2 web cameras and .net

Hi All,

I need help once again, I have tried searching all day with no luck.

Im making a camera/video capture app for my shinny new windows tablet (win 7 ultimate). I have tried a few apps but all are really crap and not what im after.

From searching I found the avicap32.dll method which on my dev computer works perfect, on my tablet however it doesnt.

The reason for this is the tablet has 2 webcams, front and back, both use the very same driver so show as 1 source on the tablet. when i select the source it gives me the option of picking abc usb cam or cba usb cam but still doesnt work.

I have no idea how to get around this :(

also skype can list the name of the webcams and display perfectly as can the trialed apps.

Please see below code

Code:

---


    Const WM_CAP_START = &H400S
    Const WS_CHILD = &H40000000
    Const WS_VISIBLE = &H10000000

    Const WM_CAP_DRIVER_CONNECT = WM_CAP_START + 10
    Const WM_CAP_DRIVER_DISCONNECT = WM_CAP_START + 11
    Const WM_CAP_EDIT_COPY = WM_CAP_START + 30
    Const WM_CAP_SEQUENCE = WM_CAP_START + 62
    Const WM_CAP_FILE_SAVEAS = WM_CAP_START + 23

    Const WM_CAP_SET_SCALE = WM_CAP_START + 53
    Const WM_CAP_SET_PREVIEWRATE = WM_CAP_START + 52
    Const WM_CAP_SET_PREVIEW = WM_CAP_START + 50

    Const SWP_NOMOVE = &H2S
    Const SWP_NOSIZE = 1
    Const SWP_NOZORDER = &H4S
    Const HWND_BOTTOM = 1
    '--The capGetDriverDescription function retrieves the version
    ' description of the capture driver--
    Declare Function capGetDriverDescriptionA Lib "avicap32.dll" _
      (ByVal wDriverIndex As Short, _
        ByVal lpszName As String, ByVal cbName As Integer, _
        ByVal lpszVer As String, _
        ByVal cbVer As Integer) As Boolean

    '--The capCreateCaptureWindow function creates a capture window--
    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 hWnd As Integer, _
        ByVal nID As Integer) As Integer

    '--This function sends the specified message to a window or windows--
    Declare Function SendMessage Lib "user32" Alias "SendMessageA" _
      (ByVal hwnd As Integer, ByVal Msg As Integer, _
        ByVal wParam As Integer, _
      <MarshalAs(UnmanagedType.AsAny)> ByVal lParam As Object) As Integer

    '--Sets the position of the window relative to the screen buffer--
    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

    '--This function destroys the specified window--
    Declare Function DestroyWindow Lib "user32" _
      (ByVal hndw As Integer) As Boolean
    '---used to identify the video source---
    Dim VideoSource As Integer
    '---used as a window handle---
    Dim hWnd As Integer


    Private Sub btnSave_Click(sender As System.Object, e As System.EventArgs) Handles btnSave.Click
        Dim path As String
        path = "C:\data\"
        Dim number As Integer
        number = System.IO.Directory.GetFiles(path).Length
        SendMessage(hWnd, WM_CAP_EDIT_COPY, 0, 0)
        Dim loData As IDataObject = Clipboard.GetDataObject()
        If loData.GetDataPresent(GetType(System.Drawing.Bitmap)) Then
            Using loBitmap As Image = CType(loData.GetData(GetType(System.Drawing.Bitmap)), Image)
                loBitmap.Save(path & "image" & number & ".jpg", Imaging.ImageFormat.Jpeg)
                PictureBox2.Image = Image.FromFile(path & "image" & number & ".jpg")
                PictureBox2.SizeMode = PictureBoxSizeMode.StretchImage
            End Using
        End If
       

    End Sub

    Private Sub Form1_Load(sender As System.Object, e As System.EventArgs) Handles MyBase.Load
        System.IO.Directory.CreateDirectory("C:\data")
        ListVideoSources()

    End Sub
    '---list all the various video sources---
    Private Sub ListVideoSources()
        Dim DriverName As String = Space(80)
        Dim DriverVersion As String = Space(80)
        For i As Integer = 0 To 9
            If capGetDriverDescriptionA(i, DriverName, 80, _
              DriverVersion, 80) Then
                lstVideoSources.Items.Add(DriverName.Trim)

