[Mp4-tech] How to use top_field_first

[Yusong Huang]

Dear Experts,
I have some questions about MPEG-4 interlace tool and need your help.
(1) According to MPEG-4 spec, when top_field_first is set to "0", the 
bottom field of the reconstructed VOP is the first field to be 
displayed. Is this reconstructed bottom field also the bottom field of 
TV scan?
(2) In MPEG-2, top_field_first and repeat_first_field are used together 
to achieve 3:2 pull-down. In MPEG-4, there is no repeat_first_field, so 
in what situation and how to use top_field_first?
Thanks a lot.
Yusong