567P or 1080i, Which is technically better? Options

[Dolbs]

Which is supposed to provide the best HD picture?

[neogeo]

1080i.

Picture Resolution

1080i = 1920x1080i

576p = 720x576p

[:)]

geesus neogeo !!

your a man (or woman) of a few words aren't you. Perhaps you can elaborate a bit more with an explanation. The way I see it - I am not sure which is better. One is progressive - 576p the other has higher resolution, 1920x1080i but is interlaced which is not as good with text etc.

[tonymy01]

Perhaps you can elaborate a bit more with an explanation. The way I see it - I am not sure which is better. One is progressive - 576p the other has higher resolution, 1920x1080i but is interlaced which is not as good with text etc.

Well, interlaced does have its disadvantages with scrolling text, but given the pixel size is close to half the size of 576p, will be ***far*** less noticable than, say, 576i interlacing artifacts.

It has been said that you need 86cm minimum (and only a couple of metres viewing distance max) to get the most out of this higher resolution, so if you don't have a device capable of displaying all pixel of at least that size, then I would say 576p is probably going to not look any better or worse than 1080i.

[shauno]

Which is supposed to provide the best HD picture?

1080i is technically HD, 576p isn't. Easy to answer that question (IMG:style_emoticons/default/smile.gif)

720p vs 1080i is a closer call I think.

[dugby]

Which is supposed to provide the best HD picture?

Well you've read all the previous responses.......and I agree with 90%.

BUT here's my observations, ...... when I view at 3.0m my RankArena 86cm with my HD Thomson DTI1500HD set to 31.3KHz & 50Hz :

1) Channel 70 @576p using the DTI1500HD native pass thru
2) Channel 90 @1080i
3) Channel 12 @1080i

all watching HD shows....albeit they are different programs...they all look fantastic. I cannot say that a 70 HD program looks inferior, because it still looks stunning. If I did a double blind test, I believe no one could pick which is 576p and which is 1080i.

I have been described medically as having extremely better than 20/20 vision.

What I can say is that my 576i DVD's when played at 576i definately look inferior than when I set the RankArena to 576p.

Don't get me wrong, I'm not advocating 576p as the only way to go, but I'mm starting to think there may not be too much in the 576p vrs 1080i differences debate despite the previously mentioned technical specification.

[:)]

If I did a double blind test, I believe no one could pick which is 576p and which is 1080i.

I have been described medically as having extremely better than 20/20 vision.

What I can say is that my 576i DVD's when played at 576i definately look inferior than when I set the RankArena to 576p.

Don't get me wrong, I'm not advocating 576p as the only way to go, but I'mm starting to think there may not be too much in the 576p vrs 1080i differences debate despite the previously mentioned technical specification.

Thanks for the extensive tests and comments Dugby

- so what your saying for even upto an including a 86cm TV, anything more than 576p capability is basically a waste of time? - no need to go for 1080i capability - very interesting !, these are the kind of tests you just can't do at a retailer...think your going to save a lot of people out there a lot of money.

Wonder if the same goes for TVs bigger than 86cm - plasmas etc. Wonder how many people owning TVs bigger than 86cm will be honest enough to admit this....if this is the case.

[JasonBB]

1080i is double the resolution, you may not be able to really notice it at times but it depends on the program as well, the bigger you go the better the resolution you need for a perfect picture. (IMG:style_emoticons/default/wink.gif)

[Dreamcazman]

You may not notice the difference in resolution that much with DVD's and DTV, but you definately see the pixel difference with things like a PC connection or games consoles, where the edges are more precisely defined.

[Owen]

I quote myself from another thread.

“The issue of screen size when comparing SD screens to HD screens seems to have been forgotten.
Size does matter for high definition displays.
If you compare a relatively small 42” 16:9 SD display with the same size HD display the differences are small to undetectable at a normal viewing distance of 2.5-3 meters. For smaller displays, HD is pretty much a waste of time unless you are going to view it from an unreasonably close distance of less then 2 meters and how many people watch TV from less then 2 meters.
For larger screens like 57” or bigger the difference between SD and HD displays is blatantly obvious at 2.5-3 meters. Even for SD source (DVD) up scaled to HD resolution.
It all comes down to the viewing distance to screen size ratio. HD TV was designed to allow large screens to be viewed up close so that your field of vision is filled while maintaining a crystal clear image for that better then cinema experience.
Small screens can never take advantage of this due to the viewing distances required.”

