Camera Control needed for Tablet

[Antonio Linares]

Tim,

Please copy my PRG to FWH\samples\dshow.prg and do buildh32.bat dshow

Thats how I am testing it here

[Antonio Linares]

[TimStone]

Are these still Borland builds ? I still cannot get it to compile with MSVC 2015

Tim

[Antonio Linares]

I am using MSVC 2015 Community Edition

do samples\buildh32.bat dshow

[Antonio Linares]

going to bed

[TimStone]

I'm getting an error at line 5, and the a has an ' over it.

[TimStone]

I cleaned up the space around that line, and now get the following build error following your instructions:

Code: Select all | Expand

Lines 4861, Functions/Procedures 1
Generating C source output to 'dshow.c'... Done.
dshow.c
dshow.prg(22): error C3873: '0xa0': this character is not allowed as a first character of an identifier
dshow.prg(22): error C2065: 'ÿ': undeclared identifier
dshow.prg(22): error C2146: syntax error: missing ';' before identifier 'ÿHRESULT'
dshow.prg(22): error C2065: 'ÿHRESULT': undeclared identifier
dshow.prg(22): error C2146: syntax error: missing ';' before identifier 'hr'
dshow.prg(22): error C2065: 'hr': undeclared identifier
dshow.prg(23): error C3873: '0xa0': this character is not allowed as a first character of an identifier
dshow.prg(23): error C2065: 'ÿ': undeclared identifier
dshow.prg(23): error C2146: syntax error: missing ';' before identifier 'ÿICreateDevEnum'
dshow.prg(23): error C2065: 'ÿICreateDevEnum': undeclared identifier
dshow.prg(23): error C2065: 'pDevEnum': undeclared identifier
dshow.prg(24): error C3873: '0xa0': this character is not allowed as a first character of an identifier
dshow.prg(24): error C2065: 'ÿ': undeclared identifier
dshow.prg(24): error C2146: syntax error: missing ';' before identifier 'ÿIEnumMoniker'
dshow.prg(24): error C2065: 'ÿIEnumMoniker': undeclared identifier
dshow.prg(24): error C2065: 'pEnum': undeclared identifier
dshow.prg(25): error C3873: '0xa0': this character is not allowed as a first character of an identifier
dshow.prg(25): error C2065: 'ÿ': undeclared identifier
dshow.prg(25): error C2146: syntax error: missing ';' before identifier 'ÿIMoniker'
dshow.prg(25): error C2065: 'ÿIMoniker': undeclared identifier
dshow.prg(25): error C2065: 'pMoniker': undeclared identifier
dshow.prg(26): error C3873: '0xa0': this character is not allowed as a first character of an identifier
dshow.prg(26): error C2065: 'ÿ': undeclared identifier
dshow.prg(26): error C2146: syntax error: missing ';' before identifier 'ÿIPropertyBag'
dshow.prg(26): error C2065: 'ÿIPropertyBag': undeclared identifier
dshow.prg(26): error C2065: 'pPropBag': undeclared identifier
dshow.prg(27): error C3873: '0xa0': this character is not allowed as a first character of an identifier
dshow.prg(27): error C2065: 'ÿ': undeclared identifier
dshow.prg(27): error C2146: syntax error: missing ';' before identifier 'ÿIGraphBuilder'
dshow.prg(27): error C2065: 'ÿIGraphBuilder': undeclared identifier
dshow.prg(27): error C2065: 'pGraph': undeclared identifier
dshow.prg(28): error C3873: '0xa0': this character is not allowed as a first character of an identifier
dshow.prg(28): error C2065: 'ÿ': undeclared identifier
dshow.prg(28): error C2146: syntax error: missing ';' before identifier 'ÿICaptureGraphBuilder2'
dshow.prg(28): error C2065: 'ÿICaptureGraphBuilder2': undeclared identifier
dshow.prg(28): error C2065: 'pBuilder': undeclared identifier
dshow.prg(29): error C3873: '0xa0': this character is not allowed as a first character of an identifier
dshow.prg(29): error C2065: 'ÿ': undeclared identifier
dshow.prg(29): error C2146: syntax error: missing ';' before identifier 'ÿIBaseFilter'
dshow.prg(29): error C2065: 'ÿIBaseFilter': undeclared identifier
dshow.prg(29): error C2065: 'pCap': undeclared identifier
dshow.prg(30): error C3873: '0xa0': this character is not allowed as a first character of an identifier
dshow.prg(30): error C2065: 'ÿ': undeclared identifier
dshow.prg(30): error C2146: syntax error: missing ';' before identifier 'ÿIBaseFilter'
dshow.prg(30): error C2065: 'ÿIBaseFilter': undeclared identifier
dshow.prg(30): error C2065: 'pSampleGrabberFilter': undeclared identifier
dshow.prg(31): error C3873: '0xa0': this character is not allowed as a first character of an identifier
