As a starting point, both consoles get the basics right. There are no drawbacks on the resolution front: this is a true 1920x1080 game on PS4, and a pixel count reveals it's the very same situation on Xbox One, with both backed by FXAA anti-aliasing. It's an interesting result given the console's trend of adopting lower native resolutions than PS4 to secure a smooth frame-rate, or to achieve parity in graphical features. However, Dark Souls 2's lock at 1080p plants it in the upper echelons of multi-format releases so far, at least in terms of visuals.
Xbox One pays a persistent price for matching the PS4's visual standard. Both formats target 60fps and engage v-sync at all times, but Microsoft's platform suffers the greater drops between the two in each scene of our frame-rate analysis. The Forest of Fallen Giants area is a good example, where a barrage of enemies causes a read-out of between 40-50fps on Xbox One, while PS4 operates within the 50-60fps range. Even while uncontested beneath the giant, arching trees of Things Betwixt, a regular margin of 10fps exists between the two - PS4 operating at a near perfect 60fps, while Xbox stutters along at 50fps.
Unfortunately this has the knock-on effect of making combat sluggish on Xbox One. In one example, an encounter with The Last Giant boss gives us our lowest drop, a record tumble to 36fps cued by a batch of floating souls. The PS4 goes entirely unruffled by the effect here, and it's fair to say the smoother controller response makes it easier to tackle a lingering knight after this boss battle's finished. Sony's machine does not produce a perfect 60fps of course, but it is a consistently better performer - and in a game that demands pinpoint timing for rolls and ripostes, the smoother frame-rate can make a difference.
Conclusion:
From Software has described the Dark Souls 2 engine in terms of its viability for this generation, but it's now clear that PS4 hands in results closest to the developer's intention. Within the console bracket, it's no doubt the best version to date, while Xbox One claims second place in the running owing to its less stable frame-rate. By bullishly matching Sony's platform point-for-point across all graphical settings, Xbox One places Dark Souls 2's visual presentation above its playability to a certain extent. However, compared to the 20-30fps performance of last-gen releases it 's still a fulsome upgrade for owners of Microsoft's console.
More: http://www.eurogamer.net/articles/digitalfoundry-2015-dark-souls-2-performance-analysis
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Update re: Xbox One 36fps that occurred while an Achievement Unlocked notification popped up at the same time:
I emailed Digital Foundry concerning the Achievement Unlock being the cause for the slowdown. I got a very quick response from Tom Morgan (the author of the DF piece)
Thomas Morgan said:I used the same Xbox One profile as before to avoid the Achievement Unlocked prompt of my first run - as you rightly suggest - and started up a new save so I could re-face The Last Giant. Took a bit of a speed-run but I got there fast enough!
The 36fps drop doesn't seem to be related to that Achievement prompt, sadly. The second time around I get a minimum fps reading of 32fps just as the souls start flying across - so essentially in the same ballpark as what we had before.
This is with patch 1.01 installed as well. Unfortunately the game updated just after our article went up, which is based on 1.00. But based on tests so far it's fair to say this patch doesn't affect Xbox One performance in this section.