That being said, I would add that 576p is the same RESOLUTION as 576i just with less flicker.
1080i is near double the resolution of 576p or 576i and the difference is very noticeable on large screens at normal viewing distances. Also with 1080i, the scan lines are so close together that any visible affect of interlacing is almost completely removed.

So 1080i IS technically better then 576p but it is wasted on smaller screens.
Remember, for the purpose of this discussion a 42” 16:9 display viewed at 3 meters is small.
Pay close attention to viewing distance when evaluating TV’s.
Only you can say whether the improvement in resolution is noticeable at the viewing distance you will be using.

Also note that Foxtel/Austar satellite or digital cable is no where near full 576i resolution due to excessive compression of the data stream and even free to air content is often of poor quality as well. DVD is only 576p but can look very good if a good quality scaler is used to up convert to 1080i. I use a PC to scale all source to the native 1080i resolution of my display and it works very well. The scalers used in TV’s are often not very good and it is common to find that displays work best when fed with there native resolution so as to avoid using the displays own scaler.


Owen

[Dolbs]

Thank you all for your valuable comments. The water is much clearer now. (IMG:style_emoticons/default/biggrin.gif) PS i ahve a 50inch 127cm Pioneer Plasma screen.

[HoffY]

yes i was going to mention that with smaller lower quality displays HD doesnt "seem" to give any/much quality advantage. But as owen touches on... size matters.

i explained to a few people the other day this exact thing. I have an 86cm 12:9 analog TV and it displays analog beatifully. But on a PC Monitor that same analog signal is CRAP!! Why? Because the PC Monitor is of high enough quality to actally show the flaws of analog pictures. The CRT 86cm TV simply "hides" the flaws of analog (not to mention is a native interlaced device so you NEVER see any interlacing negatives like you would on a progressive scan high resolution PC Monitor).

Bottom line... if you're going to watch TV on even an 86cm or even 76cm display (even though they make the "hd compatible") chances are the quality will be "close" for similar reasons ablove (and plenty more but this is one huge one that people often over look).

If we had a 2 or 3 meter high resolution display you'd see how much more you get from 1080i over 576p (IMG:style_emoticons/default/smile.gif)

Oh and dont forget bad quality in large size is a negative for HD. Its similar to how a Analog CRT will display an analog FTA image "better" then a hi rez PC monitor will.

This is probably confusing and i apologize. But its knock off time and i aint sticking around longer then i have to! (IMG:style_emoticons/default/tongue.gif)

[Darklord]

576p vs. 1080i is not as "black and white" as many people seem to think.

This topic really interests me as there is a lot of misinformation floating around about the 576p format, and just what exactly it does offer (if anything according to some of you!). I took the time to write down my thoughts on this issue, based on a large amount of experience, research, and of course discussion surrounding progressive and interlaced scan formats in the home theatre industry. I hope it’s of interest to readers of this thread. I certainly welcome any debate surrounding the points that I raise below.

576p is the same RESOLUTION as 576i just with less flicker.

Hi Owen. I'm afraid this simply isn’t true for a number of important reasons.

1. The 720x576/50i format (PAL) actually only contains 288 lines of resolution “per motion update” (288 lines per 50th of a second). The difference being that the first 288 lines in field one are the even lines, and the second lot of 288 lines in field two are the odd lines (but its important to note that with native 50i both are from different moments in time so don’t entirely line up). The idea is our brain tends to combine these fields to a degree, creating the illusion of them being more detail than there actually is (hence it earns the 576i title rather than 288i).

720x576/50p (progressive PAL or Enhanced Definition) on the other hand is the full 576 lines of resolution per motion update (576 lines per 50th of a second). There is no interlacing and all lines are presented in the one frame, or one motion update, so you're getting twice as much vertical detail in the same amount of time.

Another way to look at it is raw pixel count. With 576i you're getting 207,360 pixels (720x288) per 50th of a second. With 576p you're getting 414,720 (720x576) in the same amount of time! That's twice as many pixels!

The question is does this translate into twice as much detail at all times? In most cases, no. The reason being the motion updates at 50 a second are very quick, and with interlaced scan you're brain is actually interleaving those 288 lines fields together to often get close to the perception of 576 lines being present at one time (particularly when there is little motion). However you do certainly notice more resolution with true progressive video vs interlaced due to the simple fact that there is twice as much detail being presented in the same amount of time.

