使用directShow以90度预览网络摄像头

问题描述

我已成功使用directshow预览并记录网络摄像头中的图像，但问题是当我使用平板电脑中的应用程序时，方向与我在PC中看到的方向不同。是否有可能旋转此预览图像？我可以在保存之前旋转从预览中获取的位图图像，但如果我可以在预览中显示正确的方向，那对我来说非常有帮助。



我已经阅读了一些喜欢使用igraphbuilder，渲染文件等的建议....但由于我不是一个非常有经验的VB.net开发人员，我很难理解所有这些概念。我花了很多天才找到不同的代码来使相机捕捉工作。但是现在遇到了方向问题。



这就是代码的样子，如果有人可以帮忙添加一些过滤器，以便我可以预览90学位视图。

I have successfully use directshow to preview and record an image from webcam, but the problem is when I used the application from the tablet, the orientation is not the same as what I saw in PC. Is there a possibility to rotate this preview image? I can rotate the bitmap image taken from the preview before it is saved, but if I can show the correct orientation in the preview , that would be very helpful for me.

I have read through some of the suggestion liked using igraphbuilder, render file and etc.... but since I am not an very experienced VB.net developer, I have a very hard time to understand all these concept. I spend many many days just to find out different code to make the camera capture works. But now came across the orientation problem.

This is what the code looks like and if anyone can help to add some filter so that I can preview the image in a 90 degree view.

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

Public Class Form2

Dim MyPicturesFolder As String = Environment.GetFolderPath(Environment.SpecialFolder.MyPictures)

Dim D As Integer = &H8000
'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)
    closeinterfaces()
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
        GetInterfaces()

        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 GetInterfaces()
    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 closeinterfaces()
    '//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

Private Sub btnGrab_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles btnGrab.Click

    GrabImage()
End Sub

Public Sub GrabImage()
    '
    '' Get image from clipboard and convert it to a bitmap
    'Try
    '    MediaControl.Pause()

    '    Clipboard.SetImage(PictureBox1.Image)
    '    '
    '    If Clipboard.ContainsImage Then
    '        PictureBox2.Image = Clipboard.GetImage()
    '    End If
    'Catch
    'End Try
    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
        PictureBox2.Visible = True

        'PictureBox1.Visible = False
    Catch
        MsgBox("error")
    End Try

End Sub

Private Sub Button1_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles Button1.Click, btnGrab.Click
    MediaControl.Run()
End Sub

Private Sub btnSave_Click(sender As System.Object, e As System.EventArgs) Handles BtnSave.Click

    Dim newimage As Image = PictureBox2.Image

    Dim gr As Graphics = Graphics.FromImage(newimage)
    Dim myFontLabels As New Font("Arial", 40)
    Dim myBrushLabels As New SolidBrush(Color.Black)

    Dim FolderBrowser As New FolderBrowserDialog
    If FolderBrowser.ShowDialog = Windows.Forms.DialogResult.OK Then
        Me.lblPath.Text = FolderBrowser.SelectedPath & "\Amytest.bmp"
        MsgBox("msg" & Me.lblPath.Text)

    End If

    'newimage.Save(Me.lblPath.Text, ImageFormat.Jpeg)
    'MsgBox("The picture has been successfully copied and saved")

End Sub

Private Sub Button2_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles Button2.Click

    Dim newimage As Image = PictureBox2.Image

    Dim gr As Graphics = Graphics.FromImage(newimage)
    Dim myFontLabels As New Font("Arial", 40)
    Dim myBrushLabels As New SolidBrush(Color.Black)

    Dim _sourcefilename$ = Me.lblPath.Text
    Dim _destinationfilename$ = "C:\test.jpg"
    JpegSaveClass.SaveImage(_sourcefilename, _destinationfilename)

End Sub

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