在DirectShow中预览相机并捕获静止图像-VB.net [英] Preview a camera in DirectShow and capture a still image - in VB.net
本文介绍了在DirectShow中预览相机并捕获静止图像-VB.net的处理方法，对大家解决问题具有一定的参考价值，需要的朋友们下面随着小编来一起学习吧！
问题描述
我试图在Visual Studio 2008中编写一个程序，该程序将访问网络摄像头，在屏幕上显示预览，然后在按下按钮时保存静态快照（.jpg）。稍后，我将其与数据库集成，但是那部分应该没有问题。经过研究后，DirectShow似乎是最好的选择，因为WIA不能在我拥有的相机上使用（并且我不确定它将来是否会继续使用）。最好是，我需要从Windows XP到Windows 7的解决方案。
我以前从未使用过DirectShow（或类似的产品）。我遇到的一个问题是，大多数代码都是用C＃编写的，这是我从未学过的。我发现一个DirectShow.Net库也使用vb.net，这很有帮助，但是我仍然遇到问题。
下面的代码取自库中的示例，并且可以运行，但是我想对其进行一些更改并且不能完全使它工作。现在，该代码将摄像机捕获的图像保存到文件中。我可以删除 capGraph.SetOutputFileName行，视频将直接在其自己的窗口中启动，但是我不怎么控制它。基本上，我想知道如何做两件事：
I am trying to write a program in Visual Studio 2008 that will access a webcam, show a preview on the screen and then save a still snapshot (.jpg) when the button is pushed. Later I am going to integrate it with a database, but I shouldn't have a problem with that part. After doing some research, it looks like DirectShow is the best bet, because WIA didn't work on the camera I had (and I'm not sure it will continue to work into the future). Preferably, I need my solution to work from Windows XP to Windows 7. I have never used DirectShow (or similar) before. One problem I am running into is that most of the code is written in C#, which I have never learned. I found a DirectShow.Net library that also uses vb.net, so that is helpful, but I am still having problems. The following code is taken from the samples in the library, and works, but I want to alter it somewhat and can't quite get it to work. The code right now saves the camera capture to a file. I can rem out the "capGraph.SetOutputFileName" line, the video will just launch into its own window, but I don't how to control that. Basically, I would like to know how to do two things:
- 如何让DirectShow在我所使用的表单上的控件中显示指定（图片框？）？
- 当用户单击按钮时，是否可以获取该视频的快照（它可以暂停视频或其他操作，因为那时我不需要恢复预览，至少要花几秒钟的时间。）
非常感谢，如果其中的一部分措辞不太好。我是自学成才的，并且在vba和php中做了很多工作，但这超出了我的经验。
Thanks a lot, and sorry if some of this is not phrased very well. I am self-taught, and have done a lot in vba and php, but this is a little beyond my experience.
'****************************************************************************
'While the underlying libraries are covered by LGPL, this sample is released
'as public domain. It is distributed in the hope that it will be useful, but
'WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY
'or FITNESS FOR A PARTICULAR PURPOSE.
'*****************************************************************************/
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"
' <summary> graph builder interface. </summary>
Private m_graphBuilder As IFilterGraph2 = Nothing
Private m_mediaCtrl As IMediaControl = Nothing
' <summary> Set by async routine when it captures an image </summary>
Private 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, ByVal FileName As String)
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, FileName)
Catch
Dispose()
Throw
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
' <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, ByVal FileName As String)
Dim hr As Integer
Dim sampGrabber As ISampleGrabber = Nothing
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
' Get the graphbuilder object
m_graphBuilder = DirectCast(New FilterGraph(), IFilterGraph2)
m_mediaCtrl = DirectCast(m_graphBuilder, IMediaControl)
#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)
' 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.SetOutputFileName(MediaSubType.Avi, FileName, muxFilter, fileWriterFilter)
DsError.ThrowExceptionForHR(hr)
hr = capGraph.RenderStream(PinCategory.Capture, MediaType.Video, capFilter, baseGrabFlt, muxFilter)
DsError.ThrowExceptionForHR(hr)
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 = 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.SetCallback(Me, 0)
DsError.ThrowExceptionForHR(hr)
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 = 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)
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 ((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
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
Dim hr As Integer
'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)
for i = 0 to myLen-1 step 2
buf(i) = (255 - buf(i))
Next i
Dim g_RowSizeBytes As Integer
Dim g_PixBytes() As Byte
Dim bm As Bitmap = Nothing
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 modified data
Marshal.Copy(buf, 0, m_BitmapData.Scan0, mylen)
' Unlock the bitmap.
