Dive into the world of video on Apple platforms, exploring ways to integrate video functionalities within your iOS,iPadOS, macOS, tvOS, visionOS or watchOS app.

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Importing pictures with non-QT metadata
Movies taken with Android phones store their location metadata (and probably others) in ways that are ignored by Apple's ecosystem (QuickTime Player, Photos.app). I am considering creating a Spotlight importer so that this metadata is available to the sytem. But I have a couple of questions: Can a Spotlight importer add new data (like location) to the data that the standard importer already captured? Or would the new importer need to take over the whole data gathering? If so, would macOS allow that? Would that Spotlight importer be somehow used by e.g. Photos.app and QT Player to capture the location? Or would this end up in Spotlight "knowing" the location but Photos.app ignoring it? If so, maybe there is something more broadly useful than a Spotlight importer?
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116
May ’25
AVPlayer freezes after ReplaceCurrentItemWithPlayerItem + immediate seek on iOS 18.4 (streaming only)
Starting in iOS 18.4, (and still in the iOS 18.5 beta), the AVPlayer seems to freeze when we: Replace the current AVPlayerItem, ReplaceCurrentItemWithPlayerItem and then: Call Seek very shortly afterwards (seekToTime:toleranceBefore:toleranceAfter: / seek(to:)) And then subsequent calls to play after have no effect. However, it feels scrubbing to see after works and also changing the playback rate (i.e. fast forward) tends to clear up the frozen state. Our primary workflow involves video playback, replacing video to show new clips and in some cases seeking to specific frames. This appears to only be occurring while streaming video, reports are all that local downloaded video playback remains fine. This same code path has worked without issue on 17.x and 18.3.2 and for years before that. What is particularly strange is that time observers log that video is still playing or feeding frames. The reported status is ReadyToPlay, IsLikelyToKeepUp is true, and there are no indications of stalling or buffering. A similar issue is true for our web application in Safari. While on Sonoma and Safari 17.x, there is no issue. When you update to macOS Sequoia 15.4.1 and Safari 18.4, you begin observing a similar freezing. The same does not occur on Chrome or other tested browsers. There appears to be in the release notes for Safari 18.4, an interesting "fix" note that seems similar to what we are now experiencing: https://developer.apple.com/documentation/safari-release-notes/safari-18_4-release-notes "Fixed an issue where playback doesn’t always resume after a seek. (140097993)" "Fixed playing video generating non-monotonic ‘timeupdate’ events. (142275184) (FB16222910)" "Fixed websites calling play() during a seek() is allowed by the specification so that the play event is fired even if the seek hasn’t completed. (142517488)" "Fixed seek not completing for WebM under some circumstances. (143372794)" "Fixed MediaRecorderPrivateEncoder writing frames out of order. (143956063)"
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183
May ’25
How to disable automatic updates to MPNowPlayingInfoCenter from AVPlayer
I’m building a SwiftUI app whose primary job is to play audio. I manage all of the Now-Playing metadata and Command center manually via the available shared instances: MPRemoteCommandCenter.shared() MPNowPlayingInfoCenter.default().nowPlayingInfo In certain parts of the app I also need to display videos, but as soon as I attach another AVPlayer, it automatically pushes its own metadata into the Control Center and overwrites my audio info. What I need: a way to show video inline without ever having that video player update the system’s Now-Playing info (or Control Center). In my app, I start by configuring the shared audio session do { try AVAudioSession.sharedInstance().setCategory(.playback, mode: .default, options: [ .allowAirPlay, .allowBluetoothA2DP ]) try AVAudioSession.sharedInstance().setActive(true) } catch { NSLog("%@", "**** Failed to set up AVAudioSession \(error.localizedDescription)") } and then set the MPRemoteCommandCenter commands and MPNowPlayingInfoCenter nowPlayingInfo like mentioned above. All this works without any issues as long as I only have one AVPlayer in my app. But when I add other AVPlayers to display some videos (and keep the main AVPlayer for the sound) they push undesired updates to MPNowPlayingInfoCenter: