Rémi Bernon (@rbernon) commented about dlls/winegstreamer/video_decoder.c:
- transform_SetOutputType,
 - transform_GetInputCurrentType,
 - transform_GetOutputCurrentType,
 - transform_GetInputStatus,
 - transform_GetOutputStatus,
 - transform_SetOutputBounds,
 - transform_ProcessEvent,
 - transform_ProcessMessage,
 - transform_ProcessInput,
 - transform_ProcessOutput,
 +};
+HRESULT WINAPI winegstreamer_create_video_decoder(IMFTransform **out) +{
- FIXME("out %p.\n", out);
 - return E_NOTIMPL;
 
You should at least allocate the object, set the vtable and implement refcounting, otherwise all the stub methods are dead code.