Digital Foundry Article Technical Discussion Archive [2011]

[Arwin]

I thought that on the PS3, system ram can be accessed for video but video ram can not be accessed for system

Correct.

But of course it is more complicated than just having one unified memory pool. But so far I've consistently read from multi-platform developers that they need that system half for non-video stuff anyway on both systems, so that's rarely the real issue these days. Just being able to save up to 30-40 MB of memory in the memory that's still available for graphics memory thanks to the use of EDRAM and having slightly more memory available 'after tax' for video is the main difference that counts. As we were also talking about Mass Effect 2 though, I expect that type of renderer (UE3) does not benefit as much from EDRAM as some others would.

Obviously, things start to look different when you build a system that streams textures from BD to HDD cache to RAM like ND do with Uncharted, but that kind of implementation remains rare in multi-platform titles because on the 360 developers cannot count on having an HDD present.

 

[ultragpu]

Watching the 720p comparsion gallery of ME2 I have spotted more graphical differences which hasn't been mentioned by Grandmaster. For example the shadow and blood splatter are missing in the 360 version.
http://images.eurogamer.net/assets/articles//a/1/3/1/8/6/8/3/PS3_007.jpg.jpg
http://images.eurogamer.net/assets/articles//a/1/3/1/8/6/8/3/360_007.jpg.jpg
Also I disagree about the parring down of Normalmap on the PS3, it's true that from a couple of shots the texture seems sharper or prominent on the 360 but in other palces they are equal. I believe it's mainly due to the drastic lighting tweak which alters the look of normalmap, the textures are just not very adequately lit rather than removing the normalmap completely.
http://images.eurogamer.net/assets/articles//a/1/3/1/8/6/8/3/PS3_036.jpg.jpg
http://images.eurogamer.net/assets/articles//a/1/3/1/8/6/8/3/360_036.jpg.jpg

 

[nightshade]

The difference in shadowing is simply cause of different lighting placement. For the blood splatter, I'm pretty sure its present in the Xbox 360 version as well, the thing is the blood splatter appears when the mech squashes that woman but then it disappears completely ie. its just a splatter, you won't see it spilled all over the ground.

 

[AlNom]

The blood texture tends to clip very heavily during that scene anyway. It just looks wrong with the quarian's head popping through it.

I mean, if you really really really want to nitpick, there's even the wrist cuff holding Jack down, which is low poly on PS3 or there is the missing lighting underneath the shuttle. Pretty odd differences considering how insignificant they appear to be, but not exactly mind blowing enough to give much mention.

Also I disagree about the parring down of Normalmap on the PS3, it's true that from a couple of shots the texture seems sharper or prominent on the 360 but in other palces they are equal. I believe it's mainly due to the drastic lighting tweak which alters the look of normalmap, the textures are just not very adequately lit rather than removing the normalmap completely.

Did you actually look at the screenshots making the point of the loss of normal map detail? They look pretty well lit! Garrus' face is even brighter! You can see very simply that there's a loss in finer detail (mouth, forehead). Contrast this to his armour, which is lit differently, but the detail level is the same. Yes, it's not everywhere, just in various places.[/URL]

 

[ultragpu]

The blood texture tends to clip very heavily during that scene anyway. It just looks wrong with the quarian's head popping through it.




Did you actually look at the screenshots making the point of the loss of normal map detail? They look pretty well lit! Garrus' face is even brighter! You can see very simply that there's a loss in finer detail (mouth, forehead). Contrast this to his armour, which is lit differently, but the detail level is the same. Yes, it's not everywhere, just in various places.

Yeah I looked at every shots and I know the shot's you're talking about, but it's hard to explain since the closeup shots of Gaurrus show exactly the same amount of finer details as I linked above. That leads me to think it very well could be the lighting position coz the texture res and detail map is absolutely the same from that character.
http://images.eurogamer.net/assets/articles//a/1/3/1/8/6/8/3/PS3_025.jpg.jpg
http://images.eurogamer.net/assets/articles//a/1/3/1/8/6/8/3/360_025.jpg.jpg
Maybe a bug or something?

