWidth As Integer = picCapture.Width

        ' Open Preview window in picturebox .
        ' Create a child window with capCreateCaptureWindowA so you can display it in a picturebox.

        hHwnd = capCreateCaptureWindowA(iDevice, WS_VISIBLE Or WS_CHILD, 0, 0, 640, _
            480, picCapture.Handle.ToInt32, 0)

        'Label1.Text = SendMessage(hHwnd, WM_CAP_DRIVER_CONNECT, iDevice, 0)
        ' Connect to device
        If SendMessage(hHwnd, WM_CAP_DRIVER_CONNECT, iDevice, 0) Then

            ' Set the preview scale
            SendMessage(hHwnd, WM_CAP_SET_SCALE, True, 0)

            ' Set the preview rate in milliseconds
            SendMessage(hHwnd, WM_CAP_SET_PREVIEWRATE, 15, 0)

            ' Start previewing the image from the camera 
            SendMessage(hHwnd, WM_CAP_SET_PREVIEW, True, 0)

            ' Resize window to fit in picturebox 
            SetWindowPos(hHwnd, HWND_BOTTOM, 0, 0, picCapture.Width, picCapture.Height, _
                                   SWP_NOMOVE Or SWP_NOZORDER)
            'btnSave.Enabled = True
            btnStop.Enabled = True
        Else
            ' Error connecting to device close window 
            DestroyWindow(hHwnd)
        End If
    End Sub

    ' Finally, to close the preview window, disconnect from the device and destroy the preview window. 

    Private Sub ClosePreviewWindow()
        ' Disconnect from device
        SendMessage(hHwnd, WM_CAP_DRIVER_DISCONNECT, iDevice, 0)

        ' close window 
        DestroyWindow(hHwnd)
    End Sub

    Private Sub StartVideoCap()
        Try
            SendMessage(hHwnd, WM_CAP_SEQUENCE, 0, 0)
        Catch ex As Exception
            MsgBox(ex.ToString)
        End Try
    End Sub
    Private Sub StopVideoCap()
        Dim avi As String = shortName & "_avi" & ".avi"

        'SAVE FILE
        Try
            SendMessage(hHwnd, WM_CAP_FILE_SAVEAS, 0, avi)
        Catch ex As Exception
            MsgBox(ex.Message)
        End Try
    End Sub

    Private Sub btnTestStart_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles btnTestStart.Click
        StartVideoCap()
    End Sub

    Private Sub btnStop_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles btnStop.Click
        StopVideoCap()
    End Sub

End Class

inilm · May 28, 2011

hi sspears2020
do u manage to solve your problem?
I had the same problem too that freeze up my applications. If yes, please update me. TQ

Question Capturing screen and webcam video simultaneously?

sspears2020

New member

inilm

New member

Similar threads