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PostPosted: Sun Feb 18, 2007 4:43 pm 
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Location: USA
Hi All

I'm shopping for a new 50" + plasma TV. I have read recently about 1080i and 1080p HDTVs and while I understand one is interlaced and the other progressive ... I'm wondering what is the real difference between the two when viewing 1080i screens vs 1080p?

I haven't been able to find any local retailers here hat have a decent set of screens for me to view - am plannig on going to a bigger city to do my shopping and research but wanted to narrow down what I should be looking for.

Am planning on buying in April - so I have a bit of time to do some research. I checked out the AVSForum - but I can't make head or tail of what people are talking about there ... :oops:

As always I default to the expertise of Zulmis ... !

Thanks!


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PostPosted: Wed Feb 21, 2007 2:38 am 
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My understanding:

Full 1080i or 1080P resolution is 1920x1080 pixels and 1920x1080 processing.

A monitor may have less than 1920x1080 pixels but the processor may be able to process 1080i or 1080P. For example a 1366x768 monitor may be associated with a 1080P processor and the manufacturer falsely claim (and they do) it to be 1080P monitor.

A 1920x540 pixel monitor can be used for 1080i signal if they use same row pixels for both fields. But, it's not real 1080i (real 1080i will be 1920x1080 with alternate row pixels lighting up for 2 consequitive fields). Instead of 1920x540, they often use 1366x768 or 1024x1024, all three combos having 1 million pixels each instead of 2 million for full 1080P (1920x1080).
Interesting: what's the use of using 1080i assuming monitor to be full 1920x1080 ?? It's that 1980i needs half the bandwidth of 1980P.

A 1920 x 1080 pixel monitor can also be used to show just a 640x240 or 640x480 image, using interpolation/ extrapolation.

1080i signal is 1920x540 images (fields), say 50 or 60 times per second.

1080P signal is 1920x1080 images say 24, 25, 50, 30 or 60 times per second.
Film has 24 frames per second and 1080P content is 1080P 24 times per second that's recorded. It's upto the monitor/ processor whether to flash it 24 times per sec, 25 times per sec, 50 times per sec, 60 times per sec or 72 times per sec or ---. In NTSC countries, present 1080P standard display is 1920x1080 60 times per sec, even if coming from 1080P24.

Confusing ?? Yes, but not really.


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PostPosted: Wed Feb 21, 2007 6:05 pm 
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bottom line, 1080p is far superior than 1080i, and 1080i shows more depth and detail as compare to 720p.

a display could be 1080p, e.g lcd pannel, but if can not accept 1080p diect then it is redundant.

All 1080p display will upscale 1080i to 1080p but results will be inferior than 1080p direct.

whenever there is conversion on the way, player or signal, results will never be like native to native!

In dvds HD BR, 1080 p, with or without HDMi 1.3 super enhancement is ultimate.

On the air/broadcast will not be able to catch up in time!


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PostPosted: Wed Feb 21, 2007 6:10 pm 
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I just found:

Quote:
1080i vs 1080p -> MYTH VS REALITY (the ultimate test sequence)!

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Oh no, not another 1080i vs 1080p/60/24 thread...

I know, I know...This has been discussed ad absurdum.

I will spare you the general discussion about this topic - the search function is your friend.

To put it simple: Generally there are two "opinions"/ point of views about the whole matter:

1) 1080i holds all the resolution of the original film frame and is just another method of transfering the picture information (fields vs frames delivery). Given that we talk about film based (24p) content. And given that the display unit or an intermediate video processor is able to restore (-> Inverse Telecine) the original progressive film frames from the 1080i stream. Given the very nature of HD-DVDs pure progressive encoding this should be an easy enough task for just about any modern display device.

THEREFOR 1080i output is indistinguishable from 1080p output. It just doesn't matter and is only a marketing instrument.

2) The other view is to agree with the above arguments BUT also to recognize that in reality things are a little different... I've always been a very STRONG proponent of untouched, unaltered, unprocessed 1080p output (ignoring the inherent HD-DVD 3:2 pulldown flags and decode the native 1080p stream), ideally @ 24p. But does it really matter?

MYTH versus REALITY.

Instead of arguing and picking sides based on beliefs and which expert's opinion one trust is there no real world test sequence that proves beyond any doubt if there is relevance to pure 1080p output or not?

YES, there is.

No, it is not some artificial, strange cadence sequence from a special HD-DVD test disc. It is a sequence from a common disc many of us have right at home.

Mission Impossible III. Chapter 8. Timecode 46:54. The staircase.

Before you ask - NO, this is not an artifact. This is just a real world sequence with very fine, high frequency detail. In movement. That shows how inadequate 1080i processing in reality really is. HD-DVDs are said to be mastered in 1080p - although there really still isn't any way of seeing the native, progressive stream (with the exception of some immature HTPC solution). This this sequence is stored perfectly on the disc. So why is just about anybody seeing moire and "shimmering" artifacts???

