C++远程监控系统接收端- CAsyncOutputPin

HRESULT CAsyncOutputPin::GetMediaType(int iPosition, CMediaType *pMediaType)
{
    if(iPosition < 0)
    {
        return E_INVALIDARG;
    }
    if(iPosition > 0)
    {
        return VFW_S_NO_MORE_ITEMS;
    }

    CheckPointer(pMediaType,E_POINTER);
    CheckPointer(m_pReader,E_UNEXPECTED);
    
    *pMediaType = *m_pReader->LoadType();

    return S_OK;
}

HRESULT CAsyncOutputPin::CheckMediaType(const CMediaType* pType)
{
    CAutoLock lck(m_pLock);

    /*  We treat MEDIASUBTYPE_NULL subtype as a wild card */
    if((m_pReader->LoadType()->majortype == pType->majortype) &&
       (m_pReader->LoadType()->subtype == MEDIASUBTYPE_NULL   ||
        m_pReader->LoadType()->subtype == pType->subtype))
    {
        return S_OK;
    }

    return S_FALSE;
}

HRESULT CAsyncOutputPin::InitAllocator(IMemAllocator **ppAlloc)
{
    CheckPointer(ppAlloc,E_POINTER);

    HRESULT hr = NOERROR;
    CMemAllocator *pMemObject = NULL;

    *ppAlloc = NULL;

    /* Create a default memory allocator */
    pMemObject = new CMemAllocator(NAME("Base memory allocator"), NULL, &hr);
    if(pMemObject == NULL)
    {
        return E_OUTOFMEMORY;
    }
    if(FAILED(hr))
    {
        delete pMemObject;
        return hr;
    }

    /* Get a reference counted IID_IMemAllocator interface */
    hr = pMemObject->QueryInterface(IID_IMemAllocator,(void **)ppAlloc);
    if(FAILED(hr))
    {
        delete pMemObject;
        return E_NOINTERFACE;
    }

    ASSERT(*ppAlloc != NULL);
    return NOERROR;
}