struct VideoCardView: View { @State private var player: AVPlayer let videoName: String init(player: AVPlayer = AVPlayer(), videoName: String) { self.player = player self.videoName = videoName guard let path = Bundle.main.path(forResource: videoName, ofType: nil) else { return } let url = URL(fileURLWithPath: path) let item = AVPlayerItem(url: url) self.player.replaceCurrentItem(with: item) } var body: some View { VideoPlayer(player: player) .aspectRatio(contentMode: .fill) .onAppear { player.isMuted = true player.allowsExternalPlayback = false player.actionAtItemEnd = .none player.play() MPNowPlayingInfoCenter.default().nowPlayingInfo = nil MPNowPlayingInfoCenter.default().playbackState = .stopped NotificationCenter.default.addObserver(forName: .AVPlayerItemDidPlayToEndTime, object: player.currentItem, queue: .main) { notification in guard let finishedItem = notification.object as? AVPlayerItem, finishedItem === player.currentItem else { return } player.seek(to: .zero) player.play() } } .onDisappear { player.pause() } } } Which is why I tried adding: MPNowPlayingInfoCenter.default().nowPlayingInfo = nil MPNowPlayingInfoCenter.default().playbackState = .stopped // or .interrupted, .unknown But that didn't work. I also tried making a wrapper around the AVPlayerViewController in order to set updatesNowPlayingInfoCenter to false, but that didn’t work either: struct CustomAVPlayerView: UIViewControllerRepresentable { let player: AVPlayer func makeUIViewController(context: Context) -> AVPlayerViewController { let vc = AVPlayerViewController() vc.player = player vc.updatesNowPlayingInfoCenter = false vc.showsPlaybackControls = false return vc } func updateUIViewController(_ controller: AVPlayerViewController, context: Context) { controller.player = player } } Hence any help on how to embed video in SwiftUI without its AVPlayer touching MPNowPlayingInfoCenter would be greatly appreciated. All this was tested on an actual device with iOS 18.4.1, and built with Xcode 16.2 on macOS 15.5
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223
Jun ’25
Live HLS Stream Not Playing After Window Resize in Vision Pro
Hi everyone, I'm developing a visionOS app for Apple Vision Pro, and I've encountered an issue related to window resizing at runtime when using AVPlayer to play a live HLS stream. ✅ What I'm Trying to Do Play a live HLS stream (from Wowza) inside my app using AVPlayer. Support resizing the immersive window using Vision Pro’s built-in runtime scaling gesture. Stream works fine at default window size when the app launches. ❌ Problem If I resize the app’s window at runtime (using the Vision Pro pinch-drag gesture), then try to start the stream, it does not play. Instead, it just shows the "Loading live stream..." state and never proceeds to playback. This issue only occurs after resizing the window — if I don’t resize, the stream works perfectly every time. 🧪 What I’ve Tried Verified the HLS URL — it’s working and plays fine in Safari and in the app before resizing. Set .automaticallyWaitsToMinimizeStalling = false on AVPlayer. Observed that .status on AVPlayerItem never reaches .readyToPlay after resizing. Tried to force window size back using UIWindowScene.requestGeometryUpdate(...), but behavior persists.
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244
Jul ’25
AVSampleBufferDisplayLayer drop frame when play uncompressed video with bframe>3
When using AVSampleBufferDisplayLayer to play uncompressed H.264 and H.265 video with B-frames more than 7, frame drops occur. The more B-frames there are, the more noticeable the frame drops become, for example 15 bframes. Use FFmpeg to transcode a video file with visible timestamps and frame numbers (x264 or x265 ): ffmpeg -i test.mp4 -vf "drawtext=fontsize=45:text=%{pts} %{n}:y=400" -c:v libx264 -x264-params "bframes=15:b-adapt=0" -crf 30 -y x264_bf15.mp4 ffmpeg -i test.mp4 -vf "drawtext=fontsize=45:text=%{pts} %{n}:y=400" -c:v libx265 -x265-params "bframes=15:b-adapt=0" -crf 30 -y x265_bf15.mp4 Use the demo player from this repository to reproduce the issue: https://github.com/msfrms/CustomPlayer frame drops can be observed. And following log can be found in devices console. mediaserverd <<<< IQ-CA >>>> piqca_gmstats_dump: FIQCA(0x1266f4000) recent frames: enqueued: 184, displayed: 138, dropped: 42, flushed: 0, evicted: 3, >16ms late: 2 PS. I was using iphone11 iOS14.6, to replay this issue. May I ask why frame drops occur in this case? Is there any configuration or API usage change that could help fix the frame drop issue? Many thanks!
