low framerate when use with SCNView.

[noppefoxwolf]

When use SCNView's scene, output video file's framerate very low.

let sceneView = SCNView()
let scene = SCNScene()
sceneView.scene = scene
writer = try SCNVideoWriter(scene: sceneView.scene)

[okaris]

Can be probably overcome by using this https://developer.apple.com/documentation/avfoundation/avassetwriterinput/1387508-requestmediadatawhenreadyonqueue Instead of using the display link. This might need a control over frame rate manually and a semaphore to wait until the previous frame is finished writing.

[noppefoxwolf]

Thanks. looks like requestMediaDataWhenReadyOnQueue:usingBlock: running 120 fps on iPhone6s.
If the problem of fps can be solved, I use requestMediaDataWhenReadyOnQueue:usingBlock:.

Or, add completion task re encode video to optimize fps.(maybe slow)

[okaris]

I have forked your project and will be maintaining it here https://github.com/svtek/SceneKitVideoRecorder

I have also given credit on the Readme. I will be changing more in the coming days.