directshow 显示有黑边的有关问题

bool CDXGraph::SetWindow(HWND inWindow){    mVideoWindow->put_Owner((OAHWND)inWindow);    mVideoWindow->put_Visible(OATRUE);    mVideoWindow->put_AutoShow(OATRUE);    mVideoWindow->put_MessageDrain((OAHWND) inWindow);    mVideoWindow->put_WindowStyle(WS_CHILD | WS_CLIPSIBLINGS | WS_CLIPCHILDREN);    return S_OK;}bool CDXGraph::SetDisplayWindow(HWND inWindow){        if (mVideoWindow)    {                RECT windowRect;        GetClientRect(inWindow, &windowRect);        HRESULT hr = NULL;                LONG lVideoWidth, lVideoHeight, lNewWidth, lNewHeight, lWidth, lHeight;        //Read the default video size        hr = mBasicVideo->GetVideoSize(&lVideoWidth, &lVideoHeight);        if (FAILED(hr))        {            mBasicVideo->Release();            mVideoWindow->Release();            return FALSE;        }        // Ignore the video's original size and stretch to fit bounding rectangle        hr = mVideoWindow->SetWindowPosition(0,0,windowRect.right, windowRect.bottom );        if (FAILED(hr))        {            return S_FALSE;        }        return S_OK;    }    return S_FALSE;}