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264
Jul ’25
Looking for solutions to build a video chat app (Omegle/Chatroulette style) on Vision Pro
Hi everyone, We are working on a prototype app for Apple Vision Pro that is similar in functionality to Omegle or Chatroulette, but exclusively for Vision Pro owners. The core idea is: – a matching system where one user connects to another through a virtual persona; – real-time video and audio transmission; – time limits for sessions with the ability to extend them; – users can skip a match and move on to the next one. We have explored WebRTC and Twilio, but unfortunately, they don’t fit our use case. Question: What alternative services or SDKs are available for implementing real-time video/audio communication on Vision Pro that would work with this scenario? Has anyone encountered a similar challenge and can recommend which technologies or tools to use? Thanks in advance!
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268
Aug ’25
Threading guarantees with AVCaptureVideoDataOutput
I'm writing some camera functionality that uses AVCaptureVideoDataOutput. I've set it up so that it calls my AVCaptureVideoDataOutputSampleBufferDelegate on a background thread, by making my own dispatch_queue and configuring the AVCaptureVideoDataOutput. My question is then, if I configure my AVCaptureSession differently, or even stop it altogether, is this guaranteed to flush all pending jobs on my background thread? For example, does [AVCaptureSession stopRunning] imply a blocking call until all pending frame-callbacks are done? I have a more practical example below, showing how I am accessing something from the foreground thread from the background thread, but I wonder when/how it's safe to clean up that resource. I have setup similar to the following: // Foreground thread logic dispatch_queue_t queue = dispatch_queue_create("qt_avf_camera_queue", nullptr); AVCaptureSession *captureSession = [[AVCaptureSession alloc] init]; setupInputDevice(captureSession); // Connects the AVCaptureDevice... // Store some arbitrary data to be attached to the frame, stored on the foreground thread FrameMetaData frameMetaData = ...; MySampleBufferDelegate *sampleBufferDelegate = [MySampleBufferDelegate alloc]; // Capture frameMetaData by reference in lambda [sampleBufferDelegate setFrameMetaDataGetter: [&frameMetaData]() { return &frameMetaData; }]; AVCaptureVideoDataOutput *captureVideoDataOutput = [[AVCaptureVideoDataOutput alloc] init]; [captureVideoDataOutput setSampleBufferDelegate:sampleBufferDelegate queue:queue]; [captureSession addOutput:captureVideoDataOutput]; [captureSession startRunning]; [captureSession stopRunning]; // Is it now safe to destroy frameMetaData, or do we need manual barrier? And then in MySampleBufferDelegate: - (void)captureOutput:(AVCaptureOutput *)captureOutput didOutputSampleBuffer:(CMSampleBufferRef)sampleBuffer fromConnection:(AVCaptureConnection *)connection { // Invokes the callback set above FrameMetaData *frameMetaData = frameMetaDataGetter(); emitSampleBuffer(sampleBuffer, frameMetaData); }
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431
Sep ’25
The behavior of AVPlayerItem.didPlayToEndTimeNotification is not as expected in iOS 26.
