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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Retrieving the DRM expiration time for FairPlay offline assets on iOS
I’m implementing FairPlay offline streaming on iOS and ran into a question about DRM expiration handling. As far as I understand, when issuing a FairPlay offline license, there are typically two time windows: 1. The period during which the user can start offline playback (the longer “rental window”). 2. Once playback starts, the duration allowed to complete playback (the shorter “playback window”). I’d like to display this information (the remaining validity or expiration time) in the app’s UI next to each downloaded asset. My question is: 👉 Is there a way to programmatically check or retrieve the expiration time for a FairPlay offline asset on the client side (via AVFoundation or AVContentKeySession)? Any guidance or best practices for surfacing DRM expiration info in the UI would be greatly appreciated.
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625
Oct ’25
AVFoundation Custom Video Compositor Skipping Frames During AVPlayer Playback Despite 60 FPS Frame Duration
I'm building a Swift video editor with AVFoundation and a custom compositor. Despite setting AVVideoComposition.frameDuration to 60 FPS, I'm seeing significant frame skipping during playback. Console Output Shows Frame Skipping Frame #0 at 0.0 ms (fps: 60.0) Frame #2 at 33.333333333333336 ms (fps: 60.0) Frame #6 at 100.0 ms (fps: 60.0) Frame #10 at 166.66666666666666 ms (fps: 60.0) Frame #32 at 533.3333333333334 ms (fps: 60.0) Frame #62 at 1033.3333333333335 ms (fps: 60.0) Frame #96 at 1600.0 ms (fps: 60.0) Instead of frames every ~16.67ms (60 FPS), I'm getting irregular intervals, sometimes 33ms, 67ms, or hundreds of milliseconds apart. Renderer.swift (Key Parts) @MainActor class Renderer: ObservableObject { @Published var playerItem: AVPlayerItem? private let assetManager: ProjectAssetManager? private let compositorId: String func buildComposition() async { // ... load mouse moves/clicks data ... let composition = AVMutableComposition() let videoTrack = composition.addMutableTrack( withMediaType: .video, preferredTrackID: kCMPersistentTrackID_Invalid ) var currentTime = CMTime.zero var layerInstructions: [AVMutableVideoCompositionLayerInstruction] = [] // Insert video segments for videoURL in videoURLs { let asset = AVAsset(url: videoURL) let tracks = try await asset.loadTracks(withMediaType: .video) let assetVideoTrack = tracks.first let duration = try await asset.load(.duration) try videoTrack.insertTimeRange( CMTimeRange(start: .zero, duration: duration), of: assetVideoTrack, at: currentTime ) let layerInstruction = AVMutableVideoCompositionLayerInstruction(assetTrack: videoTrack) let transform = try await assetVideoTrack.load(.preferredTransform) layerInstruction.setTransform(transform, at: currentTime) layerInstructions.append(layerInstruction) currentTime = CMTimeAdd(currentTime, duration) } let videoComposition = AVMutableVideoComposition() videoComposition.frameDuration = CMTime(value: 1, timescale: 60) // 60 FPS // Set render size from first video if let firstURL = videoURLs.first { let firstAsset = AVAsset(url: firstURL) let firstTrack = try await firstAsset.loadTracks(withMediaType: .video).first let naturalSize = try await firstTrack.load(.naturalSize) let transform = try await firstTrack.load(.preferredTransform) videoComposition.renderSize = CGSize( width: abs(naturalSize.applying(transform).width), height: abs(naturalSize.applying(transform).height) ) } let instruction = CompositorInstruction() instruction.timeRange = CMTimeRange(start: .zero, duration: currentTime) instruction.layerInstructions = layerInstructions instruction.compositorId = compositorId videoComposition.instructions = [instruction] videoComposition.customVideoCompositorClass = CustomVideoCompositor.self let playerItem = AVPlayerItem(asset: composition) playerItem.videoComposition = videoComposition self.playerItem = playerItem } } class CompositorInstruction: NSObject, AVVideoCompositionInstructionProtocol { var timeRange: CMTimeRange = .zero var enablePostProcessing: Bool = false var containsTweening: Bool = false var requiredSourceTrackIDs: [NSValue]? var passthroughTrackID: CMPersistentTrackID = kCMPersistentTrackID_Invalid var layerInstructions: [AVVideoCompositionLayerInstruction] = [] var compositorId: String = "" } class CustomVideoCompositor: NSObject, AVVideoCompositing { var