ShadowPlay And Benchmarks
ShadowPlay doesn't have anything to do with Nvidia's Shield update, but the company's proprietary NVEnc encoder is a critical piece of GameStream, so we still wanted to test its capabilities.
Like GameStream, ShadowPlay is controlled from Nvidia's GeForce Experience software. You can set it to Manual mode (start and save recordings on-demand), Shadow mode (always record the last one to 20 minutes of video, and save on-demand), or a combination of both. In-game, controlling ShadowPlay is easy; Alt-F10 saves the Shadow recording and Alt-F9 begins/ends a Shadow recording. A small green dot on the screen indicates a recording in progress, if you want visual confirmation.
Nvidia claims that, unlike Fraps, the performance hit attributable to ShadowPlay is negligible due to its hardware-based nature. Despite initial skepticism, during gameplay, I couldn't tell whether the feature was running or not. In the interest of getting more specific, let's look at the benchmark data at 1920x1080 and 2560x1600. Note that the higher-resolution tests are run at lower detail settings so we can compare playable frame rates around 60 FPS. In addition, it's worth noting that ShadowPlay is currently limited to 1920x1080, so a 1600p stream gets scaled down. Moreover, all of these tests were performed on a platform driven by AMD's $110 FX-4170 CPU.
Regardless of resolution average frame rates take a roughly 10% with ShadowPlay enabled. Given enough performance, I couldn't tell the difference. The higher-resolution result ran into more of a hit to its minimum frame rate, though.
Does encoding video in real-time affect frame time variance?
ShadowPlay has a negligible effect on any of our frame time variance measurements. You can see a few spikes in the over-time chart, but we're already limiting the chart's sample size to 300 frames for readability, and Far Cry 3 inherently demonstrates more variance than other titles.
Next, let's see if the GeForce GTX 660 fares better or worse than a Titan when it comes to ShadowPlay. We again vary the detail levels to keep frame rates in the same ballpark.
Because NVEnc is a fixed-function hardware block, its performance doesn't appear to scale. Instead, we see similar deltas with ShadowPlay on or off.
At the end of the day, ShadowPlay's ability to offload video encoding is very impressive. Capturing boss kills in a game like World of Warcraft is popular, but every genre can enjoy visual commemoration of epic moments. Previously, this was very processing- and capacity-intensive. Now, it's not bad at all. If in-game video capture is important to you, ShadowPlay might be a very compelling feature. In addition, Nvidia will add one-click broadcasting of ShadowPlay to Twitch, a popular online provider that specializes in game video.