dshow.prg(31): error C2065: 'ÿ': undeclared identifier
dshow.prg(31): error C2146: syntax error: missing ';' before identifier 'ÿIBaseFilter'
dshow.prg(31): error C2065: 'ÿIBaseFilter': undeclared identifier
dshow.prg(31): error C2065: 'pNullRenderer': undeclared identifier
dshow.prg(32): error C3873: '0xa0': this character is not allowed as a first character of an identifier
dshow.prg(32): error C2065: 'ÿ': undeclared identifier
dshow.prg(32): error C2146: syntax error: missing ';' before identifier 'ÿIMediaControl'
dshow.prg(32): error C2065: 'ÿIMediaControl': undeclared identifier
dshow.prg(32): error C2065: 'pMediaControl': undeclared identifier
dshow.prg(33): error C3873: '0xa0': this character is not allowed as a first character of an identifier
dshow.prg(33): error C2065: 'ÿ': undeclared identifier
dshow.prg(33): error C2146: syntax error: missing ';' before identifier 'ÿchar'
dshow.prg(33): error C2065: 'ÿchar': undeclared identifier
dshow.prg(33): error C2065: 'pBuffer': undeclared identifier
dshow.prg(34): error C3873: '0xa0': this character is not allowed as a first character of an identifier
dshow.prg(34): error C2065: 'ÿ': undeclared identifier
dshow.prg(34): error C2146: syntax error: missing ';' before identifier 'ÿVARIANT'
dshow.prg(34): error C2065: 'ÿVARIANT': undeclared identifier
dshow.prg(34): error C2146: syntax error: missing ';' before identifier 'var'
dshow.prg(34): error C2065: 'var': undeclared identifier
dshow.prg(35): error C3873: '0xa0': this character is not allowed as a first character of an identifier
dshow.prg(35): error C2065: 'ÿ': undeclared identifier
dshow.prg(35): error C2146: syntax error: missing ';' before identifier 'ÿ'
dshow.prg(35): error C2144: syntax error: 'int' should be preceded by ';'
dshow.prg(36): error C3873: '0xa0': this character is not allowed as a first character of an identifier
dshow.prg(36): error C2065: 'ÿ': undeclared identifier
dshow.prg(36): error C2146: syntax error: missing ';' before identifier 'ÿ'
dshow.prg(36): error C2144: syntax error: 'int' should be preceded by ';'
dshow.prg(37): error C3873: '0xa0': this character is not allowed as a first character of an identifier
dshow.prg(37): error C2065: 'ÿ': undeclared identifier
dshow.prg(37): error C2146: syntax error: missing ';' before identifier 'ÿ'
dshow.prg(37): error C2144: syntax error: 'char' should be preceded by ';'
dshow.prg(38): error C3873: '0xa0': this character is not allowed as a first character of an identifier
dshow.prg(38): error C2065: 'ÿ': undeclared identifier
dshow.prg(38): error C2146: syntax error: missing ';' before identifier 'ÿchar'
dshow.prg(38): error C2065: 'ÿchar': undeclared identifier
dshow.prg(38): error C2146: syntax error: missing ';' before identifier 'char_buffer'
dshow.prg(38): error C2065: 'char_buffer': undeclared identifier
dshow.prg(39): error C3873: '0xa0': this character is not allowed as a first character of an identifier
dshow.prg(39): error C2653: 'ÿDexterLib': is not a class or namespace name
dshow.prg(39): error C2065: 'ÿ': undeclared identifier
dshow.prg(39): error C2146: syntax error: missing ';' before identifier 'ISampleGrabber'
dshow.prg(39): error C2065: 'ISampleGrabber': undeclared identifier
dshow.prg(39): error C2065: 'pSampleGrabber': undeclared identifier
dshow.prg(41): error C3873: '0xa0': this character is not allowed as a first character of an identifier
dshow.prg(41): error C2065: 'ÿ': undeclared identifier
dshow.prg(41): error C2146: syntax error: missing ';' before identifier 'ÿstrcpy'
dshow.prg(41): error C3861: 'ÿstrcpy': identifier not found
dshow.prg(43): error C3873: '0xa0': this character is not allowed as a first character of an identifier
dshow.prg(43): error C2065: 'ÿ': undeclared identifier
dshow.prg(43): error C2146: syntax error: missing ';' before identifier 'ÿhr'
dshow.prg(43): error C2065: 'ÿhr': undeclared identifier
dshow.prg(45): error C3873: '0xa0': this character is not allowed as a first character of an identifier
dshow.prg(45): error C2065: 'ÿ': undeclared identifier
dshow.prg(45): fatal error C1003: error count exceeds 100; stopping compilation
LINK : fatal error LNK1181: cannot open input file 'dshow.obj'
* Linking errors *
 

