Video aspect transform resizing

resize.swift

// let targetSize = CGSize(width: 100, height: 100) // whatever you want

var transform = videoAssetTrack.preferredTransform
let naturalSize = videoAssetTrack.naturalSize
let videoSize = CGRect(origin: .zero, size: naturalSize).applying(videoAssetTrack.preferredTransform).size

let rotation = atan2(transform.b, transform.a)
let isRotated = rotation.remainder(dividingBy: .pi) > 0.01
let offset = CGPoint.zero.applying(transform.inverted())

if videoSize != targetSize {

	// move back to rotation point if rotated
	transform = transform.translatedBy(x: offset, y: offset)

	let scale = CGSize(width: targetSize.width / videoSize.width, height: targetSize.height / videoSize.height)
	let maxScale = max(scale.width, scale.height)
	let scaledSize = videoSize * maxScale
	transform = transform.scaledBy(x: maxScale, y: maxScale)

	let scale = CGSize(width: targetSize.width / videoSize.width, height: targetSize.height / videoSize.height)
	let maxScale = max(scale.width, scale.height)
	let scaledSize = videoSize * maxScale
	transform = transform.scaledBy(x: maxScale, y: maxScale)

	// return to correct rotation offset
	transform = transform.translatedBy(x: -offset.x, y: -offset.y)

	var aspectOffset: CGPoint = .zero

	if scaledSize.width > targetSize.width {
		aspectOffset.x = -((scaledSize.width - targetSize.width) / 2) / maxScale
	} else if scaledSize.height > targetSize.height {
		aspectOffset.y = -((scaledSize.height - targetSize.height) / 2) / maxScale
	}

	if isRotated {
		transform = transform.translatedBy(x: aspectOffset.y, y: aspectOffset.x)
	} else {
		transform = transform.translatedBy(x: aspectOffset.x, y: aspectOffset.y)
	}
}