Early Access: Why Ratchet's 40fps Fidelity Mode is a big deal (Patreon)

Hello, Rich here. So, the higher the frame-rate, the less you notice the difference. Move from 30fps to 60fps and that's a 30fps boost, yet the improvement to the experience is far more dramatic than the 30fps boost you get moving from 90fps to 120fps. The explanation is simple: frame-rate increases are ever-diminishing divisions of a single second, rather a consistent measurement of time itself. So, with that in mind, Ratchet and Clank: Rift Apart's 40fps mode is actually a big deal - and in this video, John and myself explain why.

Insomniac use the 120Hz mode on newer TVs and monitors to update the game every 25ms - a clean division that ensures consistent frame-times. And owing to GPU overhead they had left over at 30fps, combined with dynamic resolution scaling, they can produce an experience that retains all of the visual features of the 30fps fidelity mode (render time: 33.3ms) without the compromises of the performance RT mode (render time: 16.7ms).

You'll note that 25ms is an exact mid-point between 33.3ms and 16.7ms - and that's 40fps, not 45fps. Frame-rate suggests that 40fps is 'only 10fps' higher than 30fps, yet frame-time tells us it is an exact mid-point between the standard ways that games present - what you might expect 45fps to be. 

And I do highly recommend playing Ratchet in this mode if you can. You get an experience that's significantly richer than performance RT mode, looks pretty much the same as fidelity mode, yet moves with a fluidity at a mid-point between the two. 40fps is absolutely a viable way to have your cake and eat it - if the game has GPU overhead and/or if DRS is in there. 

So why not just unlock frame-rate and let a variable refresh rate display handle everything? It is certainly an option and a good one. However, 40fps/25ms typically sits outside of many screens' VRR window. Plus a VRR presentation is still inherently a variable update and the perception of what is smooth and consistent varies from one person to the next: to me, 50-60fps in VRR looks much the same, but lurches from the mid-40s to the mid-50s are noticeable. There is much to commend the consistency we get with Ratchet's 120Hz fidelity mode, plus locking to 40fps like this gives DRS algorithms a target to aim work with.

The issue is, of course, that you need a 120Hz screen to get that even delivery of 40fps, so how do we show that in a video destined for a 60fps video delivery system? I chose the route of slowing all three modes down to 50 percent speed, so you can appreciate the difference more easily. However, I will be sharing 120fps comparisons as separate downloads, shortly.

Download linkage: https://www.digitalfoundry.net/2021-07-09-why-ratchet-and-clank-rift-aparts-40fps-fidelity-mode-is-a-big-deal-for-consoles