如何将我的directshow筛选器添加到筛选器图中

我已经编写了一个自定义的directshow过滤器，它派生自directshow CBaseRenderer类。下面的代码是我的过滤器。

class CRenderSamples : public CBaseRenderer
{
// private data members
// constructors and destructors are private, need to use CoCreateInstance(.)
protected:
    //BYTE *m_pCopyBuffer;
    CMediaType m_MediaType;
    CRenderSamples(LPUNKNOWN pUnk,HRESULT *phr);
    virtual ~CRenderSamples();
public:
    //The CheckMediaType method determines if the 
    //filter accepts a specific media type.
    virtual HRESULT CheckMediaType(const CMediaType *pMediaType);
    // The DoRenderSample method renders a sample.
    virtual HRESULT DoRenderSample(IMediaSample *pMediaSample);
    // Instantiate filter object
    static CUnknown * WINAPI CreateInstance(LPUNKNOWN pUnk, HRESULT *phr);
};

我已经成功地构建了过滤器并将其注册到COM中。同时，我已经在GraphEdit中测试了我的过滤器和pushsourcedesktop过滤器，它可以正常工作。问题出在编码上。对于实例化过滤器对象应该使用哪种类型的指针，我有点困惑。如果我用IBaseFilter指针实例化过滤器对象，一切都很好，但我不能使用我在自己的过滤器中实现的DoRenderSamBple（）方法。但是，如果我使用CBaseRenderer，AddFilter（）函数会生成运行时错误，因为它的第一个参数需要IBaseFilter指针。以下代码是我的应用程序。

#include <stdio.h>
#include <windows.h>
#include <ObjBase.h>
#include <DShow.h>
#include <initguid.h>
#include <stdlib.h>
#include <streams.h>
#include "PushGuids.h"
//#pragma once
#pragma comment(lib,"Strmiids.lib") 
static const GUID CLSID_RENDER_SAMPLES = {0x9ddd8a2a, 0xa66c, 0x423a, { 0xa7, 0xb1, 
                    0xc3, 0x22, 0xae, 0xbc, 0x1c, 0x1e } };

int CALLBACK WinMain(
  _In_  HINSTANCE hInstance,
  _In_  HINSTANCE hPrevInstance,
  _In_  LPSTR lpCmdLine,
  _In_  int nCmdShow
){
    IGraphBuilder *pGraph = NULL;
    IMediaControl *pControl = NULL;
    IMediaEvent*   pEvent = NULL;

    HRESULT hr = CoInitialize(NULL);
    if (FAILED(hr)) {
         MessageBox(NULL,TEXT("ERROR - Could not initialize COM library."),TEXT("Error!"),MB_OK);
        return EXIT_FAILURE;
    }

    hr = CoCreateInstance(CLSID_FilterGraph, NULL, CLSCTX_INPROC_SERVER, 
            IID_IGraphBuilder, (void **)&pGraph);
    if (FAILED(hr)) {
        MessageBox(NULL,TEXT("Could not create the Filter Graph    Manager."),TEXT("Error!"),MB_OK);
        return EXIT_FAILURE;
    }
    hr = pGraph -> QueryInterface(IID_IMediaControl, (void **)&pControl);
    hr = pGraph -> QueryInterface(IID_IMediaEvent, (void **)&pEvent);

    IBaseFilter* pPushSourceDesktop = 0;
    hr = CoCreateInstance(CLSID_PushSourceDesktop, 0, CLSCTX_INPROC_SERVER,
                IID_IBaseFilter, (void**)&pPushSourceDesktop);
    if (FAILED(hr)) {
        MessageBox(NULL,TEXT("Could not create PushSourceDesktop filter."),TEXT("Error!"),MB_OK);
        return EXIT_FAILURE;
    }

