Image Capture on Windows 8 Tablet - windows

Question

I'm working with a Dell Latitude ST2 tablet. It's running Windows 8 Pro on an Intel Atom processor.
I'm trying to do a simultaneous image capture from both the front and rear facing cameras. I'm messing around with the code from here: http://www.codeproject.com/Articles/18511/Webcam-using-DirectShow-NET
I can only get the rear facing camera, and even then the image capture doesn't work. The stream is just fine. (Less concerned about this than I am the dual streams.)
The two image sensors in the tablet are OV8830 and OV2720.
Also, is there a better API or method rather than using DirectShow for what I'm trying to accomplish?
Thanks!
Edit: I forgot to mention I'm working in VB. I'd prefer to stick with an Windows Forms Application.

Answer 1

I have tried this method just a day back with small modifications in the code.For me the image stream as well as the capture is working great.i will place my code here.you can have your modification for application to work for you.
Imports System.Runtime.InteropServices
Imports System.IO
Public Class FrmCam
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
Public Const WM_CAP_GET_STATUS As Integer = WM_CAP + 54
Public Const WM_CAP_DLG_VIDEOFORMAT As Integer = WM_CAP + 41
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
Private DeviceID As Integer = 0 ' Current device ID
Private hHwnd As Integer ' Handle to preview window
Declare Function SendMessage Lib "user32" Alias "SendMessageA" _
(ByVal hwnd As Integer, ByVal wMsg As Integer, ByVal wParam As Integer, _
ByRef lParam As CAPSTATUS) As Boolean
Declare Function SendMessage Lib "user32" Alias "SendMessageA" _
(ByVal hwnd As Integer, ByVal wMsg As Integer, ByVal wParam As Boolean, _
ByRef lParam As Integer) As Boolean
Declare Function SendMessage Lib "user32" Alias "SendMessageA" _
(ByVal hwnd As Integer, ByVal wMsg As Integer, ByVal wParam As Integer, _
ByRef lParam As Integer) As Boolean
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
Structure POINTAPI
Dim x As Integer
Dim y As Integer
End Structure
Public Structure CAPSTATUS
Dim uiImageWidth As Integer '// Width of the image
Dim uiImageHeight As Integer '// Height of the image
Dim fLiveWindow As Integer '// Now Previewing video?
Dim fOverlayWindow As Integer '// Now Overlaying video?
Dim fScale As Integer '// Scale image to client?
Dim ptScroll As POINTAPI '// Scroll position
Dim fUsingDefaultPalette As Integer '// Using default driver palette?
Dim fAudioHardware As Integer '// Audio hardware present?
Dim fCapFileExists As Integer '// Does capture file exist?
Dim dwCurrentVideoFrame As Integer '// # of video frames cap'td
Dim dwCurrentVideoFramesDropped As Integer '// # of video frames dropped
Dim dwCurrentWaveSamples As Integer '// # of wave samples cap'td
Dim dwCurrentTimeElapsedMS As Integer '// Elapsed capture duration
Dim hPalCurrent As Integer '// Current palette in use
Dim fCapturingNow As Integer '// Capture in progress?
Dim dwReturn As Integer '// Error value after any operation
Dim wNumVideoAllocated As Integer '// Actual number of video buffers
Dim wNumAudioAllocated As Integer '// Actual number of audio buffers
End Structure
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
Private Sub Form1_Load(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles MyBase.Load
LoadDeviceList()
If Not Directory.Exists(Application.StartupPath & "\Images") Then
Directory.CreateDirectory(Application.StartupPath & "\Images")
End If