sourcePixelBufferAttributes: [String : Any]? = [ kCVPixelBufferPixelFormatTypeKey as String: Int(kCVPixelFormatType_32BGRA) ] var requiredPixelBufferAttributesForRenderContext: [String : Any] = [ kCVPixelBufferPixelFormatTypeKey as String: Int(kCVPixelFormatType_32BGRA) ] func renderContextChanged(_ newRenderContext: AVVideoCompositionRenderContext) {} func startRequest(_ asyncVideoCompositionRequest: AVAsynchronousVideoCompositionRequest) { guard let sourceTrackID = asyncVideoCompositionRequest.sourceTrackIDs.first?.int32Value, let sourcePixelBuffer = asyncVideoCompositionRequest.sourceFrame(byTrackID: sourceTrackID), let outputBuffer = asyncVideoCompositionRequest.renderContext.newPixelBuffer() else { asyncVideoCompositionRequest.finish(with: NSError(domain: "VideoCompositor", code: -1)) return } let videoComposition = asyncVideoCompositionRequest.renderContext.videoComposition let frameDuration = videoComposition.frameDuration let fps = Double(frameDuration.timescale) / Double(frameDuration.value) let compositionTime = asyncVideoCompositionRequest.compositionTime let seconds = CMTimeGetSeconds(compositionTime) let frameInMilliseconds = seconds * 1000 let frameNumber = Int(round(seconds * fps)) print("Frame #\(frameNumber) at \(frameInMilliseconds) ms (fps: \(fps))") asyncVideoCompositionRequest.finish(withComposedVideoFrame: outputBuffer) } func cancelAllPendingVideoCompositionRequests() {} } VideoPlayerViewModel @MainActor class VideoPlayerViewModel: ObservableObject { let player = AVPlayer() private let renderer: Renderer func loadVideo() async { await renderer.buildComposition() if let playerItem = renderer.playerItem { player.replaceCurrentItem(with: playerItem) } } } What I've Tried Frame skipping is consistent—exact same timestamps on every playback Issue persists even with minimal processing (just passing through buffers) Occurs regardless of compositor complexity Please note that I need every frame at exact millisecond intervals for my application. Frame loss or inconsistent frameInMillisecond values are not acceptable.
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348
Oct ’25
AVAssetExportSession ignores frameDuration 60fps and exports at 30fps, but AVPlayer playback is correct
Hey everyone, I'm stuck on a really frustrating AVFoundation problem. I'm building a video editor that uses a custom AVVideoCompositor to add effects, and I need the final output to be 60 FPS. So basically, I create an AVMutableComposition to sequence my video clips. I create an AVMutableVideoComposition and set the frame rate to 60 FPS: videoComposition.frameDuration = CMTime(value: 1, timescale: 60) I assign my CustomVideoCompositor class to the videoComposition. I create an AVPlayerItem with the composition and video composition. The Problem: Playback Works: When I play the AVPlayerItem in an AVPlayer, it's perfect. It plays at a smooth 60 FPS, and my custom compositor's startRequest method is called 60 times per second. Export Fails: When I try to export the exact same composition and video composition using AVAssetExportSession, the final .mp4 file is always 30 FPS (or 29.97). I've logged inside my custom compositor during the export, and it's definitely being called 30 times per second, so it's generating the 30 frames. It seems like AVAssetExportSession is just dropping every other frame when it encodes the video. My source videos are screen recordings which I recorded using ScreenCaptureKit itself with the minimum frame interval to be 60. Here is my export function. I'm using the AVAssetExportPresetHighestQuality preset :- func exportVideo(to outputURL: URL) async throws { guard let composition = composition, let videoComposition = videoComposition else { throw VideoCompositionError.noValidVideos } try? FileManager.default.removeItem(at: outputURL) guard let exportSession = AVAssetExportSession( asset: composition, presetName: AVAssetExportPresetHighestQuality // Is this the problem? ) else { throw VideoCompositionError.trackCreationFailed } exportSession.outputFileType = .mp4 exportSession.videoComposition = videoComposition // This has the 60fps setting try await exportSession.export(to: outputURL, as: .mp4) } I've created a bare bones sample project that shows this exact bug in action. The resulting video is 60fps during playback, but only 30fps during the export. https://github.com/zaidbren/SimpleEditor My Question: Why is AVAssetExportSession ignoring my 60 FPS frameDuration and defaulting to 30 FPS, even though AVPlayer respects it?