    hr = pGraph -> AddFilter(pPushSourceDesktop, L"PushSourceDesktop"); 
    if (FAILED(hr)) {
        MessageBox(NULL,TEXT("Could not add PushSourceDesktop filter."),TEXT("Error!"),MB_OK);
        return 0;
    }
    //IBaseFilter *pRenderSamples;  
    CBaseRenderer *pRenderSamples;
    //IBaseFilter *pRenderer;
    hr = CoCreateInstance(CLSID_RENDER_SAMPLES,0,CLSCTX_INPROC_SERVER,
                IID_IBaseFilter, (void**)&pRenderSamples);
    if (FAILED(hr)) {
        MessageBox(NULL,TEXT("Could not instantiate RenderSamples."),TEXT("Error!"),MB_OK);
        return EXIT_FAILURE;
    }else{
        MessageBox(NULL,TEXT("Successfully instantiate RenderSamples filter."),TEXT("Success!"),MB_OK);
    }
    hr = pGraph -> AddFilter(pRenderSamples, L"Render Samples"); 
    if (FAILED(hr)) {
        MessageBox(NULL,TEXT("Could not add RenderSamples filter."),TEXT("Error!"),MB_OK);
        return EXIT_FAILURE;
    }else{
        MessageBox(NULL,TEXT("Successfully add RenderSamples filter."),TEXT("Success!"),MB_OK);
    }
    IPin **ppPushPinDesktop = new (IPin*);
    hr = pPushSourceDesktop -> FindPin(L"1", ppPushPinDesktop); 
    if (FAILED(hr)) {
        MessageBox(NULL,TEXT("Could not find pin of filter PushSourceDesktop."),TEXT("Error!"),MB_OK);
        return EXIT_FAILURE;
    }
    IPin **ppRenderSamples = new (IPin*);
    hr = pRenderSamples -> FindPin(L"In", ppRenderSamples); 
    switch(hr)
    {
        case S_OK:
            MessageBox(NULL,TEXT("Successfully find pin."),TEXT("Success!"),MB_OK);
            break;
        case E_POINTER:
            MessageBox(NULL,TEXT("Null pointer argument."),TEXT("Null Pointer!"),MB_OK);
            return EXIT_FAILURE;
        case VFW_E_NOT_FOUND:
            MessageBox(NULL,TEXT("Could not find a pin with this identifier."),TEXT("Error!"),MB_OK);
            return EXIT_FAILURE;
    }
    hr = pGraph -> Connect(*ppPushPinDesktop,*ppRenderSamples);
    switch(hr){
        case S_OK:
            MessageBox(NULL,TEXT("Successfully connect PushSourceDesktop and RenderSamples."),TEXT("Success!"),MB_OK);
            break;
        case VFW_S_PARTIAL_RENDER:
            MessageBox(NULL,TEXT("Partial success; some of the streams from this pin use an unsupported format."),
                        TEXT("Partial success!"),MB_OK);
            break;
        case E_ABORT:
            MessageBox(NULL,TEXT("Operation aborted."),TEXT("Aborted!"),MB_OK);
            break;
        case E_POINTER:
            MessageBox(NULL,TEXT("NULL pointer argument."),TEXT("NULL Pointer!"),MB_OK);
            break;
        case VFW_E_CANNOT_CONNECT:
            MessageBox(NULL,TEXT("No combination of intermediate filters could be found to make the connection."),TEXT("Aborted!"),MB_OK);
            break;
        case VFW_E_NOT_IN_GRAPH:
            MessageBox(NULL,TEXT("At least one of the filters is not in the filter graph."),TEXT("Filter no in filter graph"),MB_OK);
            break;
        default:
            MessageBox(NULL,TEXT("Unknow error"),TEXT("Error!"),MB_OK);
            return EXIT_FAILURE;
    }
    pControl -> Release();
    pEvent -> Release();
    (*ppPushPinDesktop) -> Release();
    pPushSourceDesktop -> Release();
    pRenderSamples-> Release();
    (*ppRenderSamples)->Release();
    pGraph -> Release();
    CoUninitialize(); 
    return EXIT_SUCCESS;
}

有人能想出解决这个问题的办法吗。非常感谢您！！！