Recording software that records last X seconds from when you hit record

Question

EDIT: I now want this functionality for my iPad also, and not just screen capture of iOS's functioning, but also for the video camera--I want to leave my video camera recording for hours so I can film a hardware malfunction on my TV. As soon as the malfunction happens, I want to hit the save button and be able to save the part of interest.

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A friend told me about NVIDIA GeForce's audio recording software that will record up to the last 20 minutes worth of audio & video from your computer as soon as you hit the Record button:

Shadow every game. Share every victory. ShadowPlay records up to the last 20 minutes of your gameplay. Just pulled off an amazing stunt? Hit a hotkey and the game video will be saved to disk. Or, use the manual mode to capture video for as long as you like.

I do not have this hardware, so I have been looking for software with the same functionality.

Does anyone know the name for this kind of functionality? Or is NVIDIA the only company to make this software?

I want it because I'm playing a video game and there is a sound I want to capture, but it only occurs very rarely, so I don't want to have software recording hours of gameplay sound just for the 3 seconds when it finally happens.

(I'm running OS X 10.10)

Answer 1

As a more computer-oriented solution for folks looking to do something similar on their computer, OBS has a "replay recording" feature where you can configure a set amount of memory for OBS to just recording to in the background. Then whevever you click the "save replay" button, OBS will save the contents of this memory buffer (the clip duration depends on how much memory you allow OBS to use for this) as a video clip in a configured location. This often used by streamers to save particularly awesome moments of gameplay moments after they happen, but it will also work for anything you plan to record using OBS.

OBS is open source and should have download links for Mac, Windows, and Linux.

Answer 2

I have found a solution for iOS: there are many pieces of software that allow your mobile device to function as a dashboard camera.