How to record video with ARCore with Unity?

I have been stuck on this problem for over a month now. I just need to record the video feed when people are using the AR app.

There are several options:

1. Take the screenshot in Unity for every frame.
I tried taking a screenshot every frame. This is way too slow. The fps is only 5.
Then I tried saving the texture to an array and encode them to images afterwards.
This would take a lot of memory and would cause a significant frame drop on mobile phone. The fps is around 10.
If anyone has a great idea for this method, please let me know.

2. Use native plugins to record video.
I haven't found any solutions on this one. I am afraid that this may conflict with the ARCore.

I know that there is an Android solution but ideally I want to use Unity. Any help is appreciated, thank you!

3. Save the texture from the texture reader api provided by ARCore computer vision example.
There is a Computer Vision example in the directory. And I can get the texture directly from GPU with its api.

However, the fps is still low. With its edge detector example, the fps is around 15. I succeeded in saving those frames to local directory in another thread. But the fps is still not acceptable. The bottomline is 720p at 30fps.

PS: I just need to save the frames. I can handle encoding them into videos.

PPS: Just recording the camera feed and recording the camera feed and the augmented objects together are both okay. Either one achieved is great.

You can easily implement video recording AND sharing using the (really great) NatCorder unity asset (asset store link) and the related NatShare API. I did this very same thing in my own ARCore experiment/"game."

Edit: you may have to implement this workaround to get a smooth framerate.