Setting AVMutableVideoComposition instruction causes handler not to be called

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I have a function to filter an AVPlayerItem's asset. One of the problems was setting the transform of the video. However, whenever I set the AVMutableVideoCompositionInstruction of the AVMutableVideoComposition, the handler is no longer called.

Here is my code:

private func filter(playerItem: AVPlayerItem) {

    let videoComposition = AVMutableVideoComposition(asset: playerItem.asset, applyingCIFiltersWithHandler: { (request) in
        print("Composing") // does not print whenever the instructions are added
        if let filteredImage = filterImage(request.sourceImage) {
            request.finish(with: filteredImage, context: nil)
        } else {
            request.finish(with: RenderError.couldNotFilter) // An error
        }
    })

    guard let videoTrack = playerItem.asset.tracks(withMediaType: .video).first else { return }

    let size = CGSize(width: videoTrack.naturalSize.height, height: videoTrack.naturalSize.width)
    videoComposition.renderSize = size

    let videoInstruction = AVMutableVideoCompositionInstruction()
    videoInstruction.timeRange = CMTimeRange(start: kCMTimeZero, duration: playerItem.asset.duration)

    let transformInstruction = AVMutableVideoCompositionLayerInstruction(assetTrack: videoTrack)
    let translate = CGAffineTransform(translationX: size.width, y: size.height)
    let rotate = CGAffineTransform(rotationAngle: CGFloat.pi)
    transformInstruction.setTransform(translate.concatenating(rotate), at: kCMTimeZero)
    videoInstruction.layerInstructions.append(transformInstruction)
    videoComposition.instructions.append(videoInstruction)

    playerItem.videoComposition = videoComposition
}

Why is the handler no longer called, and how can I fix it?

I will give you so many brownie points if you can answer!

1 Answers
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