I’m empirically trying to get the right instructions from an AVCompositionTrack.

func compositionLayerInstruction(for track: AVCompositionTrack, assetTrack: AVAssetTrack) -> AVMutableVideoCompositionLayerInstruction {
    
    let instruction = AVMutableVideoCompositionLayerInstruction(assetTrack: track)
    
    var transform = assetTrack.preferredTransform
    let assetSize = assetTrack.naturalSize

    let tranA = transform.a
    let tranB = transform.b
    let tranC = transform.c
    let tranD = transform.d
    
    if tranA == 0 && tranB == 1 && tranC == -1 && tranD == 0 {
        transform = CGAffineTransform(a: 0, b: 1, c: -1, d: 0, tx: assetSize.height, ty: 0)
    }
    if tranA == 0 && tranB == 1 && tranC == 1 && tranD == 0 {
        transform = CGAffineTransform(a: 0, b: 1, c: 1, d: 0, tx: 0, ty: 0)
    }
    if tranA == 1 && tranB == 0 && tranC == 0 && tranD == 1 {
        transform = CGAffineTransform(a: 1, b: 0, c: 0, d: 1, tx: assetSize.width, ty: assetSize.height)
    }
    
    instruction.setTransform(transform, at: .zero)
    
    return instruction
}

I’m doing it using a trial and error approach.
I get the preferredTransform property of the assetTrack and I try to apply the correct CGAffineTransform transformation verifying that the video is in the right orientation.
The first 2 transformations are working fine.

This process is driving me crazy.
The questions I have are these:

How can I understand what is the 4th case in the if statements if I haven’t already encountered it?

What kind of transformation should I apply to the 3rd and 4th cases?
Is there a way to understand how this transform thing works?