I must be missing something in my available files.

Tim

[Antonio Linares]

Tim,

Please use this dshow.prg:

https://bitbucket.org/fivetech/fivewin-contributions/downloads/dshow.prg

[rhlawek]

Antonio,

I am able to get this to compile and run using VS 2015, but I needed to do/change a couple things:

1) Explicitly set to compile as CPP code instead of C.
2) Changed MessageBox() calls to MessageBoxA() to get around a unicode/casting error.

[Antonio Linares]

Robb,

Yes, it has to be compiled in C++ mode

FWH\samples\buildh32.bat does it automatically

[Antonio Linares]

> 2) Changed MessageBox() calls to MessageBoxA() to get around a unicode/casting error

that may be as you are using unicode at compiling time.

buildh32.bat works fine and does not use unicode

[rhlawek]

One other thing I forgot is I had to add "strmiids" to my list of libs to resolve a bunch of unresolved externals. I don't see that lib referenced in buildh32.bat so I'm not sure why I see the missing externals and you don't.

I am able to get it to run both as 32 and 64 bit.

[Antonio Linares]

Robb,

I mentioned here that strmiids.lib has to be linked:

viewtopic.php?p=193422#p193422

many thanks for your feedback

[Antonio Linares]

This version turns the ActiveMovie Window as a child window of our app:

dshow.prg

Code: Select all | Expand

#include "FiveWin.ch"

function Main()

   local oWnd, hWnd
   
   DEFINE WINDOW oWnd

   ACTIVATE WINDOW oWnd MAXIMIZED ;
      ON INIT ( DShowCamera(),;
                SetParent( hWnd := FindWindow( 0, "ActiveMovie Window" ), oWnd:hWnd ),;
                SetWindowPos( hWnd, 0, 10, 10, 300, 300 ) )

return nil

#pragma BEGINDUMP

#include <dshow.h>
#include <uuids.h>
#include <objbase.h>

#import "qedit.dll" raw_interfaces_only named_guids

EXTERN_C const CLSID CLSID_NullRenderer;
EXTERN_C const CLSID CLSID_SampleGrabber;

HB_FUNC( DSHOWCAMERA )
{
   HRESULT hr;
   ICreateDevEnum *pDevEnum = NULL;
   IEnumMoniker *pEnum = NULL;
   IMoniker *pMoniker = NULL;
   IPropertyBag *pPropBag = NULL;
   IGraphBuilder *pGraph = NULL;
   ICaptureGraphBuilder2 *pBuilder = NULL;
   IBaseFilter *pCap = NULL;
   IBaseFilter *pSampleGrabberFilter = NULL;
   IBaseFilter *pNullRenderer = NULL;
   IMediaControl *pMediaControl = NULL;
   char *pBuffer = NULL;
   VARIANT var;
    int n = 0;
    int device_number = 0;
    char device_name[ 100 ];
   char char_buffer[100];
   DexterLib::ISampleGrabber *pSampleGrabber = NULL;

