Why 720p?

[JimmyBarnes]

When transcoding BD to x264, the most common resolutions to seem to be 1080p and 720p.

Using 1080p, one isn't losing anything by way of resolution downscaling, but I have always wondered "Why 720p?" Linearly it's two thirds of 1080p so by area it's 44.4 %. Obviously using 720p gives a significantly smaller encode than 1080p.

Is there anything "special" about 720p which gives a better visual result than another resolution reduction, say to 50 % (approx. 70 % linearly), or to 64 % (80 % linearly), when the reduction in encode size is taken into account?

[GodofaGap]

I would think the main reason is compatibility. 1280x720 is defined in the Bluray standard.

[nurbs]

Why downscale?
Because it saves space and most Blu Ray don't have enough details to make 1080p necessary anyway. There is hardly more detail than could be kept with 720p on the majority of Blu Rays. All you get from the extra resolution is a more accurate representation of noise/grain in the source.
Besides if you reencode instead of just remuxing the source you want lower filesizes and noise/grain is the first thing you lose anyway.

Why 720p?
Because it's a standard resolution, it's big enough to keep most of the details and small enough so you can encode with HP@3.1 restrictions which is the limit of some portable devices. It is a good compromise between compatibility, quality and filesize. A couple of percent more or less pixels wouldn't matter much for the latter two.
Also I guess when people say they resize to 720p they actually resize to 1280*xxx depending on aspect ratio for 16/9 and wider ARs.

[Ghitulescu]

Most people that encode for themselves use 1080p. The others use 720p as they save bandwidth. It's not even 720p but ~544p ;) as any google search can confirm.

And since these encodings are generally made for PC play, the optical resolution plays no role.

[Groucho2004]

It's not even 720p but ~544p ;) as any google search can confirm.

How is 720p not 720p? I suppose you are talking about the resolution after cropping but how is this relevant? If it were relevant, how does it not apply to 1080p??


And since these encodings are generally made for PC play, the optical resolution plays no role.

WTF? If I connect my PC to a 72 inch HD display the resolution is not important? Are you sure you are taking the right meds?

[Ghitulescu]

How is 720p not 720p? I suppose you are talking about the resolution after cropping but how is this relevant? If it were relevant, how does it not apply to 1080p??
Because cropping 1080 would still land in the HD realm, while 544 can no longer be HD, as it's below regular PAL SD.

WTF? If I connect my PC to a 72 inch HD display the resolution is not important? Are you sure you are taking the right meds?
The higher the screen size, the higher the needed optical/stored resolution.
Obviously, people downconverting to 720p do not have your setup.

[GodofaGap]

Because cropping 1080 would still land in the HD realm, while 544 can no longer be HD, as it's below regular PAL SD.
Not for ~2.35:1.

[nurbs]

Because cropping 1080 would still land in the HD realm, while 544 can no longer be HD, as it's below regular PAL SD.
Not really. 1280*544 has 68% more pixels than 720*576 and that's ignoring that a 2.35:1 PAL DVD would only have around 720*436 pixels containing the movie.

[yetanotherid]

Because cropping 1080 would still land in the HD realm, while 544 can no longer be HD, as it's below regular PAL SD.

I'd been wondering what your logic would be. I even came up with a few theories. I never would have guessed that one.

A 1280x720 wide screen image might be 1280x544 after you decide not to encode the black bars, but it's still displaying at full width on a 1280x720, 16:9 screen. The video itself is still no different in resolution to the original 1280x720 video without the black bars removed.... yet it's no longer HD?

A 720x576 (given you had to use PAL rather than NTSC) standard definition DVD, even when it's anamorphic pixels are stretched out, would still be only at best be equivalent to 1024x576 square pixels. Then crop off those same black bars and it's only equivalent to 1024x432 square pixels.

In what way could a square pixel encode at 1280x544 be considered to have less resolution than a 720x432 anamorphic encode, which when displayed at it's original resolution would still only be 1024 square pixels wide?

The higher the screen size, the higher the needed optical/stored resolution.
Obviously, people downconverting to 720p do not have your setup.

Maybe the people converting to 720p are doing so according to what they can see and not according to a screen size related theory.
I've not done any comparisons myself but I've read quite a few reviews of LCD TVs and the general consensus from those who should know is that when it comes to watching video on a typical size TV, 1080p video doesn't offer a substantial improvement over 720p even if the TV has a 1080p resolution.

