Hands-On With QSSR: AI-Driven Upscaling for the Standard PS5

Sony has revealed QSSR - Quick Spectral Super Resolution - bringing machine learning based upscaling to the standard PlayStation 5. It's a refined refactoring of PSSR upscaling available on PS5 Pro, available initially for Marvel's Wolverine and Ghost of Yōtei. We had the chance to go hands-on with the technology for around six hours a couple of weeks back and we've also spoken to Sony about how it works.

We've only seen the two games so far (video coming very soon), but the potential here is remarkable: low resolution and poor upscaling have impacted so many titles in this generation, but QSSR could make a big difference. In Marvel's Wolverine especially, the quality boost can be exceptional.

In terms of image quality analysis, suffice it to say that temporal stability is substantially improved, detail level increases, sub-pixel integrity is considerably superior, while artefacts from elements like moving foliage are much reduced. That said, with Ghost of Yotei, a game with already decent image quality saw less dramatic improvements.

The most immediate question you may have is this: why would Sony release QSSR when high quality upscaling is one of the unique selling points of the PS5 Pro? The bottom line is this: PS5 Pro has much more performance in delivering higher output upscaled resolution and higher base resolutions too. There remains a big divide between the same game running QSSR on standard PS5 and PSSR on Pro.

Daniel Craig, Principal Engineer for Graphics R&D at SIE says, "It's great to be improving the PS5 this far into the generation, enabling developers to make even better-looking games. The reality is that the PS5 Pro has 300 TOPS of dedicated hardware for this purpose and is free to pick a much more generous spot on that cost-versus-quality curve."

Refactoring PSSR for the standard PlayStation 5 is a remarkable achievement. PS5 Pro has dedicated ML silicon and PSSR, which has commonalities with AMD's FSR 4, uses INT8 instructions. The base PS5 does not support this.

"It's true that PS5 Pro was purpose built for the task, so QSSR relies primarily on FP16 math," explains Craig. "A streamlined neural network architecture got us close but from there we leveraged a variety of less obvious hardware features to maximise efficiency (as console developers tend to do)... packed math instructions are used extensively. The real challenge is keeping the pipeline full and reducing or amortising the costs around the math."

And while QSSR has many of the characteristics - and the obvious plus points - of ML upscalers, it's not a straight port. Compromises were required but Sony is happy with the final result:

"Game development is always about trade-offs, but we didn’t have to compromise as aggressively as you might think," says Daniel Craig "We keep a close eye on the cost-versus-quality curve of the model architecture, and the 'hard choice' was just deciding where to land for base hardware. We think we picked a spot that developers can afford while still providing an upgrade over standard TAA."

The key word there is "afford". None of the upscalers out there are a free lunch - they all have a computational cost and that cost needs to be as low as possible. Looking at PS5 Pro's PSSR, the upscaling frame-time is around 2ms upscaling to 4K. To ascertain the cost of QSSR, I performed three tests in total: running a Marvel's Wolverine cutscene with QSSR on and off in performance mode, uncapped with VRR. QSSR is slower than Insomniac's upscaler, to the tune of around 1.5ms to 1.8ms, upscaling a base 864p to 1440p. That amounts to an 8-10fps difference. However, in 60Hz performance mode, dynamic resolution scaling targets 60fps instead where the gap lessens significantly - internal resolution is lower to accommodate QSSR, but output frame-rate will be similar and image quality is much higher.

I then re-ran the test in fidelity uncapped mode, which targets a 2160p output - a much more challenging job for QSSR. Frame-rate is lower for this more challenging content but again, there's an 8-10fps difference. However, the frame-time "hit" of QSSR seemed to come in at 4.4ms. That's very high compared to the PS5 Pro alternative. Put simply, upscaling to 1440p is the more natural target for QSSR - which is what a lot of lower resolution PS5 games are doing anyway.

"Your intuition is spot on here," says Craig (note: we didn't share our numbers with Sony, only that 4K was somewhat more expensive.) "On PS5 Pro, developers almost uniformly output to 4K and adjust render resolution beneath it. On PS5, teams have to be more flexible, tuning not just render resolution, but also their intermediate and final presentation targets depending on the graphics mode. We provide tools and flexibility to help them find the right options for their title. It's not a one size fits all solution."

On the flip side, running Ghost of Yōtei's performance mode uncapped with VRR saw QSSR running almost identically to its stock FSR 3 implementation. It's just one game and we'd need to confirm similar input and output resolutions, but assuming QSSR is as fast as FSR 3, this makes it a highly compelling alternative for PS5 game developers. We'll need more games for analysis to see whether this is borne out.

Integration should be relatively straightforward for game makers. If their title supports PSSR for Pro, QSSR for the standard PS5 shouldn't require too much effort. "QSSR is fundamentally a drop-in replacement for titles that already support PSSR," explains Daniel Craig. "That said, tuning game settings takes a bit more time, perhaps a few days. For example, teams may need to adjust streaming settings to ensure higher quality mips are resident."

Similar to the Pro's PSSR roll-out, seeing QSSR added to existing games should also be expected. "Retrofits are relatively easy and low risk, but I am most excited about future titles which are authored with both QSSR and PSSR in mind."

It'll be down to Rockstar to decide whether QSSR and PSSR are supported in Grand Theft Auto 6 but the fact is that the tools are there to be used - and image quality was one of our few criticisms with the recent "extended look" trailer. And more generally, so many titles of this generation have pushed upscalers too hard - native 720p rarely looks attractive when scaled up to 1440p or 2160p. Now there is a potentially game-changing alternative - and we're looking forward to testing more supported titles.