DirectShow — Выбор видео устройства

Это код, который я смог написать после ссылки MSND:
http://msdn.microsoft.com/en-us/library/dd407269(v=vs.85).aspx

#include <iostream>
#include <conio.h>
#include <dshow.h>

// Helper function for initializing ICaptureGraphBuilder2 and IGraphBuilder
// MSDN function: http://msdn.microsoft.com/en-us/library/dd373396(v=vs.85).aspx
// Arguments are passed  by pointers
HRESULT InitCaptureGraphBuilder(ICaptureGraphBuilder2 **, IGraphBuilder **);

// Helper function for retriving an enumerator for a specified device category
// MSDN function:          http://msdn.microsoft.com/en-us/library/dd377566(v=vs.85).aspx
// MSDN about moniker:     http://msdn.microsoft.com/en-us/library/ms679705(v=vs.85).aspx
// MSDN about enumerator:  http://msdn.microsoft.com/en-us/library/dd407292(v=vs.85).aspx
// You need to pass by reference the type of device a nd by pointer the IEnumMoniker
HRESULT EnumerateDevices(REFGUID, IEnumMoniker **);

// Helper function for preparing the output video file
// You need to pass by ponter ICaptureGraphBuilder2 and IBaseFilter
HRESULT PrepareOutputFile(ICaptureGraphBuilder2 **, IBaseFilter **);

int main()
{
ICaptureGraphBuilder2   *capture_graph       = NULL;
IGraphBuilder           *graph               = NULL;
IEnumMoniker            *device_enumerator;
IBaseFilter             *capture_filter;
HRESULT                 hr;

hr = CoInitialize(NULL);
hr = InitCaptureGraphBuilder(&capture_graph, &graph);
hr = EnumerateDevices(CLSID_VideoInputDeviceCategory, &device_enumerator);

// hr = PrepareOutputFile(&capture_graph, &capture_filter);

// At the end:
// capture_graph->Release();
// graph->Release();

}

HRESULT InitCaptureGraphBuilder(ICaptureGraphBuilder2 **ppCapture_graph, IGraphBuilder **ppGraph)
{
if (!ppCapture_graph || !ppGraph) {
return E_POINTER;
}

ICaptureGraphBuilder2   *capture_graph  = NULL;
IGraphBuilder           *graph  = NULL;

// Create the Capture Graph Builder
HRESULT hr = CoCreateInstance(CLSID_CaptureGraphBuilder2, NULL, CLSCTX_INPROC_SERVER, IID_ICaptureGraphBuilder2, (void**)&capture_graph);

if (SUCCEEDED(hr)) {
// Create the Filter Graph Manager
hr = CoCreateInstance(CLSID_FilterGraph, 0, CLSCTX_INPROC_SERVER, IID_IGraphBuilder, (void**)&graph);

if (SUCCEEDED(hr)) {
// Initialize the Capture Graph Builder
capture_graph->SetFiltergraph(graph);

// Return both interface pointers to the caller
// !! The caller must release both interfaces !!
*ppCapture_graph  = capture_graph;
*ppGraph          = graph;

return S_OK;
} else {
capture_graph->Release();
}
}

// Failed
return hr;
}

HRESULT EnumerateDevices(REFGUID category, IEnumMoniker **ppDevice_enumerator)
{
ICreateDevEnum *create_dev_enum;

// Create the System Device Enumerator
HRESULT hr = CoCreateInstance(CLSID_SystemDeviceEnum, NULL, CLSCTX_INPROC_SERVER, IID_PPV_ARGS(&create_dev_enum));

if (SUCCEEDED(hr)) {
// Create an enumerator for the selected category
hr = create_dev_enum->CreateClassEnumerator(category, ppDevice_enumerator, 0);

if (hr == S_FALSE) {
// The category is empty. Treat as an error
hr = VFW_E_NOT_FOUND;
}
create_dev_enum->Release();
}

return hr;
}

Теперь я все еще не понимаю, как выбрать видеоустройство, которое я хочу.
С EnumerateDevices() Функция Я возвращаю перечислитель (я думаю, что это своего рода вектор со всеми устройствами), но как мне использовать его до PrepareOutputFile() (что я должен написать)?!