VB.Net Directshow攝像頭快照

Question

我是新來的stackoverflow，但我註冊，因爲我認爲這裏是獲得專業編程幫助的正確地方:) 我的目標是創建一個網絡攝像頭快照工具，直接將快照保存到文件。 我不需要任何預覽在一個picturebox或類似的東西。 我想這樣的應用：

一個簡單的接口，與所連接的攝像頭設備組合框和一個按鈕，將拍攝快照，並將其保存到一個文件中。 我喜歡爲此使用DirectShow，因爲所有其他方式使用AForge或advcap32.dll，因爲它們有時會導致一個Videoourcedialog彈出，我不想這樣做。 我喜歡手動選擇我的組合框中的webcamdevice，並能夠拍攝快照。 這樣我喜歡使用DirectShow。

我已經添加了DirectShowLib-2005.dll我的VB.Net項目 我也加入這個類：

Imports System 
Imports System.Drawing 
Imports System.Drawing.Imaging 
Imports System.Runtime.InteropServices 
Imports System.Diagnostics 

Imports DirectShowLib 

Public Class Capture 
    Implements ISampleGrabberCB 
    Implements IDisposable 

#Region "Member variables" 

    Private m_graphBuilder As IFilterGraph2 = Nothing 
    Private m_mediaCtrl As IMediaControl = Nothing 
    Private mediaEventEx As IMediaEventEx = Nothing 
    Private videoWindow As IVideoWindow = Nothing 
    Private UseHand As IntPtr = MainForm.PictureBox1.Handle 
    Private Const WMGraphNotify As Integer = 13 
    Private m_takePicture As Boolean = False 
    Public mytest As String = "yes" 
    Dim sampGrabber As ISampleGrabber = Nothing 

    Private bufferedSize As Integer = 0 
    Private savedArray() As Byte 
    Public capturedPic As bitmap 
    Public captureSaved As Boolean 
    Public unsupportedVideo As Boolean 

    ' <summary> Set by async routine when it captures an image </summary> 
    Public m_bRunning As Boolean = False 

    ' <summary> Dimensions of the image, calculated once in constructor. </summary> 
    Private m_videoWidth As Integer 
    Private m_videoHeight As Integer 
    Private m_stride As Integer 

    Private m_bmdLogo As BitmapData = Nothing 
    Private m_Bitmap As Bitmap = Nothing 

#If DEBUG Then 
    ' Allow you to "Connect to remote graph" from GraphEdit 
    Private m_rot As DsROTEntry = Nothing 
#End If 

#End Region 

#Region "API" 

    Declare Sub CopyMemory Lib "Kernel32.dll" Alias "RtlMoveMemory" (ByVal Destination As IntPtr, ByVal Source As IntPtr, <MarshalAs(UnmanagedType.U4)> ByVal Length As Integer) 

#End Region 

    ' zero based device index, and some device parms, plus the file name to save to 
    Public Sub New(ByVal iDeviceNum As Integer, ByVal iFrameRate As Integer, ByVal iWidth As Integer, ByVal iHeight As Integer) 
     Dim capDevices As DsDevice() 

     ' Get the collection of video devices 
     capDevices = DsDevice.GetDevicesOfCat(FilterCategory.VideoInputDevice) 

     If (iDeviceNum + 1 > capDevices.Length) Then 
      Throw New Exception("No video capture devices found at that index!") 
     End If 

     Dim dev As DsDevice = capDevices(iDeviceNum) 

     Try 
      ' Set up the capture graph 
      SetupGraph(dev, iFrameRate, iWidth, iHeight) 
     Catch 
      Dispose() 
      If unsupportedVideo Then 
       msgbox("This video resolution isn't supported by the camera - please choose a different resolution.") 
      Else 
       Throw 
      End If 

     End Try 
    End Sub 
    ' <summary> release everything. </summary> 
    Public Sub Dispose() Implements IDisposable.Dispose 
     CloseInterfaces() 
     If (Not m_Bitmap Is Nothing) Then 
      m_Bitmap.UnlockBits(m_bmdLogo) 
      m_Bitmap = Nothing 
      m_bmdLogo = Nothing 
     End If 
    End Sub 
    Protected Overloads Overrides Sub finalize() 
     CloseInterfaces() 
    End Sub 