My test setup: Toshiba XE1 (= rebadged european XA2, I use the term "XA2" in the following to avoid misunderstandings), HDMI connection to a Sharp Z20000 native 1080p DLP front projector (it is fair to call it state of the art...).

Test 1: XA2 set to 1080i output, Sharp Z20k does the "deinterlacing"/IVTC. This (=1080i output from A1, A2, E1) certainly is the most common configuration among HD-DVD users.

result: Very disturbing moire and interlacing artifacts, nomatter which "deinterlacing" mode I choose with the Sharp. The staircase is a real mess. So my display unit is not any good then... Quick reality update -> the Sharp Z20k is a bleeding edge $11,999 unit, introduced to the market Q406, native 1080p resolution (no scaling whatsoever involved, perfect 1:1 pixel mapping). It may not have the very best internal processing out there (no hyped Gennum or HQV processor to be found ) BUT is likely far beyond any ordinary HDTV/plasma/LCD set - Greg Rogers (WSR) rates the 1080i IVTC as "flawless" in his review...


Test 2: XA2 set to 1080p output. Film progressive mode selected in setup menu. Straight 1080p HDMI connection to the Sharp Z20k.

result: Obviously better. No excessive moire and interlacing artifacts. BUT far from being perfect - or acceptable for that matter. During this ~ 3 seconds sequence the XA2 1080p mode shows clear "bob/weave interlacing pumping" - it looses cadence track for at least 4 times during this sequence...


Test 3: A friend of mine brings his DVDO VP50 video scaler over. XA2 1080i output to the video scaler. VP50 IVTC and 1080p output straight to the Z20k.

result: Perfection. So this is how this scene is supposed to look like No shimmering of fine details. Full resolution (some distant steps have just ~1 pixel height...). No moire.


Conclusion:

1) In order to get an artifact free picture (even with moving, very fine high frequency details, (vertically) filtered transfers sure don't show this behaviour) out of HD-DVD you need an additional, specialized >$2,990 video processor to do the IVTC. To get the most out of it this is the sad and expensive truth.

2) HD-DVD as a format is 1080i as long as no player out there is able to output the native 1080p stream encoded on the disc. Toshiba with its XA2 dropped the ball big time with its inadequate Silicon Optix REON implementation. Lets hope for a firmware upgrade ASAP. Still the XA2 is just doing the very same 1080i decoding -> internal IVTC/deinterlacing for 1080p output process the Samsung Blu-Ray player was "trashed" for... Even though the REON processor SHOULD be able to do a better job than it does with its current XA2 implementation.

3) The (hopefully) upcoming 1080p/24 upgrade for the XA2 is the chance for Toshiba to finally do it right. Native PROGRESSIVE processing from decoding to output. And please, Toshiba engineers, buy yourself a MI:III disc and make sure the most obvious 1080i interlacing artifacts are avoided with your "state of the art player".

4) THIS is not about one single disc showing some interlacing related artifacts - this "problem" is generally present with any single disc - but this sequence is the most obvious example as it shows unfiltered (thank you for that, Paramount) high frequency detail in movement. Something I would very much enjoy seeing much more often in the future (The Departed is the latest prime example of a filtered mess of a transfer - despite the glowing reviews ) MI:III is "stored correctly" on the disc - but no player (not even the "1080p" XA2) is able to show it this way. You need $2,990 for that...


I encourage everybody to try this at home! Comments are welcome.

__________________
HD DVD Blu-Ray FORMAT NEUTRALITY: Be a discerning customer and NOT a cheerleader. Own both for the total experience - everything else is too much of a compromise for any self-respecting enthusiast!

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Last edited by TheLion : Today at 08:04 AM.
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PostPosted: Sat Mar 03, 2007 3:09 pm 
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Joined: Mon Dec 03, 2001 6:17 pm
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Guys

Thanks for the advice and help! Interesting read - I was looking at the Panasonic 60U and 600U. It's strange as consumer reports rated the 1080i higher than the 1080p version!

I guess this is why it gets so confusing. I don't want to buy this TV and then have to replace it in a year because it is out of date. Will be sure to go for 1080p. Any model recomendations at all?

Thanks,

Muz.


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PostPosted: Sat Mar 03, 2007 7:14 pm 
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Joined: Mon Dec 03, 2001 5:53 pm
Posts: 14989
Muz wrote:
Guys

Thanks for the advice and help! Interesting read - I was looking at the Panasonic 60U and 600U. It's strange as consumer reports rated the 1080i higher than the 1080p version!

I guess this is why it gets so confusing. I don't want to buy this TV and then have to replace it in a year because it is out of date. Will be sure to go for 1080p. Any model recomendations at all?

Thanks,

Muz.


you are making a wise decision imho 8)


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