AVMutableComposition resizing issue

Question

I\'m trying to render an image into a video captured with the front camera using AVMutableComposition. The size of the resulting video (including the image) is

Answer 1

Try applying a negative scale transform to flip the video when mirrored:

// Create an AvmutableVideoCompositionLayerInstruction
let videoLayerInstruction = AVMutableVideoCompositionLayerInstruction.init(assetTrack: videoTrack!)
let flipped = videoAssetTrack.preferredTransform.scaledBy(x: -1.0, y: 1.0)
videoLayerInstruction.setTransform(flipped, at: kCMTimeZero)
compositionInstructions.layerInstructions = [videoLayerInstruction]