    ' <summary> capture the next image </summary> 
    Public Sub Start() 
     If (m_bRunning = False) Then 
      Dim hr As Integer = m_mediaCtrl.Run() 
      DsError.ThrowExceptionForHR(hr) 

      m_bRunning = True 
     End If 
    End Sub 
    ' Pause the capture graph. 
    ' Running the graph takes up a lot of resources. Pause it when it 
    ' isn't needed. 
    Public Sub Pause() 
     If (m_bRunning) Then 
      Dim hr As Integer = m_mediaCtrl.Pause() 
      DsError.ThrowExceptionForHR(hr) 

      m_bRunning = False 
     End If 
    End Sub 

    'Added by jk 
    Public Sub TakePicture() 

     m_takePicture = True 

    End Sub 

    ' <summary> Specify the logo file to write onto each frame </summary> 
    Public Sub SetLogo(ByVal fileName As String) 
     SyncLock Me 
      If (fileName.Length > 0) Then 
       m_Bitmap = New Bitmap(fileName) 

       Dim r As Rectangle = New Rectangle(0, 0, m_Bitmap.Width, m_Bitmap.Height) 
       m_bmdLogo = m_Bitmap.LockBits(r, ImageLockMode.ReadWrite, PixelFormat.Format24bppRgb) 
      Else 
       If Not m_Bitmap Is Nothing Then 
        m_Bitmap.UnlockBits(m_bmdLogo) 
        m_Bitmap = Nothing 
        m_bmdLogo = Nothing 
       End If 
      End If 
     End SyncLock 
    End Sub 

    ' <summary> build the capture graph for grabber. </summary> 
    Private Sub SetupGraph(ByVal dev As DsDevice, ByVal iFrameRate As Integer, ByVal iWidth As Integer, ByVal iHeight As Integer) 

     Dim hr As Integer 

     Dim baseGrabFlt As IBaseFilter = Nothing 
     Dim capFilter As IBaseFilter = Nothing 
     Dim muxFilter As IBaseFilter = Nothing 
     Dim fileWriterFilter As IFileSinkFilter = Nothing 
     Dim capGraph As ICaptureGraphBuilder2 = Nothing 
     Dim sampGrabberSnap As ISampleGrabber = Nothing 

     ' Get the graphbuilder object 
     m_graphBuilder = DirectCast(New FilterGraph(), IFilterGraph2) 
     m_mediaCtrl = DirectCast(m_graphBuilder, IMediaControl) 

     'if taking a picture (a still snapshot), then remove the videowindow 
     If Not m_takePicture Then 
      mediaEventEx = DirectCast(m_graphBuilder, IMediaEventEx) 
      videoWindow = DirectCast(m_graphBuilder, IVideoWindow) 
     Else 
      mediaEventEx = Nothing 
      videoWindow = Nothing 
     End If 

#If DEBUG Then 
     m_rot = New DsROTEntry(m_graphBuilder) 
#End If 

     Try 


      ' Get the ICaptureGraphBuilder2 
      capGraph = DirectCast(New CaptureGraphBuilder2(), ICaptureGraphBuilder2) 

      ' Get the SampleGrabber interface 
      sampGrabber = DirectCast(New SampleGrabber(), ISampleGrabber) 
      sampGrabberSnap = DirectCast(New SampleGrabber(), ISampleGrabber) 

      ' Start building the graph 
      hr = capGraph.SetFiltergraph(DirectCast(m_graphBuilder, IGraphBuilder)) 
      DsError.ThrowExceptionForHR(hr) 

      ' Add the video device 
      hr = m_graphBuilder.AddSourceFilterForMoniker(dev.Mon, Nothing, dev.Name, capFilter) 
      DsError.ThrowExceptionForHR(hr) 

      baseGrabFlt = DirectCast(sampGrabber, IBaseFilter) 
      ConfigureSampleGrabber(sampGrabber) 

      ' Add the frame grabber to the graph 
      hr = m_graphBuilder.AddFilter(baseGrabFlt, "Ds.NET Grabber") 
      DsError.ThrowExceptionForHR(hr) 

      ' If any of the default config items are set 
      If (iFrameRate + iHeight + iWidth > 0) Then 

       SetConfigParms(capGraph, capFilter, iFrameRate, iWidth, iHeight) 
      End If 

      hr = capGraph.RenderStream(PinCategory.Capture, MediaType.Video, capFilter, baseGrabFlt, muxFilter) 
      DsError.ThrowExceptionForHR(hr) 

