1080p rendering: Xbox360

[TheChefO]

Wouldn't it make better sense to render all games on xb360 at 1080p and let the scaler down sample the image to 720p and lesser displays? Even if devs could not get 2xaa at 1080p it would still enable those with 1080p displays to run their games in full resolution while lower res displays would get supersampling.

2 tiles 1080p no aa
2 tiles 720p 2xaa

Post processing would not have the benefit of a smaller 720 front buffer but couldn't these fx be applied at a lower resolution, upscaled, and then applied to the full res back buffer?

From my understanding postprocessing comprises of things like color adjustment, blur, grain, etc.
These seem like operations that would not be overly sensitive to upscaling.

Would the performance hit be the same in these two render modes? If so, why would a dev not use (1080p) over (720p+2xaa)?

 

[Titanio]

Wouldn't it make better sense to render all games on xb360 at 1080p and let the scaler down sample the image to 720p and lesser displays? Even if devs could not get 2xaa at 1080p it would still enable those with 1080p displays to run their games in full resolution while lower res displays would get supersampling.

2 tiles 1080p no aa
2 tiles 720p 2xaa

It depends..tiling costs are not the only costs involved here at all. One can't assume because the same number of tiles are involved that the two approaches bear the same performance cost. For starters, 1080p will require twice as many pixels to be shaded.

An interesting spin on this choice is that NBA Homecourt will be 60fps at 720p, but 30fps at 1080p, for example.

If you could straight up get the same performance with the two approaches, then sure, it could make sense to just do 1080p and let the scaler offer super-sampling AA at lower resolutions. So that'll depend, really, on the game. Perhaps the user could be given the choice to make trade offs for themselves, as in that NBA game.

 

[Jesus2006]

Maybe raw fillrate (without MSAA) or the quality of the scaler is also an issue for not down-scaling but using 720p instead?

 

[Laa-Yosh]

1080p noAA and 720p 2xAA aren't the same.
At the higher resolution, you need to shade 2 times as many pixels, so shader perfomance can become a bottleneck. It also requires more texture samples, so texture bandwith can become a bottleneck.
Actually, due to the nature of the EDRAM, even 720p and 4xAA is probably less taxing then 1080p with no AA.

Coders here may be able to give you some more insight.

 

[infinity4]

720p + MSAAx4 + HDR ftw

i don't have $5000 to spend for 1080p tv

 

[Bigus Dickus]

What you are suggesting is the equivalent of asking why we have moved from supersampling to multisampling AA. Rending to 1080p and downsampling to 720 is just a form of SSAA, though not 2X. And it comes with all the good and bad thereof.

It seems the community long ago decided that multisampling was the most efficient use of available power towards producing the desired effect... less pixels to shade, so more effects possible, and a more efficient means to achieve the desired antialiasing effect for edges (and AF being more efficient - though perhaps not visually superior - for textures).

 

[Cal]

Supersampling is bad bad bad. Rendering into 1080p means 2.25 times pixels than 720p, that's enough to kill almost all kinds of lighting effects.

Tiling is not a performance bottleneck of X360. But it requires the programmers to rewrite their rendering pipeline.

 

[Graham]

Supersampling is bad bad bad

I slap you on behalf of SD-TV owners everwhere

 

[Panajev2001a]

Supersampling is bad bad bad. Rendering into 1080p means 2.25 times pixels than 720p, that's enough to kill almost all kinds of lighting effects.

True, but shader aliasing is becoming a big problem (MSAA + Texture filtering have been helping out immensely to reduce edge and texture aliasing) especially on low resolution displays. Oblivion's water on an SDTV does IMHO look less pleasing to the eye than Morrowind's water (running on XBOX) as the aliasing on the water's surface is much more evident.

I am sure that at 720p the problem is GREATLY reduced, but it will still be there.

 

[TheChefO]

Thanks for the replys guys. 720p it is then. :smile:

 

[Crayon]

Hmm. Nice,tidy, informative thread.

(Raises hand)

Can it be said that the resolution / framerate tradeoff is pretty straightforward and even? Basically just using fillrate for one or the other when all else is equal? Is this what's going on with the 1080p NBA game?

 

[assen]

Hmm. Nice,tidy, informative thread.

(Raises hand)

Can it be said that the resolution / framerate tradeoff is pretty straightforward and even? Basically just using fillrate for one or the other when all else is equal? Is this what's going on with the 1080p NBA game?

Ummm... no. Higher framerates taxes everything (CPU, CPU->GPU bandwidth, vertex processing, texture bandwidth, framebuffer bandwidth), higher resolution taxes mostly framebuffer bandwidth, and requires more memory. There is no formula that would predict your framerate at resolution X1, if you know the framerate at resolution X0.

 

[Shifty Geezer]

higher resolution taxes mostly framebuffer bandwidth.

And shader performance, which is oft forgotten. If you had infinite framebuffer bandwidth, you'd still experience other demands at higher resolutions. I think it's bandwidth, fillrate and shaders in equal measure (all get doubled with 2x resolution).

 

[Xeinon]

Actually. Virtua Tennis Is in 1080p AND 2xAA.

 

[Metalmurphy]

How do u know it has x2AA?

I know an announcement was made for the 1080p, but i didn't heard anything about a x2AA

 

[Mmmkay]

How do u know it has x2AA?

I know an announcement was made for the 1080p, but i didn't heard anything about a x2AA

A Sumo Digital developer confirmed it:
http://www.neogaf.com/forum/showpost.php?p=5506881&postcount=84

I'll clear something up, VT3 Xbox 360 does run in 1080p natively and at 60fps. This is with 2xAA too

It's not like existing games which get upscaled when you choose 1080p in the Dash.

That is all
---
S0L
---

 

[jetrii]

Do both versions have 2AX? Or is it just the Xbox 360 one?

 

[nAo]

supersampling has tipically a sublinear cost (if you can afford the memory for your buffers and textures), even though the sampling grid pretty sucks

 

[Acert93]

I'll clear something up, VT3 Xbox 360 does run in 1080p natively and at 60fps. This is with 2xAA too :smile:

It's not like existing games which get upscaled when you choose 1080p in the Dash.

That is all :smile:
---
S0L
---

1080p, 2xMSAA, and 60fps? Ok, I totally underestimated these folks. True, VT3 is in smallish stadiums (predictable rendering) and originally an arcade game with a NV40 class GPU, but they are looking at a 31.6MB framebuffer. That is 4 tiles (unless they fiddle around to get into 3) at 60fps. Quite impressive for a port.

I cannot wait to see the 720p "native next gen" version down the road

 

[pakotlar]

1080p, 2xMSAA, and 60fps? Ok, I totally underestimated these folks. True, VT3 is in smallish stadiums (predictable rendering) and originally an arcade game with a NV40 class GPU, but they are looking at a 31.6MB framebuffer. That is 4 tiles (unless they fiddle around to get into 3) at 60fps. Quite impressive for a port.

I cannot wait to see the 720p "native next gen" version down the road

Yeah that is sweet. I want people to take back all the hurtful comments they made about this studio (I think I was one of them).

edit: It would kill me in the sides if the PS3 version came out looking graphically inferior. Sue me, I like seeing the little guy win (though in this case I'm not sure Microsoft could be considered the *little* guy).