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Phil Harrison on PS3 Graphics, Power Supply, Blu-ray Performance

"At Sony's Gamer's Day event today, GamePro editor Vicious Sid had the chance to grab a few minutes with Sony's PS3 frontman, Phil Harrison. We touched on several topics: Blu-ray disc speeds, internal power supplies, and that nagging question -- is the PS3 graphically inferior to the Xbox 360?"

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THAMMER13986d ago

It makes you think differently about their logic. Now the way he worded:

Harrison: ....and so that's why they can't do 1080p full frame. Because the image has to be in the frame buffer and a full 1080p image is 8 megabytes, so you can't double buffer.

I wonder if this is true^^^^^^^^? It is a very bold statement.

Mainly because he also said this:

Harrison: No, the way that Xbox 360 works is that they have 512 MB of memory, same as PlayStation 3. But they have general purpose memory, rather than system-specified memory. But they only have a 10 MB internal frame buffer...

8 ^ I

HHHMMMMMM

AuburnTiger3986d ago

i'm with Thammer on this one, what the heck is a bouble buffer?

lalaland3986d ago

But it is only a half-truth on Phil's part.

Double buffering is there to make games look smooth -- if they weren't there, the image would look flickering. Basicly you show one frame (buffer 1) while you draw on the other one (buffer 2). Once you are finished drawing buffer 2, you switch buffers, show buffer 2, and start to draw on buffer 1 again. You switch when the scanline has just finished showing the entire frame (called vertically lock), to avoid showing half of buffer 1 and half of buffer 2.

While Phil is right you can't fit an entire doublebuffer, or other buffers for framebuffer effects in 1080p, developers are trying to use a tiling technique, where they shift parts of frame in and out of mainmemory, before they finally assembles everything to be shown on the TV.

This isn't a "free" way of doing stuff as it is taxing on the mainmemory bus (22GB/s), and although it is difficult to code in an effective way, it is possible. So one day we will see games utilizing the eDRAM framebuffer effects to the max -- the question is when...

Retard3986d ago

Came out the 19th, and someone already posted this.

TheXgamerLive3986d ago

than the ps3". He quickly didn't touch that one and moved on to buffer memory, which was only a partial truth.

But I mean the guy isn't going to come out and speak the truth when the truth will hurt him is he?

Sidherich3986d ago (Edited 3986d ago )

actually it was a non-truth ;)

the 360 framebuffer works different than that.

actually phils math was already off when he said that a 1080p frame is 8mb in video memory.

the math goes something like this:

Back Buffer:
Pixels * FSAA Depth * ( Pixel Colour Depth + Z Depth )
Front Buffer:
Pixels * (Pixel Colour Depth + Z Buffer Depth)
Total = Front Buffer + BackBuffer

1920x1080pixel * 2x32Bit/pixel (32Bit Color Depth and 32Bit Z-Buffer/Stencil Depth)
= 2073600 * 8 Byte
= 16588800 Byte
= 16200 kB
= 15,82 MB

And that is only the BackBuffer without any AA. with AA you can either double (2xAA) or make it 4x (4xAA) to get your total memory usage. Actually on the 360 only the backbuffer is in eDram. The Front Buffer is in Main Memory (UMA)

Maybe Phil left out the Z-Buffer/Stencil or he just computed with 16Bit color depth (ugly as hell) and 16Bit dephth/stencil (artifacts).

Double Buffering means that you have one back buffer and one front buffer. Front buffer displays the graphic while the next frame is drawn to the back buffer. once the back buffer is ready it is copied to the front buffer for display. Having no double buffering would be noticable immediately as it would be a terrible flickering (even the oldest video games like doom used some sort of double buffering).

a simple 720p frame with 2xAA wouldnt fit into eDram as well so MS does a trick. They tile the frame. Imagine it as dividing the 720p picture into 2 pieces. one piece is the left half of the screen and the other one is the right half of the screen. In reality the algorith that seperates the frames is alot more complex but the core principles are the same.

First you render the left half of the screen in eDram, resolve the AA samples and copy 640x720x32Bit to VideoRam which is UMA (unified memory architecture) in the case of the 360. Then it renders the right part of the frame in eDram, resolves AA and then copies it to VideoRam making it one full 720p frame with 2xAA.

This tiling process has been highly optimized and doesnt impact performance. This tiling would allow the 360 to render 1080p with 4xAA (64 MB for the backbuffer!!!) but if that would increase visuals that much i doubt.

There actually is another advantage with that eDram and thats the reason MS choosed that way. This way only texture lookups, vertex lookups and that final copying from eDram to VideoRam are actually done on the main memory bandwidth. Texture and vertex lookups are cheap and the backbufer to frontbuffer copy is efficient because it is a large chunk of data.

There are however a few things you do that are more expensive in terms of memory bandwidth.
alpha/depth/stencil or Anti-Aliasing (more samples that need to be blended into one final fragment). these computations are done on the 265GB memory line between GPU and eDram thus relieving the main memory bandwidth.

damn i hate it how i plan to write only two two lines and end up with (a few) more. kudos to the one actually reading all this :D

AuburnTiger3986d ago

"a simple 720p frame with 2xAA wouldnt fit into eDram as well so MS does a trick. They tile the frame. Imagine it as dividing the 720p picture into 2 pieces. one piece is the left half of the screen and the other one is the right half of the screen. In reality the algorith that seperates the frames is alot more complex but the core principles are the same."

Could you say that this could be considered 720i even though it's not really interlaced but more "half-laced"?

THAMMER13986d ago

Is really a good thing. Cool

lalaland3986d ago

"Could you say that this could be considered 720i even though it's not really interlaced but more "half-laced"?"

No, unless you do fieldrendering. But as that is very complicated most if not all developers choose to render the entire frame. So although only a 720i signal is transmitted to the TV, internally they render a full 720p image.

But you are right that the devs basicly splits the image in two, but the important thing to notice is, the image is assembled again before it is sent to the TV.

Sidherich3986d ago

its still a pure 720p frame when displayed. The tiles are assembled together again BEFORE sent to the TV set. with 720i there would at every time only half of the picture sent to the TV set.

Daewoodrow3985d ago

Sid mate, i'm jealous of your bubbles. So i'll go ahead and try and get you another one.
Top class mate, keep it up.

+ Show (4) more repliesLast reply 3985d ago
Mikey_Gee3986d ago (Edited 3986d ago )

......... THAT WAS FUKN AWSOME DUDE !!!!

Well written and very informative. Actually made a good deal of sense to me believe it or not.

Regardless ..... I think a TRUE 1080p will for sure make me future proof for a good bit and at least the technology is at my hands when it IS INDEED taken full advantage of.

Once gain ....... HUGE PROPS DUDE !!

Very nice post indeed !!!

I even copied and pasted it in my "TO KEEP" files.

THAMMER13986d ago (Edited 3986d ago )

WOW LOL

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