When the final request appears before generating the
DVD file structure, the contents of the fields showing
the commands should be saved.
E.g. there is a bug "Could not read YUV4MPEG2 header:
stream requires unsupported features!" that can be
solved by adding the parameter "-S 420mpeg2" for the
call of ppmtoy4m. Unfortunately, I have to add this
option every time ... :-(