   strcpy( device_name, "" );

   hr = CoInitializeEx( NULL, COINIT_MULTITHREADED );

   if( hr != S_OK )
      MessageBox( 0, "CoInitializeEx error", "ok", 0 );

   hr = CoCreateInstance( CLSID_FilterGraph, NULL,
              CLSCTX_INPROC_SERVER, IID_IGraphBuilder,
              ( void ** ) &pGraph );
           
   if( hr != S_OK )
      MessageBox( 0, "CoCreateInstance error", "ok", 0 );
      
    hr = CoCreateInstance( CLSID_CaptureGraphBuilder2, NULL,
            CLSCTX_INPROC_SERVER, IID_ICaptureGraphBuilder2,
            ( void ** ) &pBuilder );      

   if( hr != S_OK )
      MessageBox( 0, "CoCreateInstance 2 error", "ok", 0 );

    hr = ( ( ICaptureGraphBuilder * ) pBuilder )->SetFiltergraph( pGraph );
   
    if( hr != S_OK )
        MessageBox( 0, "Could not attach capture graph builder to graph", "ok", 0 ); 
      
    hr = CoCreateInstance( CLSID_SystemDeviceEnum, NULL,
            CLSCTX_INPROC_SERVER, IID_PPV_ARGS( &pDevEnum ) );
         
    if( hr != S_OK )
        MessageBox( 0, "Could not crerate system device enumerator", "ok", 0 );
      
    hr = pDevEnum->CreateClassEnumerator(
                    CLSID_VideoInputDeviceCategory, &pEnum, 0 );
               
    if( hr != S_OK )
        MessageBox( 0, "No video devices found", "ok", 0 );      
      
    while(1)
    {
        // Access next device
        hr = pEnum->Next(1, &pMoniker, NULL);
        if( hr == S_OK )
            n++; // increment device count
      else   
         break;
        
        // If device was specified by name rather than number...
        if( device_number == 0 )
        {
            // Get video input device name
            hr = pMoniker->BindToStorage(0, 0, IID_PPV_ARGS(&pPropBag));
            if (hr == S_OK)
            {
                // Get current device name
                VariantInit(&var);
                hr = pPropBag->Read(L"FriendlyName", &var, 0);
                
                // Convert to a normal C string, i.e. char*
                sprintf(char_buffer, "%ls", var.bstrVal);
                VariantClear(&var);
                pPropBag->Release();
                pPropBag = NULL;
                
                // Exit loop if current device name matched devname
            // MessageBox( 0, char_buffer, "device_name", 0 );
            
                if (strcmp(device_name, char_buffer) == 0) break;
            }
            else
         {
                MessageBox( 0, "Error getting device names", "ok", 0 );
            break;
         }   
        }
        else if (n >= device_number) break;
    }   
   
    // Get video input device name
    hr = pMoniker->BindToStorage(0, 0, IID_PPV_ARGS(&pPropBag));
    VariantInit(&var);
    hr = pPropBag->Read(L"FriendlyName", &var, 0);
    // MessageBoxW( 0, L"Capture device", var.bstrVal, 0 );
    VariantClear(&var);   
   
    // Create capture filter and add to graph
    hr = pMoniker->BindToObject(0, 0,
                    IID_IBaseFilter, (void**)&pCap);
               
    if( hr != S_OK ) 
      MessageBox( 0, "Could not create capture filter", "ok", 0 );   

    // Add capture filter to graph
    hr = pGraph->AddFilter(pCap, L"Capture Filter");
   
    if( hr != S_OK ) 
      MessageBox( 0, "Could not add capture filter to graph", "ok", 0 );

    // Create sample grabber filter
    hr = CoCreateInstance(CLSID_SampleGrabber, NULL,
        CLSCTX_INPROC_SERVER, IID_IBaseFilter,
        (void**)&pSampleGrabberFilter);
      
    if( hr != S_OK )
        MessageBox( 0, "Could not create Sample Grabber filter", "ok", 0 );