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442
Oct ’25
PhotosPickerItem.itemIdentifier always nil
I'm using the SwiftUI Photos Picker to select videos from the users Photos library and then opening the video using the PhotosPickerItem. I'm looking for a way to allow the user to open the same video on their other devices as the app uses SwiftData and CloudKit to provide access to a recently watched list of videos. The URL from the PhotosPickerItem appears to be device specific and so I was looking to see if I can use the itemIdentifier and then the init that takes the itemIdentifier to create the PhotosPickerItem on the other devices. The itemIdentifier however is always nil and so wouldn't be able to be used in this way. Is there an alternative approach whereby the users can open a video using a PhotosPickerItem and that item would be viewable on their other devices with an item identifier or a URL that is device agnostic. This approach should also not involve copying the video into other storage as it would simply expand the use of the users iCloud storage, providing a less than ideal user experience. If the user has opened the video from their Photos library, there should be a way to allow the same user (e.g. same Apple ID), to use the same app on another device to open the video again.
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680
Nov ’25
AVCaptureSession setting preset has no effect if HDR configured with AVCaptureVideoDataOutput
I want to confirm if this is a bug or a programming error. Very easy to reproduce it by modifying AVCam sample code. Steps to reproduce: Add AVCaptureVideoDataOutput to AVCaptureSession, no need to set delegate in AVCam sample code (CaptureService actor) private let videoDataOutput = AVCaptureVideoDataOutput() and then in configureSession method, add the following line try addOutput(videoDataOutput) if videoDataOutput.availableVideoPixelFormatTypes.contains(kCVPixelFormatType_420YpCbCr8BiPlanarFullRange) { videoDataOutput.videoSettings = [kCVPixelBufferPixelFormatTypeKey as AnyHashable as! String : kCVPixelFormatType_420YpCbCr8BiPlanarFullRange] } And next modify set HDR method: /// Sets whether the app captures HDR video. func setHDRVideoEnabled(_ isEnabled: Bool) { // Bracket the following configuration in a begin/commit configuration pair. captureSession.beginConfiguration() defer { captureSession.commitConfiguration() } do { // If the current device provides a 10-bit HDR format, enable it for use. if isEnabled, let format = currentDevice.activeFormat10BitVariant { try currentDevice.lockForConfiguration() currentDevice.activeFormat = format currentDevice.unlockForConfiguration() isHDRVideoEnabled = true if videoDataOutput.availableVideoPixelFormatTypes.contains(kCVPixelFormatType_420YpCbCr10BiPlanarVideoRange) { videoDataOutput.videoSettings = [kCVPixelBufferPixelFormatTypeKey as AnyHashable as! String : kCVPixelFormatType_420YpCbCr10BiPlanarVideoRange] } } else { captureSession.sessionPreset = .high isHDRVideoEnabled = false if videoDataOutput.availableVideoPixelFormatTypes.contains(kCVPixelFormatType_32BGRA) { print("Setting sdr pixel format \(kCVPixelFormatType_32BGRA)") videoDataOutput.videoSettings = [kCVPixelBufferPixelFormatTypeKey as AnyHashable as! String : kCVPixelFormatType_32BGRA] } try currentDevice.lockForConfiguration() currentDevice.activeColorSpace = .sRGB currentDevice.unlockForConfiguration() } } catch { logger.error("Unable to obtain lock on device and can't enable HDR video capture.") } The problem now is toggling HDR on and off no longer works in video mode. If after setting HDR on, you set HDR to off, active format of device does not change (setting sessionPreset has no effect). This does not happen if video data output is not added to session. Is there any workaround available?
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327
Nov ’25
VideoPlayer crashes on Archive build
I have found that following code runs without issue from Xcode, either in Debug or Release mode, yet crashes when running from the binary produced by archiving - i.e. what will be sent to the app store. import SwiftUI import AVKit @main struct tcApp: App { var body: some Scene { WindowGroup { VideoPlayer(player: nil) } } } This is the most stripped down code that shows the issue. One can try and point the VideoPlayer at a file and the same issue will occur. I've attached the crash log: Crash log Please note that this was seen with Xcode 26.2 and MacOS 26.2.
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542
Dec ’25
AVAssetDownloadConfiguration: How many video variants are actually downloaded when multiple variants exist in the HLS master playlist?