720p vs. 1080p (http://reviews.cnet.com/720p-vs-1080p-hdtv/)
"We still believe that when you're dealing with TVs 50 inches and smaller, the added resolution has only a very minor impact on picture quality. In our tests, we put 720p (or 768p) sets next to 1080p sets, then feed them both the same source material, whether it's 1080i or 1080p, from the highest-quality Blu-ray player. We typically watch both sets for a while, with eyes darting back and forth between the two, looking for differences in the most-detailed sections, such as hair, textures of fabric, and grassy plains. Bottom line: It's almost always very difficult to see any difference--especially from farther than 8 feet away on a 50-inch TV."

[Groucho2004]

Because cropping 1080 would still land in the HD realm, while 544 can no longer be HD, as it's below regular PAL SD.

And yet again (and as almost always) you're diverting from your original statement which was "It's not even 720p but ~544p". No mention of HD.

If you keep doing this you're going to lose your credibility very quickly. I wonder if you are even aware of this very annoying habit.

[Ghitulescu]

Not really. 1280*544 has 68% more pixels than 720*576 and that's ignoring that a 2.35:1 PAL DVD would only have around 720*436 pixels containing the movie.
It's not the number of pixels :) it's the number of active scanlines the decisive issue. Everything that has more scanlines than PAL is HDTV. For economy reasons, these resolutions have been standardized to 720p and 1080p and soon it would be added more.

720p has 720. However, the video was cropped, so on a PC one would see only, as an example, 544 lines. I am not talking about displaying on a TV set, because that would mean adding matting, as 1280x544 is illegal for any HD TV set. People that crop do this obviously for watching on a PC with a PC display.

I'd been wondering what your logic would be. I even came up with a few theories. I never would have guessed that one.

A 1280x720 wide screen image might be 1280x544 after you decide not to encode the black bars, but it's still displaying at full width on a 1280x720, 16:9 screen. The video itself is still no different in resolution to the original 1280x720 video without the black bars removed.... yet it's no longer HD?

A 720x576 (given you had to use PAL rather than NTSC) standard definition DVD, even when it's anamorphic pixels are stretched out, would still be only at best be equivalent to 1024x576 square pixels. Then crop off those same black bars and it's only equivalent to 1024x432 square pixels.

In what way could a square pixel encode at 1280x544 be considered to have less resolution than a 720x432 anamorphic encode, which when displayed at it's original resolution would still only be 1024 square pixels wide?


Maybe the people converting to 720p are doing so according to what they can see and not according to a screen size related theory.
I've not done any comparisons myself but I've read quite a few reviews of LCD TVs and the general consensus from those who should know is that when it comes to watching video on a typical size TV, 1080p video doesn't offer a substantial improvement over 720p even if the TV has a 1080p resolution.

720p vs. 1080p (http://reviews.cnet.com/720p-vs-1080p-hdtv/)
"We still believe that when you're dealing with TVs 50 inches and smaller, the added resolution has only a very minor impact on picture quality. In our tests, we put 720p (or 768p) sets next to 1080p sets, then feed them both the same source material, whether it's 1080i or 1080p, from the highest-quality Blu-ray player. We typically watch both sets for a while, with eyes darting back and forth between the two, looking for differences in the most-detailed sections, such as hair, textures of fabric, and grassy plains. Bottom line: It's almost always very difficult to see any difference--especially from farther than 8 feet away on a 50-inch TV."
I don't trust CNET's reviews, and for the rest you have the answers above.

However, I cannot stop commenting that your mathematics can bring nice results, too. 720 is just 1.25x PAL, and 1080 is just 1.5x 720. It follows that there should be less vizible differences between PAL progressive and 720p than between 720p and 1080p.

But video is not all pixels.

[nurbs]

720p has 720. However, the video was cropped, so on a PC one would see only, as an example, 544 lines. I am not talking about displaying on a TV set, because that would mean adding matting, as 1280x544 is illegal for any HD TV set. People that crop do this obviously for watching on a PC with a PC display.
What's that supposed to mean? If I take a 720p (2.35:1) video and crop the black bars it turns into SD, but as soon as I add them back it's HD again?
And why would cropping imply that one watches on a PC? I crop. I watch my stuff on an HD TV. Why do I crop? Because there is no reason to keep the black bars. They don't contain any information and the player will add them back on playback.
The only reason not to crop when you reencode is that you need the file to be some standard resolution like when you want to be Blu Ray compatible.