Hello, Environment macOS 15.6.1 / Xcode 26 beta 7 / iOS 26 Beta 9 In a simple AVFoundation video-playback sample, I’m seeing different behavior between iOS 18 and iOS 26 regarding AVPlayerItem.didPlayToEndTimeNotification. I’ve attached a minimal sample below. Please replace videoURL with a valid short video URL. Repro steps Tap “Play” to start playback and let the video finish. The AVPlayerItem.didPlayToEndTimeNotification registered with NotificationCenter should fire, and you should see Play finished. in the console. Without relaunching, tap “Play” again. This is where the issue arises. Observed behavior On iOS 18 and earlier: The video does not play again (it does not restart from the beginning), but AVPlayerItem.didPlayToEndTimeNotification is posted and Play finished. appears in the console. The same happens every time you press “Play”. On iOS 26: Pressing “Play” does not post AVPlayerItem.didPlayToEndTimeNotification. The code path that prints Play finished. is never called (the callback enclosing that line is not invoked again). Building the same program with Xcode 16.4 and running it on an iOS 26 beta device shows the same phenomenon, which suggests there has been a behavioral change for AVPlayerItem.didPlayToEndTimeNotification on iOS 26. I couldn’t find any mention of this in the release notes or API Reference. Because the semantics around AVPlayerItem.didPlayToEndTimeNotification appear to differ, we’re forced to adjust our logic. If there is a way to achieve the iOS 18–style behavior on iOS 26, I would appreciate guidance. Alternatively, if this change is intentional, could you share the reasoning? Is iOS 26 the correct behavior from Apple’s perspective and iOS 18 (and earlier) behavior considered incorrect? Any official clarification would be extremely helpful. import UIKit import AVFoundation final class ViewController: UIViewController { private let videoURL = URL(string: "https://......mp4")! private var player: AVPlayer? private var playerItem: AVPlayerItem? private var playerLayer: AVPlayerLayer? private var observeForComplete: NSObjectProtocol? // UI private let playerContainerView = UIView() private let playButton = UIButton(type: .system) private let stopButton = UIButton(type: .system) private let replayButton = UIButton(type: .system) deinit { if let observeForComplete { NotificationCenter.default.removeObserver(observeForComplete) } } override func viewDidLoad() { super.viewDidLoad() view.backgroundColor = .systemBackground setupUI() setupPlayer() } override func viewDidLayoutSubviews() { super.viewDidLayoutSubviews() playerLayer?.frame = playerContainerView.bounds } // MARK: - Setup private func setupUI() { playerContainerView.translatesAutoresizingMaskIntoConstraints = false playerContainerView.backgroundColor = .black view.addSubview(playerContainerView) // Buttons playButton.setTitle("Play", for: .normal) stopButton.setTitle("Pause", for: .normal) replayButton.setTitle("RePlay", for: .normal) [playButton, stopButton, replayButton].forEach { $0.titleLabel?.font = .systemFont(ofSize: 16, weight: .semibold) $0.translatesAutoresizingMaskIntoConstraints = false $0.contentEdgeInsets = UIEdgeInsets(top: 10, left: 16, bottom: 10, right: 16) } let stack = UIStackView(arrangedSubviews: [playButton, stopButton, replayButton]) stack.axis = .horizontal stack.spacing = 16 stack.alignment = .center stack.distribution = .equalCentering stack.translatesAutoresizingMaskIntoConstraints = false view.addSubview(stack) NSLayoutConstraint.activate([ playerContainerView.topAnchor.constraint(equalTo: view.safeAreaLayoutGuide.topAnchor, constant: 20), playerContainerView.leadingAnchor.constraint(equalTo: view.leadingAnchor), playerContainerView.trailingAnchor.constraint(equalTo: view.trailingAnchor), playerContainerView.heightAnchor.constraint(equalToConstant: 200), stack.topAnchor.constraint(equalTo: playerContainerView.bottomAnchor, constant: 20), stack.centerXAnchor.constraint(equalTo: view.centerXAnchor) ]) // Action playButton.addTarget(self, action: #selector(didTapPlay), for: .touchUpInside) stopButton.addTarget(self, action: #selector(didTapStop), for: .touchUpInside) replayButton.addTarget(self, action: #selector(didTapReplayFromStart), for: .touchUpInside) } private func setupPlayer() { // AVURLAsset -> AVPlayerItem → AVPlayer let asset = AVURLAsset(url: videoURL) let item = AVPlayerItem(asset: asset) self.playerItem = item let player = AVPlayer(playerItem: item) player.automaticallyWaitsToMinimizeStalling = true self.player = player let layer = AVPlayerLayer(player: player) layer.videoGravity = .resizeAspect playerContainerView.layer.addSublayer(layer) layer.frame = playerContainerView.bounds self.playerLayer = layer // Notification if let observeForComplete { NotificationCenter.default.removeObserver(observeForComplete) } if let playerItem { observeForComplete = NotificationCenter.default.addObserver( forName: AVPlayerItem.didPlayToEndTimeNotification, object: playerItem, queue: .main ) { [weak self] _ in guard self != nil else { return } Task { @MainActor in print("Play finished.") } } } } // MARK: - Actions @objc private func didTapPlay() { player?.play() } @objc private func didTapStop() { player?.pause() } // RePlay @objc private func didTapReplayFromStart() { player?.seek(to: .zero, toleranceBefore: .zero, toleranceAfter: .zero) { [weak self] _ in self?.player?.play() } } } I would greatly appreciate an official response from Apple engineering on whether this is an intentional change, a regression, or an API contract clarification, and what the recommended approach is going forward. Thank you.
