[mythtv-users] HDTV on Myth -- is it a "myth?"
papenfuss at juneau.me.vt.edu
Mon Oct 11 12:16:33 UTC 2004
>> What is the same, Doug? The horizontal scanning
>> frequency of 33.75kHz? I agree. How about the image?
>> With 1080i you get two different frames of
>> information, 30 times each second. With 540p you get
>> two identical frames 30 times each second. Shouldn't
>> they look different? I think they should.
> 1080i = 2 fields of 540 lines, at 30 Hz
> 540p = 1 frame of 540 lines, at 60 Hz.
> Six of one, half a dozen of the other. Almost literally.
Same frequencies for the TV, agreed. It's not exactly the same,
perceptually, however. An 1080i signal will resolve higher vertical
resolution (Kell factor notwithstanding) than a 540p signal, even though
the TV's H/V PLL's will by running at the same rate. The difference would
be most apparent on a still frame with horizontal lines on it.... annoying
30Hz flicker, granted, but higher resolution yes.
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