HDTVoice.com - High-Definition Television Talk - 720P vs. 1080i (if you have any lingering doubts)

01-28-2003, 04:45 PM	#1
robmx Reged User Tier 2 Join Date: Mar 2002 Location: NYC Posts: 455	720P vs. 1080i (if you have any lingering doubts) Is this a fair comparison? If so it answers any lingering doubts I might have had. 720P rules. Bob Miller AVSFORUM

01-29-2003, 06:19 PM	#2
hdexpert Reged User Tier 2 Join Date: Jan 2003 Location: houston Posts: 78	dont know about that 720p super bowl didnt look any better than 1080i did on other things i have seen.. i dont wanna sound like i am starting a fight but unless you have an lcd, plasma, dlp, or some other fixed pixel device you are watching 1080i anyway because all the traditional crt based devices upconvert to 1080i

01-29-2003, 06:31 PM	#3
57U Runner/Cyclist/X-C Skier Join Date: May 2002 Location: Toronto Posts: 17,115	You are correct that this discussion is essentially moot for most people because their TV can only show one format or the other. __________________ 57U - Toronto, Rogers Cable, SA8300HD, 500GB HDD & Hitachi 61UWX10B HDTV, Yamaha RX-V1 A/V Receiver, Martin Logan Speakers. Photos --> 57U's HT SA8300HD, 250GB HDD & KDL40W3000 (Upstairs) Please don't PM me with questions that can (and should) be asked in the forum, thanks. Personal Question? Fire away.

01-29-2003, 08:49 PM	#4
aj327 Reged User Tier 2 Join Date: Nov 2002 Location: New York City Posts: 188	Hdexpert, I have the 43 inch hitachi widescreen I think the model number is fwx 20b...or something like that - the most recent model. Anyway, it says that it's able to display both 720p and 1080i. Are you saying that it upconverts the 720p, because that's certainly not what the specs imply? -aj327

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01-29-2003, 08:52 PM	#5
hdexpert Reged User Tier 2 Join Date: Jan 2003 Location: houston Posts: 78	yes it does upconvert..what the specs are telling you is that it will accept a 720p signal but it is displayining at 1080i

01-29-2003, 11:20 PM	#6
aj327 Reged User Tier 2 Join Date: Nov 2002 Location: New York City Posts: 188	So what about the new 46 inch sony...I don't think the specs say anything about 720p...does that mean it gets downconverted to a 480 res, or are you just not able to even receive the signal? And why does it matter if you have a fixed pixel tv...why are they capable of displaying the 720p resolution while the crt based technology is not? Thanks, -aj327 Last edited by aj327 : 01-29-2003 at 11:22 PM.

01-30-2003, 12:20 PM	#7
hdexpert Reged User Tier 2 Join Date: Jan 2003 Location: houston Posts: 78	the 46 inch sony is hi scan 1080i (they are apprehensive about using the word hd so they use hi scan) so if there was a 720 signal input it would upconvert to 1080i...all tvs display in what is called the tv's "native resolution"....fixed pixel devices plasmas, lcds, dlps,etc generally have a progressive "native resolution" (480p for edtv and 720p for hdtv) and crt based tvs (man is this gonna start a debate) generally look better with and have an interlaced "native resolution"....both of these are general statements because there are cases when crts display progressive (480p dvd players) and there are a very few cases where fixed pixel devices display interlaced.......but the picture always looks better whenever it displays its "native resolution"

01-30-2003, 06:09 PM	#8
e95 Reged User Tier 2 Join Date: Jan 2003 Location: kansas city Posts: 62	43" hitachi you were quite wise to purchase the hitachi because it can accept [accept being the key word here] just about any signal, to include 720p most rear projection hd sets only accept 480i(p) and 1080i - they scramble anything else, meaning you have to use a stb just to see them - which is fine for tv cause you need a stb just to get hd ota or hd cable. but for me? i have the three game systems - and notably the xbox has games that output in 720p so i can plug the box right into the tv and away we go without the need of anything additional e95

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01-31-2003, 06:40 PM	#9
MrFister HDTVoice Member Join Date: Aug 2002 Location: Lansing MI Posts: 28	720p is for me ABC and 720p picture was much nicer to watch sports on my 34XBR800 which does all formats. The motion artifacts I get on CBS 1080i were gone on the 720p signal. It's sure much nicer to watch sports with 720p. I can't wait for ESPN-HD in 720p. Glad I jumped into HDTV when I did and chose a TV which could carry it all.

