Hi Kwag !
Encoded high action 1min clip with 720x480 & original 1-18-3-1-48 => 13288 kb
The same clip with 1-18-3-1-60 => 12454kb
Save 834 kb - 6.3% !!!
(~Same effect in slow scenes)
No quality degradation !!!! looks same as original GOP but ....

After encoding of about 45sec remaining time in TMPGenc window starts rise slowly from 2:36 to 3:55 min until end of encoding of 15sec clip.
I know that original GOP u made is optimal .
Longer GOP can't give more compression(according u and u are my GURU) but how it can be that there is more additional compression .
I wonder if increasing of encoding time is related to LONGER GOP .
Tryed bigger numbers 60->72 but no success.
Can u make it clear for me ???
Is there more in TMPGenc abilities that we haven't used yet ???
bman