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716
Sep ’25
Enterprise API Passthrough in screen capture not working after visionOS26 update
We have been using passthrough in screen capture since visionOS26 with broadcast upload extension which was working in visionOS2.2 but now with visionOS26 it doesn't update. It fails with Invalid Broadcast session started, after a few seconds of starting the broadcast session. Is there a bug filed for it? or is it a known bug for it?
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404
Oct ’25
iPhone 17 Pro, 17 Pro Maxで撮った映像をWebRTCで送るとブラウザで表示した際に緑の映像になる
iPhoneで撮影した映像をブラウザのアプリへ送信して画面に映す機能を持ったアプリを開発しています。 iPhone 17 Pro, 17 Pro Maxでこのアプリを利用するとブラウザ側に表示される映像が緑一色や、緑がメインのカラフルな映像になってしまいます。 調べてみると17Proと17ProMaxで超広角カメラと望遠カメラの画素数が変更になっている(1200万画素→4800万画素)ためエンコーディングで失敗しているのではないかと疑っています。 なんでも情報下さい。 環境情報 WebRTCライブラリ: GoogleWebRTC バージョン 1.1 (CocoaPodsで導入) シグナリングサーバー: AWS Kinesis Video Streams 問題が発生するデバイス: モデル名: iPhone18,1, OS: 26.0 モデル名: iPhone18,1, OS: 26.1 問題が発生しないデバイス: iPhone17,5 以前の多数のモデル モデル名: iPhone18,1, OS: 26.0 モデル名: iPhone18,3, OS: 26.0
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223
Nov ’25
WKWebView Crashes on iOS During YouTube Playlist Playback
I’m encountering a consistent crash in WebKit when using WKWebView to play a YouTube playlist in my iOS app. Playback starts successfully, but the web process terminates during the second video in the playlist. This only occurs on physical devices, not in the simulator. Here’s a simplified Swift example of my setup: import SwiftUI import WebKit struct ContentView: View { private let playlistID = "PLig2mjpwQBZnghraUKGhCqc9eAy0UbpDN" var body: some View { YouTubeWebView(playlistID: playlistID) .edgesIgnoringSafeArea(.all) } } struct YouTubeWebView: UIViewRepresentable { let playlistID: String func makeUIView(context: Context) -> WKWebView { let config = WKWebViewConfiguration() config.allowsInlineMediaPlayback = true let webView = WKWebView(frame: .zero, configuration: config) webView.scrollView.isScrollEnabled = true let html = """ <!doctype html> <html> <head> <meta name="viewport" content="initial-scale=1.0, maximum-scale=1.0"> <style>body,html{height:100%;margin:0;background:#000}iframe{width:100%;height:100%;border:0}</style> </head> <body> <iframe src="https://www.youtube-nocookie.com/embed/videoseries?list=\(playlistID)&controls=1&rel=0&playsinline=1&iv_load_policy=3" frameborder="0" allow="encrypted-media; picture-in-picture; fullscreen" webkit-playsinline allowfullscreen ></iframe> </body> </html> """ webView.loadHTMLString(html, baseURL: nil) return webView } func updateUIView(_ uiView: WKWebView, context: Context) {} } #Preview { ContentView() } Observed behavior: First video plays without issue. Web process crashes when the second video in the playlist starts. Console logs show WebProcessProxy::didClose and repeated memory status messages. Using ProcessAssertion or background activity does not prevent the crash. Only occurs on physical devices; simulators do not reproduce the issue. Questions: Is there something I should change or add in my WKWebView setup or HTML/iframe to prevent the crash when playing the second video in a playlist on physical iOS devices? Is there an officially supported way to limit memory or prevent WebKit from terminating the web process during multi-video playback? Are there recommended patterns for playing YouTube playlists in a WKWebView on iOS without risking crashes? Any tips for debugging or configuring WKWebView to make it more stable for continuous playlist playback? Thanks in advance for any guidance!
