I’m experiencing a crash at runtime when trying to extract audio from a video. This issue occurs on both iOS 18 and earlier versions. The crash is caused by the following error: *** Terminating app due to uncaught exception 'NSInternalInconsistencyException', reason: '*** -[AVAssetExportSession exportAsynchronouslyWithCompletionHandler:] Cannot call exportAsynchronouslyWithCompletionHandler: more than once.' *** First throw call stack: (0x1875475ec 0x184ae1244 0x1994c49c0 0x217193358 0x217199899 0x192e208b9 0x217192fd9 0x30204c88d 0x3019e5155 0x301e5fb41 0x301af7add 0x301aff97d 0x301af888d 0x301aff27d 0x301ab5fa5 0x301ab6101 0x192e5ee39) libc++abi: terminating due to uncaught exception of type NSException My previous code worked fine, but it's crashing with Swift 6. Does anyone know a solution for this? ## **Previous code:** func extractAudioFromVideo(from videoURL: URL, exportHandler: ((AVAssetExportSession, CurrentValueSubject<Float, Never>?) -> Void)? = nil, completion: @escaping (Swift.Result<URL, Error>) -> Void) { let asset = AVAsset(url: videoURL) // Create an AVAssetExportSession to export the audio track guard let exportSession = AVAssetExportSession(asset: asset, presetName: AVAssetExportPresetAppleM4A) else { completion(.failure(NSError(domain: "com.example.app", code: -1, userInfo: [NSLocalizedDescriptionKey: "Failed to create AVAssetExportSession"]))) return } // Set the output file type and path guard let filename = videoURL.lastPathComponent.components(separatedBy: ["."]).first else { return } let outputURL = VideoUtils.getTempAudioExportUrl(filename) VideoUtils.deleteFileIfExists(outputURL.path) exportSession.outputFileType = .m4a exportSession.outputURL = outputURL let audioExportProgressPublisher = CurrentValueSubject<Float, Never>(0.0) if let exportHandler = exportHandler { exportHandler(exportSession, audioExportProgressPublisher) } // Periodically check the progress of the export session let timer = Timer.scheduledTimer(withTimeInterval: 0.1, repeats: true) { _ in audioExportProgressPublisher.send(exportSession.progress) } // Export the audio track asynchronously exportSession.exportAsynchronously { switch exportSession.status { case .completed: completion(.success(outputURL)) case .failed: completion(.failure(exportSession.error ?? NSError(domain: "com.example.app", code: -1, userInfo: [NSLocalizedDescriptionKey: "Unknown error occurred while exporting audio"]))) case .cancelled: completion(.failure(NSError(domain: "com.example.app", code: -1, userInfo: [NSLocalizedDescriptionKey: "Export session was cancelled"]))) default: completion(.failure(NSError(domain: "com.example.app", code: -1, userInfo: [NSLocalizedDescriptionKey: "Unknown export session status"]))) } // Invalidate the timer when the export session completes or is cancelled timer.invalidate() } } ## New Code: func extractAudioFromVideo(from videoURL: URL, exportHandler: ((AVAssetExportSession, CurrentValueSubject<Float, Never>?) -> Void)? = nil, completion: @escaping (Swift.Result<URL, Error>) -> Void) async { let asset = AVAsset(url: videoURL) // Create an AVAssetExportSession to export the audio track guard let exportSession = AVAssetExportSession(asset: asset, presetName: AVAssetExportPresetAppleM4A) else { completion(.failure(NSError(domain: "com.example.app", code: -1, userInfo: [NSLocalizedDescriptionKey: "Failed to create AVAssetExportSession"]))) return } // Set the output file type and path guard let filename = videoURL.lastPathComponent.components(separatedBy: ["."]).first else { return } let outputURL = VideoUtils.getTempAudioExportUrl(filename) VideoUtils.deleteFileIfExists(outputURL.path) let audioExportProgressPublisher = CurrentValueSubject<Float, Never>(0.0) if let exportHandler { exportHandler(exportSession, audioExportProgressPublisher) } if #available(iOS 18.0, *) { do { try await exportSession.export(to: outputURL, as: .m4a) let states = exportSession.states(updateInterval: 0.1) for await state in states { switch state { case .pending, .waiting: break case .exporting(progress: let progress): print("Exporting: \(progress.fractionCompleted)") if progress.isFinished { completion(.success(outputURL)) }else if progress.isCancelled { completion(.failure(NSError(domain: "com.example.app", code: -1, userInfo: [NSLocalizedDescriptionKey: "Export session was cancelled"]))) }else { audioExportProgressPublisher.send(Float(progress.fractionCompleted)) } } } }catch let error { print(error.localizedDescription) } }else { // Periodically check the progress of the export session let publishTimer = Timer.publish(every: 0.1, on: .main, in: .common) .autoconnect() .sink { [weak exportSession] _ in guard let exportSession else { return } audioExportProgressPublisher.send(exportSession.progress) } exportSession.outputFileType = .m4a exportSession.outputURL = outputURL await exportSession.export() switch exportSession.status { case .completed: completion(.success(outputURL)) case .failed: completion(.failure(exportSession.error ?? NSError(domain: "com.example.app", code: -1, userInfo: [NSLocalizedDescriptionKey: "Unknown error occurred while exporting audio"]))) case .cancelled: completion(.failure(NSError(domain: "com.example.app", code: -1, userInfo: [NSLocalizedDescriptionKey: "Export session was cancelled"]))) default: completion(.failure(NSError(domain: "com.example.app", code: -1, userInfo: [NSLocalizedDescriptionKey: "Unknown export session status"]))) } // Invalidate the timer when the export session completes or is cancelled publishTimer.cancel() } }