      'if you set the m_takePicture it won't 
      If Not m_takePicture Then 

       'Set the output of the preview 
       hr = mediaEventEx.SetNotifyWindow(UseHand, WMGraphNotify, IntPtr.Zero) 
       DsError.ThrowExceptionForHR(hr) 

       'Set Owner to Display Video 
       hr = videoWindow.put_Owner(UseHand) 
       DsError.ThrowExceptionForHR(hr) 

       'Set window location - this was necessary so that the video didn't move down and to the right when you pushed the start/stop button 
       hr = videoWindow.SetWindowPosition(0, 0, 320, 240) 
       DsError.ThrowExceptionForHR(hr) 

       'Set Owner Video Style 
       hr = videoWindow.put_WindowStyle(WindowStyle.Child) 
       DsError.ThrowExceptionForHR(hr) 

      End If 


      SaveSizeInfo(sampGrabber) 

     Finally 

      If (Not fileWriterFilter Is Nothing) Then 
       Marshal.ReleaseComObject(fileWriterFilter) 
       fileWriterFilter = Nothing 
      End If 
      If (Not muxFilter Is Nothing) Then 
       Marshal.ReleaseComObject(muxFilter) 
       muxFilter = Nothing 
      End If 
      If (Not capFilter Is Nothing) Then 
       Marshal.ReleaseComObject(capFilter) 
       capFilter = Nothing 
      End If 
      If (Not sampGrabber Is Nothing) Then 
       Marshal.ReleaseComObject(sampGrabber) 
       sampGrabber = Nothing 
      End If 
     End Try 
    End Sub 

    ' <summary> Read and store the properties </summary> 
    Private Sub SaveSizeInfo(ByVal sampGrabber As ISampleGrabber) 

     Dim hr As Integer 

     ' Get the media type from the SampleGrabber 
     Dim media As AMMediaType = New AMMediaType() 
     hr = sampGrabber.GetConnectedMediaType(media) 
     DsError.ThrowExceptionForHR(hr) 

     If (Not (media.formatType.Equals(FormatType.VideoInfo)) AndAlso Not (media.formatPtr.Equals(IntPtr.Zero))) Then 
      Throw New NotSupportedException("Unknown Grabber Media Format") 
     End If 

     ' Grab the size info 
     Dim vInfoHeader As VideoInfoHeader = New VideoInfoHeader() 
     Marshal.PtrToStructure(media.formatPtr, vInfoHeader) 
     m_videoWidth = vInfoHeader.BmiHeader.Width 
     m_videoHeight = vInfoHeader.BmiHeader.Height 
     m_stride = CInt(m_videoWidth * (vInfoHeader.BmiHeader.BitCount/8)) 

     DsUtils.FreeAMMediaType(media) 
     media = Nothing 
    End Sub 
    ' <summary> Set the options on the sample grabber </summary> 
    Private Sub ConfigureSampleGrabber(ByVal sampGrabber As ISampleGrabber) 
     Dim hr As Integer 
     Dim media As AMMediaType = New AMMediaType() 

     media.majorType = MediaType.Video 
     media.subType = MediaSubType.RGB24 
     media.formatType = FormatType.VideoInfo 
     hr = sampGrabber.SetMediaType(media) 
     DsError.ThrowExceptionForHR(hr) 

     DsUtils.FreeAMMediaType(media) 
     media = Nothing 

     ' Configure the samplegrabber callback 
     hr = sampGrabber.SetOneShot(False) 
     DsError.ThrowExceptionForHR(hr) 

     If m_takePicture Then 
      hr = sampGrabber.SetCallback(Me, 0) 
     Else 
      hr = sampGrabber.SetCallback(Me, 0) 
     End If 
     DsError.ThrowExceptionForHR(hr) 

     DsError.ThrowExceptionForHR(hr) 

     'set the samplegrabber 
     sampGrabber.SetBufferSamples(False) 

    End Sub 

    ' Set the Framerate, and video size 
    Private Sub SetConfigParms(ByVal capGraph As ICaptureGraphBuilder2, ByVal capFilter As IBaseFilter, ByVal iFrameRate As Integer, ByVal iWidth As Integer, ByVal iHeight As Integer) 
     Dim hr As Integer 

     Dim o As Object = Nothing 
     Dim media As AMMediaType = Nothing 
     Dim videoStreamConfig As IAMStreamConfig 
     Dim videoControl As IAMVideoControl = DirectCast(capFilter, IAMVideoControl) 