    // Query the ISampleGrabber interface of the sample grabber filter
    hr = pSampleGrabberFilter->QueryInterface(
            DexterLib::IID_ISampleGrabber, (void**)&pSampleGrabber);
         
    if( hr != S_OK )
        MessageBox( 0, "Could not get ISampleGrabber interface to sample grabber filter", "ok", 0 );

    // Enable sample buffering in the sample grabber filter
    hr = pSampleGrabber->SetBufferSamples(TRUE);
   
    if( hr != S_OK )
        MessageBox( 0, "Could not enable sample buffering in the sample grabber", "ok", 0 );

    // Set media type in sample grabber filter
    AM_MEDIA_TYPE mt;
    ZeroMemory(&mt, sizeof(AM_MEDIA_TYPE));
    mt.majortype = MEDIATYPE_Video;
    mt.subtype = MEDIASUBTYPE_RGB24;
    hr = pSampleGrabber->SetMediaType((DexterLib::_AMMediaType *)&mt);
   
    if( hr != S_OK )
        MessageBox( 0, "Could not set media type in sample grabber", "ok", 0 );

    // Add sample grabber filter to filter graph
    hr = pGraph->AddFilter(pSampleGrabberFilter, L"SampleGrab");
   
    if( hr != S_OK )
        MessageBox( 0, "Could not add Sample Grabber to filter graph", "ok", 0 );

    // Create Null Renderer filter
    hr = CoCreateInstance(CLSID_NullRenderer, NULL,
        CLSCTX_INPROC_SERVER, IID_IBaseFilter,
        (void**)&pNullRenderer);

   if( hr != S_OK )
        MessageBox( 0, "Could not create Null Renderer filter", "ok", 0 );

    // Add Null Renderer filter to filter graph
    hr = pGraph->AddFilter(pNullRenderer, L"NullRender");

   if( hr != S_OK )
        MessageBox( 0, "Could not add Null Renderer to filter graph", "ok", 0 );
      
   // Connect up the filter graph's capture stream
    hr = pBuilder->RenderStream(
        &PIN_CATEGORY_CAPTURE, &MEDIATYPE_Video,
        pCap,  pSampleGrabberFilter, pNullRenderer);
      
    if( hr != S_OK )
        MessageBox( 0, "Could not render capture video stream", "ok", 0 );

    hr = pBuilder->RenderStream(
                &PIN_CATEGORY_PREVIEW, &MEDIATYPE_Video,
                pCap, NULL, NULL);
    
   if (hr != S_OK && hr != VFW_S_NOPREVIEWPIN)
            MessageBox( 0, "Could not render preview video stream", "ok", 0 );

    // Get media control interfaces to graph builder object
    hr = pGraph->QueryInterface(IID_IMediaControl,
                    (void**)&pMediaControl);

   if( hr != S_OK ) 
      MessageBox( 0, "Could not get media control interface", "ok", 0 );

    // Run graph
    while(1)
    {
        hr = pMediaControl->Run();
        
        // Hopefully, the return value was S_OK or S_FALSE
        if (hr == S_OK) break; // graph is now running
        if (hr == S_FALSE) continue; // graph still preparing to run
        
        // If the Run function returned something else,
        // there must be a problem
        // fprintf(stderr, "Error: %u\n", hr);
        MessageBox( 0, "Could not run filter graph", "ok", 0 );
    }
}

#pragma ENDDUMP

[Antonio Linares]

Now we turn it into a control

Code: Select all | Expand

#include "FiveWin.ch"

#define GWL_STYLE -16

function Main()

   local oWnd, hWnd
   
   DEFINE WINDOW oWnd

   ACTIVATE WINDOW oWnd MAXIMIZED ;
      ON INIT ( DShowCamera(),;
                SetParent( hWnd := FindWindow( 0, "ActiveMovie Window" ), oWnd:hWnd ),;
                SetWindowLong( hWnd, GWL_STYLE, nOr( WS_CHILD, WS_VISIBLE ) ),;
                SetWindowPos( hWnd, 0, 10, 10, 300, 300 ) )

return nil

#pragma BEGINDUMP

#include <dshow.h>
#include <uuids.h>
#include <objbase.h>

#import "qedit.dll" raw_interfaces_only named_guids

EXTERN_C const CLSID CLSID_NullRenderer;
EXTERN_C const CLSID CLSID_SampleGrabber;

