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Posted 13 May 2007

Visual Studio C++ .NET Express: Using DirectShow in a Webcam Capture Application

, 19 Jun 2007
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Using DirectShow in a Webcam Capture Application
Screenshot - Article.gif


This project is intended to make it easier for beginners to learn how to use DirectShow with Visual Studio C++ .NET Express. This project consist of a Windows Forms application that can be used to capture images from a webcam. From this project, along with the many other projects available on this site, you should be able to gain a better understanding of how to create your own DirectShow applications.

Starting a New Project for Use with DirectShow

Step 1: Start Visual Studio C++ .NET Express.

Step 2: Create new project.

Step 3: Select Windows Form as the project type.

As an alternative, you could just download the project and use it as your project template.

Configuring Properties Page

Make the following changes in the Property Pages:

Make sure Common Language Runtime Support is selected.

Screenshot - pp2.gif

Make sure Not using pre-complied headers is selected (optional).

Screenshot - pp1.gif

Make sure the additional dependencies are added.

Screenshot - pp3.gif

Also you may need to set your include directories as shown below. The order in which the directories are listed matters. Make sure The Microsoft Platform SDK is first. The path to this window is:

Tools->Options->Projects and Solutions->VC++ Directories

Using the Code

This code uses two header files, easyshowH.h and BHImaging.h. The header file easyshowH.h contains an unmanaged class of DirectShow functions and interfaces, the class is called BensShow but you can rename it to whatever you like. The BHImaging.h contains a managed class that I wrote to handle the bitmap data. I wrote my easyshowH.h class so that I wouldn't have to remember all of the details needed to use DirectShow. To use the class in the easyshowH.h file, you still need to have some knowledge of how DirectShow works, particularly how initialization, querying, and enumeration work. While using a class like the one in easyshowH.h means that you don't have to remember all of the technical things associated with DirectShow, like CLID identifiers and GUID types, it is still a good idea to have a look at them to find out what kind of things they are. This project should give you a basic understanding of how to create Windows Forms applications that can use DirectShow. Check the Platform SDK documentation to learn more about using DirectShow, as most of what I have written come from examples give in the Platform SDK documentation.

Usage Sample

This is only a part of the code from the project. Download the source or the binary from the links provided above.

When using, pay attention to the comments provided and the order of events.

In this project, very little error checking has been provided, If you intend to make extensive use of any of the code in this project, I would recommend that you put in place some form of error checking. In the case of this project, you could check the value of the HRESULT 'hr' value that is returned to see if the operation was successful.

private: System::Void Start_CamCap_Click(System::Object^  sender, System::EventArgs^  e) 
    BSTR  filtername;
    ULONG cFetched;    VARIANT varName;        
    //initializes the a CaptureGraphBuilder2
    hr = test.intCaptureGraphBuilder2();
    //initializes the a GraphBuilder
    hr = test.intGraphBuilder();
    //initializes the a SysDevEnum
    hr = test.intCreateDevEnum();
    //Query GraphBuilder for necessary Interfaces
    hr = test.QueryIMediaControl();
    hr = test.QueryIMediaEvent();
    hr = test.QueryIVideoWindow();
    hr = test.QueryIMediaFilter();

    //Specifies the CaptureGraphBuilder2 to use test.pGraphBuilder as its filter graph
    hr = test.pCaptureGraph2->SetFiltergraph(test.pGraphBuilder);
    //called in order to Enumerate all the Video capture devices installed on system
    hr = test.VideoCaptureSources();

    //Saves the names of the installed devices into a vector
    //the vector can be used to populate a list box
    //on my system I have only one video capture device
    vector<bstr> filternames = (test.getFilterName());

    //binds filter to device matching the name 
    // in this case a basefilter is bound to the device with name == filternames[0]

    //Add the Sample Grabber filter to the graph.
        //initializes the a sample grabber
        hr = test.intSampleGrabber();  
        //adds the sample grabber to the GraphBuilder
        hr = test.pGraphBuilder->AddFilter(test.pSG_Filter, L"SampleGrab"); 
        //connects the filers that are on the CaptureGraphBuilder2
        hr = test.pCaptureGraph2->RenderStream
    // Configure the Sample Grabber.
    hr = test.QueryISampleGrabber();
    hr = test.pSampleGrabber->SetOneShot(false);
    hr = test.pSampleGrabber->SetBufferSamples(true);
    hr = test.pSampleGrabber->SetMediaType(&(test.MediaType));
    hr = test.pSampleGrabber->GetConnectedMediaType(&(test.MediaType));
    //locks active window to form panel
    Rectangle rc = this->Play_Panel->ClientRectangle;
    hr = test.pWindow->put_Owner(OAHWND(this->Play_Panel->Handle.ToInt64()));
    hr = test.pWindow->put_WindowStyle( WS_CHILD | WS_CLIPSIBLINGS | WS_CLIPCHILDREN );
    hr = test.pWindow->SetWindowPosition( 0, 0, rc.Right, rc.Bottom );
    hr = hr = test.pMediaControl->Run();
    //Pause to let the window load

    // Sets initial conditions needed to grab frames
    // These setting are only when video is started
    // when a frame is grabbed do not need to be updated
    hr = test.cbBuffer = 0;
    hr = test.pSampleGrabber->GetCurrentBuffer(&(test.cbBuffer), NULL);
         test.pBuffer = new BYTE[test.cbBuffer];
         test.pVideoHeader = (VIDEOINFOHEADER*)test.MediaType.pbFormat;
         test.Bitmp_Info_header  = test.pVideoHeader->bmiHeader;
     // You cannot grab frames before you perform all of the steps above
     // You cannot stop video that is not playing
     // Make sure to properly order operations
         this->Start_CamCap->Enabled = false;
         this->Grab->Enabled = true;
         this->stop_bnt->Enabled = true;         


No updates planned at the moment


This article has no explicit license attached to it but may contain usage terms in the article text or the download files themselves. If in doubt please contact the author via the discussion board below.

