NTSC metod to 23.976 fps and back to the 29.97fps
 

Hi and sory for my bad english.

NTSC 29.97fps frame format:
1frame-progressive; 2frame-progressive; 3frame-progressive;
4frame-interlaced; 5frame-interlaced.

We use Inverse Telecine 3:2 pool down to receive 23.976fps progressive frame format. DIVX frame format:
1frame-progressive; 2frame-progressive; 3frame-progressive;
4frame-progressive.

If I made DivX frame format without 3:2 pool down (decimate-5) and receive:
1frame-progressive; 2frame-progressive; 3frame-progressive;
4frame-progressive; 5frame-same as 4frame <- 29.97fps.

IF The BSplayer apply Telecine method for two identical frames and the Human eye do not to notice step effect on the big speeds of horizontal moving of a scene.

Result:
DivX(1-2-3-[4-5] all progressive) -> BSplayer(1-2-3-[4telecine-5telecine])

Sory if I not right.