 

[Shifty Geezer]

The thing is, it's not quite that simple.

It's even less simple, because standard components on the PS3 are known to take up set amounts of RAM. things like the on screen keyboard take up several MBs, friends list adds several megabytes. When that list was first revealed, it was possible for something like 100MBs to be consumed adding online features. We've no idea how that has changed over the years, or what the differences are on 360, whether they need to load in extra consuming modules or if it's 100% in the OS reserved space, but it remains true that you can be using in excess of the reserved quantities for implementing standard features, making the real difference potentially much more than 18MBs.

 

[kagemaru]

Obviously, things start to look different when you build a system that streams textures from BD to HDD cache to RAM like ND do with Uncharted, but that kind of implementation remains rare in multi-platform titles because on the 360 developers cannot count on having an HDD present.

I thought Halo 3 streamed from DVD to HDD cache to RAM, which is one of the reasons why the game loads slower once installed.

It's even less simple, because standard components on the PS3 are known to take up set amounts of RAM. things like the on screen keyboard take up several MBs, friends list adds several megabytes. When that list was first revealed, it was possible for something like 100MBs to be consumed adding online features. We've no idea how that has changed over the years, or what the differences are on 360, whether they need to load in extra consuming modules or if it's 100% in the OS reserved space, but it remains true that you can be using in excess of the reserved quantities for implementing standard features, making the real difference potentially much more than 18MBs.

Not sure what the numbers are now for PS3 usage, but I was told by a dev who worked at EA Chicago (RIP) a while ago that all features on the 360 are reserved in the OS and no extra memory is used.

 

[AlNom]

I thought Halo 3 streamed from DVD to HDD cache to RAM, which is one of the reasons why the game loads slower once installed.

Well, what's happening is that the game makes both heavy use of the HDD cache and streaming from DVD. Yo dawg, I heard they love streaming so when it's installed, it's streaming while it it's streaming, so it loads while it loads!

 

[joker454]

It's even less simple, because standard components on the PS3 are known to take up set amounts of RAM. things like the on screen keyboard take up several MBs, friends list adds several megabytes.

It's even less less simple than that, because the twin gpu setup (rsx+spu) requires having additional buffers, data structures, etc, to get things working correctly, which in turn means even less ram available above and beyond anything else you and SB mentioned.

 

[eloic]

It's even less less simple than that, because the twin gpu setup (rsx+spu) requires having additional buffers, data structures, etc, to get things working correctly, which in turn means even less ram available above and beyond anything else you and SB mentioned.

Yep, and (I'm not trolling here but) that's what makes so impressive that a console with less available resources has all those great looking games which graphics some people consider even better (technically, I mean) than those in another console with more available resources, which in turn are more easily accessed, too.

Is this just because of the SPUs, code optimization apart? (real question, here, not a rhetorical one)

 

[Gitaroo]

http://images.eurogamer.net/assets/articles//a/1/3/1/8/6/8/3/PS3_025.jpg.jpg
http://images.eurogamer.net/assets/articles//a/1/3/1/8/6/8/3/360_025.jpg.jpg
Maybe a bug or something?

those comparison are interesting, by looking at the texture on the armor, looks like the specular map is tone down on PS3 so the base texture will pop out more? Bioware did commented about the texture detail poping out more with the ME3 engine in the PS blog video I think.

same with this

http://img718.imageshack.us/img718/3901/comparisonmp4snapshot07.jpg

I think you can see Jack's tatoo better especially the one on the top.

 

[Arwin]

I thought Halo 3 streamed from DVD to HDD cache to RAM, which is one of the reasons why the game loads slower once installed.

