Vb.net 我应该改变什么来使用另一个USB摄像头，而不是笔记本集成摄像头

我发现了一个有趣的应用程序代码，您可以通过DirectShow在PictureBox1中捕获图像并将其放置在另一个PictureBox2中

我已经试过了，它和我的笔记本集成相机配合使用效果很好

有谁能告诉我，我应该改变什么参数来使用另一个我放在笔记本电脑USB端口的wecam，而不是集成摄像头

这是完整的代码，只需要引用DirectShowLib.dll

多谢各位

Imports DirectShowLib
Imports System
Imports System.Diagnostics
Imports System.Drawing
Imports System.Runtime.InteropServices
Imports System.Windows.Forms
Imports System.Runtime.InteropServices.ComTypes

Public Class Form1

Dim D As Integer = Convert.ToInt32("0X8000", 16)
Public WM_GRAPHNOTIFY As Integer = D + 1

Dim VideoWindow As IVideoWindow = Nothing
Dim MediaControl As IMediaControl = Nothing
Dim MediaEventEx As IMediaEventEx = Nothing
Dim GraphBuilder As IGraphBuilder = Nothing
Dim CaptureGraphBuilder As ICaptureGraphBuilder2 = Nothing

Enum PlayState
    Stopped
    Paused
    Running
    Init
End Enum
Dim CurrentState As PlayState = PlayState.Stopped

Dim rot As DsROTEntry = Nothing

Private Sub Form1_FormClosing(ByVal sender As Object, ByVal e As System.Windows.Forms.FormClosingEventArgs)
    On Error Resume Next
    closeinter()
End Sub

Private Sub Form1_FormClosed(sender As Object, e As System.Windows.Forms.FormClosedEventArgs) Handles Me.FormClosed
    On Error Resume Next
End Sub

Private Sub Form1_Load(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles MyBase.Load
    CaptureVideo()
    PictureBox1.Visible = True
End Sub

Private Sub CaptureVideo()
    Dim hr As Integer = 0
    Dim sourceFilter As IBaseFilter = Nothing
    Try
        GetInter()

        hr = CaptureGraphBuilder.SetFiltergraph(GraphBuilder) 'Specifies filter graph "graphbuilder" for the capture graph builder "captureGraphBuilder" to use.

        sourceFilter = FindCaptureDevice()

        hr = GraphBuilder.AddFilter(sourceFilter, "Video Capture")

        hr = CaptureGraphBuilder.RenderStream(PinCategory.Preview, MediaType.Video, sourceFilter, Nothing, Nothing)

        Marshal.ReleaseComObject(sourceFilter)

        SetupVideoWindow()

        rot = New DsROTEntry(GraphBuilder)

        hr = MediaControl.Run()

        CurrentState = PlayState.Running

    Catch ex As Exception
        MessageBox.Show("An unrecoverable error has occurred.With error : " & ex.ToString)
    End Try
End Sub

Private Sub GetInter()
    Dim hr As Integer = 0
    GraphBuilder = CType(New FilterGraph, IGraphBuilder)
    CaptureGraphBuilder = CType(New CaptureGraphBuilder2, ICaptureGraphBuilder2)
    MediaControl = CType(GraphBuilder, IMediaControl)
    VideoWindow = CType(GraphBuilder, IVideoWindow)
    MediaEventEx = CType(GraphBuilder, IMediaEventEx)
    hr = MediaEventEx.SetNotifyWindow(Me.Handle, WM_GRAPHNOTIFY, IntPtr.Zero) 'This method designates a window as the recipient of messages generated by or sent to the current DirectShow object
End Sub

Public Function FindCaptureDevice() As IBaseFilter

    Dim hr As Integer = 0
    Dim classEnum As IEnumMoniker = Nothing
    Dim moniker As IMoniker() = New IMoniker(0) {}
    Dim source As Object = Nothing
    Dim devEnum As ICreateDevEnum = CType(New CreateDevEnum, ICreateDevEnum)
    hr = devEnum.CreateClassEnumerator(FilterCategory.VideoInputDevice, classEnum, 0)