            End If
        Next
    End Sub

    '---list all the video sources---
    Private Sub lstVideoSources_SelectedIndexChanged( _
      ByVal sender As System.Object, ByVal e As System.EventArgs) _
      Handles lstVideoSources.SelectedIndexChanged
        '---check which video source is selected---
        VideoSource = lstVideoSources.SelectedIndex
        '---preview the selected video source
        PreviewVideo(picCapture)
    End Sub
    '---preview the selected video source---
    Private Sub PreviewVideo(ByVal pbCtrl As PictureBox)
        hWnd = capCreateCaptureWindowA(VideoSource, _
            WS_VISIBLE Or WS_CHILD, 0, 0, 0, _
            0, pbCtrl.Handle.ToInt32, 0)
        If SendMessage( _
          hWnd, WM_CAP_DRIVER_CONNECT, _
          VideoSource, 0) Then
            '---set the preview scale---
            SendMessage(hWnd, WM_CAP_SET_SCALE, True, 0)
            '---set the preview rate (ms)---
            SendMessage(hWnd, WM_CAP_SET_PREVIEWRATE, 30, 0)
            '---start previewing the image---
            SendMessage(hWnd, WM_CAP_SET_PREVIEW, True, 0)
            '---resize window to fit in PictureBox control---
            SetWindowPos(hWnd, HWND_BOTTOM, 0, 0, _
              pbCtrl.Width, pbCtrl.Height, _
              SWP_NOMOVE Or SWP_NOZORDER)
        Else
            '--error connecting to video source---
            DestroyWindow(hWnd)
        End If
    End Sub
    '---stop the preview window---
    Private Sub btnStopCamera_Click( _
      ByVal sender As System.Object, _
      ByVal e As System.EventArgs)

        StopPreviewWindow()
    End Sub
    '--disconnect from video source---
    Private Sub StopPreviewWindow()
        SendMessage(hWnd, WM_CAP_DRIVER_DISCONNECT, VideoSource, 0)
        DestroyWindow(hWnd)
    End Sub
    '---Start recording the video---
    Private Sub btnStartRecording_Click( _
      ByVal sender As System.Object, _
      ByVal e As System.EventArgs) _
      Handles btnStartRecording.Click
        btnStartRecording.Enabled = False
        btnStopRecording.Enabled = True
        '---start recording---
        SendMessage(hWnd, WM_CAP_SEQUENCE, 0, 0)
    End Sub
    '---stop recording and save it on file---
    Private Sub btnStopRecording_Click( _
      ByVal sender As System.Object, _
      ByVal e As System.EventArgs) _
      Handles btnStopRecording.Click
        btnStartRecording.Enabled = True
        btnStopRecording.Enabled = False
        '---save the recording to file---
        SendMessage(hWnd, WM_CAP_FILE_SAVEAS, 0, _
          "C:\RecordedVideo.avi")
    End Sub

---

so basically the listbox on the form fills with driver details, i would then select it and the preview would appear in the picture box, on the tablet this doesnt happen, both webcams are listed under same driver, select it and windows asks which camera but never loads the preview (ideally i would like that windows pop up to not show as well i have the camera names if that helps).

I did look into some other options like directshow.net and even webcamlib.dll (which looks simple but cant even load the dll).


EDIT**** I added a msgbox to the area that errors on connecting and it ran so it seems like a connection error, seeing as it connects using driver and both have same driver it must not know which one to use. stil any help appriciated**

any and all help is appriciated, i thought this would be easy and is was, until 2 webcams came into it :(

avicap32.dll is almost certainly (actually, scrap 'almost') NOT the method used by any of the applications that work with the tablet. It is, like, so last century. You'll need something considerably more sophisticated such as DirectShow

Thanx dunfiddlin
I have gone down the directshow road and have hit a wall, the only thing left is to be able to select which camera to use, the code I have below will always bring up the first video device. I have tried playing around with things in the findcapturedevice sub but to no avail. Any ideas how I could select which camera to use?

cheers for the help

Code:

---

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 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)
        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

---

Just in case you want to try a different approach, I can recommend the Aforge.Net library - http://www.aforgenet.com/aforge/framework/

I too gave up on avicap32.dll because I wanted better support for multiple webcams.

thanx paulg4ije, worked like a charm and effortlessly. THANKYOU EVERYONE :)

Hello,
Could one of you send me a sample VB.Net code showing how to use the AForge.Net lib to select an imaging device as a source for capture ?
Bensonsearch, how did you do exactly ?
Thanks.