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426
Oct ’25
Accessing External Timecode from Blackmagic ProDock in Custom App
Hi everyone, I’m exploring using the iPhone 17 Pro with the Blackmagic ProDock in a custom capture app. The genlock functionality seems accessible via AVExternalSyncDevice and related APIs, which is great. I’m specifically curious about external timecode coming in from the ProDock: • Is there a public way to access the timecode feed in a custom app via AVFoundation or another Apple API? • If so, what is the recommended approach to read or apply that timecode during capture? • Are there any current limitations or entitlements required to access timecode from ProDock in a third-party app? I’m excited to start integrating synchronized capture in my app, and any guidance or sample patterns would be greatly appreciated. Thanks in advance! — [Artem]
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284
Oct ’25
VTLowLatencyFrameInterpolationConfiguration supported dimensions
Is there limits on the supported dimension for VTLowLatencyFrameInterpolationConfiguration. Querying VTLowLatencyFrameInterpolationConfiguration.maximumDimensions and VTLowLatencyFrameInterpolationConfiguration.minimumDimensions returns nil. When I try the WWDC sample project EnhancingYourAppWithMachineLearningBasedVideoEffects with a 4k video this statement try frameProcessor.startSession(configuration: configuration) executes but try await frameProcessor.process(parameters: parameters) throws error Error Domain=VTFrameProcessorErrorDomain Code=-19730 "Processor is not initialized" UserInfo={NSLocalizedDescription=Processor is not initialized}. Also, why is VTLowLatencyFrameInterpolationConfiguration able to run while app is backgrounded but VTFrameRateConversionParameters can't (due to gpu usage)?
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336
Dec ’25
Control system video effects support for CMIO extension
We're distributing a virtual camera with our app that does not profit in the slightest from automatically applied system video effects both to the video going in (physical camera device) or out (virtual camera device). I'm aware of setting NSCameraReactionEffectGesturesEnabledDefault in Info.plist and determining active video effects via AVCaptureDevice API. Those are obviously crutches, because having to tell users to go look for and click around in menu bar apps is the opposite of a great UX. To make our product's video output more deterministic, I'm looking for a way to tell the CMIO subsystem that our virtual camera does not support any of the system video effects. I'm seeing properties like AVCaptureDevice.Format.isPortraitEffectSupported and AVCaptureDevice.Format.isStudioLightSupported whose documentation refers to the format's ability to support these effects. Since we're setting a CMFormatDescription via CMIOExtensionStreamSource.formats I was hoping to find something in the extensions, but wasn't successful so far. Can this be done?