Hello! Just curious if AVAssetWriter append() randomly fails for anyone but me? Seems to happen when live streaming (encoding with VTCompressionSession) and recording (with AVAssetWriter) at the same time.

i have a CarPlay implementation eand I want to show previous/next track button on player UI MPRemoteCommandCenter.shared().seekForwardCommand.isEnabled = false MPRemoteCommandCenter.shared().seekBackwardCommand.isEnabled = false MPRemoteCommandCenter.shared().previousTrackCommand.isEnabled = true MPRemoteCommandCenter.shared().nextTrackCommand.isEnabled = true It works correctly on CarPlay simulator , but on some car only SEEK button are shown . I have to suppose that it is that a problem on the car side , but I would ask about your opinion , maybe there is some pieces I'm missing

We move to another streaming service and need to deliver a ASK, .PEM &amp;key, and CRT to enable DRM. Now the issue is that we don't have that information anymore. Most logical would be to revoke the current certificate and create a new one. Unfortunately for Fairplay Streaming Certificates there is no revoke button. We asked developer support who isn't able to help. We then did a request to revoke as described in article 2.7 of the Apple Developer Program License Agreement. They can only do this when the certificate is compromised. So now we are stuck. Anyone out there who had the same issue and found a solution? Your help is much appreciated.

I have used AVQueuePlayer in my music app to play sequence of audios from a remote server, this how I have defined things my player in my ViewModel Variables private var cancellables = Set() private let audioSession = AVAudioSession.sharedInstance() private var avQueuePlayer: AVQueuePlayer? @Published var playbackSpeed: Float = 1.0 before starting playback, I am making sure that audio session is set properly, the code snippet used for that is do { try audioSession.setCategory(.playback, mode: .default, options: []) try audioSession.setActive(true, options: []) } catch { return } and this is the function I am using to update playback speed func updatePlaybackSpeed(_ newSpeed: Float){ if newSpeed > 0.0, newSpeed <= 2.0{ playbackSpeed = newSpeed avQueuePlayer?.rate = newSpeed print("requested speed is (newSpeed) and actual speed is (String(describing: avQueuePlayer?.rate))") } } sometimes whatever speed is set, player seems to play at the same speed as it was set, e.g. Once I got "requested speed is 1.5 and actual speed is 1.5", and player also seemed to play at the speed of 1.5 but another time I got "requested speed is 2.0 and actual speed is 2.0", but player still seemed to play at the speed of 1.0 to observe changes in rate, I used this **private func observeRateChanges() { guard let avQueuePlayer = self.avQueuePlayer else { return } NotificationCenter.default.publisher(for: AVQueuePlayer.rateDidChangeNotification, object: avQueuePlayer) .compactMap { $0.userInfo?[AVPlayer.rateDidChangeReasonKey] as? AVPlayer.RateDidChangeReason } .sink { reason in switch reason { case .appBackgrounded: print("The app transitioned to the background.") case .audioSessionInterrupted: print("The system interrupts the app’s audio session.") case .setRateCalled: print("The app set the player’s rate.") case .setRateFailed: print("An attempt to change the player’s rate failed.") default: break } } .store(in: &cancellables) }** when rate was set properly, I got this "The app set the player’s rate." from the above function, but when it wasn't, I got this "An attempt to change the player’s rate failed.," now I am not able to understand why rate is not being set, and if it gave "requested speed is 2.0 and actual speed is 2.0" from updatePlaybackSpeed function, why does the player seems to play with the speed of 1.0?