Hi, I’m trying to better understand how AVAssetDownloadConfiguration selects video variants when downloading HLS content for offline playback. Suppose I have an HLS master playlist (.m3u8) that contains several video variants defined with #EXT-X-STREAM-INF. For example, the master playlist may contain multiple video streams like this: Same resolution, different BANDWIDTH Or different resolutions (for example 720p, 1080p, etc.) My question is: How many video variants are actually downloaded when using AVAssetDownloadConfiguration without specifying any variantQualifiers? In other words: If the master playlist contains multiple video variants, will the download task fetch only one variant, or multiple variants? Does the behavior differ depending on whether the variants differ only by BANDWIDTH or also by RESOLUTION? What I observed in testing In my tests, I always end up with only one video variant downloaded, specifically the one with the highest BANDWIDTH parameter. In the m3u8 files I tested, all video variants had identical parameters (resolution, codec, frame rate, etc.) and differed only by the BANDWIDTH attribute in the master playlist. However, when inspecting the downloaded .movpkg, I noticed something interesting in boot.xml. It lists two video streams: one with complete="true" (the one with highest bandwidth) another with complete="no" (the one with lowest bandwidth) I actually had 3 video streams listed in m3u8, but the one with middle bandwidth wasn't listed in boot.xml file at all. There are also additional streams for audio and subtitles in boot.xml file. This made me wonder whether the system initially attempts to download another video variant (possibly a lower bitrate one), but then switches to the highest-quality variant and only completes that one. Additional question about variantQualifiers If I provide a predicate such as: NSPredicate(format: "peakBitRate > 0") which should theoretically match all variants, will the download task attempt to download all matching video variants, or will it still select only one? Summary So the main questions are: Without variantQualifiers, does AVAssetDownloadConfiguration always download a single video variant, and if so, how is it chosen? Does the behavior differ if variants have different resolutions vs only different bitrates? When a predicate matches multiple variants, can multiple video variants actually be downloaded in a single .movpkg? Why might boot.xml list multiple video streams when only one appears to be fully downloaded? Any clarification on the intended behavior would be greatly appreciated. Thanks!
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2w
Videos viewed in WKWebView have Spatial Audio issues
I have an app that has a WKWebView for watching YouTube videos. When the videos are windowed the audio seems fine, positionally as well. All perfectly. When I fullscreen the video and it goes into the native visionOS video player the audio messes up. It will suddenly sound like it is in your ears, or maybe even just one ear channel, or the position will be wrong. It might be fine for a moment but the second I touch the controls or move the window the sound jumps across the room, away from the window, or switches to stereo. Sometimes exiting windows entirely you will still hear the videos playing. Even if you open the window back up and go to another screen and open another video, now you hear 2 videos playing at the same time with no way to stop the first one in the background, requiring to force restart the app. It is all sorts of glitchy. I haven't the slightest clue what is happening here. I am strongly feeling this is a visionOS bug. I tried using AVAudioSession to change some of the sound settings, and that makes zero difference in behavior. Multiple testers have also reported this behavior and it has been seen on both visionOS 2.3 and 2.4 betas. Thanks for the help! This is driving me mad! It is extremely consistent behavior!
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184
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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148
Mar ’25
iOS AVPlayer Subtitles / Captions
As of iOS 18, as far as I can tell, it appears there's still no AVPlayer options that allow users to toggle the caption / subtitle track on and off. Does anyone know of a way to do this with AVPlayer or with SwiftUI's VideoPlayer? The following code reproduces this issue. It can be pasted into an app playground. This is a random video and a random vtt file I found on the internet. import SwiftUI import AVKit import UIKit struct ContentView: View { private let video = URL(string: "https://server15700.contentdm.oclc.org/dmwebservices/index.php?q=dmGetStreamingFile/p15700coll2/15.mp4/byte/json")! private let captions = URL(string: "https://gist.githubusercontent.com/samdutton/ca37f3adaf4e23679957b8083e061177/raw/e19399fbccbc069a2af4266e5120ae6bad62699a/sample.vtt")! @State private var player: AVPlayer? var body: some View { VStack { VideoPlayerView(player: player) .frame(maxWidth: .infinity, maxHeight: 200) } .task { // Captions won't work for some reason player = try? await loadPlayer(video: video, captions: captions) } } } private struct VideoPlayerView: UIViewControllerRepresentable { let player: AVPlayer? func