how to tell the output pins in a filter?

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hi all
i am try to connect a source filter to the next filter and i faced a problem.
the source filter now has two output pins. and i have checked them in the graphedit ,and i found their catagory are all zero . but there has a difference in type(major type).but i have no idea how to implement it.
and i stumble across a post:

//-----------------------------------------------------------------

Use IKsPropertySet Interface and see example code in section Pin Property Set.

and more details about this method:
http://msdn.microsoft.com/en-us/library/ms787483(VS.85).aspx[^]

Pin Property Set
The pin property set returns the pin category for a pin on a filter. The category is set by the filter when it creates the pin; the category indicates what type of data the pin is delivered or receives by this pin.

Example Code

The following code shows how to check whether a pin supports this property set, and if so, how to obtain the pin category:

HRESULT GetPinCategory(IPin *pPin, GUID *pPinCategory)
{
    HRESULT hr;
    IKsPropertySet *pKs;
    hr = pPin->QueryInterface(IID_IKsPropertySet, (void **)&pKs);
    if (FAILED(hr))
    {
        // The pin does not support IKsPropertySet.
        return hr;
    }
    // Try to retrieve the pin category.
    DWORD cbReturned;
    hr = pKs->Get(AMPROPSETID_Pin, AMPROPERTY_PIN_CATEGORY, NULL, 0, 
        pPinCategory, sizeof(GUID), &cbReturned);

    // If this succeeded, pPinCategory now contains the category GUID.

    pKs->Release();
    return hr;
}
//--------------------------------------------------------------------

i doubt weather it can work in my situation.

if anyone have any ideas or have experiences in this .just help me !

thanks in advance!

[EDIT] Added <pre> tags to the example code - Code-o-mat [/EDIT]