Valve’s Answer To Asynchronous Timewarp Arrives (UPDATE)

by Ian Hamilton • October 25th, 2016
Valve Software launched a new SteamVR beta with its answer to "Asynchronous Timewarp" from Oculus, which helps VR experiences run smoothly.

Update: Valve released an update to its SteamVR beta today with initial support for asynchronous reprojection. The feature does not support AMD GPUs in its current version. With NVIDIA, an updated driver is required.

Valve’s answer to a technique employed by Oculus that helps VR experiences run smoothly is here.

Facebook-owned Oculus uses a technique called “Asynchronous Timewarp” (ATW) to compensate for situations where the hardware drawing a virtual experience can’t keep up with the rate needed to make it feel smooth. With PC’s, that rate is currently 90 frames every second and drops below this rate could make VR uncomfortable. So various techniques, some of them known as reprojection, are employed to try and get to 90 frames per second.

Oculus, in fact, recently announced a secondary technique it calls “Asynchronous Spacewarp” (ASW). This new approach gave the company the confidence to announce a minimum specification for the Rift. In other words, a year and a half after Oculus announced hardware specifications “recommended” to run the Rift with a good experience, the company added a new “minimum” set of hardware requirements that would use this ASW method to help produce a good experience. NVIDIA, for example, is evaluating whether its newly announced $140 GTX 1050 Ti graphics card is capable of meeting this minimum specification.

The graphics card is typically the most expensive part of a VR computer, and just two years ago enthusiasts and developers could spend $700 for a graphics card that could run the second Oculus Rift development kit at its full frame rate. Gains expected from ASW, however, led Oculus to show off a $500 PC said to meet the Rift minimum specification. This new low-cost PC dramatically lowers the barrier to entry, but what kind of an experience it offers in VR across the wide range of software available is still unknown.

Valve, for its part, took a different approach. For the SteamVR-powered Vive headset, the company recommended to its partner HTC very similar specifications to the original ones recommended by Oculus for Rift. Valve originally implemented an “Interleaved Reprojection” technique instead of something like ATW,  graphics programmer Alex Vlachos told UploadVR, because Valve’s approach works on all modern graphics processing units (GPUs) — even those in use on Mac and Linux. The Rift, in contrast, is only supported on Windows.

“Asynchronous Reprojection (what Oculus calls ATW) works on only a subset of GPUs out there, and ASW works on an even smaller subset of GPUs,” Vlachos wrote in an email. “We are close to releasing our Asynchronous Reprojection feature which is very similar to ATW.” (UPDATE: It is here now)

Valve is also planning on working with GPU vendors to move forward with reprojection technology that makes “use of the hardware-generated motion vectors,” so something like ASW could be in the offing for Valve as well. That said, don’t expect a minimum specification coming from Valve.

“We have no plans to suggest a minimum spec that is based on reprojection right now,” Vlachos wrote. “Our goal is to provide high-quality VR to customers, and we see all reprojection techniques as a safety net for the occasional dropped frame… it is up to each software application to specify their min spec for that engine, since only they can vet what minimum GPU is actually required to render their assets at framerate.”

As both Oculus and Valve acknowledge, these techniques have different drawbacks. Among them are visual artifacts that might make someone uncomfortable. That’s why Valve, Vlachos wrote, is “going to continue to suggest a recommended spec to customers where most VR software applications hit 90 fps natively without requiring reprojection. We will continue to work with devs to improve their engines to hit framerate.”

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What's your reaction?
  • Well, in my opinion the specs lowering has been the most important announcement of Oculus Connect 3. People want to spend less for VR, that’s the only way to guarantee broader adoption. About the little number of GPUs supported, no one cares: people will buy graphics card with that supported GPUs. Good to know that Valve is working on a similar thing… competition is helping a lot this world

    • DougP

      Re: “the specs lowering has been the most important announcement”
      I think it’s a mistake.
      So more people will have an inferior experience & possibly be turned off of VR.
      I think that instead just waiting out 6mos for the latest gen GPUs from AMD & Nvidia to offer “low end/entry level” which can reliably hit 90fps was a better approach.

      I trust the Valve & Oculus people who said:
      “Among them are visual artifacts that might make someone uncomfortable.”
      Making more people uncomfortable in VR, because Oculus convinced them that they could save $75 or $100 on cheaper gaming setup…. is NOT a good trade-off.

      Lastly, I was very encouraged that Valve instead focused on 90fps being reliable ….AND using techniques which can work across OSes & on different hardware. Valve has consistently been much MUCH more supportive of “openness”, including encouraging the likes of Linus/MacOS.

