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This modified openvr_api.dll allows you to apply FidelityFX SuperResolution upscaling to many SteamVR games, as long as they use D3D11.

FidelityFX Super Resolution (FSR for short) is an upscaling technique developed by AMD, but it works on pretty much any graphics card, including NVIDIA cards. The idea is that the game internally renders to a lower resolution, thus saving GPU time and reaching higher FPS, as long as it is not bottlenecked by the CPU. The resulting lower resolution render is then upscaled to the target resolution by FSR, with the aim of restoring some of the lost detail due to the lower resolution rendering. It does so in two steps - the first being the actual upscaling to the target resolution, where particular attention is paid to edges in the lower resolution picture. The second step is a sharpening step to counter some of the blur introduced by the upscaling.

Note that, unlike DLSS, FSR is not an anti-aliasing solution. Any aliasing and shimmering edges present in the original image will not be fixed by FSR. As such, the final image quality of FSR depends a lot on the particular game you are using it with. AMD specifically advises that FSR should be used in conjunction with the highest-quality anti-aliasing setting a game has to offer. In the case of VR games, that means enabling MSAA if it is available, or else TAA. You may also want to experiment with turning off any sort of post-processing effects in the games, as some of these should ideally run after FSR, but with this plugin will run before it and so may negatively affect the image quality.

First, download the openvr_fsr.zip file from the latest release under "Assets".

Then find the location of the openvr_api.dll in the game's installation folder:

• It might be located right next to the main executable (e.g. Skyrim, FO4).
• For Unity games, look in: <GameDir>\<Game>_Data\Plugins
• For Unreal 4 games, look in: <GameDir>\Engine\Binaries\ThirdParty\OpenVR\OpenVRvX_Y_Z

Rename the existing openvr_api.dll to openvr_api.orig.dll, then extract both the openvr_api.dll and the openvr_mod.cfg from the archive to this directory. You should now edit the openvr_mod.cfg to your liking and adjust the renderScale and sharpness parameters to your liking.

In case you want to uninstall the mod, simply remove the openvr_api.dll file again and rename the original openvr_api.orig.dll back to openvr_api.dll.

In case you run into issues, the log file (openvr_mod.log) may provide clues to what's going on.

The mod is configured by editing the values in its config file, openvr_mod.cfg. The most important setting is renderScale, which determines the lowered render resolution that the game will be using internally. If you have set a render resolution of e.g. 2244x2492 in SteamVR, then that's the target resolution. The internal resolution will be scaled by the value of renderScale in both dimensions. For example, if renderScale is set to 0.75, then the actual render resolution will become 1683x1869. The render is then upscaled by FSR to the original resolution of 2244x2492.

If you set a value higher than 1 for renderScale, then the game will render at the native resolution, i.e. the one configured in SteamVR. But FSR will then take this render and upscale it to a resolution multiplied by the value of renderScale in each dimension. For example, if the resolution in SteamVR is 2242x2492 and you have configured a value of 1.3 for renderScale, then the game will render at 2242x2492, but the image will be upscaled by FSR to 2915x3240.

The second relevant parameter is sharpness. Generally, the higher you set sharpness, the sharper the final image will appear. You probably want to set this value higher if you lower renderScale, but beware of over-sharpening. The default of 0.9 gives a fairly sharp result. You can increase it up to 1.0 if you like an even sharper image. But if the image is too sharp for your taste, consider experimenting with lower values.

While rendering at a lower resolution will save you performance (which is the entire point), the FSR upscaler does have a fixed cost in GPU time, and this time depends on your GPU and the target resolution (not the render resolution). So the higher your target resolution, the higher the cost of the FSR upscaler. It means that, the higher your target resolution, the lower you may have to set the render resolution (by lowering renderScale) before you see an actual net benefit for your GPU times.

A part of the overhead of FSR can be mitigated by using a sort of "fixed foveated" optimization where only the center of the image is upscaled by the more expensive FSR algorithm, while the edges are upscaled by cheaper bilinear sampling. This can be controlled in the mod by the radius setting, where anything within the radius from the center of the image is upscaled with FSR, and anything outside is upscaled with bilinear filtering. Due to the natural loss of clarity in the edges of current HMD lenses, even with a fairly small radius you will probably have a hard time to tell the difference.

Example results:

• Skyrim VR
• Fallout 4 VR Native vs FSR modes
• Fallout 4 VR Native vs FSR upsampling vs CAS sharpening

• If you encounter issues like the view looking misaligned or mismatched between the eyes, or one eye is sharper than the other, try setting radius to 2 in the config and check if that fixes it. This will disable a performance optimization, but it doesn't always work with all games or headsets.
• If you encounter missing textures or banding, try setting applyMIPBias to false in the config.
• If your tracking stops working or is misbehaving with the mod applied, there is a chance that you copied the mod DLL to the wrong place. Please re-read the installation instructions and take special note of the plugin subfolders for Unity and Unreal engines.

This is a best-effort experiment and hack to bring this upscaling technique to VR games which do not support it natively. Please understand that the approach taken here cannot guarantee the optimal quality that FSR might, in theory, be capable of. AMD has specific recommendations where and how FSR should be placed in the render pipeline. Due to the nature of this generic hack, I cannot guarantee nor control that all of these recommendations are actually met for any particular game. Please do not judge the quality of FSR solely by this mod :)

I intend to keep working on the performance, quality and compatibility of this mod, so do check back occasionally.

• Half Life: Alyx and Star Wars: Squadrons do not work, because they don't like you replacing their openvr_dll.api.
• Please report any other game that isn't working, assuming that it is a SteamVR game and uses D3D11 for rendering.

OpenVR is an API and runtime that allows access to VR hardware from multiple vendors without requiring that applications have specific knowledge of the hardware they are targeting. This repository is an SDK that contains the API and samples. The runtime is under SteamVR in Tools on Steam.

Documentation for the API is available on the GitHub Wiki

More information on OpenVR and SteamVR can be found on http://steamvr.com