Hello there, I need to move through video loaded in an AVPlayer one frame at a time back or forth. For that I tried to use AVPlayerItem's method step(byCount:) and it works just fine. However I need to know when stepping happened and as far as I observed it is not immediate using the method. If I check the currentTime() just after calling the method it's the same and if I do it slightly later (depending of the video itself) it shows the correct "jumped" time. To achieve my goal I tried subclassing AVPlayerItem and implement my own async method utilizing NotificationCenter and the timeJumpedNotification assuming it would deliver it as the time actually jumps but it's not the case. Here is my "stripped" and simplified version of the custom Player Item: import AVFoundation final class PlayerItem: AVPlayerItem { private var jumpCompletion: ( (CMTime) -> () )? override init(asset: AVAsset, automaticallyLoadedAssetKeys: [String]?) { super .init(asset: asset, automaticallyLoadedAssetKeys: automaticallyLoadedAssetKeys) NotificationCenter.default.addObserver(self, selector: #selector(timeDidChange(_:)), name: AVPlayerItem.timeJumpedNotification, object: self) } deinit { NotificationCenter.default.removeObserver(self, name: AVPlayerItem.timeJumpedNotification, object: self) jumpCompletion = nil } @discardableResult func step(by count: Int) async -> CMTime { await withCheckedContinuation { continuation in step(by: count) { time in continuation.resume(returning: time) } } } func step(by count: Int, completion: @escaping ( (CMTime) -> () )) { guard jumpCompletion == nil else { completion(currentTime()) return } jumpCompletion = completion step(byCount: count) } @objc private func timeDidChange(_ notification: Notification) { switch notification.name { case AVPlayerItem.timeJumpedNotification where notification.object as? AVPlayerItem [==](https://www.example.com/) self: jumpCompletion?(currentTime()) jumpCompletion = nil default: return } } } In short the notification never gets called thus the above is not working. I guess the key there is that in the docs about the timeJumpedNotification: is said: "A notification the system posts when a player item’s time changes discontinuously." so the step(byCount:) is not considered as discontinuous operation and doesn't trigger it. I'd be really helpful if somebody can help as I don't want to use seek(to:toleranceBefore:toleranceAfter:) mainly cause it's not accurate in terms of the exact next/previous frame as the video might have VFR and that causes repeating frames sometimes or even skipping one or another. Thanks a lot

I am trying to use AVAudioEngine for recording and playing for a voice chat kind of app, but when the speaker plays any audio while recording, the recording take the speaker audio as input. I want to filter that out. Are there any suggestions for the swift code

In our Apple TV application, we use the native AVPlayer for live playback functionality. Until tvOS 17.6 and during the tvOS 18 beta, the Pause/Resume feature worked as expected, allowing us to pause live playback. However, after updating to tvOS 18.1, the pause functionality no longer works. The same app still works fine on tvOS 17, but on tvOS 18, attempting to pause live playback has no effect. We reviewed the tvOS 18 release notes but couldn't find any relevant changes or deprecations related to AVPlayer or live playback behavior. Has there been any change in the handling of live playback or the Pause/Resume functionality in tvOS 18.1? Any guidance or suggestions to address this issue would be greatly appreciated. Thank you!

Hi all, we try migrate project to Swift 6 Project use AVPlayer in MainActor Selection audio and subtitiles not work Task { @MainActor in let group = try await item.asset.loadMediaSelectionGroup(for: AVMediaCharacteristic.audible) get error: Non-sendable type 'AVMediaSelectionGroup?' returned by implicitly asynchronous call to nonisolated function cannot cross actor boundary and second example `if #available(iOS 15.0, *) { player?.currentItem?.asset.loadMediaSelectionGroup(for: AVMediaCharacteristic.audible, completionHandler: { group, error in if error != nil { return } if let groupWrp = group { DispatchQueue.main.async { self.setupAudio(groupWrp, audio: audioLang) } } }) }` get error: Sending 'groupWrp' risks causing data races

iPadOS 18.3 beta 3 (22D5055b) fixed the issue for me and my 7th generation iPad.