makeUIViewController(context: Context) -> AVPlayerViewController { let controller = AVPlayerViewController() controller.player = player controller.modalPresentationStyle = .overFullScreen return controller } func updateUIViewController(_ uiViewController: AVPlayerViewController, context: Context) { uiViewController.player = player } } private func loadPlayer(video: URL, captions: URL?) async throws -> AVPlayer { let videoAsset = AVURLAsset(url: video) let videoPlusSubtitles = AVMutableComposition() try await videoPlusSubtitles.add(videoAsset, withMediaType: .video) try await videoPlusSubtitles.add(videoAsset, withMediaType: .audio) if let captions { let captionAsset = AVURLAsset(url: captions) // Must add as .text. .closedCaption and .subtitle don't work? try await videoPlusSubtitles.add(captionAsset, withMediaType: .text) } return await AVPlayer(playerItem: AVPlayerItem(asset: videoPlusSubtitles)) } private extension AVMutableComposition { func add(_ asset: AVAsset, withMediaType mediaType: AVMediaType) async throws { let duration = try await asset.load(.duration) try await asset.loadTracks(withMediaType: mediaType).first.map { track in let newTrack = self.addMutableTrack(withMediaType: mediaType, preferredTrackID: kCMPersistentTrackID_Invalid) let range = CMTimeRangeMake(start: .zero, duration: duration) try newTrack?.insertTimeRange(range, of: track, at: .zero) } } }
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116
Apr ’25
How correctly setup AVSampleBufferDisplayLayer
How can I setup correctly AVSampleBufferDisplayLayer for video display when I have input picture format kCVPixelFormatType_32BGRA? Currently video i visible in simulator, but not iPhone, miss I something? Render code: var pixelBuffer: CVPixelBuffer? let attrs: [String: Any] = [ kCVPixelBufferPixelFormatTypeKey as String: kCVPixelFormatType_32BGRA, kCVPixelBufferWidthKey as String: width, kCVPixelBufferHeightKey as String: height, kCVPixelBufferBytesPerRowAlignmentKey as String: width * 4, kCVPixelBufferIOSurfacePropertiesKey as String: [:] ] let status = CVPixelBufferCreateWithBytes( nil, width, height, kCVPixelFormatType_32BGRA, img, width * 4, nil, nil, attrs as CFDictionary, &pixelBuffer ) guard status == kCVReturnSuccess, let pb = pixelBuffer else { return } var formatDesc: CMVideoFormatDescription? CMVideoFormatDescriptionCreateForImageBuffer( allocator: nil, imageBuffer: pb, formatDescriptionOut: &formatDesc ) guard let format = formatDesc else { return } var timingInfo = CMSampleTimingInfo( duration: .invalid, presentationTimeStamp: currentTime, decodeTimeStamp: .invalid ) var sampleBuffer: CMSampleBuffer? CMSampleBufferCreateForImageBuffer( allocator: kCFAllocatorDefault, imageBuffer: pb, dataReady: true, makeDataReadyCallback: nil, refcon: nil, formatDescription: format, sampleTiming: &timingInfo, sampleBufferOut: &sampleBuffer ) if let sb = sampleBuffer { if CMSampleBufferGetPresentationTimeStamp(sb) == .invalid { print("Invalid video timestamp") } if (displayLayer.status == .failed) { displayLayer.flush() } DispatchQueue.main.async { [weak self] in guard let self = self else { print("Lost reference to self drawing") return } displayLayer.enqueue(sb) } frameIndex += 1 }
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258
Apr ’25
AirDropped Videos from Photos Save to Files Instead of Photos on Receiving Device
My app allows users to capture and save videos to the Photos app using the following Swift code: PHPhotoLibrary.shared().performChanges { PHAssetChangeRequest.creationRequestForAssetFromVideo(atFileURL: fileURL) } completionHandler: { success, error in Videos are successfully saved to Photos and play correctly. However, users report that when they AirDrop these videos from the Photos app to another device (e.g., iPad to iPhone), the videos are saved in the Files app on the receiving device instead of the Photos app. This issue is more common with higher-resolution videos, such as 2K, recorded in HEVC format at 30 fps. I wasn't able to reproduce the issue locally. I've found a thread in public apple forum: https://discussions.apple.com/thread/255276865?sortBy=rank but I wonder maybe there are some special flags that I should clear or add to my videos (e.g. PHAssetChangeRequest)? Thank you!
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153
May ’25
​​Can VideoToolbox properly decode HEVC bitstreams when a single frame is split into multiple slice NALUs?​
I am currently developing an HEVC player using VideoToolbox on an iOS device. I have successfully created an HEVC decoder that receives HEVC streams from our custom image capture and encoding device, and it can decode and display images properly. However, when my image capture and encoding device configures the encoder to output HEVC streams with ​​fragmented NALUs​​ (i.e., an I-frame or P-frame is split and stored across multiple slice NALUs), the iOS decoder can be initialized successfully but fails to decode and output images. ​​Can VideoToolbox properly decode HEVC bitstreams when a single frame is split into multiple slice NALUs?​​ Key Observations: ​​1. Single-NALU frames​​ work fine. ​​2. Multi-NALU frames​​ (sliced I/P-frames) cause decoding failure. 3. The decoder session is created successfully (VTDecompressionSessionCreate returns no error).