Halo is a rare case, going back to the original Halo for the first Xbox, which was one of the few games that used the HDD extensively back then. Microsoft provides SDK support for streaming from DVD with auto-caching to HDD when one is present (which is why I think it's a pity that there aren't more sites testing if there are differences in load-times with a proper HDD-less Arcade). Which is yet another reason why it happens less in multi-platform games, albeit that you could blame Sony for not attempting to provide similar SDKs (if they don't, but by default that would be my guess to be honest).

Not sure what the numbers are now for PS3 usage, but I was told by a dev who worked at EA Chicago (RIP) a while ago that all features on the 360 are reserved in the OS and no extra memory is used.

That could very well be true. They did a good job in optimising stuff there, learning from the original Xbox. I hope Sony will make a simlarly big step forwards next gen.

 

[Arwin]

to get things working correctly

May I be so bold as to qualify this with "when you're porting a game from 360 to PS3"?

 

[joker454]

May I be so bold as to qualify this with "when you're porting a game from 360 to PS3"?

Generally speaking. Think about it from a very simplified macro point of view. On a PC or 360, you probably have a sequential post process setup that works like:

gpu: step 1 -> step 2 -> step 3 -> step 4 -> step 5 -> final buffer

...on ps3 you would instead likely break up the mutually exclusive steps so that you can parallelize it better since the gpu won't do it for you, so perhaps you end up with something like this:

gpu: step 1 -> step 2 -> temp buffer 1
spu: step 3 -> step 4 -> temp buffer 2
gpu: temp buffer 1 + temp buffer 2 -> final buffer

Having to manually split up work loads like that means the need for more code, more data structures to maintain it all, and more work buffers, all of which take up ram, and none of which are needed on other platforms. Note that this isn't a bad thing, and if the gpu's on both machines were equal it would have given the ps3 a significant performance advantage. In this case though it's more needed for performance parity at the expense of ram.

Incidentally this is one of the reasons sometimes games on 360 load faster even when comparing 360+dvd to PS3+bluray+hdd. If you port a game from PS3 to 360, normally you throw away all that custom code and just let the gpu do it all, freeing up ram in the process. That extra ram can be used to load and process some stuff just one time on 360, then leave them resident in ram forever. It's a quick and easy way to make use of the extra ram and maintain visual parity in the process, since load time parity generally isn't as important for most people. In other words, if you used the extra ram on 360 to improve visuals here and there you may get some backlash, but if instead you use it to speed up load times then most people won't care and you will get a pass.

 

[Nesh]

Generally speaking. Think about it from a very simplified macro point of view. On a PC or 360, you probably have a sequential post process setup that works like:

gpu: step 1 -> step 2 -> step 3 -> step 4 -> step 5 -> final buffer

...on ps3 you would instead likely break up the mutually exclusive steps so that you can parallelize it better since the gpu won't do it for you, so perhaps you end up with something like this:

gpu: step 1 -> step 2 -> temp buffer 1
spu: step 3 -> step 4 -> temp buffer 2
gpu: temp buffer 1 + temp buffer 2 -> final buffer

Having to manually split up work loads like that means the need for more code, more data structures to maintain it all, and more work buffers, all of which take up ram, and none of which are needed on other platforms. Note that this isn't a bad thing, and if the gpu's on both machines were equal it would have given the ps3 a significant performance advantage. In this case though it's more needed for performance parity at the expense of ram.

Incidentally this is one of the reasons sometimes games on 360 load faster even when comparing 360+dvd to PS3+bluray+hdd. If you port a game from PS3 to 360, normally you throw away all that custom code and just let the gpu do it all, freeing up ram in the process. That extra ram can be used to load and process some stuff just one time on 360, then leave them resident in ram forever. It's a quick and easy way to make use of the extra ram and maintain visual parity in the process, since load time parity generally isn't as important for most people. In other words, if you used the extra ram on 360 to improve visuals here and there you may get some backlash, but if instead you use it to speed up load times then most people won't care and you will get a pass.

Sounds like the PS3 is the lowest common denominator. Yet it amazes me that when it comes to exclusive games, they come up with stuff that set the bar to the top in visuals compared to any multiplatform or exclusive game released on competitive platforms?