    Marshal.ReleaseComObject(devEnum)
    If classEnum Is Nothing Then
        Throw New ApplicationException("No video capture device was detected.\r\n\r\n" & _
                       "This sample requires a video capture device, such as a USB WebCam,\r\n" & _
                       "to be installed and working properly.  The sample will now close.")
    End If
    If classEnum.Next(moniker.Length, moniker, IntPtr.Zero) = 0 Then
        Dim iid As Guid = GetType(IBaseFilter).GUID
        moniker(0).BindToObject(Nothing, Nothing, iid, source)
    Else
        Throw New ApplicationException("Unable to access video capture device!")
    End If
    Marshal.ReleaseComObject(moniker(0))
    Marshal.ReleaseComObject(classEnum)
    Return CType(source, IBaseFilter)
End Function

Public Sub SetupVideoWindow()
    Dim hr As Integer = 0
    'set the video window to be a child of the main window
    'putowner : Sets the owning parent window for the video playback window. 
    hr = VideoWindow.put_Owner(PictureBox1.Handle) 'Me.Handle)
    PictureBox1.Visible = False

    hr = VideoWindow.put_WindowStyle(WindowStyle.Child Or WindowStyle.ClipChildren)

    'Use helper function to position video window in client rect of main application window
    ResizeVideoWindow()

    'Make the video window visible, now that it is properly positioned
    'put_visible : This method changes the visibility of the video window. 
    hr = VideoWindow.put_Visible(OABool.True)

End Sub

Public Sub ResizeVideoWindow()
    'Resize the video preview window to match owner window size
    'left , top , width , height
    If Not (VideoWindow Is Nothing) Then 'if the videopreview is not nothing
        VideoWindow.SetWindowPosition(0, 0, Me.Width, Me.ClientSize.Height)
    End If
End Sub

Public Sub closeinter()
    On Error Resume Next
    '//stop previewing data
    If Not (Me.MediaControl Is Nothing) Then
        Me.MediaControl.StopWhenReady()
    End If

    Me.CurrentState = PlayState.Stopped

    '//stop recieving events
    If Not (Me.MediaEventEx Is Nothing) Then
        Me.MediaEventEx.SetNotifyWindow(IntPtr.Zero, WM_GRAPHNOTIFY, IntPtr.Zero)
    End If

    '// Relinquish ownership (IMPORTANT!) of the video window.
    '// Failing to call put_Owner can lead to assert failures within
    '// the video renderer, as it still assumes that it has a valid
    '// parent window.
    If Not (Me.VideoWindow Is Nothing) Then
        Me.VideoWindow.put_Visible(OABool.False)
        Me.VideoWindow.put_Owner(IntPtr.Zero)
    End If

    ' // Remove filter graph from the running object table
    If Not (rot Is Nothing) Then
        rot.Dispose()
        rot = Nothing
    End If

    '// Release DirectShow interfaces
    Marshal.ReleaseComObject(Me.MediaControl) : Me.MediaControl = Nothing
    Marshal.ReleaseComObject(Me.MediaEventEx) : Me.MediaEventEx = Nothing
    Marshal.ReleaseComObject(Me.VideoWindow) : Me.VideoWindow = Nothing
    Marshal.ReleaseComObject(Me.GraphBuilder) : Me.GraphBuilder = Nothing
    Marshal.ReleaseComObject(Me.CaptureGraphBuilder) : Me.CaptureGraphBuilder = Nothing

End Sub


Public Sub GrabImage()

    ' Get image from clipboard and convert it to a bitmap

    MediaControl.Pause()

    Try
        MediaControl.Pause()



        Dim bmp As New Bitmap(PictureBox1.Width, PictureBox1.Height)
        Using g As Graphics = Graphics.FromImage(bmp)
            Dim pt As Point = PictureBox1.PointToScreen(New Point(0, 0))
            g.CopyFromScreen(pt.X, pt.Y, 0, 0, bmp.Size)
        End Using
        PictureBox2.Image = bmp

        MediaControl.Run()
    Catch
    End Try
End Sub


Private Sub btnRun_Click_1(sender As System.Object, e As System.EventArgs) Handles btnRun.Click
    MediaControl.Run()
End Sub

Private Sub btnGrab_Click_1(sender As System.Object, e As System.EventArgs) Handles btnGrab.Click
    GrabImage()
End Sub

Private Sub btnClose_Click(sender As System.Object, e As System.EventArgs) Handles btnClose.Click
    End
    Me.Close()
End Sub

---

End Class

您需要在方法FindCaptureDevice中查看classEnum变量的内容。好的，非常感谢。最后一个问题。假设我已经连接到我的Lapto，假设有5台设备（假设），我希望找到4号设备。。。请你帮我看看我应该把循环的代码放在哪里好吗？我认为我们应该从0开始，继续从1,2,3开始，如此类推。。。