     ' Find the stream config interface 
     hr = capGraph.FindInterface(PinCategory.Capture, MediaType.Video, capFilter, GetType(IAMStreamConfig).GUID, o) 

     videoStreamConfig = DirectCast(o, IAMStreamConfig) 
     Try 
      If (videoStreamConfig Is Nothing) Then 
       Throw New Exception("Failed to get IAMStreamConfig") 
      End If 

      ' Get the existing format block 
      hr = videoStreamConfig.GetFormat(media) 
      DsError.ThrowExceptionForHR(hr) 

      ' copy out the videoinfoheader 
      Dim v As VideoInfoHeader = New VideoInfoHeader() 
      Marshal.PtrToStructure(media.formatPtr, v) 

      ' if overriding the framerate, set the frame rate 
      If (iFrameRate > 0) Then 
       v.AvgTimePerFrame = CLng(10000000/iFrameRate) 
      End If 

      ' if overriding the width, set the width 
      If (iWidth > 0) Then 
       v.BmiHeader.Width = iWidth 
      End If 

      ' if overriding the Height, set the Height 
      If (iHeight > 0) Then 
       v.BmiHeader.Height = iHeight 
      End If 

      ' Copy the media structure back 
      Marshal.StructureToPtr(v, media.formatPtr, False) 

      ' Set the new format 
      hr = videoStreamConfig.SetFormat(media) 
      If hr <> 0 Then unsupportedVideo = True Else unsupportedVideo = False 
      DsError.ThrowExceptionForHR(hr) 

      DsUtils.FreeAMMediaType(media) 
      media = Nothing 

      ' Fix upsidedown video 
      If (Not videoControl Is Nothing) Then 
       Dim pCapsFlags As VideoControlFlags 

       Dim pPin As IPin = DsFindPin.ByCategory(capFilter, PinCategory.Capture, 0) 
       hr = videoControl.GetCaps(pPin, pCapsFlags) 
       DsError.ThrowExceptionForHR(hr) 

       If (CDbl(pCapsFlags & VideoControlFlags.FlipVertical) > 0) Then 
        hr = videoControl.GetMode(pPin, pCapsFlags) 
        DsError.ThrowExceptionForHR(hr) 

        hr = videoControl.SetMode(pPin, 0) 
       End If 
      End If 
     Finally 
      Marshal.ReleaseComObject(videoStreamConfig) 
     End Try 
    End Sub 

    ' <summary> Shut down capture </summary> 
    Private Sub CloseInterfaces() 
     Dim hr As Integer 

     Try 
      If (Not m_mediaCtrl Is Nothing) Then 

       ' Stop the graph 
       hr = m_mediaCtrl.Stop() 
       m_mediaCtrl = Nothing 
       m_bRunning = False 

       'Release Window Handle, Reset back to Normal 
       hr = videoWindow.put_Visible(OABool.False) 
       DsError.ThrowExceptionForHR(hr) 

       hr = videoWindow.put_Owner(IntPtr.Zero) 
       DsError.ThrowExceptionForHR(hr) 

       If mediaEventEx Is Nothing = False Then 
        hr = mediaEventEx.SetNotifyWindow(IntPtr.Zero, 0, IntPtr.Zero) 
        DsError.ThrowExceptionForHR(hr) 
       End If 

      End If 
     Catch ex As Exception 
      Debug.WriteLine(ex) 
     End Try 

#If DEBUG Then 
     If (Not m_rot Is Nothing) Then 
      m_rot.Dispose() 
      m_rot = Nothing 
     End If 
#End If 

     If (Not m_graphBuilder Is Nothing) Then 
      Marshal.ReleaseComObject(m_graphBuilder) 
      m_graphBuilder = Nothing 
     End If 
     GC.Collect() 
    End Sub 

    ' <summary> sample callback, Originally not used - call this with integer 0 on the setcallback method </summary> 
    Function SampleCB(ByVal SampleTime As Double, ByVal pSample As IMediaSample) As Integer Implements ISampleGrabberCB.SampleCB 
     myTest = "In SampleCB" 

     Dim i As Integer = 0 

     'jk added this code 10-22-13 
     If IsDBNull(pSample) = True Then Return -1 
     Dim myLen As Integer = pSample.GetActualDataLength() 
     Dim pbuf As IntPtr 
     If pSample.GetPointer(pbuf) = 0 And mylen > 0 Then 
      Dim buf As Byte() = New Byte(myLen) {} 
      Marshal.Copy(pbuf, buf, 0, myLen) 

