Black Rock's Jefferies talks LCD screen resolutions
Here at Black Rock we use 26-inch widescreen Sony Bravia LCD TVs. We chose these devices because they gave good image quality and were very popular; the theory being that we should develop games on hardware as similar as possible to that which our customers use.
This LCD model advertises its display format as 720p, but on closer inspection it’s not 1280x720 like you’d expect. In actual fact, it’s got a pixel resolution of 1366x768. Of course, LCD TVs can only display images at their native pixel resolution; if they try and display any other resolution then they need to first scale that image or letterbox it. The Bravias we use don’t have the option to display letterbox through HDMI-A and, in any case, even if they did it’s doubtful the consumer would know about it.
So, in order to display the 1280x720 output image from our game, the LCD must first use its hardware scaler to scale the image by 106.66 per cent in both axes. The lovingly crafted 1280x720 image has gone to be replaced by something dependent on the quality of the LCD scaler. But no matter how competent the scaler is, it’s difficult to image how scaling by 106.66% could do any good to the image.
So what is it about 1366x768? There are millions of these LCDs out there but the resolution doesn’t look familiar. It’s not a power-of-two, it’s not divisible by 640 and it’s not even an exact 16:9 aspect ratio (although it is pretty close).
NEW YEAR’S RESOLUTION
The best I’ve managed to come up with is that it’s the highest resolution at nearly 16:9 that will fit into a megabyte boundary.
Multiply 1366 and 768 together and you get very nearly 1024x1024, or 1 megabyte. This means that the LCD manufacturers can use off-the-shelf video memory with very little wastage. On the other hand, if they were to use true 720p then they’d waste 13 per cent of the video memory and possibly lose sales to their rivals who could claim slightly higher resolutions.
So you can’t trust your customer’s display devices. That’s not exactly news – that’s been the case for as long as consoles have existed – but what’s interesting is that this time the problem is being exasperated by our desire to hit 720p.
The first thing to note is that we all make trade-offs between image resolution and quality. Probably the most noticeable example of this is multi-sample anti-aliasing. Both hi-def consoles support either 4xMSAA, where the scene is anti-aliased vertically and horizontally, or 2xMSAA, where the scene is only anti-aliased vertically or horizontally. However, if you’re throwing a lot of graphics around then you won’t be able to afford 4XMSAA at 1280x720 because the GPU hit is just too great.
At this point most games, including our games here at Black Rock, drop down to 2xMSAA at 1280x720. We are making a trade-off and saying that the screen resolution is more important to us than the quality of the anti-aliasing. This isn’t necessarily an entirely voluntary move because, until recently, Microsoft had a TCR insisting that games run at 1280x720 – providing you weren’t one of the lucky ones like Halo, who got it waived and ran at 1152x640, that is.
By asserting that screen resolution is more important than anti-aliasing we’re leaving ourselves vulnerable when the customer’s LCD decides it’s going to rescale the image to a new resolution anyway. If we instead assume that the LCD is going to rescale then, for some games, it might be more sensible to present it with a better anti-aliased but lower resolution image in the first place.
As more and more LCDs ship with the full HD resolution of 1920x1080 then this will become less of an issue, but I’ve just had a look on Amazon and all the 26" and 32" Sony and Samsung TVs are still 1366x768.
It’s is for this reason that Microsoft recently retired the TCR insisting on 1280x720. Now we are free to make the trade-off between resolution and image quality as we see fit.
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David Jefferies started in the industry at Psygnosis in Liverpool in 1995, eventually working on Global Domination and WipEout 3. He later moved to Rare where he worked on the Perfect Dark and Donkey Kong franchises. Next came a move down to Brighton to join Black Rock Studio (which was then known as Climax Racing) in 2003. On this generation of consoles he’s been the technical director of MotoGP’06 and MotoGP’07 before starting work on new racer Split/Second.
www.blackrockstudio.com
it's too bad these consoles just didn't ship with more powerful gpu's to resolve the issue... certainly sony, shipping a year after microsoft, could have made ps3 the only platform to perform 720p and 4xaa by simple putting a more expensive version of the RSX in the ps3.
They couldn't put a more powerful version of the RSX in there because the RSX was already one of the most powerful GPUs at the time of design and release. The only things faster were the newer high end 8 series cards, which costed the same price as the PS3 itself. Sony definitely could not afford to double the price and also couldn't sell it at the same price. So they had to settle for less.
The retail pricing on GPU's has little to do with cost and a lot to do with market slotting. The bill of materials on even most high end GPU's such as GTX285 is generally $120-$150. That includes RAM and PCB! The actual die which is what is used in console would probably be around $100.
Point being, G80 didn't cost anything near the same as a PS3! The end price might have (though I doubt there were any $600 G80's!), but that has nothing to do with cost.
It still would have been MORE expensive though, if RSX cost Sony say $80 at the time, then G80 might have cost them oh, $140. Given all the money they were already losing on PS3 it was too much. And another factors is it takes years to design/fab these things. Changing the PS3 to include a different GPU would have required internal rewiring of both the GPU and the PS3 that might have taken a year or more to design/test/validate. It's not as simple as dropping a new GPU in. So depending on the timeframes, time was a factor as well. Further, Sony probably figured RSX was "about as good" as the competition, and they probably figured at the time that was all they needed, they could coast off the immense popularity of the PS2, maybe with a little help on the graphics from Cell if needed. So why do something more expensive if you dont have to? Of course that turned out incorrect...