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212
Nov ’25
Attaching color properties to CVPixelBufferRef
I believe this should work: CFMutableDictionaryRef attrs = CFDictionaryCreateMutable(kCFAllocatorDefault, 0, &kCFTypeDictionaryKeyCallBacks, &kCFTypeDictionaryValueCallBacks); CFDictionaryAddValue(attrs, kCVImageBufferColorPrimariesKey, kCVImageBufferColorPrimaries_ITU_R_709_2); CFDictionaryAddValue(attrs, kCVImageBufferTransferFunctionKey, kCVImageBufferTransferFunction_ITU_R_709_2); CFDictionaryAddValue(attrs, kCVImageBufferYCbCrMatrixKey, kCVImageBufferYCbCrMatrix_ITU_R_709_2); CVPixelBufferRef pixelBuffer = NULL; CVPixelBufferCreate(kCFAllocatorDefault, width, height, kCVPixelFormatType_32ARGB, attrs, &pixelBuffer); assert(CFDictionaryGetCount(CVBufferGetAttachments(pixelBuffer, kCVAttachmentMode_ShouldPropagate)) > 0); But that last assert fails, so it appears the color info does not get attached. kCVImageBufferColorPrimariesKey and the others are not one of the keys listed under BufferAttributeKeys, but I think they're supposed to be allowed because they're listed by CMVideoFormatDescriptionGetExtensionKeysCommonWithImageBuffers(). I'm hoping that putting the color matrix info in there will control how AVAssetWriter converts the RGB to YCbCr.
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330
Nov ’25
AVPlayer unpredictable range requests on iOS when streaming *.mov file
Hi all, I'm trying to diagnose and resolve an issue with stuttering video playback using the standard AVPlayer. The video in question is a 4K, 39-second file in *.mov format, being played on an iOS device. It's served via a local HTTP server that proxies requests to a backend to fetch and process the content. The project uses end-to-end encrypted storage, which necessitates the proxy for handling data processing. While playback in offline scenarios is smooth, we are encountering issues with smooth playback during streaming. The same video streams smoothly on other platforms using the same connection, so network limitations are not a factor. On iOS, playback is consistently choppy, with pauses every 1-3 seconds. The video does not appear to buffer adequately for smooth playback. One particularly curious aspect is the seemingly random pattern of Content-Range requests made by the AVPlayer when streaming the video. Below is an example of the range requests:
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521
Apr ’25
Missing Depth Frames When Recording with AVCaptureVideoDataOutputSampleBufferDelegate/AVCaptureDataOutputSynchronizerDelegate and AVAssetWriter
I’ve tried both AVCaptureVideoDataOutputSampleBufferDelegate (captureOutput) and AVCaptureDataOutputSynchronizerDelegate (dataOutputSynchronizer), but the number of depth frames and saved timestamps is significantly lower than the number of frames in the .mp4 file written by AVAssetWriter. In my code, I save: Timestamps for each frame to a metadata file Depth frames to a binary file Video to an .mp4 file If I record a 4-second video at 30fps, the .mp4 file correctly plays for 4 seconds, but the number of stored timestamps and depth frames is much lower—around 70 frames instead of the expected 120. Does anyone know why this mismatch happens? func dataOutputSynchronizer(_ synchronizer: AVCaptureDataOutputSynchronizer, didOutput synchronizedDataCollection: AVCaptureSynchronizedDataCollection) { // Read all outputs guard let syncedDepthData: AVCaptureSynchronizedDepthData = synchronizedDataCollection.synchronizedData(for: depthDataOutput) as? AVCaptureSynchronizedDepthData, let syncedVideoData: AVCaptureSynchronizedSampleBufferData = synchronizedDataCollection.synchronizedData(for: videoDataOutput) as? AVCaptureSynchronizedSampleBufferData else { // only work on synced pairs return } if syncedDepthData.depthDataWasDropped || syncedVideoData.sampleBufferWasDropped { return } let depthData = syncedDepthData.depthData let depthPixelBuffer = depthData.depthDataMap let sampleBuffer = syncedVideoData.sampleBuffer guard let videoPixelBuffer = CMSampleBufferGetImageBuffer(sampleBuffer), let formatDescription = CMSampleBufferGetFormatDescription(sampleBuffer) else { return } addToPreviewStream?(CIImage(cvPixelBuffer: videoPixelBuffer)) if !canWrite() { return } // Extract the presentation timestamp (PTS) from the sample buffer let timestamp = CMSampleBufferGetPresentationTimeStamp(sampleBuffer) //sessionAtSourceTime is the first buffer we will write to the file if self.sessionAtSourceTime == nil { //Make sure we don't start recording until the buffer reaches the correct time (buffer is always behind, this will fix the difference in time) guard sampleBuffer.presentationTimeStamp >= self.recordFromTime! else { return } self.sessionAtSourceTime = sampleBuffer.presentationTimeStamp self.videoWriter!.startSession(atSourceTime: sampleBuffer.presentationTimeStamp) } if self.videoWriterInput!.isReadyForMoreMediaData { self.videoWriterInput!.append(sampleBuffer) self.videoTimestamps.append( Timestamp( frame: videoTimestamps.count, value: timestamp.value, timescale: timestamp.timescale ) ) let ddm = depthData.depthDataMap depthCapture.addDepthData(pixelBuffer: ddm, timestamp: timestamp) } }
