[MEncoder-users] settings to convert ATSC HDTV 1080i30 to 720p24

[Dieter]

> > I've seen a lot of  mencoder -vf pullup,softskip to get 1080i ~30fps
> > down to a progressive 24fps... won't that crate a lot of jitter on
> > motion scenes unless the original source really was filmed at 24fps?
> 
> Yes.  You have to determine whether the video is interlaced or telecine
> before you start encoding.  

The obvious next question is: how does one detirmine whether the video
is interlaced or telecine?

I read somewhere that most or all 1080i content started life as 24 fps
progressive.  I have to wonder why they decided to mangle that into
30 fps interleaved instead of transmitting 24 fps progressive?