Microsoft's Xbox 360, Sony's PS3 - A Hardware Discussion

Will Sony Deliver on 1080p?

Sony appears to have the most forward-looking set of outputs on the PlayStation 3, featuring two HDMI video outputs.  There is no explicit support for DVI, but creating a HDMI-to-DVI adapter isn’t too hard to do.  Microsoft has unfortunately only committed to offering component or VGA outputs for HD resolutions.

Support for 1080p will most likely be over HDMI, which will be an issue down the road.  If you’re wondering whether or not there is a tangible image quality difference between 1080p and 720p, think about it this way - 1920 x 1080 looks better on a monitor than 1280 x 720, now imagine that blown up to a 36 - 60” HDTV - the difference will be noticeable. 

At 720p, the G70 is entirely CPU bound in just about every game we’ve tested, so the RSX should have no problems running at 720p with 4X AA enabled, just like the 360’s Xenos GPU.  At 1080p, the G70 is still CPU bound in a number of situations, so it is quite possible for RSX to actually run just fine at 1080p which should provide for some excellent image quality. 

You must keep one thing in mind however; in order for the RSX to be CPU limited and not texture bandwidth limited at 1080p, the games it is running must be pixel shader bound. 

For example, Doom 3 is able to run at 2048 x 1536 at almost 70fps on the 7800 GTX, however Battlefield 2 runs at less than 50 fps.  Other games run at higher and lower frame rates; the fact of the matter is that the RSX won’t be able to guarantee 1080p at 60 fps in all games, but there should be some where it is possible.  The question then becomes, as a developer, do you make things look great at 720p or do you make some sacrifices in order to offer 1080p support. 

One thing is for sure, support for two 1080p outputs in spanning mode (3840 x 1080) on the PS3 is highly unrealistic.  At that resolution, the RSX would be required to render over 4 megapixels per frame, without a seriously computation bound game it’s just not going to happen at 60 fps. 

Microsoft’s targets for the Xbox 360 are far more down to earth, with 720p and 4X AA being the requirements for all 360 titles.  With a 720p target for all games, you can expect all Xbox 360 titles to render (internally) at 1280 x 720.  We’ve already discussed that the 360’s GPU architecture will effectively give free 4X AA at this resolution, so there’s no reason not to have 4X AA enabled as well. 

Most HDTVs will support either 1080i or 720p; those that natively support 720p will simply get a 720p output from the 360 with no additional signal processing.  We’d be willing to bet that the game will still render internally at 720p and rely on either the Xbox 360’s TV encoder to scale the output to 1080i, or you can rely on your TV to handle the scaling for you.  But for all discussion here, you can expect the Xbox 360 GPU to render games at 1280 x 720 with 4X AA enabled. 

The support for 4X AA across the board is important, because on a large TV, even 720p is going to exhibit quite a bit of aliasing.  But the lack of 1080p support is disturbing, especially considering it is a feature that Sony has been touting quite a bit.  The first 1080p displays just hit the market this year, and the vast majority of the installed HDTV user base will only support 720p or 1080i, not 1080p.  In the latter half of the Xbox 360 and PS3 life cycle, 1080p displays will be far more common place but it may be one more console generation before we get hardware that is capable of running all games at 1080p at a constant 60 fps. 

In the end, Sony’s support for 1080p is realistic, but not for all games.  For the first half of the console’s life, whether or not game developers enable AA will matter more than whether 1080p is supported.  By the second half, it’s going to be tough to say.   

Microsoft’s free 4X AA is wonderful and desperately needed, especially on larger TVs, but the lack of 1080p support is disappointing.  It is a nice feature to have, even if only a handful of games can take advantage of it, simply because 1080p HDTV owners will always appreciate anything that can take full advantage of their displays.  It’s not a make or break issue, simply because the majority of games for both platforms will still probably be rendered internally at 720p.