01-31-2003, 06:52 PM	#10
57U Runner/Cyclist/X-C Skier Join Date: May 2002 Location: Toronto Posts: 17,115	You are, as many people are, under the mistaken impression that your TV actually displays 720P. It does not. The 720P signals are converted to 1080i. See the link below and read the end of the second paragraph. http://www.crutchfield.com/S-IxLd2G...sp?I=15834XB800 There are almost no TVs that can display both 1080i and 720P natively. They are extremely rare and quite expensive. As I have stated here many times, the 720P vs 1080i discussion is a moot point for 99.9% of HDTV owners, because their TVs display one or the other, but not both. If you want 720P, you'll need to buy a DLP, LCD or Plasma TV, or the new Toshiba LCoS at about $10k. Someone once told me that the 9"CRT RPTVs can do 720P, but I looked at the specs for one and it only did 1080i too (although better than a 7" CRT RPTV) If there is someone out there that actually has a TV (other than the new Toshiba LCoS) that can natively display both 720P and 1080i, I'd like to hear from you.... Please advise make and model number of TV and perhaps provide a link to the specs showing the capability. __________________ 57U - Toronto, Rogers Cable, SA8300HD, 500GB HDD & Hitachi 61UWX10B HDTV, Yamaha RX-V1 A/V Receiver, Martin Logan Speakers. Photos --> 57U's HT SA8300HD, 250GB HDD & KDL40W3000 (Upstairs) Please don't PM me with questions that can (and should) be asked in the forum, thanks. Personal Question? Fire away. Last edited by 57U : 01-31-2003 at 07:04 PM.

01-31-2003, 08:43 PM	#11
DTC mac Reged User Tier 2 Join Date: Mar 2002 Location: Palo Alto, CA Posts: 67	JUST AS I HAVE ALWAYS SUSPECTED!!! RobMx is simply a contrarian. EX: spouts blue in the face over COFDM vs 8-VSB 720p is better than 1080I SOME PEOPLE WOULD CLAIM THE SKY IS GREEN IF THEY THOUGHT ANYONE WOULD LISTEN. at least he is supporting an ATSC standard on the second one.

01-31-2003, 09:43 PM	#12
MrFister HDTVoice Member Join Date: Aug 2002 Location: Lansing MI Posts: 28	720p is different 57U I pump a native 720p signal to my TV with the Sony HD-200 using the variable 1 mode. I can tell you by just looking at the picture on the set if the signal is 720p or 1080i. With 720p the display icons are much smaller even though the picture fills the screen. There is a noticeable difference between the 2 formats on the 34XBR800. If the TV is displaying all HD in 1080i like the site says then the 720p signal is still making the difference and I am happy my set can accept it and convert it still keeping 720p's superior quality like no motion artifacts. I just wish I knew why the resolution increases in 720p even though it is supposedly converted to 1080i.

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01-31-2003, 10:49 PM	#13
aj327 Reged User Tier 2 Join Date: Nov 2002 Location: New York City Posts: 188	This probbly doesn't really address your question, but it's interesting nonetheless. From what reading I've done, for various reasons 1080i can actually have less resolution than 720p. 720p always displays 720 lines of resolution but 1080i will vary from around 540 to 1080 - depending on how much motion is taking place on the screen. Why it's motion dependent I haven't really figured out yet, but apparently the average resolution for a 1080i display is somewhere in the 600s, actually LOWER than the constant 720p. Once again, I'm a bit confused why this happens, but it has to do with the progressive vs interlacing technology. Another problem with the 1080i is that it's cumbersome which makes it difficult for broadcasters to fit it into the allotted 6 MHZ slot. Apparently this has led to broadcasters leaving out a significant percentage of the transmission...720p, however, fits quite nicely into the 6MHz bandwidth.