However, I cannot stop commenting that your mathematics can bring nice results, too. 720 is just 1.25x PAL, and 1080 is just 1.5x 720. It follows that there should be less vizible differences between PAL progressive and 720p than between 720p and 1080p.
Yeah, that's true if you ignore that difference in width. In reality for 16/9 content 720p is 2.22 times PAL and 1080p is 2.25 times 720p or 5 times PAL in terms of actual data (number of pixels). So ideally there should be about the same difference between the resolutions. What actually happens is that you get diminishing returns.

[Ghitulescu]

For both issues: It's not me the one that created the standards.

For both issues again: it's your brain the thing that sees the top and bottom lines are black. And it were initially a "recogniscible" image there, but it just has been artificially matted. An SD image won't be an HDTV one just because one rounded it with black bars to add black pixels up to 1920x1080/1088, but for the purpose of a standard it would be.

And you said already that if you want to observe the standards you don't crop.

[nurbs]

The next time when you argue a purely technical point please make it more explicit, it would have saved me a lot of typing. The way I read it I thought you were saying that there is an actual difference between the cropped and uncropped video.

[Ghitulescu]

Visually no.

[yetanotherid]

It's not the number of pixels :) it's the number of active scanlines the decisive issue. Everything that has more scanlines than PAL is HDTV. For economy reasons, these resolutions have been standardized to 720p and 1080p and soon it would be added more.

Pixels or scanlines, it doesn't matter, the principle is exactly the same.

720p has 720. However, the video was cropped, so on a PC one would see only, as an example, 544 lines. I am not talking about displaying on a TV set, because that would mean adding matting, as 1280x544 is illegal for any HD TV set. People that crop do this obviously for watching on a PC with a PC display.

I'd crop regardless, but your argument is silly. The actual image itself still only uses 544 scanlines on a TV set.

I don't trust CNET's reviews, and for the rest you have the answers above.

Well I could provide more links of other reviewers saying the same thing. Feel free to provide one which contradicts CNET. Feel free to offer your own experiences when comparing a typically sized 1080p and 720p television, if you've ever done so.
For the rest you had no answers.

However, I cannot stop commenting that your mathematics can bring nice results, too. 720 is just 1.25x PAL, and 1080 is just 1.5x 720. It follows that there should be less vizible differences between PAL progressive and 720p than between 720p and 1080p.

I've no idea how "it follows". I can scan a picture at 600 DPI and then again at 1200 DPI, but it doesn't necessarily follow there will be visible differences between them. It depends how the images are viewed or the size at which they're printed etc.

But video is not all pixels.

Maybe not, but it's certainly not semantics which sees HD become SD simply because it's been cropped, when the picture itself contains the same number of pixels or scanlines either way.

An SD image won't be an HDTV one just because one rounded it with black bars to add black pixels up to 1920x1080/1088, but for the purpose of a standard it would be.

Yeah, but if it's a HD image that's been cropped, and if it's re-encoded with the black bars added back, it's still a HDTV image and it then conforms to the standard which has you arguing semantics where encoded black bars count towards a definition of HD while artificial matting does not. It's a silly argument.

[Ghitulescu]

Pixels or scanlines, it doesn't matter, the principle is exactly the same.
You want to start another polemic. However, before going into a debate please take your time and read the standards. After reading them (and understand them) you'll probably realise that I was right :), it's not the principle, it's not the common sense, it's not your imagination, but it's the standard the one that decides what HDTV is.