      'Alter the video - you could use this to adjust the brightness/red/green, etc. 
      'for i = myLen-1 to 0 step -1 
      ' buf(i) = (255 - buf(i)) 
      'Next i 

      If m_takePicture Then 
       Dim bm As New Bitmap(m_videoWidth, m_videoHeight, Imaging.PixelFormat.Format24bppRgb) 
       Dim g_RowSizeBytes As Integer 
       Dim g_PixBytes() As Byte 

       mytest = "Execution point #1" 
       Dim m_BitmapData As BitmapData = Nothing 
       Dim bounds As Rectangle = New Rectangle(0, 0, m_videoWidth, m_videoHeight) 

       mytest = "Execution point #2" 
       m_BitmapData = bm.LockBits(bounds, Imaging.ImageLockMode.ReadWrite, Imaging.PixelFormat.Format24bppRgb) 

       mytest = "Execution point #4" 
       g_RowSizeBytes = m_BitmapData.Stride 

       mytest = "Execution point #5" 
       ' Allocate room for the data. 
       Dim total_size As Integer = m_BitmapData.Stride * m_BitmapData.Height 
       ReDim g_PixBytes(total_size) 

       mytest = "Execution point #10" 

       'this writes the data to the Bitmap 
       Marshal.Copy(buf, 0, m_BitmapData.Scan0, mylen) 
       capturedPic = bm 
       mytest = "Execution point #15" 

       ' Release resources. 
       bm.UnlockBits(m_BitmapData) 
       g_PixBytes = Nothing 
       m_BitmapData = Nothing 
       bm = Nothing 
       buf = Nothing 

       m_takePicture = False 
       captureSaved = True 
       mytest = "Execution point #20" 
      End If 
     End If 


     Marshal.ReleaseComObject(pSample) 
     Return 0 

    End Function 

    ' <summary> buffer callback, Not used - call this with integer 1 on the setcallback method </summary> 
    Function BufferCB(ByVal SampleTime As Double, ByVal pBuffer As IntPtr, ByVal BufferLen As Integer) As Integer Implements ISampleGrabberCB.BufferCB 

     SyncLock Me 

      myTest = "In BufferCB" 

     End SyncLock 

     Return 0 
    End Function 
End Class 

有人能幫助實現上述我的目標。 1）枚舉Combobox中的設備 2）將選定的攝像頭設備快照到文件。

任何幫助表示讚賞:)

Answer 1

我使用AForge（我的程序確實有點多，但是這會給你一個開始） 礦不彈出的對話框中，因爲它枚舉它本身（您可能只需要該代碼塊） 您也可以將所有My.Settings設置爲硬編碼設置。 這確實爲視頻創建了一個顯示，但如果您不希望它顯示，則可以簡單地設置vspMonitor.visible = False。

Imports AForge.Controls 
Imports AForge.Video 
Imports AForge.Video.DirectShow 
Imports AForge.Video.VFW 
Imports System.IO 

Public Class Main 

    Private WithEvents timer As New Timer 
'Stores the file path, e.g.: "F:\Temp" 
    Friend Shared strICLocation As String = My.Settings.ICSet 
'Stores the common name for the file, such as "Capture" (Screenshot, whatever you want) 
    Friend Shared strICFileRootName As String = My.Settings.ICRootName 
'Stores the image format to save in a 3 char string: PNG, JPG, BMP 
    Friend Shared strICType As String = My.Settings.ICType 

Dim VideoCaptureSource As VideoCaptureDevice 
Dim VideoDevices As New FilterInfoCollection(FilterCategory.VideoInputDevice) 
Private Property VideoCapabilities As VideoCapabilities() 
Dim frame As System.Drawing.Bitmap 
Dim filename As String 

Private Sub Main_Load(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles MyBase.Load 
'You'll need the following items in your UI at minimum: 
'Button named btnConnect, button named btnDisconnect, Video Source Player (From AForge libraries) named vspMonitor, a Combo Box named cmbVideoSource 
    EnumerateVideoDevices() 
    btnDisconnect.Enabled = False 
      btnConnect.Enabled = True 
    strICFileRootName = My.Settings.ICRootName 
      strICLocation = My.Settings.ICSet 
      lblICLocation.Text = strICLocation 
    End Sub 