01-31-2003, 11:17 PM

#14

57U

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Re: 720p is different

Quote:

Originally posted by MrFister
I just wish I knew why the resolution increases in 720p even though it is supposedly converted to 1080i.

You're simply seeing the difference in the original format. Some people prefer the more "film-like" look of 720P. Some like the "crisper" look of 1080i. Red or white wine...

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Please don't PM me with questions that can (and should) be asked in the forum, thanks. Personal Question? Fire away.

02-01-2003, 02:44 PM	#15
dsmith HDTVoice Member Join Date: Feb 2003 Posts: 1	I am pretty sure that a few years back Panasonic made a 720P capable HDTV RPTV that used CRTs and did display that format. Actually, I am not sure it displayed 1080i - it may have converted that to 720P also. I forget the model number but it was 57" as I recall. dsmith

02-01-2003, 06:11 PM	#16
MrFister HDTVoice Member Join Date: Aug 2002 Location: Lansing MI Posts: 28	More than just a preference When watching a 720p signal with my 34xbr800 it is like going from 640x480 to 1024x768 on your computer. There are more pixels giving you smaller icons. As far as 1080i being crisper, that is simply untrue when watching a football game at least. The game in 1080i is blurry, fuzzy, blocky or whatever you call it during motion. 720p takes away the artifacts. 720p vs 1080i is more like McDonalds vs Ruth's Chris Steakhouse than a wine preference. If I am indeed watching converted 1080i , then why the noticable resolution change between the two is what I am wondering. Afterall it's all 1080i.

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02-01-2003, 06:25 PM	#17
57U Runner/Cyclist/X-C Skier Join Date: May 2002 Location: Toronto Posts: 17,115	What you're seeing is perhaps a difference in the original material. If your "1080i" looks bad it's because the original material is not as good, or the signal is not as good, not because of anything inherently wrong with 1080i. Look at Jay Leno and that should give you an excellent 1080i image, or if you get PBS, look at the show "Smart Travels" or some of the other 1080i material. It is just excellent. As for pixels, CRTs are not pixel based. The only pixel based TVs are DLPs, LCDs and plasmas and they are all "720P". I know you were trying to make an analogy, but the analogy simply should not work on CRTs. I have certainly seen slight differences when viewing 720P originating material vs 1080i, however, it's not McD, vs Steak. It's more like Bordeaux vs Burgundy, both excellent, but different. You may wish to check out your equipment to see if there is something leading to what you are saying is a vast difference. Perhaps your STB is outputting a "bad" 1080i or doing a bad "convert" of the 720P material while the TV is doing a better "convert"? __________________ 57U - Toronto, Rogers Cable, SA8300HD, 500GB HDD & Hitachi 61UWX10B HDTV, Yamaha RX-V1 A/V Receiver, Martin Logan Speakers. Photos --> 57U's HT SA8300HD, 250GB HDD & KDL40W3000 (Upstairs) Please don't PM me with questions that can (and should) be asked in the forum, thanks. Personal Question? Fire away. Last edited by 57U : 02-01-2003 at 07:33 PM.

02-01-2003, 07:17 PM

#18

woodman

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Quote:

Originally posted by aj327
This probbly doesn't really address your question, but it's interesting nonetheless. From what reading I've done, for various reasons 1080i can actually have less resolution than 720p. 720p always displays 720 lines of resolution but 1080i will vary from around 540 to 1080 - depending on how much motion is taking place on the screen. Why it's motion dependent I haven't really figured out yet, but apparently the average resolution for a 1080i display is somewhere in the 600s, actually LOWER than the constant 720p.

Once again, I'm a bit confused why this happens, but it has to do with the progressive vs interlacing technology.