HB_FUNC( DSHOWCAMERA )
{
   HRESULT hr;
   ICreateDevEnum *pDevEnum = NULL;
   IEnumMoniker *pEnum = NULL;
   IMoniker *pMoniker = NULL;
   IPropertyBag *pPropBag = NULL;
   IGraphBuilder *pGraph = NULL;
   ICaptureGraphBuilder2 *pBuilder = NULL;
   IBaseFilter *pCap = NULL;
   IBaseFilter *pSampleGrabberFilter = NULL;
   IBaseFilter *pNullRenderer = NULL;
   IMediaControl *pMediaControl = NULL;
   char *pBuffer = NULL;
   VARIANT var;
    int n = 0;
    int device_number = 0;
    char device_name[ 100 ];
   char char_buffer[100];
   DexterLib::ISampleGrabber *pSampleGrabber = NULL;

   strcpy( device_name, "" );

   hr = CoInitializeEx( NULL, COINIT_MULTITHREADED );

   if( hr != S_OK )
      MessageBox( 0, "CoInitializeEx error", "ok", 0 );

   hr = CoCreateInstance( CLSID_FilterGraph, NULL,
              CLSCTX_INPROC_SERVER, IID_IGraphBuilder,
              ( void ** ) &pGraph );
           
   if( hr != S_OK )
      MessageBox( 0, "CoCreateInstance error", "ok", 0 );
      
    hr = CoCreateInstance( CLSID_CaptureGraphBuilder2, NULL,
            CLSCTX_INPROC_SERVER, IID_ICaptureGraphBuilder2,
            ( void ** ) &pBuilder );      

   if( hr != S_OK )
      MessageBox( 0, "CoCreateInstance 2 error", "ok", 0 );

    hr = ( ( ICaptureGraphBuilder * ) pBuilder )->SetFiltergraph( pGraph );
   
    if( hr != S_OK )
        MessageBox( 0, "Could not attach capture graph builder to graph", "ok", 0 ); 
      
    hr = CoCreateInstance( CLSID_SystemDeviceEnum, NULL,
            CLSCTX_INPROC_SERVER, IID_PPV_ARGS( &pDevEnum ) );
         
    if( hr != S_OK )
        MessageBox( 0, "Could not crerate system device enumerator", "ok", 0 );
      
    hr = pDevEnum->CreateClassEnumerator(
                    CLSID_VideoInputDeviceCategory, &pEnum, 0 );
               
    if( hr != S_OK )
        MessageBox( 0, "No video devices found", "ok", 0 );      
      
    while(1)
    {
        // Access next device
        hr = pEnum->Next(1, &pMoniker, NULL);
        if( hr == S_OK )
            n++; // increment device count
      else   
         break;
        
        // If device was specified by name rather than number...
        if( device_number == 0 )
        {
            // Get video input device name
            hr = pMoniker->BindToStorage(0, 0, IID_PPV_ARGS(&pPropBag));
            if (hr == S_OK)
            {
                // Get current device name
                VariantInit(&var);
                hr = pPropBag->Read(L"FriendlyName", &var, 0);
                
                // Convert to a normal C string, i.e. char*
                sprintf(char_buffer, "%ls", var.bstrVal);
                VariantClear(&var);
                pPropBag->Release();
                pPropBag = NULL;
                
                // Exit loop if current device name matched devname
            // MessageBox( 0, char_buffer, "device_name", 0 );
            
                if (strcmp(device_name, char_buffer) == 0) break;
            }
            else
         {
                MessageBox( 0, "Error getting device names", "ok", 0 );
            break;
         }   
        }
        else if (n >= device_number) break;
    }   
   
    // Get video input device name
    hr = pMoniker->BindToStorage(0, 0, IID_PPV_ARGS(&pPropBag));
    VariantInit(&var);
    hr = pPropBag->Read(L"FriendlyName", &var, 0);
    // MessageBoxW( 0, L"Capture device", var.bstrVal, 0 );
    VariantClear(&var);   
   
