[mythtv-users] HDTV on Myth -- is it a "myth?"

Cory Papenfuss 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.
> No.
> 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.
> -Doug
 	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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