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Zeger Knaepen wrote:
> "Stefan Viljoen polard.com>" <spamnot@<removethis> wrote in message
news:446968eb@news.povray.org...
>>> Personaly, I would go for a resolution around 3 to 5 times the TV
>>> resolution's.
>> Which, for an ordinary non-HD set is what? 460x200? I know it is very low,
>> compared to PC monitors, but how low?
> 
> :)
> it's not that low :)
> PAL-resolution (which is what we use here in Europe) is 720x567 (although the number
of collumns isn't really defined, only the number of lines)
> NTSC, the American standard, has a lower resolution, but more fps (30 instead of 25,
which is useless imho, since movies are shot at 24fps)
> 
	A small typo here: PAL is 720x576. NTSC is 720x480 which translates
to the same pixel rate given the difference in fps. You should note
however that TV pixels are not square and that the screen aspect
ratio is 4/3 for both PAL and NTSC even though neither 720/576 nor
720/480 is 4/3. Moreover, digital MPEG2 broadcasting often uses
fewer than 720 pixels in width and lets the set top box do the scaling.

> (both are interlaced, so you actually get 50 or 60 fps, which 'happens' to be the
same as the AC-frequency :))
> 

	A note on frame rates:

 - The film industry originally used 12 fps because at the time
cameras were operated by a man turning a handle and 12 turns per
second was an easy rate to maintain. When they moved to mechanical
cameras, they chose 24 fps since it would be easy to convert old
film for projection in "modern" theaters. Note however that this is
still too slow and that the eye will see the scene flicker in
certain circumstances;

 - TV originally chose 50fps in Europe and 60fps in the US and Japan
because that was equal to the AC frequency. There was some
bleedthrough from the power supply to the TV signal in old receivers
that caused some parts of the screen to be darker than others. With
a frame rate equal to the AC frequency, those dark bands were
immobile which made them nearly invisible. However, if the frame
rate and the AC frequency were different, the dark bands would move
vertically and the movement would make them visible. Film frame rate
was ignored since the only way to broadcast a film on TV at the time
was to project it in a theater and film it with a TV camera and
broadcast immediately (there was no way to record TV signals in the
beginning).

		Jerome

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