I'd crop regardless, but your argument is silly. The actual image itself still only uses 544 scanlines on a TV set.No, you're wrong. Read my statement few posts above. Your brain sees there 544 lines, the TV knows there are 720.
Well I could provide more links of other reviewers saying the same thing. Feel free to provide one which contradicts CNET. Feel free to offer your own experiences when comparing a typically sized 1080p and 720p television, if you've ever done so.
I make my mind reading real magazines, those that actually measure using laboratory tools, and they are quite independent, and not market oriented.
However, the CNET testing of 720p vs 1080p is not an objective one. I said this long time ago, you may check my posts (:search: ), in short, the comparison needs two native chains for each resolution, from acquisition to display, which is hard to achieve, as no 1080p live cameras existed (in 2009) and no 720p scans of film movies. So one of the chains would have to display a resampled movie, which would disadvantage one of the two.
I can scan a picture at 600 DPI and then again at 1200 DPI, but it doesn't necessarily follow there will be visible differences between them. It depends how the images are viewed or the size at which they're printed etc.
How wrong can you be. -> http://www.andromeda.com/people/ddyer/photo/slide-transfer.html or http://clarkvision.com/articles/scandetail/index.html#testarea1. There is a sensible difference in the details a native 4000lpi scanner yields vs a native 1200. I'm talking about the details that are implicitly there, not the desired printsize (for a Poster or a website).
Maybe not, but it's certainly not semantics which sees HD become SD simply because it's been cropped, when the picture itself contains the same number of pixels or scanlines either way.
You failed to understand and your logic is faulty: it's either the same number of pixels, or one image has been cropped (less pixels, less scanlines).
Yeah, but if it's a HD image that's been cropped, and if it's re-encoded with the black bars added back, it's still a HDTV image and it then conforms to the standard which has you arguing semantics where encoded black bars count towards a definition of HD while artificial matting does not. It's a silly argument.
You failed again to see the point. This is mostly due to your wrong perception of the things. This is why standards come into play, to avoid people guessing or interpreting things like they want or need.
I know that your mind cannot accommodate the idea that black bars (the matting) are actually a part of the picture, which sometimes it's covered with subtitles (this might help you understand, because one cannot draw subtitles over something that doesn't exist ;)).

[2Bdecided]

Tangential to the discussion, but important...

http://en.wikipedia.org/wiki/Optimum_HDTV_viewing_distance
and
http://carltonbale.com/1080p-does-matter

FWIW I think the absolute limit for being able to detect a single pixel separate from the adjacent one is 1 pixel = 0.5 arcminute. This follows from the construction of the human eye: 120 cones (detectors) in 1 degree; and from mapping (at very best) 1 pixel to 1 cone. Put another way, 1 pixel on screen needs to fill 1.45 x 10^-4 times the distance from the screen (tan(1/120)). Bigger pixels could be visible as discrete pixels. Smaller pixels would be wasted.

e.g. 1920 pixels * 3m away from the screen * 1.45 * 10^-4 = 84cm wide screen.

If you convert this to feet and inches, and compare it with this graph...
http://s3.carltonbale.com/resolution_chart.html
...you'll find that the "full benefit" lines on that graph give half the viewing distance I've calculated; they probably used 1 arcminute as the reference, equivalent to mapping 1 pixel onto 2 cones (detectors) in your eye, which pretty much makes sure you get the benefit. The "benefit starts to become noticeable" areas are kind of arbitrary, because the benefit might become noticeable even earlier. Even so, I think the numbers on that graph are far more applicable in real life than the theoretical limit for detecting pixels if the source is clean.

Once you throw in some lossy coding artefacts, there's some justification for using the stricter 0.5 arcminute measure, because being able to just about resolve a single pixel means you can probably see any visible coding artefacts. Whether you care about these in motion when watching an interesting movie is a different thing entirely!

Cheers,
David.

[Ghitulescu]

Thank you David for bringing the charts, I knew about them but I couldn't find them in time for the reply.

[Sulik]

You'll also notice that both 1080p and 720p have a convenient square pixel aspect ratio for a 16:9 display (1080x16/9=1920, 720x16/9=1280).

[yetanotherid]

You want to start another polemic. However, before going into a debate please take your time and read the standards. After reading them (and understand them) you'll probably realise that I was right :), it's not the principle, it's not the common sense, it's not your imagination, but it's the standard the one that decides what HDTV is.

The standards don't change the fact that the HD picture itself has exactly the same resolution both before and after cropping black bars, and your need to define HD by your obsession with conforming to the standards inflicted on you by your standalone device doesn't change that.

No, you're wrong. Read my statement few posts above. Your brain sees there 544 lines, the TV knows there are 720.

I fully understand your argument based on semantics, but that's all it is. What the TV does or doesn't see is irrelevant to what my brain sees... as you most kindly pointed out.

I make my mind reading real magazines, those that actually measure using laboratory tools, and they are quite independent, and not market oriented.

That's great, but as is so often the case, you've not shown anything to support it. I know several people with the amazing ability to read something and take from it only what supports the conclusion they've already reached while ignoring the rest, and you appear to be one of them.

