if (decklink->QueryInterface(IID_IDeckLinkOutput, (void**)&output) != S_OK) {
fprintf(stderr, "Warning: Card %u has no outputs\n", card_index);
return false;
if (decklink->QueryInterface(IID_IDeckLinkOutput, (void**)&output) != S_OK) {
fprintf(stderr, "Warning: Card %u has no outputs\n", card_index);
return false;