But anyways, Harrisons entire supposition is incorrect, and a common fallacy. There are games right NOW on the consoles that do 4XAA. There are games that do 1080P. There are games that do 60FPS. Hell there are probably games that do all three, or there easily could be. The GPU's can easily do all these things. The problem is they all come at the tradeoff of better graphics.
It doesnt ever matter how powerful the GPU's in consoles get. They will ALWAYS be pushed to the graphical limit such that they struggle to maintain 30 FPS, skimp on AA, etc. Why? Because people care a lot more about graphics than little things like AA. And always will.
You could drop a GPU 10X more powerful in PS3, and most games would still be 30 FPS or less, theyd just look 10X better. Devs will always soak up the power rather than use it on AA, higher res, etc.
So yeah, you could mandate all the games on your console be 1080P 60 FPS, 4XAA right now. The other guy would laugh at you, have no such mandate, and destroy you with far better looking games that feature none of those things. Why do you think most PS3 games are 720P after they did all that jawing about being the 1080p console? Because if they were at 1080P while 360 was at 720P, then 360 games would look much better. It's simple stuff.
I think the problem is heat + adequate cooling. Someone had to come up with a way to make the chips smaller and it isn't the graphics card or consoles makers that do this. This is why Sony can now make the PS3 slim. Launch PS3 had 90 nanometer chips. The slim has 45 nanometer chips (some of them anyway).
Bill wrote:
" Why do you think most PS3 games are 720P after they did all that jawing about being the 1080p console? Because if they were at 1080P while 360 was at 720P, then 360 games would look much better. It's simple stuff."
I'm confused between what the marketers and fanboys want you think is better and what is actually better. How is it that 720p will look better? Is this because very few, approx 17% of Americans, actually have TVs/monitors that support 1080p? If so, then your comment makes sense. If not, please elaborate.
By the way, your postings were a good read! Thanks!
@ChrisW: it's not just about resolution. The problem is that 1080p compared to 720p consumes massively more memory bandwidth. What Bill was saying was, there's only so much memory bandwidth (processing power, memory total, other resources) to go around. If you run at 1080p, you get a sharper, more clearly defined image - but if you run at 720p, you might be able to use the spare resources to run with more polygons, more particles, more complicated shaders, anti-aliasing, etc.
So yeah, 1080p will look sharper/crisper/clearer if the underlying scene is identical, but at 720p you can turn up the effects - which is what Bill meant by "look better".
"It doesnt ever matter how powerful the GPU's in consoles get. They will ALWAYS be pushed to the graphical limit such that they struggle to maintain 30 FPS, skimp on AA, etc. Why? Because people care a lot more about graphics than little things like AA. And always will.
You could drop a GPU 10X more powerful in PS3, and most games would still be 30 FPS or less, theyd just look 10X better. Devs will always soak up the power rather than use it on AA, higher res, etc."
wrong, there is always a threshold of performance necessary for a certain resolution. if the ps3's gpu were of a newer generation doing 1080p on all games would be simple, there would be no need to move to 630p to get things to work as with the current ps3. its always a matter of what you got to work with, sure people will always strain the hardware, but to pretend that it doesn't take a certain level of hardware to reach real usability at certain resolutions is silly.
"So what is it about 1366x768?.... The best I’ve managed to come up with is that it’s the highest resolution at nearly 16:9 that will fit into a megabyte boundary."
This theory is wrong because it's OVER 1 MB. It would be about 1024.25x1024.25... in short, it's not going to fit in a neat 1 MB array.
It's the second number that's important... the 768. 768 is a more equitable number than 720. I think this is because of the very standard 4:3 resolution of 1024x768. I don't know if it's easier for them to work with the vertical scanning frequencies at 768 or if it allows for easier convience with compatiblity between 4:3 and 16:9 (my guess is the latter), but that second number is important. If you go with the premise that 768 is important, then 1366 IS in fact the integer that gets you as close as possible to 16:9 (with 768 in the denominator you can't get a perfect 16:9 resolution... 1365 puts you under and 1366 puts you slightly over).
I think the most dangerous assumption here is that the TV's do a good job of up-conversion and scaling. A lot of TV manufacturers do not put a lot of money and effort into scaling and conversion. As with any signal processing procedure, there are cheap and easy ways and there are good but difficult ways. I think you can guess where the majority of TV's go..
So by feeding a lower resolution image you are in fact making the situation worse, you are expecting that the TV can do a good job of scaling, that is a very dangerous assumption to make. You then introduce all kinds of scaling artifacts like mosquito noise, ringing etc, etc. And the more you need to scale the worse they become.
Oh and remember all those worries about latency in the system, well you just introduced more as you're making the TV do more signal processing, which introduces video lag.....
Sure you can AA on the source but it's like taking a cell phone camera picture and showing it on a PC screen. You're essentially feeding the display less information and hoping it does a good job converting it.
What would be better would be if the display and console could talk to each other to determine the correct output mode from the console, drive the display natively and bypass all the lag...
Jon H got close to what I think may be the answer to the 1366x768 mystery, but let me see if I can help out.
I believe LCDs are manufactured using large glass panels of a standard size, from which smaller panels are cut according to the required display size and shape. In the early days of LCD manufacturing you might have a standard size piece of glass that gives you, say, nine 1024x768 panels, with no waste.
Now, once the market shifted to 16:9 displays, manufacturers had to adapt their processes and tooling to make these new displays. In order to save costs, they might continue to use the uncut glass they are already set up for and cut it to the new sized panels. To minimize wasted glass, you'd want to fit the new panels as closely as possible to the constraints of the old glass.
See where this is going? Turns out that three 1366x768 panels takes up almost exactly the same area as four 1024x768 panels (assuming the same vertical measurement).
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