How wrong can you be. -> http://www.andromeda.com/people/ddyer/photo/slide-transfer.html or http://clarkvision.com/articles/scandetail/index.html#testarea1. There is a sensible difference in the details a native 4000lpi scanner yields vs a native 1200. I'm talking about the details that are implicitly there, not the desired printsize (for a Poster or a website).

Which only shows your almost super-human ability to never quite understand a point being made. I said:
"I can scan a picture at 600 DPI and then again at 1200 DPI, but it doesn't necessarily follow there will be visible differences between them. It depends how the images are viewed or the size at which they're printed etc."

So you counter that argument by telling me I'm wrong and refer to "details that are implicitly there", which I never denied or even inferred wouldn't be. I was referring to the desired print size etc, which was an analogy to screen size and viewing distance and once again you counter my point by debating something unrelated.

You failed to understand and your logic is faulty: it's either the same number of pixels, or one image has been cropped (less pixels, less scanlines).

Once again you've not got the slightest idea of what I understand because it's fairly obvious that if you crop part of an image the total number of pixels in the remaining portion will be less, but why you can't understand that doing so has no effect on the resolution of what remains is beyond me.

You failed again to see the point. This is mostly due to your wrong perception of the things. This is why standards come into play, to avoid people guessing or interpreting things like they want or need.

I totally see your point... I just think it's semantics and silly. I've not got a wrong perception of things simply because I don't worship the gods of standards the way you do. In fact it's fairly obvious not following a standards religion allows me to see things more clearly.

I know that your mind cannot accommodate the idea that black bars (the matting) are actually a part of the picture, which sometimes it's covered with subtitles (this might help you understand, because one cannot draw subtitles over something that doesn't exist ;)).

Once again you highlight points to emphasise your ability to be wrong.
Maybe this will help you understand how irrelevant the black bars are to the resolution of the actual picture whether they're part of it or not. As I'm fortunate enough not to have succumbed to the cult of HD standards and therefore not forced to limit my thinking according to any organised HD religion, I sometimes find myself reading subtitles which have been drawn under the picture even though the black bars have most definitely been cropped from the video.
Have a play with DirectVobSub. It's padding function will expand a cropped image to 16:9 and then it'll happily draw the subs over the black bars it added as extra padding, yet they're not part of the video. The resolution of the actual picture remains the same whether the black bars are encoded, whether they're removed, or whether they're added back as padding... and that doesn't change whether the TV sees the black bars as scan lines or artificial matting or because your HD religious beliefs have you convinced the world is flat.

[Groucho2004]

I make my mind reading real magazines, those that actually measure using laboratory tools, and they are quite independent, and not market oriented.

reading real magazines
Are there fake magazines as well?

not market oriented.
How bizarre! What do they test? Toasters? Which actually would be "not market oriented" in terms of video equipment...

[rotty]

Tangential to the discussion, but important...

http://en.wikipedia.org/wiki/Optimum_HDTV_viewing_distance
and
http://carltonbale.com/1080p-does-matter

FWIW I think the absolute limit for being able to detect a single pixel separate from the adjacent one is 1 pixel = 0.5 arcminute. This follows from the construction of the human eye: 120 cones (detectors) in 1 degree; and from mapping (at very best) 1 pixel to 1 cone. Put another way, 1 pixel on screen needs to fill 1.45 x 10^-4 times the distance from the screen (tan(1/120)). Bigger pixels could be visible as discrete pixels. Smaller pixels would be wasted.

e.g. 1920 pixels * 3m away from the screen * 1.45 * 10^-4 = 84cm wide screen.

If you convert this to feet and inches, and compare it with this graph...
http://s3.carltonbale.com/resolution_chart.html
...you'll find that the "full benefit" lines on that graph give half the viewing distance I've calculated; they probably used 1 arcminute as the reference, equivalent to mapping 1 pixel onto 2 cones (detectors) in your eye, which pretty much makes sure you get the benefit. The "benefit starts to become noticeable" areas are kind of arbitrary, because the benefit might become noticeable even earlier. Even so, I think the numbers on that graph are far more applicable in real life than the theoretical limit for detecting pixels if the source is clean.

Once you throw in some lossy coding artefacts, there's some justification for using the stricter 0.5 arcminute measure, because being able to just about resolve a single pixel means you can probably see any visible coding artefacts. Whether you care about these in motion when watching an interesting movie is a different thing entirely!