Hello. I am attempting to display the music inside of my app in Now Playing. I've tried a few different methods and keep running into unknown issues. I'm new to Objective-C and Apple development so I'm at a loss of how to continue. Currently, I have an external call to viewDidLoad upon initialization. Then, when I'm ready to play the music, I call playMusic. I have it hardcoded to play an mp3 called "1". I believe I have all the signing set up as the music plays after I exit the app. However, there is nothing in Now Playing. There are no errors or issues that I can see while the app is running. This is the only file I have in Xcode relating to this feature. Please let me know where I'm going wrong or if there is another object I need to use! #import <Foundation/Foundation.h> #import <UIKit/UIKit.h> #import <MediaPlayer/MediaPlayer.h> #import <AVFoundation/AVFoundation.h> @interface ViewController : UIViewController <AVAudioPlayerDelegate> @property (nonatomic, strong) AVPlayer *player; @property (nonatomic, strong) MPRemoteCommandCenter *commandCenter; @property (nonatomic, strong) MPMusicPlayerController *controller; @property (nonatomic, strong) MPNowPlayingSession *nowPlayingSession; @end @implementation ViewController - (void)viewDidLoad { [super viewDidLoad]; NSLog(@"viewDidLoad started."); [self setupAudioSession]; [self initializePlayer]; [self createNowPlayingSession]; [self configureNowPlayingInfo]; NSLog(@"viewDidLoad completed."); } - (void)setupAudioSession { AVAudioSession *audioSession = [AVAudioSession sharedInstance]; NSError *setCategoryError = nil; if (![audioSession setCategory:AVAudioSessionCategoryPlayback error:&setCategoryError]) { NSLog(@"Error setting category: %@", [setCategoryError localizedDescription]); } else { NSLog(@"Audio session category set."); } NSError *activationError = nil; if (![audioSession setActive:YES error:&activationError]) { NSLog(@"Error activating audio session: %@", [activationError localizedDescription]); } else { NSLog(@"Audio session activated."); } } - (void)initializePlayer { NSString *soundFilePath = [NSString stringWithFormat:@"%@/base/game/%@",[[NSBundle mainBundle] resourcePath], @"bgm/1.mp3"]; if (!soundFilePath) { NSLog(@"Audio file not found."); return; } NSURL *soundFileURL = [NSURL fileURLWithPath:soundFilePath]; self.player = [AVPlayer playerWithURL:soundFileURL]; NSLog(@"Player initialized with URL: %@", soundFileURL); } - (void)createNowPlayingSession { self.nowPlayingSession = [[MPNowPlayingSession alloc] initWithPlayers:@[self.player]]; NSLog(@"Now Playing Session created with players: %@", self.nowPlayingSession.players); } - (void)configureNowPlayingInfo { MPNowPlayingInfoCenter *infoCenter = [MPNowPlayingInfoCenter defaultCenter]; CMTime duration = self.player.currentItem.duration; Float64 durationSeconds = CMTimeGetSeconds(duration); CMTime currentTime = self.player.currentTime; Float64 currentTimeSeconds = CMTimeGetSeconds(currentTime); NSDictionary *nowPlayingInfo = @{ MPMediaItemPropertyTitle: @"Example Title", MPMediaItemPropertyArtist: @"Example Artist", MPMediaItemPropertyPlaybackDuration: @(durationSeconds), MPNowPlayingInfoPropertyElapsedPlaybackTime: @(currentTimeSeconds), MPNowPlayingInfoPropertyPlaybackRate: @(self.player.rate) }; infoCenter.nowPlayingInfo = nowPlayingInfo; NSLog(@"Now Playing info configured: %@", nowPlayingInfo); } - (void)playMusic { [self.player play]; [self createNowPlayingSession]; [self configureNowPlayingInfo]; } - (void)pauseMusic { [self.player pause]; [self configureNowPlayingInfo]; } @end