    // Create capture filter and add to graph
    hr = pMoniker->BindToObject(0, 0,
                    IID_IBaseFilter, (void**)&pCap);
               
    if( hr != S_OK ) 
      MessageBox( 0, "Could not create capture filter", "ok", 0 );   

    // Add capture filter to graph
    hr = pGraph->AddFilter(pCap, L"Capture Filter");
   
    if( hr != S_OK ) 
      MessageBox( 0, "Could not add capture filter to graph", "ok", 0 );

    // Create sample grabber filter
    hr = CoCreateInstance(CLSID_SampleGrabber, NULL,
        CLSCTX_INPROC_SERVER, IID_IBaseFilter,
        (void**)&pSampleGrabberFilter);
      
    if( hr != S_OK )
        MessageBox( 0, "Could not create Sample Grabber filter", "ok", 0 );

    // Query the ISampleGrabber interface of the sample grabber filter
    hr = pSampleGrabberFilter->QueryInterface(
            DexterLib::IID_ISampleGrabber, (void**)&pSampleGrabber);
         
    if( hr != S_OK )
        MessageBox( 0, "Could not get ISampleGrabber interface to sample grabber filter", "ok", 0 );

    // Enable sample buffering in the sample grabber filter
    hr = pSampleGrabber->SetBufferSamples(TRUE);
   
    if( hr != S_OK )
        MessageBox( 0, "Could not enable sample buffering in the sample grabber", "ok", 0 );

    // Set media type in sample grabber filter
    AM_MEDIA_TYPE mt;
    ZeroMemory(&mt, sizeof(AM_MEDIA_TYPE));
    mt.majortype = MEDIATYPE_Video;
    mt.subtype = MEDIASUBTYPE_RGB24;
    hr = pSampleGrabber->SetMediaType((DexterLib::_AMMediaType *)&mt);
   
    if( hr != S_OK )
        MessageBox( 0, "Could not set media type in sample grabber", "ok", 0 );

    // Add sample grabber filter to filter graph
    hr = pGraph->AddFilter(pSampleGrabberFilter, L"SampleGrab");
   
    if( hr != S_OK )
        MessageBox( 0, "Could not add Sample Grabber to filter graph", "ok", 0 );

    // Create Null Renderer filter
    hr = CoCreateInstance(CLSID_NullRenderer, NULL,
        CLSCTX_INPROC_SERVER, IID_IBaseFilter,
        (void**)&pNullRenderer);

   if( hr != S_OK )
        MessageBox( 0, "Could not create Null Renderer filter", "ok", 0 );

    // Add Null Renderer filter to filter graph
    hr = pGraph->AddFilter(pNullRenderer, L"NullRender");

   if( hr != S_OK )
        MessageBox( 0, "Could not add Null Renderer to filter graph", "ok", 0 );
      
   // Connect up the filter graph's capture stream
    hr = pBuilder->RenderStream(
        &PIN_CATEGORY_CAPTURE, &MEDIATYPE_Video,
        pCap,  pSampleGrabberFilter, pNullRenderer);
      
    if( hr != S_OK )
        MessageBox( 0, "Could not render capture video stream", "ok", 0 );

    hr = pBuilder->RenderStream(
                &PIN_CATEGORY_PREVIEW, &MEDIATYPE_Video,
                pCap, NULL, NULL);
    
   if (hr != S_OK && hr != VFW_S_NOPREVIEWPIN)
            MessageBox( 0, "Could not render preview video stream", "ok", 0 );

    // Get media control interfaces to graph builder object
    hr = pGraph->QueryInterface(IID_IMediaControl,
                    (void**)&pMediaControl);

   if( hr != S_OK ) 
      MessageBox( 0, "Could not get media control interface", "ok", 0 );

    // Run graph
    while(1)
    {
        hr = pMediaControl->Run();
        
        // Hopefully, the return value was S_OK or S_FALSE
        if (hr == S_OK) break; // graph is now running
        if (hr == S_FALSE) continue; // graph still preparing to run
        
        // If the Run function returned something else,
        // there must be a problem
        // fprintf(stderr, "Error: %u\n", hr);
        MessageBox( 0, "Could not run filter graph", "ok", 0 );
    }
}

#pragma ENDDUMP