Cheers,
David.


You have hit the nail right on the head

Forget the actual resolutions available today, this is true before HD and is still true now.

Forget the standards now, perfect resolution for human at normal viewing distance (say 8-10 feet) you should just about be able to see 1 pixel and I mean just about, if you can easily detect it then we need a higher resolution or greater distance.

If it is hard to see if the pixel is on then PERFECT. No higher res is needed. (this is for a person 20 20 vision).

For myself (and most people) HD is a compromise, after all its only 2.1 megapixels approx and on say a 50" screen I find it easy to see 1 pixel at 10 feet as most of us do. The next SHD standard will fit the (dificult to see 1 pixel at 10 feet) test.

Lets face it, we dont need total perfection. I find a good Blu Ray disk, say "Dark Knight" good enough.

[Blue_MiSfit]

Guys, please keep discussion civil and avoid personal attacks.

I understand communication misunderstandings can be very frustrating, especially if you feel like the other person is ignoring your comments on purpose.

Please remember that it's expected to conduct yourselves professionally on this forum.

Any more rudeness on this thread will result in strikes.

Derek

[Ghitulescu]

@[mostly] yetanotherid:
You fail to see the world outside your computer.
People that drafted the A/V standards use computers (laptops) mainly to draft the standards, not to watch videos or hear audios.

Any image that contains more than 625 scanlines is considered to be HDTV. I think this is not hard to be understand. The number of pixels is irrelevant, in standards people talk about samples. For people having difficulties in understanding the difference, let's have the case of a CCD/CMOS sensor. A 10 Mpixel camera doesn't have 10 Msamples, these samples are interpolated using an interpolation algorithm to recreate an image out of a Bayer pattern. The only real sample=pixel equivalence is found in Foveon sensors (Sigma). A 3Mpixel Foveon is equivalent in term of optical resolution to a ~10Mpixel Bayer/conventional one.

What I have found to be completely misunderstood or completely not understood is the case of the black bars (matting). The confusion lies, again, mainly with the people that use computers to play videos. They tend to think that these do not belong to the image, because this is how they see. They also crop the image to the "image" they see. In fact, the mattes belong to the image, they are blacked pixels, that are used to make the image look more wide than it actually is. A standalone [or a PC] doesn't care about those pixels. It's only the brain the one that sees the repeating pattern of black pixels and interpret it as matting.

In fact, all the counterarguments given resort ultimately to PC software and solutions. Cropping and DirectVobSub are computer-only things.

And I spotted one more confusion. Between high definition and HDTV. They are not the same. HDTV support the high definiton (in other words, it allows high definition videos to be recorded, stored, processed and displayed) but doesn't define the resolution. Any upsampled youtube regular video (360x240 ;)) would be technically HDTV, because it can be either 720p or 1080x, however, it's definition remains unchanged. Recording a phone conversation in 16 channels at 384kHz/32b won't make it automatically high definition. One can deposit 1 gallon of gasoline in a maritime oil tanker, no problem, although it won't make too much sense. Besides, one can put 1 gallon of water instead of 1 gallon of gasoline, the oil tanker won't sense it.

The corolar is also true, one cannot capture, store, process, display high definition videos/audios using standard definition standards. To come back to gasoline, one cannot store 1 gallon gasoline in a recipient having less than 1 gallon storage capacity.

So, according to the standards, if the HDTV image of 1280x720 pixels which contains matting bars is cropped to 1280x~544 pixels, its optical resolution won't change, yet having less scanlines than PAL SD it cannot longer be considered HDTV. In fact, the same image can be stored on a regular anamorph DVD, the DVD being also matted (to sum up to 576 scanlines).

Coming back to the 720p vs. 1080p:
Someone here said that there are not so many optical details in a movie anyway, thus a downconversion wouldn't change too much the visual quality. Yes, indeed, there are movies in HD that are no better than the good DVDs. There are bad quality DVDs and good quality DVDs, and last but not least, there are good players and bad players (in the analog domain, because for digital it won't count so much).

However, @OP, since quality is a matter of personal awareness, expectations and experience, it's only you the one who can decide to stay with 1080p or to downconvert.

[2Bdecided]

There's one definition that 520k pixels or less is SD. This is the figure used when enforcing the image constraint token. However, that figure isn't based on a classical definition of SD - it's actually calculated from 1/4 Full HD (rounded to a nice number).