      • James Abrahams

        Remember that when valve said that they are only just getting to ATW. When oculus had ATW they still had a higher spec. It’s only with ASW that oculus are getting to a point where they can lower the spec. Valve arn’t anywhere near that.

        If you look at the artifacts, they occasionally warp objects which just looks wierd but I think isn’t as likely to make you sick. Many users on reddit have reported it working where they could put settings ridiculously high and still get a buttery smooth experience.

        • DougP

          I agree that it seems the approach of ATW/ASW as a “failed state” (dropping below 90fps), but what I don’t agree with is lowering min spec on cards to *encourage* games which will run in that state for any length of time.

          I’ve read about the artefacts/issues & just prefer the best/optimal end-result.
          Then again…I’m a bit of a quality purest & don’t like any artefacts.
          In a similar vein my movie collection is bluray on a 1080p projector – for movies I care about, I don’t like to put up with the lower quality artefacts of streaming or lower-bit rate files.
          With VR the artefacts with be much more jarring as you can get distorted geometry.

          Maybe it is “good enough for the masses”, but I’d rather have seen a stake put in ground for consistent 90fps & highest quality VR as possible.

          • James Abrahams

            Yeah I think you don’t need to worry too much though because devs are still encouraged to get to native 90fps.

            The point of the minimum was for a long time is was a minimum. You literally needed a steady 90fps because even a few dropped frames could make most people so ill that it is literally better to have zero VR in your life then VR with dropped frames.

            However the artifacts you’ll get with ATW arent great but won’t make you ill at all. They will just make shapes occasionally warped so that you don’t need a steady 90fps, you can just have mostly 90fps.

            This is clearly not aimed at someone like yourself but you needn’t worry about people being encouraged to do a worse job. Devs are pushing things such that all games on the rift still benefit from a 1080 because you can change some of the pixel size settings to push every game and make things way better. (I can’t remember the name of the setting it’s that thing people like bumping to 2.0)

            I think VR is in such early stages that we need to worry much less about developers being “encouraged” to make their engines worse. Console games and some pc games have been so relaxed with performance recently that VR has attractive some of the biggest fps enthusiasts. But with the 960 supported this might mean more people can play and buy the games which is far more important!

          • DougP

            Understood & mostly agree.

            On a related note – think that Valve under-estimated the burden on small devs to tweak & tune game resources & engines.
            They’d been working on VR for many years & working through things.
            If you look at the likes of the games/experiences in “The Lab” and how gorgeous it looks, as well as performs consistently well on fairly low-end / entry-level GPUs, it’s very impressive.
            Their use of variable super-sampling made a lot of sense & was well implemented. I think that the vast majority of Vive titles are NOT using this technique & are therefore either limiting the game (/lower quality visuals) or faced with dropped frames.

            I wish that on-the-fly super-sampling was a de facto standard in games – higher quality visuals & less issues with dropping frames.
            Regardless, it’s encouraging to see continual improvement in VR, as well agree that the more people who can afford to buy-in, the better off the market will be.

          • DougP

            Re: “occasionally warped”
            ATW is rotational only – artefacts for translational movement. Much more of a problem with room-scale where the user is moving in/through 3D-space. Not as noticeable with a seated (single point of view) experience.
            With Oculus’ primary focus having been seated & 180-degree, you can see what the artefacts were less of a concern than with Valve’s – “VR = room-scale” philosophy.

      • Joe Banes

        “So more people will have an inferior experience & possibly be turned off of VR.”
        I think you are making a pretty big assumption here. A couple actually. We’ll have to see how this ends up working out before we can make these assumptions. Hitting 90fps isn’t an issue for only Nvidia/AMD to solve. Software developers have to work on it too. To have a software feature that can help with this (so long as it works well) is actually a big win. Oculus is trying to help with the part the hardware can’t control on the development side. I do agree that you want the best possible experience to show people VR and that bad VR can turn people off, but assuming the drop from the 970 to the 960 and adding something that will help, not only the min specs, but the higher ones as well, will lead to bad experiences is simply an opinion that you have no facts to back up yet. You may well be right in the end, but until we see ASW we can’t say. Even Oculus said nothing beats a true 90fps experience. It is not like they’ve lost site of that; but if someone’s intro to VR is a Gear or Cardboard and they want to move up, allowing a step up to something like a 960 rig and a $499 computer is a good start. Then people can add on and have even better experiences as they grow with it.

        • DougP

          Understood. I’ll admit I’m coming around on this one & optimistically thinking it will benefit.

