The PlayStation 4 is more powerful than the Xbox One, but it might not be this way forever, according to Metro Redux developer 4A Games chief technical officer Oles Shishkovstov. As part of a wide-ranging interview with Digital Foundry's Richard Ledbetter, he asked Shishkovstov to sum up what he thinks the technical differences between the PS4 and Xbox One are
"PS4 is just a bit more powerful," Shiskovstov said, after Ledbetter pointed out that the Xbox One has a lower compute unit count and memory bandwidth, and has also faced ESRAM issues. In a lot of cases, too, multiplatform titles run at a higher resolution on PS4 compared to Xbox One.
"You forgot to mention the ROP count, it's important too," Shishkovstov said. "And let's not forget that both CPU and GPU share bandwidth to DRAM [on both consoles]. I've seen a lot of cases while profiling Xbox One when the GPU could perform fast enough but only when the CPU is basically idle. Unfortunately I've even seen the other way round, when the CPU does perform as expected but only under idle GPU, even if it (the CPU) is supposed to get prioritised memory access. That is why Microsoft's decision to boost the clocks just before the launch was a sensible thing to do with the design set in stone."
Shishkovstov went on to say, however, that counting pixel output might not be the best way to accurately measure the differences between the PS4 and Xbox One. "There are plenty of other (and more important factors) that affect image quality besides resolution. We may push 40 percent more pixels per frame on PS4, but it's not 40 percent better as a result...your own eyes can tell you that," he said.
Also in the interview, Shishkovstov says the Xbox One's ESRAM itself is not a particularly painful thing, but rather "the small amount of it."
"Yes it is true, that the maximum theoretical bandwidth--which is somewhat comparable to PS4--can be rarely achieved (usually with simultaneous read and write, like FP16-blending) but in practice I've seen only a few cases where it becomes a limiting factor," he said.
But just because the PS4 is the most powerful new console around right now, it doesn't mean it will necessarily be this way forever. Shishkovstov says that Microsoft is constantly improving tools for developers.
"Microsoft is not sleeping, really," he said. "Each [Xbox Development Kit] that has been released both before and after the Xbox One launch has brought faster and faster draw-calls to the table. They added tons of features just to work around limitations of the DX11 API model. They even made a DX12/GNM style do-it-yourself API available--although we didn't ship with it on Redux due to time constraints."
Regarding the Xbox One's DX11 API, Shishkovstov says he doesn't understand why Microsoft went down that path. "I don't really get why they chose DX11 as a starting point for the console," he said. "It's a console! Why care about some legacy stuff at all?"
"Microsoft is not sleeping, really" -- Shishkovstov
Finally, Shishkovstov addressed the June Xbox One developer update that promised to boost GPU power by letting developers use graphics resources previously dedicated to Kinect and apps. It was previously believed that as much as 10 percent of the Xbox One's graphics power was reserved for Kinect and apps, but this might not be true, Shishkovstov says.
"The issue is slightly more complicated--it is not like 'here, take that ten percent of performance we've stolen before', actually it is variable, like sometimes you can use 1.5 percent more, and sometimes seven percent and so on," he said. "We could possibly have aimed for a higher res [for Metro Redux on Xbox One], but we went for a 100 percent stable, vsync-locked frame rate this time That is not to say we could not have done more with more time, and per my earlier answer, the XDK and system software continues to improve every month."