Hey - I am developing an app that uses the camera for recording video. I put the ability to choose a framerate and resolution and all combinations work perfectly fine, except for 4k 120fps for the new iPhone 16 pro. This just shows black on the preview. I tried to record even though the preview was black, but the recording is also just a black screen. Is there anything special that needs to be done in the camera setup for 4k 120fps to work? I have my camera setup code attached. Is it possible this is a bug in Apple's code, since this works with every other combination (1080p up to 240fps and 4k up to 60fps)? Thanks so much for the help. class CameraManager: NSObject { enum Errors: Error { case noCaptureDevice case couldNotAddInput case unsupportedConfiguration } enum Resolution { case hd1080p case uhd4K var preset: AVCaptureSession.Preset { switch self { case .hd1080p: return .hd1920x1080 case .uhd4K: return .hd4K3840x2160 } } var dimensions: CMVideoDimensions { switch self { case .hd1080p: return CMVideoDimensions(width: 1920, height: 1080) case .uhd4K: return CMVideoDimensions(width: 3840, height: 2160) } } } enum CameraType { case wide case ultraWide var captureDeviceType: AVCaptureDevice.DeviceType { switch self { case .wide: return .builtInWideAngleCamera case .ultraWide: return .builtInUltraWideCamera } } } enum FrameRate: Int { case fps60 = 60 case fps120 = 120 case fps240 = 240 } let orientationManager = OrientationManager() let captureSession: AVCaptureSession let previewLayer: AVCaptureVideoPreviewLayer let movieFileOutput = AVCaptureMovieFileOutput() let videoDataOutput = AVCaptureVideoDataOutput() private var videoCaptureDevice: AVCaptureDevice? override init() { self.captureSession = AVCaptureSession() self.previewLayer = AVCaptureVideoPreviewLayer(session: self.captureSession) super.init() self.previewLayer.videoGravity = .resizeAspect } func configureSession(resolution: Resolution, frameRate: FrameRate, stabilizationEnabled: Bool, cameraType: CameraType, sampleBufferDelegate: AVCaptureVideoDataOutputSampleBufferDelegate?) throws { assert(Thread.isMainThread) captureSession.beginConfiguration() defer { captureSession.commitConfiguration() } captureSession.sessionPreset = resolution.preset if captureSession.canAddOutput(movieFileOutput) { captureSession.addOutput(movieFileOutput) } else { throw Errors.couldNotAddInput } videoDataOutput.setSampleBufferDelegate(sampleBufferDelegate, queue: DispatchQueue(label: "VideoDataOutputQueue")) if captureSession.canAddOutput(videoDataOutput) { captureSession.addOutput(videoDataOutput) // Set the video orientation if needed if let connection = videoDataOutput.connection(with: .video) { //connection.videoOrientation = .portrait } } else { throw Errors.couldNotAddInput } guard let videoCaptureDevice = AVCaptureDevice.default(cameraType.captureDeviceType, for: .video, position: .back) else { throw Errors.noCaptureDevice } let useDimensions = resolution.dimensions guard let format = videoCaptureDevice.formats.first(where: { format in let dimensions = CMVideoFormatDescriptionGetDimensions(format.formatDescription) let isRes = dimensions.width == useDimensions.width && dimensions.height == useDimensions.height let frameRates = format.videoSupportedFrameRateRanges return isRes && frameRates.contains(where: { $0.maxFrameRate >= Float64(frameRate.rawValue) }) }) else { throw Errors.unsupportedConfiguration } self.videoCaptureDevice = videoCaptureDevice do { let videoInput = try AVCaptureDeviceInput(device: videoCaptureDevice) if captureSession.canAddInput(videoInput) { captureSession.addInput(videoInput) } else { throw Errors.couldNotAddInput } try videoCaptureDevice.lockForConfiguration() videoCaptureDevice.activeFormat = format videoCaptureDevice.activeVideoMinFrameDuration = CMTime(value: 1, timescale: CMTimeScale(frameRate.rawValue)) videoCaptureDevice.activeVideoMaxFrameDuration = CMTime(value: 1, timescale: CMTimeScale(frameRate.rawValue)) videoCaptureDevice.activeMaxExposureDuration = CMTime(seconds: 1.0 / 960, preferredTimescale: 1000000) videoCaptureDevice.exposureMode = .locked videoCaptureDevice.unlockForConfiguration() } catch { throw error } configureStabilization(enabled: stabilizationEnabled) }`

Based on the iPhone 14 Max camera, implement model recognition and draw a rectangular box around the recognized object. The width and height are calculated using LiDAR and displayed in centimeters on the real-time updated image.

I’ve been researching how to achieve a recording playback effect in iOS similar to the hands-free calling effect in the system’s phone app. How can this be implemented? I tried using the voice chat recording method, but found that the volume of the speaker output is too low. How should this issue be addressed? I couldn’t find a suitable API. Could you provide me with some documentation or sample code? Thank you.

