问题
I am new to stackoverflow but I registered because I think here is the right place to get professional help for programming :) My goal is to create a webcam snapshot tool which directly saves the snapshot to a file. I don't need any preview in a picturebox or something like that. I am thinking about a application like this:
A simple Interface with a Combobox for the connected webcam devices and one button which will take a snapshot and saves it to a file. I like to use DirectShow for this because all other ways using AForge or advcap32.dll, because they sometimes cause a Videosourcedialog to popup, which I don't want to. I like to select a webcamdevice in my combobox manually and be able to take a snapshot. So that way I like to use DirectShow.
I already added the DirectShowLib-2005.dll to my VB.Net Project And I also added this class:
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
Can someone help to achieve my goal described above. 1) Enumerating Devices in Combobox 2) Snapshot selected webcam device to a file.
Any help is appreciated :)
回答1:
I'm using AForge (My program does a bit more, but this will give you a start) Mine does not pop-up the dialog, because it enumerates it itself (You may want just that code chunk) You can also set all the My.Settings to hard-coded settings. This does create a display for the video, but you can simply set vspMonitor.visible = False if you don't want it to display.
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
There may be some extraneous (to your purpose) variables and settings (my app does Image capture, screen capture, video capture, Stop Motion capture (to images or video) and Motion Detect Capture to video, so I basically yanked this code from it trying to get you in the right direction.) I'll be happy to modify it if I've left any errors.
来源：https://stackoverflow.com/questions/21811959/vb-net-directshow-webcam-snapshot