[MPlayer-users] Re: which deinterlace filter

[Reimar Döffinger]

Hi,
 > 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"...

First of all I want to say that I don't know anymore where I read that 
the framerates have to do with the frequency of the power supply, so I'm 
not absolutely sure if it's true, but it seems to make sense to me.
First of all you must think of the fact that at the time the first TV 
sets appeared, you didn't have a quartz to create frequencies, but you 
had to use a capacitor and a coil (hope that's the right word...).
For high frequency you need only very small and simple components, so 
it's easy to get a (more or less) exact frequency.
For low frequencies (like 60Hz) you would need such a high capacity, 
that you would probably have to use for example electrolytic 
capactitors, which have a tolerance of more than 10%, which means your 
resulting frequency will be at least +- 10% and temperature dependant 
(and those old TVs got really hot because of the tubes in them), and 
also aren't supposed to be used with alternating currents.
Now suppose you use that already not too stable frequency generator in 
an environment where there is everywhere a frequency only 20% apart.
I think you would be lucky if it would continue working at all, but then 
probably at something like 52Hz instead of 60Hz...
And last but not least, I think you can use a low, exact frequency very 
easily to improve the accuracy of a high-frequency resonant circuit (if 
it's accurate enough to begin with) by simply plugging them together.
The other way round you will have to either use a counter or frequncy 
divider, with I think both couldn't support that high frequencies at 
that time (at least today they work digitally, a technology that was int 
its beginnings at that time).

Hope I could explain why I think I am right.. ;-)

   Reimar Döffinger

P.S: Sorry for starting this again, but I just couldn't resist ;-)