Hi! I get personal recommendations MusicItemCollection using this code: func getRecommendations() async throws -> MusicItemCollection<MusicPersonalRecommendation> { let request = MusicPersonalRecommendationsRequest() let response = try await request.response() let recommendations = response.recommendations return recommendations } However, all recommendations contain no more than 12 MusicItem's, while the Music.app application provides much more for some recommendations, for example, for the You recently listened recommendation, the Music.app application displays 40 items. Each recommendation has an items property that contains a collection of musical items MusicItemCollection<MusicPersonalRecommendation.Item>, the hasNextBatch property for these collections is always false. I expected that for some collections loading of new items would be available. Please tell me if I'm doing something wrong or is this a MusicKit bug? Thank you!

Will the restrictions on callkit be lifted in China in 2025? If so, how can you legally use callkit in China?

使用AVSpeechUtterance实现iOS语音播报，选择语言为简体中文“zh-CN”，读取中文“袆”（hui 第一声)错误，读成了“祎”（yi 第一声），希望能优化。

Hi, On macOS Sonoma and earlier versions, I used my script along with a LaunchDaemon to continuously record my screen. However, after upgrading to macOS Sequoia, the LaunchDaemon no longer works for screen recording. It only works when I use a LaunchAgent. For my workflow, using a LaunchDaemon and running the ffmpeg process as root is much more efficient than running it as a regular user. Does anyone know how to run a script in the background using a LaunchDaemon on macOS Sequoia? Here are my LaunchDaemon plist and script: LaunchDaemon plist: &lt;?xml version="1.0" encoding="UTF-8"?&gt; &lt;!DOCTYPE plist PUBLIC "-//Apple//DTD PLIST 1.0//EN" "http://www.apple.com/DTDs/PropertyList-1.0.dtd"&gt; &lt;?xml version="1.0" encoding="UTF-8"?&gt; &lt;!DOCTYPE plist PUBLIC "-//Apple//DTD PLIST 1.0//EN" "http://www.apple.com/DTDs/PropertyList-1.0.dtd"&gt; &lt;plist version="1.0"&gt; &lt;dict&gt; &lt;key&gt;Label&lt;/key&gt; &lt;string&gt;local.ScreenRecord&lt;/string&gt; &lt;key&gt;Disabled&lt;/key&gt; &lt;false/&gt; &lt;key&gt;RunAtLoad&lt;/key&gt; &lt;true/&gt; &lt;key&gt;KeepAlive&lt;/key&gt; &lt;true/&gt; &lt;key&gt;Nice&lt;/key&gt; &lt;integer&gt;-20&lt;/integer&gt; &lt;key&gt;ProgramArguments&lt;/key&gt; &lt;array&gt; &lt;string&gt;/bin/bash&lt;/string&gt; &lt;string&gt;/usr/local/distrib/record.bash&lt;/string&gt; &lt;/array&gt; &lt;/dict&gt; &lt;/plist&gt; Script ## !!! START CONFIGURATION !!! # FFMPEG_LOC="/usr/local/distrib/ffmpeg" FFMPEG_INPUT="-hide_banner -f avfoundation -capture_cursor 1 -pixel_format uyvy422" FFMPEG_VSET="-codec libx264 -r 22 -crf 26 -preset veryfast -b:v 5M -maxrate 7M -bufsize 14M" TIME_REC="-t 600" FOLDER_REC="/usr/local/distrib/REC/" # ## !!! END CONFIGURATION !!! # # Find number id monitor MON_ID=$($FFMPEG_LOC -hide_banner -f avfoundation -list_devices true -i "" 2&gt;&amp;1 | awk -F'[]|[]' '/Capture\ screen/ {print $4}') # if [ -n "$MON_ID" ] then # Time for name DATE_REC=$(date +"%m-%d-%Y_%H-%M-%S") # Number of output video file OUTPUT_NUM=0 # Full command to record FFMPEG_FULL_COMMAND="" for MON_NUM in $MON_ID do FFMPEG_FULL_COMMAND=""$FFMPEG_FULL_COMMAND" "$FFMPEG_INPUT" -i "$MON_NUM" "$FFMPEG_VSET" "$TIME_REC" -map "$OUTPUT_NUM" "$FOLDER_REC""$DATE_REC"_Mon"$MON_NUM".mkv" let OUTPUT_NUM=$OUTPUT_NUM+1 done $FFMPEG_LOC $FFMPEG_FULL_COMMAND else echo "No monitors" sleep 5 fi

