IltmmPlay::SetPreferredFilter Example for C++

// This function does the following:
// 1) Sets all filters to LEAD Default filters
// 2) Then resets all preferred filters to NULL, or does not use any preferred filter.
// 3) Then sets LEAD H264 Decoder (3.0) as LEAD H264 Preferred Decompressor using its Friendly Name
// 4) Gets the preferred H.264 Decompressor display name
void TestSetPreferredFilter(IltmmPlay *pPlay)
{
   HRESULT hr = S_OK;
   BSTR bstr = NULL;
   // Setting all filters to LEAD Default filters
   bstr = SysAllocString(ltmmFilter_LEADDefault);
   hr = pPlay->SetPreferredFilter(ltmmPlay_PreferredFilter_Generic, bstr);
   SysFreeString(bstr);
   // Resets all the preferred filters to NULL, or don't use any preferred filter.
   bstr = SysAllocString(ltmmFilter_DontCare);
   hr = pPlay->SetPreferredFilter(ltmmPlay_PreferredFilter_Generic, bstr);
   SysFreeString(bstr);
   // Setting H.264 Decompressor to LEAD H264 Decoder (3.0), using the Friendly Name
   bstr = SysAllocString(L"LEAD H264 Decoder (3.0)");
   hr = pPlay->SetPreferredFilter(ltmmPlay_PreferredFilter_H264Decompressor, bstr);
   SysFreeString(bstr);
   
   // Gets the preferred H.264 Decompressor
   bstr = NULL;
   hr = pPlay->GetPreferredFilter(ltmmPlay_PreferredFilter_H264Decompressor, &bstr);
   // check that the preferred filter is the LEAD H264 decoder
   if(bstr != NULL && !_wcsicmp(bstr, ltmmFilter_LEAD_H264Decompressor))
      MessageBox(NULL, TEXT("The preferred filter was set properly!"), TEXT("SUCCESS"), MB_OK);
   else
      MessageBox(NULL, TEXT("The preferred filter was not set properly!"), TEXT("FAILURE"), MB_OK);
   // free the bstr
   SysFreeString(bstr);
}