I'm assuming you mean how can you encode the output of the nvidia card to a memory buffer using an API?
The NVENC API allows you to do this on your commodity NVidia card. If you have the good stuff from NVidia, you can likely use the Capture SDK, which is a bit more scalable. If you use AMD there is AMF. And if you're cheap, you can just use QuickSync from Intel. All of the encoding API's will likely be unified with an industry wide API a la opengl at some point in the future, but it won't be implemented by everyone in a timely fashion, so you have to pick your poison right now.
One gotcha though, you can only do this if your game engine's license allows. Which means anyone who uses Unity is out of luck. Unreal and other engines? I don't know, I think you can talk to the companies and they'll probably? give you permission? (At least I'd hope they would give you permission until they go into the cloud gaming business.)
Your best shot though is just to take an open source engine, like Godot, and "NVENC it up" so to speak. It'll take maybe a couple of hours and it'll save you a lot of headache.
Nvidia's is called GameStream, and has been in consumer cards for about 4-5 years now. Moonlight[1] is an open-source client that lets you stream your PC games to most any device.
They may be referring to ShadowPlay, a feature that keeps a buffer of the output so you can save something that just happened. Again, available for 4-5 years.
The NVENC API allows you to do this on your commodity NVidia card. If you have the good stuff from NVidia, you can likely use the Capture SDK, which is a bit more scalable. If you use AMD there is AMF. And if you're cheap, you can just use QuickSync from Intel. All of the encoding API's will likely be unified with an industry wide API a la opengl at some point in the future, but it won't be implemented by everyone in a timely fashion, so you have to pick your poison right now.
One gotcha though, you can only do this if your game engine's license allows. Which means anyone who uses Unity is out of luck. Unreal and other engines? I don't know, I think you can talk to the companies and they'll probably? give you permission? (At least I'd hope they would give you permission until they go into the cloud gaming business.)
Your best shot though is just to take an open source engine, like Godot, and "NVENC it up" so to speak. It'll take maybe a couple of hours and it'll save you a lot of headache.