Meta is rolling out a new frame timing technique for Horizon OS called FrameSync. It's billed as helping to reduce stale frames and increasing responsiveness in VR, all in the name of a smoother visual experience.
There are three main benefits to FrameSync versus the existing method, PhaseSync, according to Meta:
- More consistent smoothness (and often higher fps): FrameSync helps stabilize frame pacing, which typically shows up as less judder and fewer visible hitches during motion.
- Fewer stale frames, especially long streaks: Consecutive stale frames can be especially noticeable (and uncomfortable). FrameSync reduces both the frequency of stale frames and the longer runs that can disrupt an experience.
- Lower motion-to-photon latency: Better prediction can reduce the delay between a person’s movement and the corresponding visual update to help interactions feel even more immediate and responsive.
All of which would be welcome improvements. A delay between a user's movement and obviously stuttering or judder are all contributory to a feeling of unease in VR, especially if you already suffer from motion sickness. The feeling that your vision isn't quite matching your movements, even if only by a fractional delay, can be tough to stomach—literally for some.
If you've ever played a VR game over a wireless connection, or a tethered connection to a PC with weak silicon, you know what I'm talking about.
FrameSync is rolling out as the default option for all apps on the Horizon Store with v203. Developers have some time before then to experiment with v201 to make sure everything works as intended. If not, there is an opt-out available to stick with PhaseSync.
PhaseSync delays rendering a frame until the compositor needs it, essentially making it so there's less latency between when the GPU presents a frame to composite. It's a technique that's been around for a long time now, being introduced in the Rift SDK and working alongside features like Asynchronous Timewarp. Though it runs into difficulty when an app gets much more demanding, especially if this demand is spiky, and when frame rates are lower. This can cause more stale frames if the headset can't keep up with demand.
Hence the need for a new frame timing technique, FrameSync, which reportedly allows for VR apps that are more demanding without sacrificing on user comfort.
"... as VR apps become more ambitious, richer scenes and dynamic content mean performance becomes trickier to hold steady. Small inconsistencies in frame pacing can show up quickly as hitching or discomfort and hurt the user experience," Meta says.
The downside of FrameSync is potential to increase CPU/GPU utilization, which have the knock-on effect of hurting battery life and thermals. Though Meta suggests these are only minor, we don't yet know what this will correlate to in terms of actual battery drain.
"FrameSync can increase the amount of fresh content your app delivers, which may result in a small increase in CPU/GPU utilization. Depending on your workload and session length, that can mean minor impacts to battery life and thermal behavior (including throttling)."
If you haven't updated your Quest headset in a while, you might've missed Meta Horizon OS 2, the latest update for the interface on Quest headsets. It makes everything a bit more serious; less metaverse, more Apple.
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