2. Whenever there is any motion whatsoever, the 576 perceived line of resolution with the native 576i format disappear in a major way. Why? Because the fields are from different moments in time, whenever there is any motion, field two is simply in a different spot to field one, so the lines of resolution don’t line up onscreen. That’s why if you put your nose up to an interlaced monitor screen while watching 576i, you’ll see “feathering” or “combing” of the edges of all objects as the camera moves (particularly noticeable during straight camera panning). What this means is that with interlaced scan during motion, you’re only seeing somewhere between 288 and 576 lines of resolution at any given time. Where there is even relatively rapid motion you’re always seeing much less than 576 lines.

Due to the nature of interlaced scan , motion also causes severe blurring (known as inter-field blur) which also destroys clarity, so interlaced scan is described as having a form of low temporal resolution (or in some ways more accurately described as “bad spatial resolution during movement”).

The “interlaced factor” also destroys detail (and causes a distracting associated interline flicker artefact) during any vertical movement, as detail literally flashes on and off as it falls over the even/odd line succession from field to field. You’ll clearly see a form of this during the scrolling vertical credits at the end of any film.

Progressive on the other hand is able to maintain full detail during movement as you’re seeing the full 576 vertical lines per motion update. Hence you don’t get smearing of detail, and sharpness and clarity is greatly enhanced over interlaced during any movement (particularly when material is shot in a native 50p format).

3. Interlaced artefacts. These are arguably the worst and most noticeable problems associated with interlaced scanning. Relating to the motion issues described above, there are other inherent problems with motion when you are dealing with a format that displays even and odd liens from different moments in time. Namely this causes a “stepping effect” of edges, commonly referred to as aliasing. This is particularly noticeable during any diagonal movement and even more noticeable across thin tightly spaced horizontal objects such as car grills and venetian blinds. In these cases the suspension of disbelief is all but destroyed, as your eye quickly detects the unnatural effect that aliasing causes onscreen. You’ll also often get the “moire effect” (swirling concentric circles) accompanying aliasing with interlaced scan, particularly over grid patterns such as that found on a chequered shirt pattern.

Relating to the above artefact is interline flicker. This one occurs extremely frequently with any interlaced scan material (regardless of the spatial resolution of the interlaced format) and as is caused simply by fine detail flicking “on and off” as the even and odd lines flick up and down. For example you might have a thin horizontal border that takes up exactly one line of resolution. This line will therefore be drawn in field one, but as field two is in a different place (as its drawing the surrounding odd lines) the line is not drawn at all in field two, but then reappears in field one. The result is obviously a flickering on and off effect that is highly noticeable around items such text and any other fine horizontal detail.

Progressive scan eliminates these artefacts, as all the lines are drawn at the one time, and line up perfectly with each other as they come from the same moment in time. The result is aliasing is non existent, there is no interline flicker whatsoever, and edges of objects have much greater definition and solidarity. This is particularly noticeable during any diagonal movement where progressive scan looks far more natural and uniform.

4. The final point worth bringing up is the overall solidity and natural quality of progressive scan. Often described as “film like”, progressive scan simply has a more natural appealing solidity and uniformity to the picture that is hard to actually define. Due largely to the fact that with interlaced scan, even though our brain does a good job of helping the perception of a creating a single image, it still detects that the picture is split into two even and odd line sections (even if it only does so subconsciously). With progressive scan however, you’re seeing the entire frame at once with no flickering up and down which obviously translates into a more natural “real” quality to our brain that interlaced scan. The result is a more immersive picture that is certainly more enjoyable to watch over long periods of time.


The bottom line is that you can’t simply say “1080i is better than 576p” or that “progressive is just the same as interlaced without the flicker”. All else being equal (even though it rarely is) progressive scan is vastly superior in quality over the same interlaced standard of the same resolution. Just looking at a basic progressive computer monitor displaying fine text will quickly illustrate that.

However things get tricky when you’re talking about a “low spatial resolution progressive format” vs a “high spatial resolution interlace format” (I.e. 576p vs 1080i). In these cases there is no correct answer, as to which one is technically better, as both have their own set of pros and cons, and are therefore better suited to different type of source footage and events.

Obviously from a simple “spatial resolution only stand point” the 1920x1080i format is superior to 576p, in that is has a lot more available pixels, and hence can produce a picture with far more detail. In reality though, 1920x1080i is actually only 1920x540 pixels per 50th of a second, and caries with it all the same interlaced problems as 576i. However 1920x 540 still equals 1,036,800 pixels per 50th of a second which is more than enough to produce superb picture quality with the right source material, and is more than twice as many pixels per motion update than true 576/50p. And of course your brain does perceive more than 540 lines at any given time due to the nature of even/off interlaced scan line succession (just like 576i, you’re perceiving something between 540 and 1080 vertical lines depending on how much motion is taking place at any given time.

