[MPlayer-DOCS] [PATCH] update the mencoder telecine docs

[D Richard Felker III]

On Wed, Mar 02, 2005 at 02:47:45PM -0800, Corey Hickey wrote:
> Oooh, I see what's going on now. I was under the impression that the
> NTSC clock rate was exactly 60 Hz. I understand what you mean now.
> Basing my research on that, I've finally come up with a useful page out
> of google:
> 
> http://www.edlmax.com/NTSC3.html
> 
> Some of the numbers on this page are incorrect; somebody messed up the
> precision. For instance, 4.5 * 10^6 / 286 = 15734.265734 265734 ...
> (repeating) and not 15,734.265734265700000.
> 
> If the rest of the page is correct, though, it seems that 60000/1001 is
> actually based upon the RF frequency range available. NTSC was 60 Hz
> before color, and the addition of a color subcarrier necessitated a
> slight adjustment to the frequency.
> 
> Also, if I follow the math correctly, the NTSC vertical frequency is
> exactly 60000/1001, so digital NTSC video is exactly the correct framerate.

OK, I think you understand it better than me now. I'll have to read
that article you found.

> > Anyway, the 1001 factor is not a "stupid hack" either. It's part of
> > the real fieldrate of NTSC, which is 59.94... fields per second, not
> > 60 fields per second. I'm told that NTSC was originally 60 fields per
> > second in black & white, then they had to lower the framerate slightly
> > to make bandwidth available for the color carrier. Not sure if this is
> > true though, but it makes sense..
> 
> Yes, it seems that the 1001 is derived from a very intelligent hack. :)

:)

Rich