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Comments and Discussions

AnswerRe: Two webcam test [modified] Pin
mathewmefiu13-Jan-10 10:49
membermathewmefiu13-Jan-10 10:49 
GeneralNeed help with converting the captured photo into bytes. Pin
Airkid11-Nov-09 20:55
memberAirkid11-Nov-09 20:55 
GeneralGrab image problem Pin
Member 22490015-Oct-09 22:03
memberMember 22490015-Oct-09 22:03 
GeneralExternal device not work Pin
islamicsoft30-Sep-09 3:30
memberislamicsoft30-Sep-09 3:30 
QuestionDoes not build Pin
JackSimmons24-May-09 12:09
memberJackSimmons24-May-09 12:09 
AnswerRe: Does not build Pin
dave_mm04-Jun-09 5:38
memberdave_mm04-Jun-09 5:38 
GeneralRe: Does not build Pin
JackSimmons4-Jun-09 22:25
memberJackSimmons4-Jun-09 22:25 
QuestionResolution of webcam? Pin
Member 466107919-Apr-09 22:01
memberMember 466107919-Apr-09 22:01 
AnswerRe: Resolution of webcam? Pin
merano25-Apr-10 9:53
membermerano25-Apr-10 9:53 
GeneralQuestion... using two cams Pin
Loink6-Feb-09 12:29
memberLoink6-Feb-09 12:29 
GeneralRe: Question... using two cams [modified] Pin
Member 371271220-Feb-09 10:53
memberMember 371271220-Feb-09 10:53 
QuestionHow to know if my webcam suuports Directshow Pin
cherchor24-Nov-08 13:33
membercherchor24-Nov-08 13:33 
QuestionAdd a second window with the preview Pin
mister0zorg11-Nov-08 6:36
membermister0zorg11-Nov-08 6:36 
GeneralGet Frame Streams by a callback Pin
HaniSalehi8-Nov-08 19:48
memberHaniSalehi8-Nov-08 19:48 
GeneralRe: Get Frame Streams by a callback Pin
mister0zorg13-Nov-08 5:57
membermister0zorg13-Nov-08 5:57 
Questionblank capture, assistance please! Pin
suefyzah20-Aug-08 19:50
membersuefyzah20-Aug-08 19:50 
GeneralApplication Fail to start Pin
HJC3-Jun-08 2:19
memberHJC3-Jun-08 2:19 
GeneralRe: Application Fail to start Pin
mister0zorg13-Nov-08 6:07
membermister0zorg13-Nov-08 6:07 
QuestionCompilation error KSCATEGORY_AUDIO_DEVICE [modified] Pin
SaiyanKing18-Sep-07 16:26
memberSaiyanKing18-Sep-07 16:26 
AnswerRe: Compilation error KSCATEGORY_AUDIO_DEVICE [modified] Pin
Papuc Laszlo11-Nov-09 0:27
memberPapuc Laszlo11-Nov-09 0:27 
GeneralRe: Compilation error KSCATEGORY_AUDIO_DEVICE Pin
merano25-Apr-10 7:52
membermerano25-Apr-10 7:52 
GeneralRe: Compilation error KSCATEGORY_AUDIO_DEVICE Pin
RevKeaponLaffin5-Jun-10 18:58
memberRevKeaponLaffin5-Jun-10 18:58 
GeneralNice work. Pin
Dr. Pastor29-Aug-07 13:20
memberDr. Pastor29-Aug-07 13:20 
QuestionHelp me !!! Do you have the include files (*.h)? Pin
zyberas17-Aug-07 5:34
memberzyberas17-Aug-07 5:34 
Generalresolution Pin
Gyorgy Hevizi22-Jun-07 12:54
memberGyorgy Hevizi22-Jun-07 12:54 
GeneralThanks for the example! Compiles, runs, but crashes during grabbing Pin
richard.hasty19-Jun-07 13:10
memberrichard.hasty19-Jun-07 13:10 
GeneralRe: Thanks for the example! Compiles, runs, but crashes during grabbing Pin
bjhamltn_BJH19-Jun-07 16:08
memberbjhamltn_BJH19-Jun-07 16:08 
GeneralRe: Thanks for the example! Compiles, runs, but crashes during grabbing Pin
richard.hasty19-Jun-07 17:09
memberrichard.hasty19-Jun-07 17:09 
GeneralRe: Thanks for the example! Compiles, runs, but crashes during grabbing Pin
beardedbernard21-Nov-07 23:12
memberbeardedbernard21-Nov-07 23:12 
GeneralRe: Thanks for the example! Compiles, runs, but crashes during grabbing Pin
nfltimbit7818-Jun-08 10:01
membernfltimbit7818-Jun-08 10:01 
GeneralRe: Thanks for the example! Compiles, runs, but crashes during grabbing Pin
Member 371271218-Dec-08 6:13
memberMember 371271218-Dec-08 6:13 
GeneralRe: Thanks for the example! Compiles, runs, but crashes during grabbing Pin
Gabrieloide9-Jun-10 12:36
memberGabrieloide9-Jun-10 12:36 

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