[MPlayer-users] Re: which deinterlace filter

D Richard Felker III dalias at aerifal.cx
Mon Oct 20 20:52:10 CEST 2003


On Mon, Oct 20, 2003 at 10:19:21AM +0300, Tuukka Toivonen wrote:
> [Automatic answer: RTFM (read DOCS, FAQ), also read DOCS/bugreports.html]
> On Fri, 17 Oct 2003, D Richard Felker III wrote:
> 
> >> I'm sure they didn't discuss frame rates when developing the standard,
> >> simply because they had not much choice in that - it's simply the
> >> frequency of the power supply. Creating a 60Hz frequency in a device
> >I'm very skeptical of this claim. 60 Hz (power supply) and 59.94 Hz
> >(NTSC refresh) are not the same. Maybe it has something to do with
> 
> According to
> http://www.divx.com/support/guides/guide.php?gid=10
> American TV used to go at exactly 60 Hz back when it was black&white. When
> colors were added, also framerate was changed to slightly lower.
> 
> So maybe the electric supply frequency relevant at the age of
> B&W TV.
> 
> >Besides, much smaller units of timing were needed anyway. The entire
> >frame refresh rate isn't what's significant. Horizontal refresh is.
> 
> Yes, but it's possible to multiply the frequency with some nice
> integer.

But you have the numbers upside-down. :)) I don't see how having a
60Hz clock source helps you get a clock source for horizontal refresh
(much higher). You're dividing time, not multiplying it, when you
multiply clock by a "nice integer"...

Maybe I misunderstand what you mean, or misunderstand analog/RF
circuits, but I still fail to see how having a 60Hz clock source helps
in making a TV.

Rich



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