As has often been discussed 1080i is considered by many to be the best suited format for material that originally comes from low frame rate progressive sources such as 24p or 25p film (or material shot in the 1080i segmented frame format). In these cases the interlaced field are from the same moment in time (both successive fields taken from the same original frame) and you therefore perceive a lot more spatial detail, as well as incorporating the awesome benefit that 1080i from film based sources can be easily de-interfaced by weaving the fields back together, to achieve a true 1920x1080p format with full 1080 lines of detail present per motion update (when such displays become available to de-interlace and fully resolve 1080p anyway).

However for material that is shot at a faster motion rate (material that is now commonly shot in the 50i or 60i SD formats) or particularly for sport, high frame progressive scan formats do certainly have a major advantage. That being their ability to preserve far more detail and clarity during motion. If in the future Seven do actually have the ability to shoot in a true 576/50p format (50 unique progressive frames a second) then I imagine many of you will be very surprised at just how amazing 50p can look during anything with fast motion. I have had the pleasure of experiencing the clarity of true 60p sports in the USA (admittedly this was the 1280x720p format so this also had great spatial resolution!) and the clarity and detail maintained during movement was utterly insane. Hard to put into words how good it really is.

For now though, Seven are simply up-converting most content from 576/25p or down-converting from 1080isf sources, so with a lot of their material you’re only getting 25 unique motion updates a second, with each frame doubled to achieve 50p (as opposed to the 50 motion updates you are used to seeing even with 576/50i sources). The result is the horrible “film like judder” that is present on shows like Home and Away and The Great Outdoors. In these cases the only real benefit of 576p you’re getting is the lack of interlaced artefacts, the great solidarity to the picture, and the large level of detail constantly present due to there always being 576 unique lines of detail present. It won’t be until they move to high frame rate shooting at native 576/50p that the true benefits of this format could be realised (and this may simply never happen in Seven’s case).

I just wish like many others they would adopt the 1280x720p format instead, meaning fantastic progressive image quality, combined with superb spatial and temporal resolution. The great thing about 720p is that it’s easily the “best overall HD format” given that it’s well suited to any HD source, be it low frame rate film, or high frame rate native progressive video. The reason being it has great spatial resolution, accompanied with the benefits of progressive scan, and the ability for great temporal resolution with fast motion content such as sport. It also takes up less bandwidth than 1080i, meaning a higher bit-rate can be used (translating into no visible compression artefacts). I’d say it’s well and truly too late for the 720p format to emerge as an Australian standard now though.


Sorry for the very long winded post, but I constantly see people writing off 576p altogether, as though it is a useless standard, and offers nothing over 576i. The reality is it does have its benefits like any progressive format, many of which are simply not yet illustrated by Seven due to the sources for 576p being very limited at this stage.

Don’t get me wrong either, I love 1080i, and for most material I think it does look better overall than 576p due simply to the much greater spatial resolution. I just also happen to hate interlaced scanning in general, and with fixed panel progressive displays becoming the future display type of choice, the world is moving towards progressive scan as being the format of choice, and hence native progressive formats of any resolution are an excellent thing! The sooner we do away with interlaced scanning, and move towards high frame rate/high resolution progressive sources and standards; the better off the world will be (IMG:style_emoticons/default/smile.gif)

[Owen]

Darklord,

I generally agree with all of your post and I did not intend to overly downplay the 576p format especially for use with digital displays where it can really show its worth.
However in practice on a CRT based TV the advantages of 576p over 576i is not so dramatic especially for progressive source.

The main point of discussion here is which format, 576p or 1080i is better.

In this comparison 576p has a distinct disadvantage when used on large displays.
With 576p there are simply not enough lines to cover the screen adequately and the line structure can be clearly seen. 1080i has nearly twice as many lines on screen, even though they take longer to display. This makes the lines so close together as to make them invisible on anything but a huge display.

I use a properly calibrated 57” HD CRT RPTV that can natively display 1080i and 540/576p. I use a PC to scale the video source to the required resolution using a high quality Lanczos algorithm and drive the display over Component interconnect.
Viewed at three meters the lines of 576p can be clearly seen. Not as obviously as with 576i sure, but by comparison 1080i has no visible lines. Added to that 1080i has noticeably more visible detail then 576p. On fast moving source material the detail level of 1080i may reduce a little but I can’t say that I notice much.
About 80% of source is slow moving or stationary anyway.
Also due to the very close line spacing of 1080i, interlacing artefacts and interline flicker are virtually non existent.

