Yes i would like the Closed GOP to be set, but instead of duplicating the first decodable frame for the missing reference wouldn't it be better and rather mpg conform to drop the leading incomplete GOP frames?
Lets assume the stream starts like this:
stream:
B B I P B B P B B P B B
your suggestion is to duplicate the first decodable frame which would be the I-Frame afaik to replace the forwarding reference so it would end up like this (please correct me if im wrong):
I I I P B B P B B P B B
most tools that close the opening GOP would Drop the two B frames and would start outputting the stream like this:
I P B B P B B P B B
I hope this clears out our misconception
(if any)