bm.UnlockBits(m_BitmapData)
' Release resources.
g_PixBytes = Nothing
m_BitmapData = Nothing
End If
Marshal.ReleaseComObject(pSample)
Return 0
End Function
' <summary> buffer callback, COULD BE FROM FOREIGN THREAD. </summary>
Function BufferCB(ByVal SampleTime As Double, ByVal pBuffer As IntPtr, ByVal BufferLen As Integer) As Integer Implements ISampleGrabberCB.BufferCB
SyncLock Me
If (Not m_bmdLogo Is Nothing) Then
Dim ipSource As IntPtr = m_bmdLogo.Scan0
Dim ipDest As IntPtr = pBuffer
Dim x As Integer
For x = 0 To m_bmdLogo.Height - 1
CopyMemory(ipDest, ipSource, m_bmdLogo.Stride)
ipDest = New IntPtr(ipDest.ToInt32() + m_stride)
ipSource = New IntPtr(ipSource.ToInt32() + m_bmdLogo.Stride)
Next x
End If
End SyncLock
Return 0
End Function
End Class
推荐答案
这是我最终用于项目的内容-它为您提供一个预览窗口，然后在另一种形式上您可以按一个按钮拍照。我拍照并在主窗体（稍大一点）上将静止图像作为另一个图片框显示。我添加了一个cropbox，以选择您最终希望保存图片框的哪个部分，但是为了简单起见，不在此答案中包含该部分。
Here is what I finally used for my project - it gives you a preview window, and then on another form you can push a button to take the picture. I take the picture and display that stillshot image as another picturebox on the main form (a little larger). I added a cropbox to choose what portion of that picture box you would ultimately like to save, but am not including that in this answer for simplicities sake.
您可以使用调用： cam = New Capture（my.Settings.VideoDeviceNum，FRAMERATE，my.Settings.CapturePictureWidth，my.Settings.CapturePictureHeight）
和 cam.Start（）
通过以下调用拍摄快照：
The snapshot is take with this call:
Dim picError As Boolean=False
cam.captureSaved=False
cam.TakePicture
Dim stTime As date = Now
Do Until cam.captureSaved
'do nothing - might want to have an automatic break if this takes too long
If DateDiff(DateInterval.Second,stTime,Now) >15 then
MsgBox("The camera is taking a long time to capture the picture. Please try again.")
picError=True:Exit do
End If
Loop
If not picError then
cam.Capturedpic.RotateFlip (RotateFlipType.Rotate180FlipX)
'scale the camera image and place it in the picture box
CaptureBox.Image=scaleimage(cam.capturedpic,CaptureBox.Width,CaptureBox.Height)
End If
SavePicture.Visible = True
myStatus.Text = "Picture Taken."
scaleimage函数只是将快照图像缩放到适合表单上框的适当大小。我只能缩放x，因为我只允许一定的宽高比，所以如果您不打算锁定相机的宽高比，则需要对其进行调整：
The scaleimage function simply scales the snapshot image to the appropriate size for the box I have on the form. I only work with scaling the x, because I only allow a certain aspect ratio, so if you aren't going to lock in your aspect ratios for the camera, it will need to be adjusted:
Public Function ScaleImage(source As Bitmap, x As Integer, y As Integer) As Bitmap
Dim scale As single = x / source.Width
Dim myBmp As new Bitmap(cint(source.Width*scale), cint(source.height*scale),source.PixelFormat)
Dim gr As Graphics = Graphics.FromImage(myBmp)
gr.DrawImage(source, 0, 0, myBmp.Width + 1, myBmp.Height + 1)
Return myBmp
End Function
主要摄像机类别如下：
'****************************************************************************
'While the underlying libraries are covered by LGPL, this sample is released
'as public domain. It is distributed in the hope that it will be useful, but
'WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY
'or FITNESS FOR A PARTICULAR PURPOSE.
'*****************************************************************************/
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"
' <summary> graph builder interface. </summary>
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.PreviewBox.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, my.Settings.previewwidth, my.Settings.previewHeight)
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 = 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 = 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 ((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
I’m sure this could be improved upon, but it works well for my purposes for now, and I hope it helps someone.
I'm sure this could be improved upon, but it works well for my purposes for now, and I hope it helps someone.
这篇关于在DirectShow中预览相机并捕获静止图像-VB.net的文章就介绍到这了，希望我们推荐的答案对大家有所帮助，也希望大家多多支持IT屋！
查看全文