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194
May ’25
How to USE iphone16 pro to capture HDR dolby_vision and use videotoolbox to encode with dolby_vision metadata in bitstream!
How to USE iphone16 pro to capture HDR dolby_vision and use videotoolbox to encode with dolby_vision metadata in bitstream! I know apple ios system can achieve this target,but I want to get source code how to do that ?
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352
Activity
Oct ’25
Retrieving the DRM expiration time for FairPlay offline assets on iOS
I’m implementing FairPlay offline streaming on iOS and ran into a question about DRM expiration handling. As far as I understand, when issuing a FairPlay offline license, there are typically two time windows: 1. The period during which the user can start offline playback (the longer “rental window”). 2. Once playback starts, the duration allowed to complete playback (the shorter “playback window”). I’d like to display this information (the remaining validity or expiration time) in the app’s UI next to each downloaded asset. My question is: 👉 Is there a way to programmatically check or retrieve the expiration time for a FairPlay offline asset on the client side (via AVFoundation or AVContentKeySession)? Any guidance or best practices for surfacing DRM expiration info in the UI would be greatly appreciated.
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1
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625
Activity
Oct ’25
iOS 26 VideoToolbox rejects valid H.264 SPS from Tello drone
it seems that video toolbox in ios26 is having trouble decoding h.264 streams I have filed a bug report under https://feedbackassistant.apple.com/feedback/20741484
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1
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111
Activity
Oct ’25
willEndFullScreenPresentationWithAnimationCoordinator 不执行
方法不执行,当我点击avplayerviewcontroller 全屏点击返回按钮 时 func playerViewController(_ playerViewController: AVPlayerViewController, willEndFullScreenPresentationWithAnimationCoordinator coordinator: UIViewControllerTransitionCoordinator) 没有执行
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1
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88
Activity
Oct ’25
AVFoundation Custom Video Compositor Skipping Frames During AVPlayer Playback Despite 60 FPS Frame Duration
I'm building a Swift video editor with AVFoundation and a custom compositor. Despite setting AVVideoComposition.frameDuration to 60 FPS, I'm seeing significant frame skipping during playback. Console Output Shows Frame Skipping Frame #0 at 0.0 ms (fps: 60.0) Frame #2 at 33.333333333333336 ms (fps: 60.0) Frame #6 at 100.0 ms (fps: 60.0) Frame #10 at 166.66666666666666 ms (fps: 60.0) Frame #32 at 533.3333333333334 ms (fps: 60.0) Frame #62 at 1033.3333333333335 ms (fps: 60.0) Frame #96 at 1600.0 ms (fps: 60.0) Instead of frames every ~16.67ms (60 FPS), I'm getting irregular intervals, sometimes 33ms, 67ms, or hundreds of milliseconds apart. Renderer.swift (Key Parts) @MainActor class Renderer: ObservableObject { @Published var playerItem: AVPlayerItem? private let assetManager: ProjectAssetManager? private let compositorId: String func buildComposition() async { // ... load mouse moves/clicks data ... let composition = AVMutableComposition() let videoTrack = composition.addMutableTrack( withMediaType: .video, preferredTrackID: kCMPersistentTrackID_Invalid ) var currentTime = CMTime.zero var layerInstructions: [AVMutableVideoCompositionLayerInstruction] = [] // Insert video segments for videoURL in videoURLs { let asset = AVAsset(url: videoURL) let tracks = try await asset.loadTracks(withMediaType: .video) let assetVideoTrack = tracks.first let duration = try await asset.load(.duration) try videoTrack.insertTimeRange( CMTimeRange(start: .zero, duration: duration), of: assetVideoTrack, at: currentTime ) let layerInstruction = AVMutableVideoCompositionLayerInstruction(assetTrack: videoTrack) let transform = try await assetVideoTrack.load(.preferredTransform) layerInstruction.setTransform(transform, at: currentTime) layerInstructions.append(layerInstruction) currentTime = CMTimeAdd(currentTime, duration) } let videoComposition = AVMutableVideoComposition() videoComposition.frameDuration = CMTime(value: 1, timescale: 60) // 60 FPS // Set render size from first video if let firstURL = videoURLs.first { let firstAsset = AVAsset(url: firstURL) let firstTrack = try await firstAsset.loadTracks(withMediaType: .video).first let naturalSize = try await firstTrack.load(.naturalSize) let transform = try await firstTrack.load(.preferredTransform) videoComposition.renderSize = CGSize( width: abs(naturalSize.applying(transform).width), height: abs(naturalSize.applying(transform).height) ) } let instruction = CompositorInstruction() instruction.timeRange = CMTimeRange(start: .zero, duration: currentTime) instruction.layerInstructions = layerInstructions instruction.compositorId = compositorId videoComposition.instructions = [instruction] videoComposition.customVideoCompositorClass = CustomVideoCompositor.self let playerItem = AVPlayerItem(asset: composition) playerItem.videoComposition = videoComposition self.playerItem = playerItem } } class CompositorInstruction: NSObject, AVVideoCompositionInstructionProtocol { var timeRange: CMTimeRange = .zero var enablePostProcessing: Bool = false var containsTweening: Bool = false var requiredSourceTrackIDs: [NSValue]? var passthroughTrackID: CMPersistentTrackID = kCMPersistentTrackID_Invalid var layerInstructions: [AVVideoCompositionLayerInstruction] = [] var compositorId: String = "" } class CustomVideoCompositor: NSObject, AVVideoCompositing { var sourcePixelBufferAttributes: [String : Any]? = [ kCVPixelBufferPixelFormatTypeKey as String: Int(kCVPixelFormatType_32BGRA) ] var requiredPixelBufferAttributesForRenderContext: [String : Any] = [ kCVPixelBufferPixelFormatTypeKey as String: Int(kCVPixelFormatType_32BGRA) ] func renderContextChanged(_ newRenderContext: AVVideoCompositionRenderContext) {} func startRequest(_ asyncVideoCompositionRequest: AVAsynchronousVideoCompositionRequest) { guard let sourceTrackID = asyncVideoCompositionRequest.sourceTrackIDs.first?.int32Value, let sourcePixelBuffer = asyncVideoCompositionRequest.sourceFrame(byTrackID: sourceTrackID), let outputBuffer = asyncVideoCompositionRequest.renderContext.newPixelBuffer() else { asyncVideoCompositionRequest.finish(with: NSError(domain: "VideoCompositor", code: -1)) return } let videoComposition = asyncVideoCompositionRequest.renderContext.videoComposition let frameDuration = videoComposition.frameDuration let fps = Double(frameDuration.timescale) / Double(frameDuration.value) let compositionTime = asyncVideoCompositionRequest.compositionTime let seconds = CMTimeGetSeconds(compositionTime) let frameInMilliseconds = seconds * 1000 let frameNumber = Int(round(seconds * fps)) print("Frame #\(frameNumber) at \(frameInMilliseconds) ms (fps: \(fps))") asyncVideoCompositionRequest.finish(withComposedVideoFrame: outputBuffer) } func cancelAllPendingVideoCompositionRequests() {} } VideoPlayerViewModel @MainActor class VideoPlayerViewModel: ObservableObject { let player = AVPlayer() private let renderer: Renderer func loadVideo() async { await renderer.buildComposition() if let playerItem = renderer.playerItem { player.replaceCurrentItem(with: playerItem) } } } What I've Tried Frame skipping is consistent—exact same timestamps on every playback Issue persists even with minimal processing (just passing through buffers) Occurs regardless of compositor complexity Please note that I need every frame at exact millisecond intervals for my application. Frame loss or inconsistent frameInMillisecond values are not acceptable.
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1
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348
Activity
Oct ’25
AVAssetExportSession ignores frameDuration 60fps and exports at 30fps, but AVPlayer playback is correct
Hey everyone, I'm stuck on a really frustrating AVFoundation problem. I'm building a video editor that uses a custom AVVideoCompositor to add effects, and I need the final output to be 60 FPS. So basically, I create an AVMutableComposition to sequence my video clips. I create an AVMutableVideoComposition and set the frame rate to 60 FPS: videoComposition.frameDuration = CMTime(value: 1, timescale: 60) I assign my CustomVideoCompositor class to the videoComposition. I create an AVPlayerItem with the composition and video composition. The Problem: Playback Works: When I play the AVPlayerItem in an AVPlayer, it's perfect. It plays at a smooth 60 FPS, and my custom compositor's startRequest method is called 60 times per second. Export Fails: When I try to export the exact same composition and video composition using AVAssetExportSession, the final .mp4 file is always 30 FPS (or 29.97). I've logged inside my custom compositor during the export, and it's definitely being called 30 times per second, so it's generating the 30 frames. It seems like AVAssetExportSession is just dropping every other frame when it encodes the video. My source videos are screen recordings which I recorded using ScreenCaptureKit itself with the minimum frame interval to be 60. Here is my export function. I'm using the AVAssetExportPresetHighestQuality preset :- func exportVideo(to outputURL: URL) async throws { guard let composition = composition, let videoComposition = videoComposition else { throw VideoCompositionError.noValidVideos } try? FileManager.default.removeItem(at: outputURL) guard let exportSession = AVAssetExportSession( asset: composition, presetName: AVAssetExportPresetHighestQuality // Is this the problem? ) else { throw VideoCompositionError.trackCreationFailed } exportSession.outputFileType = .mp4 exportSession.videoComposition = videoComposition // This has the 60fps setting try await exportSession.export(to: outputURL, as: .mp4) } I've created a bare bones sample project that shows this exact bug in action. The resulting video is 60fps during playback, but only 30fps during the export. https://github.com/zaidbren/SimpleEditor My Question: Why is AVAssetExportSession ignoring my 60 FPS frameDuration and defaulting to 30 FPS, even though AVPlayer respects it?
