In October, Nvidia updated its GeForce Experience software to enable ShadowPlay, a feature that lets users easily record in-game action using the video encoding block built into Kepler GPUs. ShadowPlay was initially limited to creating local video files, but the latest GFE update allows the capture tool to send footage directly to streaming site Twitch.tv.
ShadowPlay records local video at 1080p using one of three quality settings that correspond to 15, 22, and 50Mbps. Twitch streaming appears to stick with the same resolution, but the video quality is lower. Nvidia's introductory article says an Internet connection with 3.5Mbps of upstream bandwidth is required for Twitch's high-quality mode. Medium- and low-quality options call for 2Mbps and 0.75Mbps, respectively. Streaming should still have a minimal impact on in-game frame rates, but there's no word on how it might affect ping times in multiplayer games.
Nvidia has beefed up ShadowPlay with a couple of other features to complement the new streaming functionality. Game streams can now include a webcam overlay, so that audiences can watch both game and player. Broadcasters can control the size and location of the webcam window, and they can toggle the overlay with a simple key combo. It's also possible to mix microphone input with the in-game audio, which should be a boon to folks who like to provide running commentary as they play.
If you want to try ShadowPlay streaming for yourself, you can grab the GeForce Experience 1.8.1 update right here. Nvidia describes this as the "first beta release" for Twitch streaming, so there might be a few bugs. I suspect Nvidia will address any issues with future updates, and the firm has already pledged to expand ShadowPlay further. A desktop capture mode and "enhanced microphone control" are up next.