More usefully, I think it's commonly accepted (since the 18MHz variants of Rec.601 were still born!) that SD video is sampled at 13.5MHz or less. I don't think you'll find many people who will accept that a source with more than 720 active pixels across is SD.

You'll also increasingly find TV players that will happily pad cropped videos back up to 16x9. Lots of TVs, BluRay players, etc that play files do this.

So I think the argument that 1280x544 isn't HD is rather weak - but I can't believe you guys think any of this is worth arguing about.

Cheers,
David.

P.S. Do you know what the first "High Definition" video resolution was? http://en.wikipedia.org/wiki/405-line_television_system ;)

[Ghitulescu]

People outside France probably never knew (and this is equally true for the young Frenchmen) that HDTV was already a functioning system from 1950 until the mid 80ies, the 819 scanlines system. :)

[yetanotherid]

@[mostly] yetanotherid:
You fail to see the world outside your computer.
People that drafted the A/V standards use computers (laptops) mainly to draft the standards, not to watch videos or hear audios.

And your point there is?

What I have found to be completely misunderstood or completely not understood is the case of the black bars (matting). The confusion lies, again, mainly with the people that use computers to play videos.

I think you'll find it's the people who use computers to play video who understand the concept of black bars, while those such as yourself who use standalone players seem to think the presence or absence of them for some reason changes the definition of the actual video.
99% of the time you'll see a video with a resolution of 1280x544 labelled as 720p. Why? Because it's a 720p encode with the black bars removed and therefore should be labelled as such.
Why? Well ironically it's to conform to the very standards you seem to think PC users are confused over. Should they label a 1280x544 encode as 544p, or a 1920x800 encode as 800p as you seem to believe they should? Of course not, because they're not the HD standards everyone adheres to and labelling them as such would simply cause confusion when anyone with a tiny amount of common sense understands they're 720p or 1080p encodes, minus the cropped black bars. If you see a video labelled 544p then it was either created by a user of a standalone unit after his first attempt at encoding a video, it's not 720p with the black bars removed, it's most likely a lower resolution and therefore it's not really HD.
Even in the case of computer displays where only the 544 encoded lines are required, computer users still apply the same 720p label in order to conform to the very standards you hold dear, even though adding back the cropped non-picture area is optional for them. They do this for the exact reason you're offering for your argument... standards... while instead you'd prefer video was labelled 544p, 640p, etc.. making any label meaningless in terms of HD simply because you're obsessed with a definition of HD which excludes a simple allowance for the possibility of black bar cropping.

In fact, all the counterarguments given resort ultimately to PC software and solutions. Cropping and DirectVobSub are computer-only things.

So when you play a cropped 1280x544 video on your MKV compatible Blu-Ray player how does it cope? Does it ask a PC for a hand, or does it simply add the black bars back so the end result is your TV displays a 720p video at the correct aspect ratio as though the black bars had never been removed?

And I spotted one more confusion. Between high definition and HDTV.

Where'd you see that confusion?
I doubt anyone would claim upsampling a SD video makes it HD, although if it was converted to a HD resolution by your limited definition of HD there'd be no arguing that it isn't.

So, according to the standards, if the HDTV image of 1280x720 pixels which contains matting bars is cropped to 1280x~544 pixels, its optical resolution won't change, yet having less scanlines than PAL SD it cannot longer be considered HDTV.

Of course it can. Common sense makes it obvious when the cropped bars are added back during playback rather than kept as part of the video, then it's still the same HD video.
Maybe your standalone unit wouldn't know what to do with a 1280x544 video and maybe in an effort to cope it'd stretch those 544 lines to the height of a 720p display, or maybe for it to play the video at the correct aspect ratio all 720 lines would have to be encoded, but fortunately most players capable of playing an encoded 1280x544 HD file would also be smart enough to realise it's a 720p encode which needs to have the 88 lines of black bars restored top and bottom to return it to the 720p resolution required to maintain aspect ratio. What I don't understand though, is if a standalone player is capable of supporting such a simple concept, why are you having so much trouble with it?

[Sharc]

Thank you David for bringing the charts, I knew about them but I couldn't find them in time for the reply.
I just recall your previous comments on these charts:
http://forum.doom9.org/showthread.php?p=1287739#post1287739 ;)

[Blue_MiSfit]

This is no longer a productive discussion. I'm locking the thread. PM me if you think this is unfair...