Rift Display Options Added: Alpha 4

This alpha release of the CtrlAltStudio Viewer updates to Rift SDK 0.4.3 and adds the following Rift display options:

  • Dynamic prediction — Adjust prediction based on latency feedback.
  • Timewarp — Reproject scene during distortion rendering.
  • Timewarp waits — Wait until the last moment to do timewarp.
  • V Sync — Wait for and swap buffers at monitor vertical sync.
  • Low persistence — Display low persistence images.
  • Pixel overdrive — Over-drive brightness transitions to reduce artefacts.

All these options are enabled by default. Changes take effect immediately (no viewer restart required) so you can easily experiment with them.

The “Timewarp waits” option shouldn’t really be made visible to the user, but in my testing I found that it seemed to help to be able to turn it off if rendering at significantly less than the frame rate the DK2 is set at. The variability of the frame-to-frame timing in Second Life may well be why.

The optimum settings depend on what frame rate you’re achieving and your personal preferences and sensitivities to different display behaviour: if you’re achieving the ideal of 75Hz including while turning your head then the default of all options enabled is best; otherwise you will probably want to try disabling one or more, consider configuring your Rift display to 60Hz, and possibly try enabling triple buffering in your display driver.

Other changes this version:

  • Updated GPU table. This now includes NIVIDIA GTX 970 and 980 graphics cards.
  • Fixed Riftllook mouse hover target and context menu locations for in-world objects.
  • Fixed Rift positioning in third person orbit camera view.

Please note that this alpha still does not work with direct mode, and Advanced Lighting Model needs to be turned on. It is built using the 0.4.3 Rift SDK and if you haven’t done so already you should update to the 0.4.3 Oculus runtime.

Viewer download:

  • Windows installer: Alpha 4, 2 Nov 2014.
  • Mac OSX installer: Sorry, no Mac OSX installer.

Release Notes.

Comments (22) Leave a comment

    1. David Rowe Post author

      Yes, hopefully a few steps forwards and not too many backwards. I’ll try out SDK 0.4.4 as soon as I can. I’m unfortunately in the middle of resurrecting a failed C: drive but hope to get onto it soon.

      I have managed to toggle from normal display into direct mode with OpenGL and SDK 0.4.3 but haven’t managed to get it toggling back to normal display again.

  1. xanathon


    I just updated from an ATI 7850 to an GTX 970 (since nothing worked on the ATI DK2-wise, even if it should, the drivers seem just to be really bad). With the new card 95% of the OR-DK2-demos that juddered heavily work really fine. The new version of CtrlAltStudio that is compilded with the SDK 0.4.3 (1.2.2 (41214)) is one of those. It looks like the two images are not correctly overlayed and I get heavy ghosting that leads to instant dizzyness and nausea. DK2 is in Extended Mode and primary monitor. The machine is an i5 at 3,4 GHz and 16GB ram. OS is Win7 with all patches. Videocard driver ist the latest (downloaded it when installing the card on thursday). Any ideas where to tweak?


    1. David Rowe Post author

      Hi Xanathon. See the “Oculus Rift usage” and “Further Rift tips” sections in the release notes, http://ctrlaltstudio.com/viewer/releases/1-2-2-41214-alpha-4 . You can display the FPS you’re achieving by pressing Ctrl+Shift+1 to bring up a Statistics window. Reducing draw distance, in particular, has a marked effect on frame rate. Also, if you have a USB monitor connected this can seriously affect frame rates. With a GTX 970 your experience should be pretty good! And as long as you don’t try to render too much content you should be able to achieve a pretty consistent 75 FPS and be able to have most if not all of the 6 options “Dynamic prediction, timewarp, timewarp waits, V sync, low persistence, and pixel overdrive enabled in the viewer configuration.

      You say that the two images are not correctly overlaid and there’s heavy ghosting. I wonder, is your Oculus runtime / drivers up to date? In the Oculus Configuration utility, the Help > About page should show Oculus Configuration Utility version 1.5 (SDK 0.4.3) with display driver and camera driver Also, on the home page of the configuration utility it should say that you have firmware 2.12 installed in your DK2.

      1. xanathon

        Thanks for your answer. Yes, the config utility, firmware and drivers are up to date, I updated those some time ago, when 0.4.3 became available. No USB monitor. I’ll try decreasing the draw distance, but that is on standard, as I never changed it.

        When I press CTRL+SHIFT+1 nothing happens. And I am not able to set highest possible frame rate in the Nvissa settings for CtrlAltStudio. That setting is missing. I already tried the hints from the linked post.