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462
Feb ’25
Configuring CaptureVideoDelegate to avoid gamma/transfer function
I'm working on an application that uses the iPhone camera for scientific purposes - and, as a result would like to receive video in as unprocessed format as possible. In particular, I'm interested in getting pixel buffers that contain pretty much the bayer data as the sensor sees it - with the minimum processing of color possible. Currently we configure the AVCaptureDevice to fix the focus and exposure, use a low ISO with no gain and set the white balance gains to 1. AVCaptureVideoDataOutput is using 32BGRA. What I'd like to do is remove any additional color and brightness processing such that the data is effectively processed with a linear transfer function (i.e. gamma function is 1). I thought that this might be down to using the AVCaptureDevice activeColorSpace - we currently use P3_D65 for this. But there only seems to be a few choices (e.g. sRGB, HLG_BT2020) all of which I think affect the gamma. So: is it possible to control or specify the gamma / transfer function when using CaptureVideoDelegate? if not, does one of the color space settings have a defined gamma function that I can effectively reverse it from the pixel data without losing too much information? or is there a better way to capture video-ish speed images (15-30fps) from the camera sensor that skips processing like this? Many thanks for any suggestions.
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127
Mar ’25
Coverting CVPixelBuffer 2VUY to a Metal Texture
I am working on a project for macOS where I am taking an AVCaptureSession's CVPixelBuffer and I need to convert it into a MTLTexture for rendering. On macOS the pixel format is 2vuy, there does not seem to be a clear format conversion while converting to a metal texture. I have been able to convert it to a texture but the color space seems to be off as it is rendering distorted colors with a double image. I believe 2vuy is a single pane color space and I have tried to account for that, but I am unaware of what is off. I have attached The CVPixelBuffer and The distorted MTLTexture along with a laundry list of errors. On iOS my conversions are fine, it is only the macOS 2vuy pixel format that seems to have issues. My code for the conversion is also attached. If there are any suggestions or guidance on how to properly convert a 2vuy CVPixelBuffer to a MTLTexture I would greatly appreciate it. Many Thanks Conversion_Logs.txt ConversionCode.swift
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199
Apr ’25
AVCaptureSession video and audio out of sync
I'm using an AVCaptureSession to send video and audio samples to an AVAssetWriter. When I play back the resultant video, sometimes there is a significant lag between the audio compared with the video, so they're just not in sync. But sometimes they are, with the same code. If I look at the very first presentation time stamps of the buffers being sent to the delegate, via func captureOutput(_: AVCaptureOutput, didOutput sampleBuffer: CMSampleBuffer, from connection: AVCaptureConnection) I see something like this: Adding audio samples for pts time 227711.0855328798, Adding video samples for pts time 227710.778785374 That is, the clock for audio vs video is behind: the first audio sample I receive is at 11.08 something, while the video video sample is earlier in time, at 10.778 something. The times are the presentation time stamps of the buffer, and the outputPresentationTimeStamp is the exact same number. It feels like "video" vs the "audio" clock are just mismatched. This doesn't always happen: sometimes they're synced. Sometimes they're not. Any ideas? The device I'm recording is a webcam, on iPadOS, connected via the usb-c port.
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Apr ’25