          Good point about going from GearVR/Cardboard & wanting to move up, starting with a more moderate PC.
          VR isn’t cheap on its own.

          Re: ATW
          ATW is rotational only – artefacts for translational movement. Much more of a problem with room-scale where the
          user is moving in/through 3D-space. Not as noticeable with a seated (single point of view) experience.
          As for ASW – it will be interesting to see where Valve goes with this, as so many (vast majority) of Vive games are targeted at room-scale, how spacial aspect is handled will be very important.

          With Oculus’ starting primary focus having been seated & 180-degree, you can see what the artefacts were less of a concern than with Valve’s – “VR = room-scale” philosophy.

          Related – VR indie devs have not had the experience/knowledge & resources to tweak & tune their games.

          If everyone was utilizing the likes of Valve’s (demonstrated so well in “The Lab”) on-the-fly variable super-sampling, visuals can be cranked up on more moderate h/w & still maintain 90fps.

          • Joe Banes

            Yeah. Of course if it makes developers lazy, expecting the ASW to do the work for them, then I may have to come back your way as that will undoubtedly (in my mind) lead to poorer experiences. I’m just really curious about how it’s all going to work in true usage as opposed to the theory we’ve seen so far. Then again I don’t want to buy a 960 and i3 to test it out. Hah. Though I do have an old i7 2600k and 970 in one system. Perhaps I can test it on my low system now and then see what happens when games start using ASW.

          • DougP

            hehe – I hear ya.
            Hopefully with the likes of 960s (Oculus new min spec recommendation?) we’ll see most games still hitting 90fps consistently.
            Reports are that many people can feel sick from continuous ASW, so here’s hoping we don’t see devs releasing games where they’re running with ATW/ASW continuously.

            Valve just released the async reprojection in SteamVR beta, so going to try it out tonight.
            I’ve got a few titles, with graphics cranked up, that do drop frames (Raw Data for example).
            Be very interested to see how Valve handles *spacial* (~ASW) down-the-road.

        • I’ve tried ASW and it works very well. I’ve seen the artifacts produced when you push graphic settings well beyond the GPU but having said that the artifacts are very minor. The thing is not to push graphic settings to ridiculous levels versus whatever GPU the user has. Some are just pushing everything to ultra on a GTX 970 because they have ASW. That isn’t sensible for something like Pcars or Elite D. ASW works very well. On the other hand I’ve just tried the Vive async and it does feck-all so far. DCS World with mig 21 even on lowest settings is still unplayable whereas with ASW on Vive it’s smooth! I have to see if I’m doing it right with steamvr.

      • I agree in part with you. I’ve read enthusiastic feedbacks on reddit about ASW… yes, you can see artifacts, but you can actually play VR. People are saying that it is very good. So, if Oculus is enabling more people to use VR, well, that’s a welcome news.

    • Cameron Pickerill

      Oculus hasn’t actually lowered the requirements at all though, they’re just telling people they can use crappier hardware. It will work very poorly on that hardware however, and many VR experiences will not work properly with it.

      • Well, feedbacks from reddit communities are very different. I have a VR-ready PC, so I can’t judge by myself, but I’ve read enthusiastic feedbacks…

    • polysix

      Specs lowering is ok, but not the ideal situation. Better to help costs/mass adoption would have been PRICE LOWERING on the Rift itself, now outclassed in many ways (lenses, comfort, build and reliability) by the much better selling PSVR. Rift only cost $200 without R&D/wages and has at least a 50% mark up – more lies from facebook on the ‘sold at cost’ crap.

      If facebook cared about VR they would sell these things cheaper to more people, they have admitted – ADMITTED already that they priced it higher than needed so as to appear ‘aspirational’ in the same way apple do with their rabid pack of sheep. That is hardly for the good of VR at this early stage is it?

      Thank god Microsoft and Valve are in the PC VR game too (MS just announced today next year a raft of HMDS starting at $300!). THAT is what will save PC VR cos Oculus, sorry, Facebook sure as shit don’t care about PCVR only about FACEBOOK data collection and control.

      • Can you give me the sources of when facebook admitted they overpriced the Rift, please? As a blogger I’m interested in them.
        About PSVR, please don’t. PSVR is better than Oculus only for comfort and price. Everyone knows that PSVR + PS4 is the worst headset among tethered device. It’s selling a lot because it is a good headset with a good price 🙂

  • Carl Wolsey

    Valves version of ATW has just been release in SteamVR beta.

  • Lets see the progress!