With well over 100m consoles sold since 2013, backwards compatibility is an essential feature for the upcoming PlayStation 5, allowing PS4 and PS4 Pro users the chance to bring their existing library of games over to the next generation console. But in common with the precedent set by the Xbox compatibility team, Sony aims to do more - to allow the extra power of the new console to improve the experience. But realistically, what should we expect? Sony mentions more stable frame-rates and improved resolutions but to what extent can titles actually be improved?
There's still some confusion about the level of backwards compatibility we'll get from the PlayStation 5 at launch - and messaging from Sony hasn't been crystal clear. In his recent presentation, Mark Cerny said this: "Running PS4 and PS4 Pro titles at boosted frequencies has also added complexity, the boost is truly massive this time around and some game code just can't handle it - testing has to be done on a title by title basis. Results are excellent, though. We recently took a look at the top 100 PS4 titles as ranked by play time, and we're expecting almost all of them to be playable at launch on PS5."
Sony then clarified to say that Cerny was focusing on a sub-set of the available games, that hundreds of titles have been tested and hundreds more will be tested in the run-up to launch - but it sounds very much like the process will be ongoing and that you may own games in your collection that may not run at launch, or may not run with the extra power of the PlayStation 5 in place if they do. We know from a slide in the Cerny presentation (and indeed from the AMD test leak from last December) that PS5 can run in native mode with full power or in compatibility-orientated PS4 and PS4 Pro modes. It's not been explicitly confirmed, but we would hope that PS4 Pro-enabled titles will have access to the PS4 Pro performance characteristics.
But first of all, let's lay down some ground rules and try to manage expectations. Short of a developer delivering a new patch, PS4 games running on PS5 will still operate within their original design limitations. Titles with a 30fps cap will not run at 60fps, for example, even if the horsepower is almost certainly there to do so. If a game runs with a fixed resolution - say, 1080p - it's also highly unlikely that this will change. The extra power can be used to more effectively deliver on the developer's original design targets though, and from our perspective, it may well be PS4 Pro-enabled titles that offer up the most compelling opportunities for improvement.
Consider Dark Souls 3 and Sekiro: Shadows Die Twice, for example. Both of these games run at 1080p resolution with a 30fps limit on standard PS4, albeit with poor frame-pacing. That 30fps is locked: short of From Software patching the game, there's not much extra to be gleaned from running the game with extra system power, while fixing the frame-pacing issues would require a developer patch that is unlikely to happen. However, PS4 Pro offers a performance mode that unlocks frame-rate but falls some way short of delivering 60fps. With well over 2x the GPU power and even more of a performance multiplier from the new Zen 2 CPU cluster, we would really hope to see a substantial transformation to the experience via PlayStation 5 - and surely a locked 60fps should be on the table?
In fact, PS4 Pro delivered a range of 'performance modes' that typically kept the vanilla PS4 feature set and simply unlocked the frame-rate, with little in the way of tuning to actually deliver 60fps gaming. Mark Cerny's own Knack is one such title, but there are many others including Final Fantasy 15, Rise of the Tomb Raider, Hitman 2 and Monster Hunter World that stand a good chance of delivering a silky smooth locked 60fps given enough horsepower. Some games simply run with an unlocked frame-rate by default, so we would hope to see some profound benefits to the likes of Shenmue 3 and a personal favourite - Killzone Shadow Fall, a PS4 launch title that still looks incredible today, and a game we'd love to replay if its unlocked frame-rate mode would boost to 60fps.
Of course, there are also titles that underperform and that can have issues hitting their frame-rate caps. Who knows just how much extra performance we'll get out of Ark: Survival Evolved, for example? Some games were hamstrung by the relatively lacklustre CPU power in the PlayStation 4 family of consoles, so we're particularly fascinated to see whether the infamous Just Cause 3 - which could see physics-driven scenes drop beneath 20fps - hit its actual 30fps frame-rate target. However, there is some irony here in that PlayStation 4 Pro's boost mode, which delivers full CPU clocks to legacy PS4 games, already cleans up some of these issues, opening the door to the infamous Assassin's Creed Unity to hit its target 30fps. With that said, ACU's original disc release ran unlocked, so we will be testing that unpatched code on PlayStation 5, for sure and yes, it's another game we'd love to see running at 60fps.
The other vector for back-compat testing will be to investigate titles that use dynamic resolution scaling. Typically, DRS scales game resolution according to GPU load and with access to PlayStation 5's extra graphics power, we should see titles using it max out to their upper bounds in all scenarios. However, an element of expectation management is still required here. Possibly owing to inherent memory limitations in the hardware design, PS4 Pro titles typically operate with tighter DRS ranges than Xbox One X equivalents. A case in point is Wolfenstein: The New Colossus, which maxes at 1440p on PS4 Pro, while Xbox One X powers on to 2160p in best case scenarios. Series X should deliver 2160p60, but without a developer patch, PS5 can never breach that 1440p60 limit. However, other titles, such as Assassin's Creed Origins/Odyssey may see resolutions go considerably higher
But what about those crucial Sony first-party games? In most cases, we don't expect to see a huge difference and would hope to see the developers patch the games for improved results. But as things stand, the developers did a rather impressive job in achieving 1080p or 2160p resolutions in their PS4/Pro projects and typically did so with consistent performance. Titles like Death Stranding, Horizon Zero Dawn or Days Gone may only see marginal improvements to performance. The Shadow of the Colossus remake, Uncharted 4 and the Lost Legacy on PS4 Pro won't exceed their 1440p resolution limits without a patch and performance boosts will only impact the very limited problematic areas of play.
From a first party perspective, one key exception to the rule is The Last Guardian - a game that requires PS4 Pro owners to boot the game with the front-end set to 1080p mode to improve performance, while the 4K output mode could drop to the low 20s in the heaviest scenes. Hopefully, PlayStation 5's extra grunt can address the problems in that title and it could prove transformative. It's just worth remembering that as exciting as potential game improvements are with the power of the next-gen machine, many developers did an excellent job on PS4 and boosts may be limited.
Where things are potentially far more exciting is for users upgrading directly from PlayStation 4 to PlayStation 5, having not experienced the improvements already offered by PS4 Pro. In that respect, users would see the boosts offered by the enhanced machine and the backwards compatibility improvements delivered by the new console's extra horsepower. From that perspective, it's a mouthwatering prospect - and bearing in mind how important compatibility is to the potential success of the new PlayStation, hopefully we'll see some deep dive demos from Sony in the run-up to launch.