This is some of my code:

Code:

---

Imports AForge.Video
Imports AForge.Video.DirectShow

Module modCameras

    Public videoDevices As FilterInfoCollection
    'Private cam As VideoCaptureDevice

    Sub Get_Camera_List(cmb As ComboBox)

        ' Get list of available video capture devices (webcams) using AForge library
        Try

            videoDevices = New FilterInfoCollection(FilterCategory.VideoInputDevice)

            Dim iCamCount As Integer = videoDevices.Count

            If iCamCount > 0 Then
                For i As Integer = 0 To iCamCount - 1
                    cmb.items.add(videoDevices(i).Name)
                Next
            End If

        Catch ex As Exception
            MsgBox(ex.Message, MsgBoxStyle.Information)
        End Try

    End Sub

End Module

---

Code:

---

    Private Sub cmbCams_SelectedIndexChanged(sender As System.Object, e As System.EventArgs) Handles cmbCams.SelectedIndexChanged
        GsCamName = cmbCams.SelectedItem.ToString
        GiCamID = cmbCams.SelectedIndex
    End Sub

    Private Sub Camera_On()
        Try
            Dim videoSource As VideoCaptureDevice = New VideoCaptureDevice(videoDevices(GiCamID).MonikerString)
            vsp1.VideoSource = videoSource
            videoSource.DesiredFrameRate = 10
            videoSource.DesiredFrameSize = New Size(640, 480)
            vsp1.Start()
            cmdGrab.Enabled = True
            vsp1.Visible = True
            bCameraOn = True
        Catch ex As Exception
            MsgBox("Failed to connect to chosen webcam.", MsgBoxStyle.Information)
            Call Camera_Off()
        End Try
    End Sub

    Private Sub Camera_Off()
        Try
            chkPreview.Checked = False
            cmdGrab.Enabled = False
            vsp1.SignalToStop()
            vsp1.WaitForStop()
            vsp1.Visible = False
            bCameraOn = False
        Catch
        End Try
    End Sub

    Private Sub cmdGrab_Click(sender As System.Object, e As System.EventArgs) Handles cmdGrab.Click
        Call Grab_Image()
    End Sub

    Private Sub Grab_Image()
        If fnGrab_Image() Then
            vsp1.Visible = False
            vsp1.SignalToStop()
            chkPreview.Checked = False
        End If
    End Sub

---

You need an Aforge Video Source Player on your form (vsp1 in my code).

Hopefully you can adapt this code to suit your requirements.

Forgot this bit:

Code:

---

    Private Function fnGrab_Image() As Boolean

        ' Grab an image from webcam - Aforge Video Source Player must be running

        Try
            Dim bm As Bitmap = New Bitmap(640, 480)
            bm = vsp1.GetCurrentVideoFrame

            If bm.Width <> 640 Or bm.Height <> 480 Then
                bm = New Bitmap(bm, New Size(640, 480))
            End If

            Dim bm2 As Bitmap = New Bitmap(640, 512)
            Dim g As Graphics = Graphics.FromImage(bm2)
            g.DrawImage(bm, 0, 32)
            g.Dispose()
            pbTX.Image = fnAdd_Header(bm2, "Greyscale") ' Add 16 line greyscale header
            Gbm = CType(bm2.Clone, Bitmap)
            If chkStamp.Checked Then pbTX.Image = fnAdd_Date_Time_Stamp(CType(pbTX.Image, Bitmap))
            If chkLive.Checked Then pbTX.Image = fnAdd_Live_Webcam_Stamp(CType(pbTX.Image, Bitmap))
            If chkCallsign.Checked Then pbTX.Image = fnAdd_Callsign(CType(pbTX.Image, Bitmap))
            Return True
        Catch
            MsgBox("Aforge Video Source Player (webcam) not ready.")
            Return False
        End Try

    End Function

---

Ignore the "stamps" and "header" - you should be able to adapt this code to do what you want.

Paul.

Thank you, Paul.
It's so simple compared to what it could have been with avicap.

popeau