Our multimedia application Boinx FotoMagico displays media files of various kinds with a Metal rendering engine. At the moment we still use .bgra8Unorm pixel format and sRGB color space and only render in SDR, which is increasingly a problem, as much of the video content is HDR nowadays (e.g. videos shot on an iPhone). For that reason we would like to switch to EDR rendering with .rgba16Float pixel format and extendedLinearDisplayP3 color space. We have already worked out how to do this for HDR image files, but still have a technical problem when rendering HDR video files. We are using AVFoundation to get the video frames as CVPixelBuffers and convert them to MTLTexture using a CVMetalTextureCache. MTLTextures are then further processed in various compute shaders before being rendered to screen. However the pixel values in the texture are not what we expected. Video frames appear too bright/overexposed. In WWDC21 session "Explore HDR rendering with EDR" Ken Greenebaum mentioned: “AVFoundation does not presently decode HDR formats, such as HDR10, to EDR. Consequently, these need to be adapted for use with EDR rendering. This conversion is straightforward and involves two steps. First, converting to linear light by applying the inverse transfer function. And second, dividing by the medium's reference white.” https://developer.apple.com/videos/play/wwdc2021/10161?time=1498 However, the session does not explain, how to get or calculate the correct value for "reference white". We could not find any relevant info on the web. This is why we need DTS assistance. We need the code that calculates the correct value for reference white for any kind of video, whether it is SDR or HDR, and regardless of codec and encoding. I assume that Ken Greenebaum is the best Apple engineer to ask in this case, because he recorded most of the EDR related WWDC sessions in recent years? We have written a small test app that renders a short sample video (HLG encoding). The window contains two views. The upper view uses an AVPlayerLayer and renders the video natively just like QuickTime Player. The video content looks correct here. BTW, the window background is SDR white, so that bright EDR pixels can be clearly identified, e.g. the clouds just above the mountains in the upper left corner of the sample video. You may need to lower display brightness a bit if these clouds do not appear brighter than the white window background. The bottom view uses a CAMetalLayer and low-level Metal rendering. The CVPixelBuffers we receive from AVFoundation still need to be scaled down so that SDR reference white reaches pixel value 1.0. Entering a value of 9.0 to 10.0 for reference white in the text field makes it look about right on my Studio Display. But that is just experimental for this sample video file. We need code to calculate the correct value for reference white for any kind of video file! We have a couple of questions: SDR videos should probably use 1.0 as reference white, as their encoded pixel values can already be used as is? Is this assumption correct? Different video encoding of HDR video (HLG, PQ, etc) will probably lead to different values for reference white? Is the value for reference white constant throughout a video, or can it vary over time, either scene by scene, or even frame by frame? If it can vary, does the CVPixelBuffer of the current video frame contain all the necessary metadata to calculate the correct value? Does the NSScreen.maximumExtendedDynamicRangeColorComponentValue also influence the reference white value? The attached sample project is structured in a way that the only piece of code that needs to be modified is the ViewController.sdrReferenceWhiteValue() function. Please read the comments and the #warning in this function. This is where the code for calculating the reference white value should be inserted. Here is the download link for the sample project: https://www.dropbox.com/scl/fi/4w5gmftav5xhbixu9u6pb/HDRMetalTest.zip?rlkey=n8cm02soux3rx03vplgo6h1lm&dl=0

