I'm sorry. I am Japanese.
It might be strange English because it uses the software of the automatic translation.

For instance, should I code an actual code of the OMX_Init() function by myself? Or, has it already been prepared, and does it only have to be used it?

The sample source of "Bellagio" was seen.
Are contents of the OMX_Init() function sources prepared on the Khronos side?
Or, is it what "STMicroelectronics" coded?