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Watching 1080i on a 768 res tv...

M

Mildlyamused

Senior member
Does it defeat the purpose of watching 1080i if your looking at a 768 tv? How come I have difficulty in finding a tv that supports 1080i under 42"?
 
I am not an expert on this by any means, but here's what I think is correct from the research I've done, though I don't completely understand all of it, so there are holes in what I'm going to say. Not sure how much you know already, but here's what I've found. Basically, it does defeat the purpose of 1080i if you have a 768p TV. 1080i is 1080 by 1920 pixels, and that's getting downsized to 768 by 1366 (roughly). If you put a 720p signal in, which starts as 720 by 1280, it gets slightly upsized. The result is that the two will look the same as far as I've been able to tell from watching my TV (50 inch plasma with max res at 768p).

I dunno if you know the difference between the i and p, but they stand for interlaced and progressive scanning, progressive is better for displaying motion than interlaced. Progressive scan gives you a higher quality image than interlaced because it handles movement better, so hypothetically, at the same res, progressive would always be preferred (1080p isn't really available to consumers, but it's much better than either 1080i or 720p apparently). Another factor is that different display types display the image in different forms. Plasmas (and lcds I think, not sure about this at all) always do progressive and are incapable of doing interlaced. Dlp i think is interlaced, crt i have no clue. So when my TV gets a 1080i signal, it shrinks it to fit my tv and changes it from interlaced to progressive scanning, making it basically the same as a 720p image.

Another thing about 720p vs. 1080 i, is that many people prefer 720p (or 720p upconverted to 768p) over 1080i even though it isn't as high a resolution, due to the issues 1080i has with motion and panning. The higher resolution of 1080i is not the end of the story in other words. Another factor is that even though 1080i has a higher resolution and theoretically higher image quality (so long as the image isn't moving too much or it's not sports), it's tough to find a tv that even displays at a resolution of 1080 by 1920 and gets the full benefit of 1080i. They do exist i believe, but I just poked around and didn't find one in my quick search--I think they might be really expensive. That further dimishes the importance of 1080i.

Hope this is helpful.

As for not being able to find a tv that supports it, I have no clue why that would be the case. I just looked at panasonics website to check and basically all their tvs support it of all shapes and sizes, and most tvs I looked at when picking all supported both formats if I remember correctly. So I'm not sure why you can't find ones that support it. However, if you are going to be picking up hd through a cable box, it doesn't even matter b/c you can just tell the cable box to convert the images to 720p for you (with most cable boxes I would think). I bet satellite receiver or direct tv thing can do the same thing. But I think most tvs will support both, the tv just switches the signal to whatever it is capable of displaying.
 
Originally posted by: Mildlyamused
Does it defeat the purpose of watching 1080i if your looking at a 768 tv?
Click to expand...

Not exactly. By starting with superior source material you can wind up with a superior finished product (I seem to recall ATI or Nvidia using an "oversampling" technique that was simply rendering the frame at a higher resolution, then scaling it down for display back when they were starting up with their heavy AA/AF implementation). It all boils down to how well the compression is done.
 
One thing I'm really thinking about is the fact the PS3 will be able to do 1080p! And because of that I was wondering if I would be able to see the benift of 1080 resolution scaled down or not. I don't know where you heard that plasmas and LCDs only display progressive because that simply isn't true (unless you can prove otherwise). Same thing with DLPs, they support progressive resolution when stated.
Also I was wondering if there were any 1080P/i tv's that were under 42" because I've been unsucessful in finding one..
 
I heard it from some guy on a message board somewhere, but he may have not known doodly poo about what he was talking about, so I'm gonna check it out and see what I found out. I'm not claiming though that if I go to a 1080i channel nothing happens, I'm claiming that my tv displays it progressively rather than interlaced. But anyway, I'll let you know what I find....
 
Ok I found this from this website--http://buyinghdtv.com/html/hdtv_basics.html.

"When comparing screen resolution, keep in mind that most ?HDTV Compatible? TVs can display both HDTV and EDTV, and they will convert the signal to fit the TV?s resolution. For example, plasma TVs do not natively display interlaced signals, so they cross-convert a 1080i signal into 720p."

Found more stuff mainly on message boards, on this one http://www.highdefforum.com/archive/index.php/t-5895.html, someone claims that all fixed pixel tvs display progressive (ie change i signals in order to display them) with dlp natively displaying interlaced, dunno if you'd call that proof...im tired of looking now, but i don't know that it even makes a difference for your purposes.
 
To get a 1080i TV under 42 inches, you'll either need to get a CRT Tube, biggest out is Sony's 40 inch, not sure if they make it anymore, there are plenty of 36 inch 4x3 and 34 inch 16x9s. If you want a flat panel, you'll have to step up to a resolution of 1080p most likely. The Benq 37 inch from crutchfield is only 1999 and it is a 1080p lcd monitor.

All in all, I'd rather have a TV that has a native resolution of 720p, 768p or 788p then have one that is native 1080i and doesn't support the progressive scan resolutions above 480p. I find the 720p signals look better then the 1080i signals on any of my tvs that support the 720p resolution. It also depends on the scaler your TV uses, but I don't know if you want to delve into all of this.
 
Actually what I find interesting about non-ED plasmas is that the native resolution is typically 1024x768. I would expect it to be 1280x720 or 1340x768 (approximately). So plasmas are upconverting vertically and down-converting horizontally. Just seems weird. My Mitsubishi 62" DLP is 1280x720 and the 720p signal is just awsome (Fox and ABC). 1080i (CBS and NBC) still looks good for regular TV, but not as good for watching sports (motion).
BTW. Not all DLP's are interlaced. It depends on the version of the chip used.
 
Huh okidoki. I've noticed that there is a ton of deliberate confusion (progressive scan and upconverting dvd players for example) created by the sellers in the hdtv/dvd/video world that can be tough to cut through, at least it has been for me, and as you can see I still don't really understand that much of it. People who don't do any research or aren't very tech savvy must have no clue what is going on and would know the same amount as if their tv worked by magic pixie dust. And fewer reviews than with computer stuff, and most of them are just people saying, "meh it looks pretty good." With computer stuff I have found research easier, like if i see cpus--yeah i dunno what all these numbers after cpu models mean, but I can go find a site with some benchmarks or specs and figure it out pretty easily.
 
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