D Richard Felker III wrote:
My understanding is that 60000/1001 is just the only rational number within the range of tolerance of the NTSC refresh clock, without having a ridiculously huge denominator. Thus it was standardized as the "official" refresh for NTSC with the advent of digital video. 30000/1001 and 24000/1001 are just the refresh converted from fields to field-pairs or telecined frames.
I'm sure you can find better references on this somewhere if you like...
Rich
Hmm. That makes sense. So, I understand the number now, but I still don't know why a different number had to be chosen. What was wrong with 60/1, 30/1, and 24/1? I've searched google several more times and still haven't found out why. I have a few links that come close. This page says it's a stupid hack: http://homepage.mac.com/rnc/PulldownSync.html This page says "don't ask": http://stream.uen.org/medsol/digvid/html/3B_videoframerate.html This page looks promising but doesn't seem to explain it: http://www.ntsc-tv.com/ntsc-main-01.htm That last one does list a few books that at least _ought_ to. I might have to go to the library and see if I can find them. -Corey