Is HDR "Free" for the Xenos?

ralexand said:
foaud, why are you adding cost of AA for different sampling rates. You don't do 2X AA then 4X, you do 4X and the performance hit is 5% ie. approximately free. It's not 5% for 2X plus 5% for 4X.

In consumer GPUs AA is normally done in multiple passes (2x per pass), so there is, in effect, a decrease in efficiency dependent on the level of AA - Xenos can only do 2x or 4x AA so there are three coarse steps.

The efficiency losses due to AA in Xenos are caused by:

1. having to copy the entire frame, once rendered, from the back buffer to the front buffer instead of simply flipping between the two as conventional GPUs do. This loss is constant regardless of AA level

2. the (according to the hierarchical Z buffer) visible triangles that straddle tile boundaries will have to be processed multiple times. More tiles means more triangles straddle boundaries.

Jawed
 
Jawed said:
Without the daughter die, Xenos wouldn't be capable of free 4xAA.

Don't you get it?

Regardless of the size and capability of the shader arrays, M$ decided that "free AA" was a top priority feature. It's an extremely expensive feature, but M$ considered it essential.

It's no different from making FP10 and FP16 features of Xenos.

I dunno, how difficult is that to understand?

Jawed

I completely get your point but I don't think you get mine. I'm not making any judgement on the choice they made. I'm simply saying nothing is "free" in an absolute sense. Xenos/the parent die can pretty much maintain its performance regardless of whether 4xAA is there or not - hence that might be considered "free" - but from another perspective, looking at when they were making design decisions, I do believe a tradeoff exists. I'm not saying they were wrong to make the tradeoff!

This has already been debated ten ways already so I guess there's not much point in going over it again and again.
 
ralexand said:
fouad said:
Tap In said:
So anyone thinking that xbox360 games will be less aliased than ps3 games...is just dreaming...this is wrong...
People consider a 5% performance hit free in the realworld for graphic effects. The ps2 edram didn't have the logic to do AA.

Its not 5% hit in performance...its 15 % officially...like the RSX...
 
It's performance-free, not cost-free nor transistor-free nor heat-free.

I dunno, I'm utterly incredulous that you have anything meaningful to say here.

Jawed
 
fouad said:
ralexand said:
fouad said:
Tap In said:
So anyone thinking that xbox360 games will be less aliased than ps3 games...is just dreaming...this is wrong...
People consider a 5% performance hit free in the realworld for graphic effects. The ps2 edram didn't have the logic to do AA.

Its not 5% hit in performance...its 15 % officially...like the RSX...

Could you please stop posting BS? Just Try it, this forum doesnt like Fanboys coming in and trying to change people's minds with their Fanboy FUD. Just stop it, go read about the subject 1st.

ralexand said:
So how many trannies does the 520 have?

320 Million+
 
Jawed said:
ralexand said:
foaud, why are you adding cost of AA for different sampling rates. You don't do 2X AA then 4X, you do 4X and the performance hit is 5% ie. approximately free. It's not 5% for 2X plus 5% for 4X.

In consumer GPUs AA is normally done in multiple passes (2x per pass), so there is, in effect, a decrease in efficiency dependent on the level of AA - Xenos can only do 2x or 4x AA so there are three coarse steps.

The efficiency losses due to AA in Xenos are caused by:

1. having to copy the entire frame, once rendered, from the back buffer to the front buffer instead of simply flipping between the two as conventional GPUs do. This loss is constant regardless of AA level

2. the (according to the hierarchical Z buffer) visible triangles that straddle tile boundaries will have to be processed multiple times. More tiles means more triangles straddle boundaries.

Jawed

Thank you very much Jawed, for this explanation...I hope people will understand...and just stop talking about this stupid bullshit " free AA of xbox360 " Its pure marketing a la EE of ps2 capable of transferring the dream of CG toy story to a real time toy story...

I am sick of this misleading...and i am more sick poeple are believing this, and considering : free AA ( or 5 % hit in performance ) on xbox360 as a fact...which is not true. :LOL:
 
Jawed said:
It's performance-free, not cost-free nor transistor-free nor heat-free.

I dunno, I'm utterly incredulous that you have anything meaningful to say here.

Jawed

Its not performance free, its more free than RSX, but its still not totally free...you have to do tiling, this cause performance hit more than 5%...
 
Jawed said:
ralexand said:
foaud, why are you adding cost of AA for different sampling rates. You don't do 2X AA then 4X, you do 4X and the performance hit is 5% ie. approximately free. It's not 5% for 2X plus 5% for 4X.

In consumer GPUs AA is normally done in multiple passes (2x per pass), so there is, in effect, a decrease in efficiency dependent on the level of AA - Xenos can only do 2x or 4x AA so there are three coarse steps.

The efficiency losses due to AA in Xenos are caused by:

1. having to copy the entire frame, once rendered, from the back buffer to the front buffer instead of simply flipping between the two as conventional GPUs do. This loss is constant regardless of AA level

2. the (according to the hierarchical Z buffer) visible triangles that straddle tile boundaries will have to be processed multiple times. More tiles means more triangles straddle boundaries.

Jawed
I guess I was mistaken then. So the gpu does a 2X MSAA which incurs a performance hit then does a 4X MSAA which incurs a performance hit so the performance hit is additive. In that case then it does look like ATI is being deceptive in saying that using 4X AA incurs a 5% performance hit.

