Simplified screen capture: record video of only what appears within the layers of a UIView?

Question

This SO answer addresses how to do a screen capture of a UIView. We need something similar, but instead of a single image, the goal is to produce a video of eve

Answer 1

It sounds like your "fast" merge doesn't involve (re)-encoding frames, i.e. it's trivial and basically a glorified file concatenation, which is why it's getting 60x realtime. I asked about that because your "very slow" export is from 3-6 times realtime, which actually isn't that terrible (at least it wasn't on older hardware).

Encoding frames with an AVAssetWriter should give you an idea of the fastest possible non-trivial export and this may reveal that on modern hardware you could halve or quarter your export times.

This is a long way of saying that there might not be that much more performance to be had. If you think about the typical iOS video encoding use case, which would probably be recording 1920p @ 120 fps or 240 fps, your encoding at ~6x realtime @ 30fps is in the ballpark of what your typical iOS device "needs" to be able to do.

There are optimisations available to you (like lower/variable framerates), but these may lose you the convenience of being able to capture CALayers.