How to use ltmmProcessors object to register a 3rd-party DirectShow filter as a video processor (C)

The following function for C shows how to use the ltmmProcessors object from the ltmmPlayControl object to register a 3rd-party video processor.

void EnableMyVideoProcessor() 
{ 
   IltmmProcessors *pVideoProcessors = NULL;
   IltmmPlay_get_VideoProcessors(pPlayCtrl, &pVideoProcessors);
   
   if(NULL != pVideoProcessors) 
   { 
       // Register the external filter by class id
      IltmmProcessors_RegisterExternalProcessor(pVideoProcessors, L"{AFF289A6-ABF1-4d68-9A51-634BF7077CFC}", VARIANT_TRUE);
      IUnknown_Release(pVideoProcessors); 
   }
}