320 Million+
Thanks, realsky. So it looks like the R520 will have a raw shading power advantage over the xenos.
 
fouad said:
Thank you very much Jawed, for this explanation...I hope people will understand...and just stop talking about this stupid bullshit " free AA of xbox360 " Its pure marketing a la EE of ps2 capable of transferring the dream of CG toy story to a real time toy story...

I am sick of this misleading...and i am more sick poeple are believing this, and considering : free AA ( or 5 % hit in performance ) on xbox360 as a fact...which is not true.
You shouldn't thank Jawed cause you still don't understand how Xenos-like rendering works, otherwise you wouldn't repeat the same mantra again and again
 
fouad said:
Jawed said:
It's performance-free, not cost-free nor transistor-free nor heat-free.

I dunno, I'm utterly incredulous that you have anything meaningful to say here.

Jawed

Its not performance free, its more free than RSX, but its still not totally free...you have to do tiling, this cause performance hit more than 5%...

Why should we believe you over Devs, MS, and People who obviouslly know more about this stuff than you?
I think your post history speaks for yourself.

Anyway Full Auto is going to Have HDR + Full Scene AA, cool to see that early games on the Xbox 360 will use HDR.
Thanks, realsky. So it looks like the R520 will have a raw shading power advantage over the xenos.

Well try not to forget that certain stuff like VideoShaderâ„¢ HD (for dvd playback) wont be featured in it, wich means that you will gain alot of transistors, possiblly making room for....the EDRAM ;)
 
ralexand said:
Thanks, realsky. So it looks like the R520 will have a raw shading power advantage over the xenos.

LOL, supposedly Ruby 3, the R520 demo, runs faster on XB360 than it does on R520...

Who knows if that's true though, eh?

Jawed
 
3roxor said:
Anyway Full Auto is going to Have HDR + Full Scene AA, cool to see that early games on the Xbox 360 will use HDR.

Fine and all but that game doesn't look impressive. (yet)

Well, there's a video on Xboxyde, a Video interview, in it the guy says that they are still putting stuff that we have yet to see, namelly HDR and Full scene AA for starters.
 
Tap In said:
seriously Fouad.... read this in its entirety and you will find many answers heretofore unknown to you
;)

http://www.beyond3d.com/articles/xenos/

Did everyone read this ?!!!!!!!! and how after reading this you still believe on 5% hit in performance ?!!!!

look at what dave said :


(# of Tiles) NoFSAA FSAA 2x FSAA 4x
640x480 1 1 1
1280x720 1 2 3
1920x540 1 2 4




(((ATI have been quoted as suggesting that 720p resolutions with 4x FSAA, which would require three tiles, has about 95% of the performance of 2x FSAA.)))


95% of the performance of 2x AA at 720P

this what it has been said, Now you dont pass from no tiling needed to 2 tiles ( from no AA to 2x AA at 720P ) without any hit in performance...do you agree ?!!!!!!!!!!!!! if yes so just add this hit in performance to the 5%...

Than to pass to 4x AA at 1080i you need 4 tiles...add another performance hit...

do you agree ?!!!

do we still at 5% ?!!!!!!!!!!!!!!

this is officially at least 10-15 % hit in performance, now imagine what would be in real performance ?!!!!!!!!!!!

do you still believe on the myth of free AA on xbox360 ?!!!!!!!!!!!!


So please...I am sick of this...
 
FAUD your entire logic is based on faulty assertions.

THe hit for 2xAA at 720p IS NOT 5%.

ATI has explicitly said that the hit for 2xAA is 1% or less, when moving up to 4xAA the hit is less than 5% at 720p.

ALL 360 games will be rendered at 720, so this argument will take a larger hit at 1080i is baseless, since 360 will never do 1080i internally.

And you claim that it's actually 15% hit is based on the assertion that somehow 2xAA = 5%, so 4xAA must equal 10%. That's compeltely WRONG. Understand? WRONG?

This isn't marketing from MS, all you need to do is read Dave's article to explain EXACTLY how the tiling works, and the performance hits associated with it. 10MB is not to small if you would simply understand how the tiling works, and how the 256GB of bandwidth is utilized.
 
^ Then stop arguing it. 2xAA at 720p is free, its 4xAA at 720 that comes at a 5% +- hit.

You are like adding hits out of nowhere, do you forget how fast the Edram is? And the logic it has? It seems like you dont know what you are talking about, its like you are trying soo hard to make people think "AA hit on Xenos = RSx hit" ..... :rolleyes:

Yeah the EDRam is there just for show.
 
From the horses mouth as they say:

"FiringSquad: You said earlier that EDRAM gives you AA for free. Is that 2xAA or 4x?

ATI: Both, and I would encourage all developers to use 4x FSAA. Well I should say there’s a slight penalty, but it’s not what you’d normally associate with 4x multisample AA. We’re at 95-99% efficiency, so it doesn’t degrade it much is what I should say, so I would encourage developers to use it. You’d be crazy not to do it."

http://www.firingsquad.com/features/xbox_360_interview/page4.asp
 
FOUAD your entire logic is based on faulty assertions.

(((THe hit for 2xAA at 720p IS NOT 5%.)))

So how much ?!! :rolleyes:

(((ATI has explicitly said that the hit for 2xAA is 1% or less, when moving up to 4xAA the hit is less than 5% at 720p)))

Give me proof, where ATI said that ?!!
So what Dave beyond3d article said about that is false ?!! :rolleyes:

(((since 360 will never do 1080i internally.)))
:rolleyes:
 
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