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| HRESULT extractFriendlyName( IMoniker* pMk, std::wstring& str )
{
assert( pMk != 0 );
IPropertyBag* pBag = 0;
HRESULT hr = pMk->BindToStorage(0, 0, IID_IPropertyBag, (void **)&pBag );
if( FAILED( hr ) || pBag == 0 )
{
return hr;
}
VARIANT var;
var.vt = VT_BSTR;
hr = pBag->Read(L"FriendlyName", &var, NULL);
if( SUCCEEDED( hr ) && var.bstrVal != 0 )
{
str = reinterpret_cast<wchar_t*>( var.bstrVal );
SysFreeString(var.bstrVal);
}
pBag->Release();
return hr;
}
HRESULT enumerateDShowFilterList( const CLSID& category )
{
HRESULT rval = S_OK;
HRESULT hr;
ICreateDevEnum* pCreateDevEnum = 0; // volatile, will be destroyed at the end
hr = ::CoCreateInstance( CLSID_SystemDeviceEnum, NULL, CLSCTX_INPROC_SERVER, IID_ICreateDevEnum, reinterpret_cast<void**>( &pCreateDevEnum ) );
assert( SUCCEEDED( hr ) && pCreateDevEnum != 0 );
if( FAILED( hr ) || pCreateDevEnum == 0 )
{
return hr;
}
IEnumMoniker* pEm = 0;
hr = pCreateDevEnum->CreateClassEnumerator( category, &pEm, 0 );
// If hr == S_FALSE, no error is occured. In this case pEm is NULL, because
// a filter does not exist e.g no video capture devives are connected to
// the computer or no codecs are installed.
assert( SUCCEEDED( hr ) && ((hr == S_OK && pEm != 0 ) || hr == S_FALSE) );
if( FAILED( hr ) )
{
pCreateDevEnum->Release();
return hr;
}
if( hr == S_OK && pEm != 0 ) // In this case pEm is != NULL
{
pEm->Reset();
ULONG cFetched;
IMoniker* pM = 0;
while( pEm->Next(1, &pM, &cFetched) == S_OK && pM != 0 )
{
std::wstring str;
if( SUCCEEDED( extractFriendlyName( pM, str ) )
{
// str contains the friendly name of the filter
// pM->BindToObject creates the filter
std::wcout << str << std::endl;
}
pM->Release();
}
pEm->Release();
}
pCreateDevEnum->Release();
return rval;
} |