        I will do further tests tomorrow.

        1. David Rowe Post author

          Alternative to Ctrl+Shift+1:
          – Avatar > Preferences > Advanced > Show Advanced Menu
          – Advanced > Performance Tools > Statistics Bar

  2. nabz

    Worked w/ Alpha 4 on DK2 over GTX560ti with Rift Display Mode Extended. DK2 as HDMI shows up as Display 1 left of the primary display. DK1 (cables pulled for this DK2 run) as secondary DVI shows up as Display 2 right of the primary display if DK2 pulled.
    1. I had to put Rift DK2 monitor into Portrait not Landscape.
    2. Win Logo key + rt arrows did nothing (?) so I slid viewer normal window left until just window frame buttons visible and the maximized it – it expanded full screen onto the DK2.
    Leaned in on someones curio cabinet in SL to see their tiny things – pretty cool. :)

    1. David Rowe Post author

      Hey, I’m glad you’ve got it up and running. : )

      Windows logo and arrow keys: these are just standard Windows keyboard commands. With your DK2 on the left of your primary monitor, use Win + left arrow to move your viewer window onto your monitor (may have to press it a couple of times). And if you exit Riftlook you can use Win + right arrow to move it back onto your monitor. … Just a bit easier than dragging.

  3. Solomon


    – Configuration utility in tray
    – Firmware and all drivers mentioned above are up to date.
    – no Usb monitor
    – i have not measured IPD, but i dont see why this would make a difference
    – Demos work and i can use this on other games
    – Extended mode activated

    There’s another guy with the same issue on the oculus forum:

    I wonder if it has to do with my having a GTX 970. Driver Compatibility issue? I know it’s caused some other issues for people…

    I even re-installed your viewer…

    Are you using extended mode?
    What graphics card are you using?

    1. David Rowe Post author

      The GPU table that the viewer uses was been updated to include GTX 970 in the alpha 4 release. Are you using the alpha 4 version? The viewer should display “CtrlAltStudio Viewer Alpha” in the window title bar.

      Yes, you need to use extended mode. Other viewer usage instructions and tips are included in the release notes: http://ctrlaltstudio.com/viewer/releases/1-2-2-41214-alpha-4

      If you still can’t get it going, could you please send me your program log? After exiting the viewer you’ll find it in C:\Users\\AppData\Roaming\CtrlAltStudio Viewer\logs as the file CASviewer.log. It may contain some clues to help work out why the viewer isn’t working for you.

  4. Solomon Wang

    When I go into 3d mode, the two serpate screens pop up and sit in the corner of the screen. Not sure if this is a resolution issue, but no matter what resolution i used, the two side by side views didn’t line up with my dk2. I am set to extended mode and am using a GTX 970 (wondering if this might be the issue). Also, no head tracking works. It seems like it’s not picking up my oculus and properly seating the images into the viewer and doesnt enable position tracking. Someone else on the oculusvr forums is experiencing this issue as well. Has anyone else experienced this or does anyone have any thoughts on how to fix this?

    1. David Rowe Post author

      Hi. I’ve not heard of anyone having this problem before now! The display problems plus lack of tracking seem to indicate a problem with your DK2 connection and software installation or some incompatibility with your PC setup.

      You keep the Oculus Configuration Utility running in your Windows system tray? (You should.)
      The Oculus Configuration Utility’s main screen reports that your DK2 has firmware version 2.12? (If not, you need to upgrade it.)
      The Oculus Configuration Utility’s help screen reports that you have SDK 0.4.3 runtime installed?
      Also on that screen for me it reports …
      – Display Driver Version:
      – Camera Driver Version:
      – Connected to OVRService server.
      You have no USB monitors connected?
      Have you measured your IPD?
      Does the “Show Demo Scene” button in the Oculus Configuration Utility successfully show the demo scene on your Rift complete with head tracking?

      Once you have the DK2 successfully showing the demo scene then the viewer should work.

  5. pajuelo

    I will try to compile it on linux and make a 32bit linux build this weekend.

  6. Alan

    Can’t wait to try. Sounds like these optimizations may improve performance over the official viewer, which would be great!

  7. Pingback: Viewer release summaries: week 44 | Living in the Modem World

    1. David Rowe Post author

      In theory, quite possibly. Note however that the base viewer code hasn’t been updated to work with Linux; there are some mods that need to be made to get it to build. And I believe there are also some caveats in the LINUX_README in the Linux Rift SDK but I don’t know the details.

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