So I've been trying for weeks now to implement a compression mechanism into my app project that compresses MV-HEVC video files in-app without stripping videos of their 3D properties, but every single implementation I have tried has either stripped the encoded MV-HEVC video file of its 3D properties (making the video monoscopic), or has crashed with a fatal error. I've read the Reading multiview 3D video files and Converting side-by-side 3D video to multiview HEVC documentation files, but was unable to myself come out with anything useful. My question therefore is: How do you go about compressing/encoding an MV-HEVC video file in-app whilst preserving the stereoscopic/3D properties of that MV-HEVC video file? Below is the best implementation I was able to come up with (which simply compresses uploaded MV-HEVC videos with an arbitrary bit rate). With this implementation (my compressVideo function), the MV-HEVC files that go through it are compressed fine, but the final result is the loss of that MV-HEVC video file's stereoscopic/3D properties. If anyone could point me in the right direction with anything it would be greatly, greatly appreciated. My current implementation (that strips MV-HEVC videos of their stereoscopic/3D properties): static func compressVideo(sourceUrl: URL, bitrate: Int, completion: @escaping (Result<URL, Error>) -> Void) { let asset = AVAsset(url: sourceUrl) asset.loadTracks(withMediaType: .video) { videoTracks, videoError in guard let videoTrack = videoTracks?.first, videoError == nil else { completion(.failure(videoError ?? NSError(domain: "VideoUploader", code: -1, userInfo: [NSLocalizedDescriptionKey: "Failed to load video track"]))) return } asset.loadTracks(withMediaType: .audio) { audioTracks, audioError in guard let audioTrack = audioTracks?.first, audioError == nil else { completion(.failure(audioError ?? NSError(domain: "VideoUploader", code: -2, userInfo: [NSLocalizedDescriptionKey: "Failed to load audio track"]))) return } let outputUrl = sourceUrl.deletingLastPathComponent().appendingPathComponent(UUID().uuidString).appendingPathExtension("mov") guard let assetReader = try? AVAssetReader(asset: asset), let assetWriter = try? AVAssetWriter(outputURL: outputUrl, fileType: .mov) else { completion(.failure(NSError(domain: "VideoUploader", code: -3, userInfo: [NSLocalizedDescriptionKey: "AssetReader/Writer initialization failed"]))) return } let videoReaderSettings: [String: Any] = [kCVPixelBufferPixelFormatTypeKey as String: kCVPixelFormatType_32ARGB] let videoSettings: [String: Any] = [ AVVideoCompressionPropertiesKey: [AVVideoAverageBitRateKey: bitrate], AVVideoCodecKey: AVVideoCodecType.hevc, AVVideoHeightKey: videoTrack.naturalSize.height, AVVideoWidthKey: videoTrack.naturalSize.width ] let assetReaderVideoOutput = AVAssetReaderTrackOutput(track: videoTrack, outputSettings: videoReaderSettings) let assetReaderAudioOutput = AVAssetReaderTrackOutput(track: audioTrack, outputSettings: nil) if assetReader.canAdd(assetReaderVideoOutput) { assetReader.add(assetReaderVideoOutput) } else { completion(.failure(NSError(domain: "VideoUploader", code: -4, userInfo: [NSLocalizedDescriptionKey: "Couldn't add video output reader"]))) return } if assetReader.canAdd(assetReaderAudioOutput) { assetReader.add(assetReaderAudioOutput) } else { completion(.failure(NSError(domain: "VideoUploader", code: -5, userInfo: [NSLocalizedDescriptionKey: "Couldn't add audio output reader"]))) return } let audioInput = AVAssetWriterInput(mediaType: .audio, outputSettings: nil) let videoInput = AVAssetWriterInput(mediaType: .video, outputSettings: videoSettings) videoInput.transform = videoTrack.preferredTransform assetWriter.shouldOptimizeForNetworkUse = true assetWriter.add(videoInput) assetWriter.add(audioInput) assetReader.startReading() assetWriter.startWriting() assetWriter.startSession(atSourceTime: CMTime.zero) let videoInputQueue = DispatchQueue(label: "videoQueue") let audioInputQueue = DispatchQueue(label: "audioQueue") videoInput.requestMediaDataWhenReady(on: videoInputQueue) { while videoInput.isReadyForMoreMediaData { if let sample = assetReaderVideoOutput.copyNextSampleBuffer() { videoInput.append(sample) } else { videoInput.markAsFinished() if assetReader.status == .completed { assetWriter.finishWriting { completion(.success(outputUrl)) } } break } } } audioInput.requestMediaDataWhenReady(on: audioInputQueue) { while audioInput.isReadyForMoreMediaData { if let sample = assetReaderAudioOutput.copyNextSampleBuffer() { audioInput.append(sample) } else { audioInput.markAsFinished() break } } } } } }

When I try to play video on my Apple Vision Pro simulator using a custom view with an AVPlayerLayer (as seen in my below VideoPlayerView), nothing displays but a black screen while the audio for the video i'm trying to play plays in the background. I've tried everything I can think of to resolve this issue, but to no avail. import SwiftUI import AVFoundation import AVKit struct VideoPlayerView: UIViewRepresentable { var player: AVPlayer func makeUIView(context: Context) -> UIView { let view = UIView(frame: .zero) let playerLayer = AVPlayerLayer(player: player) playerLayer.videoGravity = .resizeAspect view.layer.addSublayer(playerLayer) return view } func updateUIView(_ uiView: UIView, context: Context) { if let layer = uiView.layer.sublayers?.first as? AVPlayerLayer { layer.frame = uiView.bounds } } } I have noticed however that if i use the default VideoPlayer (as demonstrated below), and not my custom VideoPlayerView, the video displays just fine, but any modifiers I use on that VideoPlayer (like the ones in my above custom struct), cause the video to display black while the audio plays in the background. import SwiftUI import AVKit struct MyView: View { var player: AVPlayer var body: some View { ZStack { VideoPlayer(player: player) Does anyone know a solution to this problem to make it so that video is able to display properly and not just appear as a black screen with audio playing in the background?