AFTERPAD

Thoughts and Concerns on the iPhone 6 and iPhone 6 Plus

What Apple’s latest and greatest flagships mean for gaming

The new iPhone’s are upon us. And with over 4 million people preordering the iPhone 6 and iPhone 6 Plus, chances are strong that a lot of you are planning on gaming on one of these.

While these new iPhones are undoubtably huge improvements over the iPhone 5 and earlier devices, the story is a little different when compared with the iPhone 5S. Unfortunately, gamers who are expecting a wholesale performance upgrade over last year’s model might be disappointed.

Before I go on, a disclaimer: nobody actually has either of the new iPhones yet. Nobody has benchmarked either of these phones, let alone gamed on them. The following is speculative, based on information from Apple, and from accurate sounding predictions from AnandTech.

With that said, lets examine the potential gaming performance of the new iPhones.

Resolution Determines Performance

Before digging into the specific details of the newer iPhones, understand that in most cases (certainly this one), the single biggest contributor to gaming performance is the number of pixels rendered. Pixels are rendered by the GPU – the graphics engine built in to the computer chip. Importantly, the performance cost associated with rendering additional pixels scales relatively linearly with the performance of the GPU – a GPU with twice the performance can render twice as many pixels at the same cost.

In terms of performance, today’s screens are limited to 60 frames per second – sixty pictures rendered by the GPU and displayed by the screen per second. The more complex the graphics being rendered – think shadows, lighting, textures – the harder it is to create 60 FPS graphics at a given resolution. But conversely, the lower the screen resolution – the fewer pixels the GPU needs to render – the more complex graphics that are possible while maintaining 60 FPS performance.

Ideally, this means that developers would start with the constraints of rendering 60 FPS at whatever the maximum resolution possible is, then implement graphics, shaders, and lighting to stay within those limits. In reality, developers cheat. They often render at reduced frame rates and lower resolutions in order to use more complex shaders and graphics. This is because games are so often sold on screenshots, where resolution and framerate aren’t relevant. It’s also used when games have to run on multiple platforms with a performance discrepancy – the same games on the Xbox One have reduced framerate and/or resolution compared with the PS4, because the GPU in the Xbox is weaker.

But what does this have to do with the new iPhones? Well…

Bigger Phones, More Pixels

Both the iPhone 6 and the iPhone 6 Plus don’t just feature bigger screens than the iPhone 5S; they also feature more pixels in those screens. The iPhone 5S sports a 1136×640 pixel screen, meaning the GPU in it’s A7 processor needs to render 727,040 pixels a total of 60 times per second in order to provide fluid gameplay at full resolution.

Along with it’s larger screen, the iPhone 6 features a 1334×750 pixel screen, translating to about a million pixels – about a quarter more pixels than the screen in the previous iPhone 5S.

The iPhone 6 Plus features a full 1920×1080 (known as 1080p) pixel screen – about 2 million pixels. This beautiful, high-resolution screen looks as good as it does because it packs over twice as many pixels into it’s screen as the already-larger iPhone 6, and almost three times as many as the previously-flagship iPhone 5S!

If we look at these numbers another way, the 1-megapixel screen of the iPhone 6 is about 140% the pixels of the iPhone 5’s screen (727,040*140%=1,017,856 – close enough). That means that the GPU inside the iPhone 6 would need to be 40% more powerful than the one in the iPhone 5S to exhibit the same level of performance while rendering additional pixels.

The iPhone 6 Plus, on the other hand, has even more work to do. It’s 2-megapixel screen is about 275% the pixels of the screen on the iPhone 5S, meaning the GPU would need to be an additional 175% more powerful – an almost 3X increase!

The question now becomes: is the new GPU up to the task?

Enter the A8 GPU

Details about the GPU in Apple’s new A8 processor are currently scarce, though this is likely to change as soon as the new iPhones are out in the wild. What we do have are Apple’s numbers. Apple claims a 50% improvement in GPU performance compared to the A7. Anandtech suggests this improvement is likely due to adding two more cores to the previous 4-core design, and is also likely being a bit under-represented by Apple (real-world improvement will probably be a little greater due to improved components). But lets take that 50% improvement as a starting point.

The smaller iPhone 6 model required about a 40% GPU improvement to perform as well as the iPhone 5S at the new resolution. With it’s 50% performance improvement, the A8 GPU seems more than capable of covering that. Expect games on the iPhone 6 to perform noticeably better than they did on the iPhone 5S.

The iPhone 6 Plus is another story. It required a full 175% performance gain in order to run games as well as the iPhone 5S at full resolution, and the A8 GPU seems woefully underqualified to provide that boost.

Caveats

I’d like to make a few things very clear. People who know a lot about GPU design are probably mashing their heads into their keyboards right now at all the oversimplifications I’ve made, and I don’t blame them. The fact is, resolution scaling is not entirely linear – most GPUs have optimizations allowing them to reach higher resolutions without needing a strictly corresponding performance increase. Also, I’ve oversimplified some of the numbers anyways. Also, most importantly, none of this is based on any real-world testing of the new iPhones. Until people actually dissect these new devices, this is all wild conjecture, and should be taken as such.

What This Means for Gaming

As many caveats as there are, we can still make a few ballpark-estimates from this data:

Luckily for gamers, developers already have experience dealing with this type of situation. Almost identical problems are at play when it comes to making cross-platform console games that scale down from the PS4 to the Xbox One to the previous-generation consoles. Similarly, iOS developers already have experience with this problem, due to the fact that the iPad faces exactly the same issues – same GPU as the iPhone, way more pixels to render. Expect developers to take advantage of the following compensation techniques on the iPhone 6 Plus:

  1. Dropping the rendering resolution
  2. Dropping the framerate, perhaps down to 30fps
  3. Reducing some on-screen effects and shaders

Those are the tricks generally used to compensate for discrepancy in hardware, and I’d expect to see developers take advantage of some combination of them as they target the iPhone 6 Plus, when necessary.

Conclusion

This article should be taken for exactly what it is – technical discussion and speculation based on assumptions about hardware that isn’t available yet. To reiterate, it is still too soon to know exactly what the performance differences between the various iPhones will be.

This article is in no way meant to imply that the iPhone 6 Plus won’t play games well. The various methods to compensate for resolution differences listed above may or may not be noticeable to most gamers. The trade-off of having a giant screen will probably be worth it for those interested in the iPhone 6 Plus. The iPhone 6 will have a better time rendering full-resolution at 60fps than any other iOS device. Gamers who find that important will want to keep it in mind.

Finally, for those considering upgrading: the iPhone 6 will not run games significantly better than the iPhone 5S, but it will likely be a noticeable improvement over the iPhone 5, and a massive improvement over anything earlier. If you’re upgrading from anything less than the iPhone 5S, expect a much better gaming experience.

For iPhone 5S gamers, the story is more difficult. The iPhone 6 Plus is, on paper, a downgrade for gaming, at least at full-resolution 60fps.

The big screens of the new iPhones offer some amazing benefits for usability and immersion, but it’s important to understand the costs associated with those gains before deciding whether or not to upgrade, and which model to upgrade to.

Personally, I’ll be looking forward to getting my hands on both of them, and am preparing to test each exhaustively. This will be a lot more productive than theoretical benchmarks – expect to see another article soon about the actual experience of gaming on these devices.