720p or 1080i with a 51h84?

tsh

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steve
I have been reading a lot on 720p and 1080i but from what I have read it is very different for each person. What would be the best option for a toshiba 51h84 tv? Any tips would be great. Please give the reason also

This is for HDtv/Hd dvds and I guess it will be also used for 360
 

tsh

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steve
so because it is native 1080i that would be the better option for me? why?
 

Jeff Gatie

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Because it displays 1080i without any conversion process. If your native language is English, but you are also able to translate French, if given a choice - would you rather read a book in English or French?
 

Allan Jayne

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HDDVD and Blu-Ray are natively 1080p and 1080i (depending on the program material). The players will output 1080i with little or no degradation and the 1080i goes right to your screen with minimal degradation. So you want to choose 1080i as the player output format. Having the player output 720p requires more processing and also having the TV convert incoming 720p back to 1080i requires more processing and that is enough to tell you there is more room for degradation.

For 720p broadcasts somebody has to convert them to end up as 1080i on the screen. The final quality depends on how well the TV converts 720p to 1080i compared with how well somebody else (for example the cable TV box) does it. You would have to do visual comparison, or take magazine review articles into account.

Using the French English analogy, if you (natively English speaking) were good at French in school, you would probably understand someone speaking French a lot better than if you had someone who didn't know much English and/or did not know much French translate the dialog first.

Video hints:
http://members.aol.com/ajaynejr/video.htm
 

Jeff Gatie

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I don't understand what you don't understand. What exactly are you trying to learn? Your TV is 1080i. Select sources that output 1080i and you are all set.
 

tsh

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You say it takes more processing to do 720p and I am just wondering why is that bad? What is going on when this is happening that could give some degradation to the screen?
 

Allan Jayne

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Let's say the program was 720p to begin with and the TV is 1080i.

The program wants to send frames of 720 scan lines 60 times a second. The TV wants 540 odd lines in the first 1/60'th second, 540 even lines in the next 1/60'th second, 540 odd lines in the next 1/60'th second, etc.

It seems simple to discard 180 scan lines from each 720p frame to come up with 540. Depending on which 180 scan lines are dropped the quality of the finished picture will vary. Better results are obtained if a different combination of scan lines are dropped from what will become odd fields versus what will become even fields and therefore each scan line position gets kept some of the time for close to 720 lines of vertical resolution. Whereas dropping the same combination of scan lines each time results in 180 of the scan line positions never being kept which in turn means the vertical resolution drops to 540. How each TV or each cable box does it is an unknown until someone reports on it in a magazine review or on this forum.

We definitely do not mean keep the first 540 scan lines and drop the last (bottom) 180.
 

Jeff Gatie

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Because the 1080i is not processed, it is shown exactly how it was transmitted. The 720p has to have something added (the missing scanlines) and something removed (the progressive scan) in order to display it at 1080i. Whenever you remove information from the original source or add information that was not there, you will suffer degradation of the picture. Some processing is better than others, but it will never equal the original. That being said, you will probably notice very little difference between the two.

Now, if you are still confused, just ignore everything that was said and watch 720p sources, cause I have the feeling that is the answer you want to hear.
 

captaincrash

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It's nice to see some folks taking the time to explain this. I understand this clearly as a lurker and as I read downward I was almost expecting sharper comments to appear - however, to my pleasant surprise I can see that gracious and constructive comments were posted.

So - compliments to all! I imagine some of MY postings and threads (past and future) will appear novel to some. As such, I hope to find cordial insightful replies like the ones here from the community gathered in the future.
 

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