What are these routes they take that really make games like God of War, Uncharted or Killzone stand out like they way they do? Whats in there that give the impression that they "bypass" the various hardware limitations that plaque so many other games ? It always struck me as odd because when I read developers' comments about the platforms, the PS3 always appears to have the most bottlenecks and hassles.

 

[kagemaru]

Halo is a rare case, going back to the original Halo for the first Xbox, which was one of the few games that used the HDD extensively back then. Microsoft provides SDK support for streaming from DVD with auto-caching to HDD when one is present (which is why I think it's a pity that there aren't more sites testing if there are differences in load-times with a proper HDD-less Arcade). Which is yet another reason why it happens less in multi-platform games, albeit that you could blame Sony for not attempting to provide similar SDKs (if they don't, but by default that would be my guess to be honest).

I thought that a game could be designed to use caching if a HDD was present.

Also according to Bungie's post mortem of Halo 3, no HDD = stripped audio permutations programatically. So that's one difference.

 

[(((interference)))]

(which is why I think it's a pity that there aren't more sites testing if there are differences in load-times with a proper HDD-less Arcade).

Yes, I've been saying that for a long time - we should get Grandmaster on it.
It's amazing that games like RDR run better on 360, at higher visual fidelity despite having no HDD to cache to and running solely from DVD.

Sounds like the PS3 is the lowest common denominator. Yet it amazes me that when it comes to exclusive games, they come up with stuff that set the bar to the top in visuals compared to any multiplatform or exclusive game released on competitive platforms?

What are these routes they take that really make games like God of War, Uncharted or Killzone stand out like they way they do? Whats in there that give the impression that they "bypass" the various hardware limitations that plaque so many other games ? It always struck me as odd because when I read developers' comments about the platforms, the PS3 always appears to have the most bottlenecks and hassles.

Well MS does not spend nearly as much money as Sony does on platform exclusives nor are their first parties as technically apt as Sony's.

However, you do have the occasional game like Alan Wake or even Halo Reach that can show what the platform can do. And who's to say that multiplat titles like Red Dead or Assassin's Creeds aren't as technically impressive as some PS3 exclusives

Perhaps Crytek's 360 exclusive will set a new bar for visuals on the system

 

[Lucid_Dreamer]

Sounds like the PS3 is the lowest common denominator. Yet it amazes me that when it comes to exclusive games, they come up with stuff that set the bar to the top in visuals compared to any multiplatform or exclusive game released on competitive platforms?

Those exclusives don't just set the bar visually, but in the audio department as well! Plus, Killzone 2 had plenty of RAM left over, according to dev screens. It must be magic, right?!

 

[joker454]

Sounds like the PS3 is the lowest common denominator. Yet it amazes me that when it comes to exclusive games, they come up with stuff that set the bar to the top in visuals compared to any multiplatform or exclusive game released on competitive platforms?

What are these routes they take that really make games like God of War, Uncharted or Killzone stand out like they way they do? Whats in there that give the impression that they "bypass" the various hardware limitations that plaque so many other games ? It always struck me as odd because when I read developers' comments about the platforms, the PS3 always appears to have the most bottlenecks and hassles.

I'm probably the wrong person to ask as I find various multiplatform games to be the most technically impressive to me this gen. Aside from Uncharted 2, I'm really not visually enamored by ps3 exclusives at all, so I'll leave it for someone else to answer.

 

[Barso]

This is something that has always amazed me.
You would think that the xbox360 would have the better developer tools to push the xbox360 beyond the PS3 but playing games such as uncharted and killzone would give the impression that the PS3 is the stronger console.
I was always under the impression that the XBOX360 is the stroger machine between the two but I don't see where halo reach looks or performs better than killzone.
Maybe with PS4 sony could be in the better position as the PS3 was plagued with the expensive cell and bluray drive. With an upgraded cell and cheaper bluray drive, they could launch with the stronger console but at a cheaper price.