Overlay changes color in HDR video When I’m using trying to add an overlay to an image with AVMutableVideoComposition, When the video is in HDR the overlay colors are changing and white becomes grey screen shot from original HDR video result from the code with the wrong overlay colorthe result when reducing to SDR (the right overlay color) the distorted colorsthe way it should look(sdr) Im creating the overlay with a CGContext class CustomHdrCompositor: NSObject, AVVideoCompositing { private let coreImageContext = CIContext(options: [CIContextOption.cacheIntermediates: false]) let combinedFilter = CIFilter(name: "CISourceOverCompositing")! var sourcePixelBufferAttributes: [String: Any]? = [String(kCVPixelBufferPixelFormatTypeKey): [kCVPixelFormatType_420YpCbCr10BiPlanarVideoRange]] var requiredPixelBufferAttributesForRenderContext: [String: Any] = [String(kCVPixelBufferPixelFormatTypeKey): [kCVPixelFormatType_420YpCbCr10BiPlanarVideoRange]] var supportsWideColorSourceFrames = true var supportsHDRSourceFrames = true func renderContextChanged(_ newRenderContext: AVVideoCompositionRenderContext) { return } func startRequest(_ request: AVAsynchronousVideoCompositionRequest) { guard let outputPixelBuffer = request.renderContext.newPixelBuffer() else { print("No valid pixel buffer found. Returning.") request.finish(with: CustomCompositorError.ciFilterFailedToProduceOutputImage) return } guard let requiredTrackIDs = request.videoCompositionInstruction.requiredSourceTrackIDs, !requiredTrackIDs.isEmpty else { print("No valid track IDs found in composition instruction.") return } let sourceCount = requiredTrackIDs.count if sourceCount > 1 { request.finish(with: CustomCompositorError.notSupportingMoreThanOneSources) return } if sourceCount == 1 { let sourceID = requiredTrackIDs[0] let sourceBuffer = request.sourceFrame(byTrackID: sourceID.value(of: Int32.self)!)! let sourceCIImage = CIImage(cvPixelBuffer: sourceBuffer) var textImage = TextLayerPlayer.instance.getTextLayerAtTimesStamp(ts:request.compositionTime.seconds) combinedFilter.setValue(textImage, forKey: "inputImage") if let outputImage = combinedFilter.outputImage { let renderDestination = CIRenderDestination(pixelBuffer: outputPixelBuffer) do { try coreImageContext.startTask(toRender: outputImage, to: renderDestination) } catch { } } } request.finish(withComposedVideoFrame: outputPixelBuffer) } } func regularCompositionHdr(asset: AVAsset) -> AVVideoComposition { self.isHdr = checkHdr(asset: asset) let avComposition = AVMutableComposition() let composition = AVMutableVideoComposition() composition.colorPrimaries = AVVideoColorPrimaries_ITU_R_2020 composition.colorTransferFunction = AVVideoTransferFunction_ITU_R_2100_HLG composition.colorYCbCrMatrix = AVVideoYCbCrMatrix_ITU_R_2020 composition.renderSize = assetSize composition.frameDuration = CMTime(value: 1, timescale: 30) composition.customVideoCompositorClass = CustomHdrCompositor.self composition.perFrameHDRDisplayMetadataPolicy = .propagate return composition } I’m using this function to transfer the transparent CGImage to CIImage that supports HDR func convertToHDRCIImage(from cgImage: CGImage, maxBrightness: CGFloat = 3.0) -> CIImage? { // Create a CIImage from the input CGImage let baseImage = CIImage(cgImage: cgImage) // Create HDR color adjustment filter let colorAdjust = CIFilter(name: "CIColorMatrix")! colorAdjust.setValue(baseImage, forKey: kCIInputImageKey) // Calculate HDR multipliers based on maxBrightness // This will maintain color ratios while increasing brightness colorAdjust.setValue(CIVector(x: maxBrightness, y: 0, z: 0, w: 0), forKey: "inputRVector") colorAdjust.setValue(CIVector(x: 0, y: maxBrightness, z: 0, w: 0), forKey: "inputGVector") colorAdjust.setValue(CIVector(x: 0, y: 0, z: maxBrightness, w: 0), forKey: "inputBVector") // Maintain alpha channel colorAdjust.setValue(CIVector(x: 0, y: 0, z: 0, w: 1), forKey: "inputAVector") guard let adjustedImage = colorAdjust.outputImage else { return nil } // Apply color space transformation using CIImage's colorSpace property let transformedImage = adjustedImage.matchedFromWorkingSpace(to: hdrWorkingSpace)! // Create context with HDR color space let context = CIContext(options: [ .workingColorSpace: hdrColorSpace, .outputColorSpace: hdrColorSpace ]) // Get the image bounds let bounds = transformedImage.extent // Create a new pixel buffer with HDR format var pixelBuffer: CVPixelBuffer? let pixelBufferAttributes = [ kCVPixelBufferPixelFormatTypeKey: kCVPixelFormatType_64RGBAHalf, kCVPixelBufferMetalCompatibilityKey: true ] as CFDictionary CVPixelBufferCreate(kCFAllocatorDefault, Int(bounds.width), Int(bounds.height), kCVPixelFormatType_64RGBAHalf, pixelBufferAttributes, &pixelBuffer) guard let destinationBuffer = pixelBuffer else { return nil } context.render(transformedImage, to: destinationBuffer, bounds: bounds, colorSpace: hdrColorSpace) // Create final CIImage from the HDR pixel buffer let finalImage = CIImage(cvPixelBuffer: destinationBuffer, options: [.colorSpace: hdrColorSpace]) return finalImage } When reducing the HDR to SDR it keeps the right color of the overlay with, but than it reduces the HDR effect which I want to keep