    Private Sub EnumerateVideoDevices() 
     ' enumerate video devices 
     VideoDevices = New FilterInfoCollection(FilterCategory.VideoInputDevice) 
     If VideoDevices.Count <> 0 Then 
      ' add all devices to combo 
      For Each device As FilterInfo In VideoDevices 
       cmbVideoSource.Items.Add(device.Name) 
       cmbVideoSource.SelectedIndex = 0 
       VideoCaptureSource = New VideoCaptureDevice(VideoDevices(cmbVideoSource.SelectedIndex).MonikerString) 
       EnumerateVideoModes(VideoCaptureSource) 
      Next 
     Else 
      cmbVideoSource.Items.Add("No DirectShow devices found") 
     End If 
     cmbVideoSource.SelectedIndex = 0 
    End Sub 
    Private Sub EnumerateVideoModes(device As VideoCaptureDevice) 
     ' get resolutions for selected video source 
     Me.Cursor = Cursors.WaitCursor 
     cmbVideoModes.Items.Clear() 
     Try 
      Dim VideoCapabilities = device.VideoCapabilities 
      For Each capabilty As VideoCapabilities In VideoCapabilities 
       If Not cmbVideoModes.Items.Contains(capabilty.FrameSize) Then 
        cmbVideoModes.Items.Add(capabilty.FrameSize) 
       End If 
      Next 
      If VideoCapabilities.Length = 0 Then 
       cmbVideoModes.Items.Add("Not supported") 
      End If 
      cmbVideoModes.SelectedIndex = 0 
     Finally 
      Me.Cursor = Cursors.[Default] 
     End Try 
    End Sub 

#Region "IC (Image Capture)" 
    Private Sub btnICOptions_Click(sender As Object, e As EventArgs) Handles btnICOptions.Click 
' I use a form to set to image save type; handle it however you want, including hard-coding it    
Dim frm As New frmICOptions 
     frm.Show() 
    End Sub 

    Private Sub btnICSet_Click(sender As Object, e As EventArgs) Handles btnICSet.Click 
'Make a button called btnICSet to set the save path 
     Dim dialog As New FolderBrowserDialog() 
     dialog.Description = "Select Image Capture save path" 
     If dialog.ShowDialog() = Windows.Forms.DialogResult.OK Then 
      strICLocation = dialog.SelectedPath 
      lblICLocation.Text = strICLocation 
     End If 
    End Sub 

    Private Sub ICCapture_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles btnICCapture.Click 
'Need a button called btnICCapture. This is what will initiate the screen cap. 
     Try 
      If vspMonitor.IsRunning = True Then 
       If My.Settings.ICType = "PNG" Then 
        Dim strFilename As String = strICFileRootName & " " & Format(Now, "yyyy-MMM-dd HH.mm.ss.fff") & ".png" 
        vspMonitor.GetCurrentVideoFrame.Save(strICLocation & "\" & strFilename, System.Drawing.Imaging.ImageFormat.Png) 
       ElseIf My.Settings.ICType = "JPG" Then 
        Dim strFilename As String = strICFileRootName & " " & Format(Now, "yyyy-MMM-dd HH.mm.ss.fff") & ".jpg" 
        vspMonitor.GetCurrentVideoFrame.Save(strICLocation & "\" & strFilename, System.Drawing.Imaging.ImageFormat.Jpeg) 
       Else 
        Dim strFilename As String = strICFileRootName & " " & Format(Now, "yyyy-MMM-dd HH.mm.ss.fff") & ".bmp" 
        vspMonitor.GetCurrentVideoFrame.Save(strICLocation & "\" & strFilename, System.Drawing.Imaging.ImageFormat.Bmp) 
       End If 
      End If 
     Catch ex As Exception 
      MessageBox.Show("Try taking snapshot again when video image is visible.", "Cannot Save Image", MessageBoxButtons.OK, MessageBoxIcon.Error) 
     End Try 
    End Sub 

#End Region 
End Class 

可能有一些多餘的（你的目的）變量和設置（我的應用程序不會圖像捕捉，屏幕捕捉，視頻捕捉，停止動作捕捉（圖片或視頻）和動態偵測捕捉到的視頻，所以我基本上是從這個代碼中抽出這個代碼，試圖讓你朝着正確的方向發展。）如果我遺漏了任何錯誤，我會很樂意修改它。