Quoting Florin Andrei <florin(a)andrei.myip.org>rg>:
it pretty much assumes
integer frame rates. That's fine for computer video. It's not fine for
video made to be watched on a TV: NTSC video is not 30 fps, it's 29.97;
"film" video (film-looking progressive digital material) is not 24 fps,
it's 23.98.
And it's even worse; since NTSC isn't even 29,97, it's 3000/1001.
Oops! Forgot a zero. It's 30000/1001
- Peder