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Discussion Starter #1
I'm just curious if anyone reading this thread has ever actually watched an ABC-DT program in both 720p and 1080i side-by-side and noticed any difference in the resolution? My HD-tuner upconverts the ABC signal to 1080i and I get a gorgeous picture. I've read in this and other forums that 720p is the better format of the two. If it is any better than the image I get from our local ABC affiliate, it must really be FANTASTIC!
 

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Yes, it looks a bit better in "native 720p"

(rather than being "sideconverted to 1080i"),

but I prefer native 1080i over 720p anyways.


If your display is really 1080i capable then

you should find a number of CBS shows which

look better than pretty much anything from

ABC (720p).


The only time (from what I see) that 720p has

any kind of advantage is for 720p video with

alot of motion. For instance when they

were doing Monday Night Football in HD.
 

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Discussion Starter #3
My CBS local looks great also. Maybe it's just me, but I don't really notice that much, if any, difference between the quality of ABC vs. CBS on my tuner. However, I prefer ABC because of the Dolby Digital 5.1 vs. CBS' 2.0. I've never seen native 720p yet and probably will not because there aren't many stores that tune in the ABC signal.
 

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It makes basic sense that 720p viewed in its native format would have to look better than 720p "side-converted" to 1080i. Any kind of conversion introduces some degradation. The amount of degradation would be dependent on the quality of the side-converter, which may account for different stories from people with regard to whether ABC looks sigificantly worse than CBS.


It would be interested to see a study on equipment vs. perceived 720p quality. I think there might be a trend there.
 

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Just remember that alot of todays HDTV displays

can't resolve much more detail than 1280x720

so for many people it is basically a "moot point"

anything (720p native, 1080i native, 720p->1080i,

1080i->720p) all look about the same.


As displays get better in coming years more

people will notice the 1080i advantage.
 

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Where's John Mason when we need him :) - in many of the previous discussions he has weighed in and provided helpful discussion and useful links ! The perceived vertical resolution of 1080i is close to 720 while the perceived resolution of 720p is close to 720 (based on ATSC testing reports he cited but I can't quickly find the link - search for 1080 & 720 and his posts).


I have a Marquee8500LC and can see the 1080i scan lines when I get within a couple of feet of the screen so the beam spot size must be (close to) small enough to resolve most of the possible 1920 horizontal (if they're ever there)


That said, I did watch ABC's MNF and have seen some CBS NFL and any difference in PQ was very small if any - I was particularly looking for motion artifacts in the 1080i CBS picture after a season of MNF and they were very hard to see. Also in Dish's demo loop of basketball and baseball (at 1080i) they're difficult to see. In either case, they have in no way been distracting or calling attention to themselves.


The NFL comparisons are the closest I've come to the only definitive way of comparing the intrinsic PQ of 1080i vs 720p which would be : the same scene shot by two cameras simulataneously (one 1080i and one 720p) encoded at the same bit rate and decoded by top quality receivers and viewed on one system as an A/B comparison (or the same movie telecine'd on the same machine at the two formats )


Beyond that, any comparison of the two PQ's is confounded by many variables which have been done to death in previous threads (different material, different cameras, different encoding rates, mpeg artifacts, up, down, side and upside-down conversion, inadequate displays, sweetspots, signal paths, you name it)

So, worry about other issues than the intrinsic differences between 1080i and 720p - they're way more likely to explain any differences you see in flawed comparison efforts!
 

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I know very little technically so I am speaking from experience watching 720p natively vs. 720p downconverted to 1080i in my home on my equipment. YMMV

I was watching CBS 1080i natively on my Panasonic PT-56WXF-95a using a HiPix card in my computer. Then I tuned in ABC to watch NYPD Blue. After a few minutes, I felt like there was something wrong with this broadcast. It was pretty "washy" looking, not at all a sharp, crisp picture. Suddenly I realized that I had not reset the HiPix card to 720p. I made the adjustment and the picture quality improved dramatically. I stood back about 10 feet and switched the HiPix back and forth for about 30 minutes. I was amazed by the difference. Subsequently, I had several other people observe and offer comment. Unanimously, all saw a clear difference. So on Tuesday, November 6th, I'll be watching the 2 hour kickoff of NYPD Blue in 720p natively. I hope you can too. :D
 

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Lucky guy. I had hoped to receive my Scenium L50000 by now to view native 720p on a 50" LCOS display. Thomson has held up ship, however, for more than two months.


Will DirecTV deliver an uncompressed or only slightly compressed 720p image on its ABC HD programs? I don't receive OTA HD on ABC.
 

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Discussion Starter #9
Quote:
Originally posted by DTVisCool



Will DirecTV deliver an uncompressed or only slightly compressed 720p image on its ABC HD programs? I don't receive OTA HD on ABC.
DirecTv will deliver a 480i on it's ABC programs, period.....
 

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I watch HDTV on my 21 inch computer monitor. It has a very high resolution, and I feel that it resolves most pixels in 1920x1080 (especially in the vertical direction).


When I view 720p material downconverted to 1080i mode and compare it to 720p material in 720p mode, the picture quality looks very close. The 720p mode has the edge due to the fact that the picture doesn't flicker as much.


However, when I view 1080i material down converted to 720p mode, the loss in resolution compared to native 1080i mode is very noticable. The picture looks softer.


This is unfortunate to me... I was considering getting a digital projector someday. Since those max out around 1280x720 (higher if you fit an anamorphic lense on a DILA), I'm not sure that I would be satisfied knowing how much better it could look on a high resolution CRT.
 
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