Another problem with the 1080i is that it's cumbersome which makes it difficult for broadcasters to fit it into the allotted 6 MHZ slot. Apparently this has led to broadcasters leaving out a significant percentage of the transmission...720p, however, fits quite nicely into the 6MHz bandwidth.

I don't know where you're doing this "reading", but you are being seriously misled by someone who doesn't actually know what in the hell they're talking about. Also, you're confusing "resolution" with scanning lines (like so many people do). The two are vastly different animals. In 1080i, there are 1080 horizontal scanning lines being painted on the screen ... it does NOT vary. There is never only 540 scan lines being put on the screen ... NEVER!

Then, there's this statement about "average resolution being somewhere in the 600s". That is so far off the mark as to be laughable. And the one about 1080i being "cumbersome" causing broadcasters to "leave out a significant percentage of the transmission". Here again, this is patently untrue! Furthermore, 720p actually is more bandwidth intensive, rather than less so, since it has a higher scanning rate than 1080i .... 43.2KHz vs. 31.5KHz.

You need to pick your information sources more carefully. The ones you've been reading are misleading you - BIGtime!

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02-01-2003, 07:48 PM	#19
kevinw un-banned Join Date: Feb 2002 Location: ? Posts: 7,162	WOW A robmx post actually having reponses. Too bad it was lifted from another sight. I wonder why only ABC and its affiliate ESPN are offering 720p at all? Everyone else is going 1080i. With the vast majority of Hd display devices unable to show 720p natively whats the motivation? Do the owners of TV's that can display 720p flip a switch when watching ABC or do they leave the STB on 1080i ? Enquiring minds want to know. Last edited by kevinw : 02-05-2003 at 01:49 PM.

02-01-2003, 07:49 PM	#20
aj327 Reged User Tier 2 Join Date: Nov 2002 Location: New York City Posts: 188	Hey Woodman, I haven't seen you around these parts for a while. Since I was hit with the HDTV craze back in November, I've been trying to learn as much about the nuances of this technology as possible, but I'm sure that I still have misconceptions about a lot of things. And if that happens to be the case in this instance maybe you could explain to me what is meant by the following paragraphs...I found them in a link that is posted in the FAQ section so I assumed that they were trustworthy... " So in the Manichean dualism of static vs. moving images, which affects performance more? As Kane explains it, the performance of 1080i varies constantly between 540 and 1080, depending on the amount of motion in the picture at any given moment. "The whole idea of television is to have moving pictures. And since there is usually motion, the average resolution is always going to be well below 1080. It's rare that the picture would ever reach a resolution of 1080. Calculations based on average motion mean vertical resolution is going to be somewhere around 635 lines. It's not a numerical average because what determines the actual resolution is the amount of motion. But 720p has a solid 720 lines all the time. I believe 720p is a better direction for the time being." And then this one about the bandwidth issue: "Because it is digitally maladroit, 1080i has a major disadvantage in transmission, according to the ABC FAQ: "The 1080 x 1920 (1080i) format ... cannot be compressed to fit in a 6MHz channel without creating objectionable artifacts and it has been recommended that the 1920 pixels be sub-sampled to 1440 to reduce compression artifacts. Therefore, encoder manufacturers have elected to discard approximately 25 percent of the picture for over-the-air transmission. This compromise is not required for 720p. More of the original picture information remains through the transmission chain." John Malone of cable giant TCI has even said he would not voluntarily carry 1080i signals, calling it a "spectrum hog," though he added he had no problem with 720p. " Maybe, I misinterpretted what is being said here - because like I confessed in my last post, I don't understand why motion would detract from the total resolution with an interlacing format - but that's what's implied anyway in this article. As far as the bandwidth issue goes - the article doesn't seem to leave a whole lot of room for interpretation with that one. So I think you might be wrong about that bit. Let me know what your interpretation is. And if you disagree with the article, then maybe the moderators should remove the link and replace it with one that isn't misleading. -aj327

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