Default field order to top field first when interlaced frame is detected and pic_struct_present_flag is not set.
Since bottom field first comes from the old NTSC standard and is not used with HD anymore I think it´s straight forward to favor the majority.
Signed-off-by: Thomas Mundt <loudmax@yahoo.de>
Reviewed-by: Kieran Kunhya <kierank@obe.tv>
Signed-off-by: Michael Niedermayer <michael@niedermayer.cc>