Blur Busters Forums

Can anyone confirm that recording with Shadowplay adds input lag? If so, how much?

Also, can anyone confirm whether or not Shadowplay adds input lag by simply being activated and set to manual/not recording (nvspcaps64.exe should be running while activated in the GFXP menu).

I'm fairly confident that I'm feeling at least a subtle amount of input lag while recording regardless of my recording settings (resolution, bitrate, frame rate).

I'm a little less confident that having Shadowplay in manual mode, but not recording, also adds some input lag, but my aim does seem to feel off during this state.

If I completely wipe nVidia drivers with DDU and install the latest driver without GFXP, my aim feels crisp and responsive as I'd expect.

Of course, I'd like to rule out placebo and I figured this would be the best community to ask in terms of getting some actual tests and data or at least thoughts from experienced users on the topic.

Whether Shadowplay adds input lag depends on whether you have the option enabled that makes it capable of capturing the desktop. If that option is enabled, the game doesn't run detached from the capture anymore. Shadowplay will inject itself into the game's code in that mode and this will add overhead. Which will most probably add input lag.

With that option disabled, shadowplay will use frame buffer capture which does not (in theory) add input lag, since the game doesn't need to wait for Shadowplay to capture the frame.

If you want to research this yourself, the two modes are "Inband Frame Readback" (NVIFR) for desktop capture (has overhead), and "Frame Buffer Capture" (NVFBC) for exclusive fullscreen capture (no overhead.)

RealNC wrote:Whether Shadowplay adds input lag depends on whether you have the option enabled that makes it capable of capturing the desktop. If that option is enabled, the game doesn't run detached from the capture anymore. Shadowplay will inject itself into the game's code in that mode and this will add overhead. Which will most probably add input lag.

With that option disabled, shadowplay will use frame buffer capture which does not (in theory) add input lag, since the game doesn't need to wait for Shadowplay to capture the frame.

If you want to research this yourself, the two modes are "Inband Frame Readback" (NVIFR) for desktop capture (has overhead), and "Frame Buffer Capture" (NVFBC) for exclusive fullscreen capture (no overhead.)

This seems counter-intuitive. If it can't record the desktop and instead only captures games, surely it must try and interact with the games in some way. On the other hand, capturing the desktop could easily be done by just using the frame buffer with no regard to whether or not you are playing a game. What am I missing?

If it does, it's negligible. I keep shadow play on at all times. It's especially useful for battlefield. Man oh man do I wish shadow play was around years ago. I just recorded this one today.

http://youtu.be/LGxR5sjbKZY

I think silikone may be correct on this one.

According to https://developer.nvidia.com/capture-sdk

NvFBC works by capturing the entire contents of the desktop to a GPU buffer without stalling, or interfering with, the other work on the GPU. On Windows, the capture can occur with the Windows Desktop Manager enabled or disabled. This buffer can then be encoded using H.264 or HEVC via on-chip hardware video encoder through the NvEncode API.

NvIFR captures the content of an application’s DirectX, OpenGL or Vulkan render context. This captured buffer can then be encoded using H.264 or HEVC via on-chip hardware video encoder and NvEncode API.

Unless I'm missing something, it seems to enable NvFBC you would select 'Yes' for desktop capture and for NvIFR, you would select 'No'.