720p would no doubt be fare more competitive but here in the land of Oz we don’t have and will almost certainly never have 720p so 1080i is the best we have.
It does not really matter that we use 1080i 50Hz as a transmission format. As long as the source is progressive, we can still display true 1080p at a film like 25 frames per second. What more do we need?

Regards,

Owen

[tonymy01]

I also read somewhere ages ago that 720p was actually more bandwidth than 1080i, due to the fact that with 1080i, the two interlaced fields have *similar* info and thus better compression?
Does anyone have any comments regarding this?

[John_Barber]

BUT here's my observations, ...... when I view at 3.0m my RankArena 86cm with my HD Thomson DTI1500HD set to 31.3KHz & 50Hz :

Dugby,

While I am not sure of the exact "measurements", I seem to recall that to get the benefit of HD, you should be viewing within 6 times picture height of the screen. That would be within 8 feet of your screen, if my calculations are correct.

It would be interesting to hear your thoughts viewing a bit closer to the screen. Too far away and your eyes cannot resolve the extra detail.

Someone may care to correct me on the recommended figures, I am going by vague memory.

Cheers

JB

[Owen]

Darklord is correct 1080i is higher bandwidth

720p or 1280x720 50 times per second = 46.08Mega pixels per second uncompressed.

1080i or 1920x1080 25 times per second = 51.84Mega pixels per second uncompressed.

Australian HD TV is not 1920x1080. It is more like 1440x1080 at the moment unless I am wrong and only uses a data rate of about 14 Megabits per second (compressed) compared to the US 19megabits per second thanks to our need to transmit standard definition digital as well as HD digital.
I dont understand why we transmit SD digital when the set top box could just down convert the HD for use with SD TV's. Its a terrible waste of bandwidth if you ask me.

Owen

[tonymy01]

Darklord is correct 1080i is higher bandwidth

720p or 1280x720 50 times per second = 46.08Mega pixels per second uncompressed.

1080i or 1920x1080 25 times per second = 51.84Mega pixels per second uncompressed.

I was referring to compressed bandwidth, rather than uncompressed. It is obvious with more pixels that 1080 will be more when uncompressed.

Cheers

[Owen]

It’s the same thing.
46.08 Mega pixels is less then 51.81Mega pixels to compress down to a 14Megabit stream.
720p is less compressed for the same bandwidth.
Or could use less bandwidth for the same compression ratio if you like.

Owen

[tonymy01]

It’s the same thing.
46.08 Mega pixels is less then 51.81Mega pixels to compress down to a 14Megabit stream.
720p is less compressed for the same bandwidth.
Or could use less bandwidth for the same compression ratio if you like.

Owen

Yes, but you are ignoring that each interlaced field in a 1080 interlaced frame is very similar, meaning you can get up to (but of course not equal to) twice the compression.
So if the rate is fixed to 14Mb/s, this would mean less compression artifacts than with 720p (I think this was the argument used a while ago).
Cheers

edit:
Hmm, I have decided to peruse the net, to find this info I read a couple of years ago, and found so many conflicting reports on this that I would say the majority suggest that 1080i is the most bandwidth hog. One site says that they could squeeze 4*720p channels into a 6Mhz carrier, where as they can only get 2*1080i channels.

I found this from here: http://www.hdtvprimer.com/ISSUES/what_is_ATSC.html

Which is better: 1080i or 720p?

1080i and 720p require about the same bandwidth when showing live action:  A 1080i image has twice as many pixels, while 720p shows twice as many frames per second.  While showing films at 24 frames per second, 720p requires about half the bandwidth of 1080i.  A common opinion is that 720p is better for sporting events, while 1080i looks better for documentaries, dramas, and anything that comes 24 frames per second.  Unfortunately the networks are picking one format for all their shows.   ABC and ESPN have chosen 720p.  FOX has chosen 480p but will switch to 720p in the future.  All other networks are using 1080i.  Hopefully some day they will choose the format according to the content.

1080i and 720p are called High Definition TV (HDTV).  480p is called Enhanced Definition TV (EDTV).  480i is Standard Definition TV (SDTV).

edit2:
Found a fantastic link about why they think 720p is a lot better than 1080i
http://www.atd.net/HDTV_faq.html

This post has been edited by tonymy01: Mar 23 2004, 12:09 AM