If lstDevices.Items.Count > 0 Then
btnStart.Enabled = True
lstDevices.SelectedIndex = 0
btnStart.Enabled = True
Else
lstDevices.Items.Add("No Capture Device")
btnStart.Enabled = False
End If
Me.AutoScrollMinSize = New Size(100, 100)
btnStop.Enabled = False
btnSave.Enabled = False
'picCapture.SizeMode = PictureBoxSizeMode.StretchImage
End Sub
Private Sub LoadDeviceList()
Dim strName As String = Space(100)
Dim strVer As String = Space(100)
Dim bReturn As Boolean
Dim x As Short = 0
'
' Load name of all avialable devices into the lstDevices
'
Do
'
' Get Driver name and version
'
bReturn = capGetDriverDescriptionA(x, strName, 100, strVer, 100)
'
' If there was a device add device name to the list
'
If bReturn Then lstDevices.Items.Add(strName.Trim)
x += CType(1, Short)
Loop Until bReturn = False
End Sub
Private Sub OpenPreviewWindow()
Dim iHeight As Integer = Piccapture.Height
Dim iWidth As Integer = Piccapture.Width
'
' Open Preview window in picturebox
'
hHwnd = capCreateCaptureWindowA(DeviceID.ToString, WS_VISIBLE Or WS_CHILD, 0, 0, 1280, _
1024, Piccapture.Handle.ToInt32, 0)
'
' Connect to device
'
If SendMessage(hHwnd, WM_CAP_DRIVER_CONNECT, DeviceID, 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, 66, 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
btnStart.Enabled = False
Else
'
MsgBox("No Device Connected", MsgBoxStyle.Information, "RStar")
'
DestroyWindow(hHwnd)
btnSave.Enabled = False
End If
End Sub
Private Sub btnStart_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles btnStart.Click
DeviceID = lstDevices.SelectedIndex
'If DeviceID = 0 Then
' MsgBox("No Device Found", MsgBoxStyle.Information, "RStar")
' Exit Sub
'End If
OpenPreviewWindow()
Dim bReturn As Boolean
Dim s As CAPSTATUS
bReturn = SendMessage(hHwnd, WM_CAP_GET_STATUS, Marshal.SizeOf(s), s)
Debug.WriteLine(String.Format("Video Size {0} x {1}", s.uiImageWidth, s.uiImageHeight))
End Sub
Private Sub ClosePreviewWindow()
'
' Disconnect from device
'
SendMessage(hHwnd, WM_CAP_DRIVER_DISCONNECT, DeviceID, 0)
'
' close window
'
DestroyWindow(hHwnd)
End Sub
Private Sub btnStop_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles btnStop.Click
ClosePreviewWindow()
btnSave.Enabled = False
btnStart.Enabled = True
btnStop.Enabled = False
End Sub
Private Sub btnSave_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles btnSave.Click
Dim data As IDataObject
Dim bmap As Bitmap
Dim filepath As String
'
' Copy image to clipboard
'
SendMessage(hHwnd, WM_CAP_EDIT_COPY, 0, 0)
'
' Get image from clipboard and convert it to a bitmap
'
data = Clipboard.GetDataObject()
If data.GetDataPresent(GetType(System.Drawing.Bitmap)) Then
bmap = CType(data.GetData(GetType(System.Drawing.Bitmap)), Bitmap)
Piccapture.Image = bmap
ClosePreviewWindow()
btnSave.Enabled = False
btnStop.Enabled = False
btnStart.Enabled = True
Trace.Assert(Not (bmap Is Nothing))
filepath = Application.StartupPath & "\Images\" & frmChartOfAccounts.txtAcName.Text & frmChartOfAccounts.txtRegNo.Text & ".jpeg"
bmap.Save(filepath)
frmChartOfAccounts.txtimg.Text = filepath
End If
End Sub
Private Sub Form1_Closing(ByVal sender As Object, ByVal e As System.ComponentModel.CancelEventArgs) Handles MyBase.Closing
If btnStop.Enabled Then
ClosePreviewWindow()
End If
End Sub
Private Sub btnInfo_Click(ByVal sender As System.Object, ByVal e As System.EventArgs)
'SendMessage(hHwnd, WM_CAP_DLG_VIDEOFORMAT, 0&, 0&)
End Sub
Private Sub cmdExit_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles cmdExit.Click
Close()
End Sub
End Class
Hope it will help you.