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442
Activity
Oct ’25
Recording ProRes RAW on iPhone 17 Pro with AVAssetWriter
When trying to record ProRes RAW (btp2) with AVAssetWriter I get several types of errors: -12780 or -11875. I wonder if recording ProRes RAW can only be done through AVCaptureMovieFileOutput, or if there a way to correctly configure AVAssetWriter to do it.
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368
Activity
Nov ’25
PhotosPickerItem.itemIdentifier always nil
I'm using the SwiftUI Photos Picker to select videos from the users Photos library and then opening the video using the PhotosPickerItem. I'm looking for a way to allow the user to open the same video on their other devices as the app uses SwiftData and CloudKit to provide access to a recently watched list of videos. The URL from the PhotosPickerItem appears to be device specific and so I was looking to see if I can use the itemIdentifier and then the init that takes the itemIdentifier to create the PhotosPickerItem on the other devices. The itemIdentifier however is always nil and so wouldn't be able to be used in this way. Is there an alternative approach whereby the users can open a video using a PhotosPickerItem and that item would be viewable on their other devices with an item identifier or a URL that is device agnostic. This approach should also not involve copying the video into other storage as it would simply expand the use of the users iCloud storage, providing a less than ideal user experience. If the user has opened the video from their Photos library, there should be a way to allow the same user (e.g. same Apple ID), to use the same app on another device to open the video again.
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680
Activity
Nov ’25
AVCaptureSession setting preset has no effect if HDR configured with AVCaptureVideoDataOutput
I want to confirm if this is a bug or a programming error. Very easy to reproduce it by modifying AVCam sample code. Steps to reproduce: Add AVCaptureVideoDataOutput to AVCaptureSession, no need to set delegate in AVCam sample code (CaptureService actor) private let videoDataOutput = AVCaptureVideoDataOutput() and then in configureSession method, add the following line try addOutput(videoDataOutput) if videoDataOutput.availableVideoPixelFormatTypes.contains(kCVPixelFormatType_420YpCbCr8BiPlanarFullRange) { videoDataOutput.videoSettings = [kCVPixelBufferPixelFormatTypeKey as AnyHashable as! String : kCVPixelFormatType_420YpCbCr8BiPlanarFullRange] } And next modify set HDR method: /// Sets whether the app captures HDR video. func setHDRVideoEnabled(_ isEnabled: Bool) { // Bracket the following configuration in a begin/commit configuration pair. captureSession.beginConfiguration() defer { captureSession.commitConfiguration() } do { // If the current device provides a 10-bit HDR format, enable it for use. if isEnabled, let format = currentDevice.activeFormat10BitVariant { try currentDevice.lockForConfiguration() currentDevice.activeFormat = format currentDevice.unlockForConfiguration() isHDRVideoEnabled = true if videoDataOutput.availableVideoPixelFormatTypes.contains(kCVPixelFormatType_420YpCbCr10BiPlanarVideoRange) { videoDataOutput.videoSettings = [kCVPixelBufferPixelFormatTypeKey as AnyHashable as! String : kCVPixelFormatType_420YpCbCr10BiPlanarVideoRange] } } else { captureSession.sessionPreset = .high isHDRVideoEnabled = false if videoDataOutput.availableVideoPixelFormatTypes.contains(kCVPixelFormatType_32BGRA) { print("Setting sdr pixel format \(kCVPixelFormatType_32BGRA)") videoDataOutput.videoSettings = [kCVPixelBufferPixelFormatTypeKey as AnyHashable as! String : kCVPixelFormatType_32BGRA] } try currentDevice.lockForConfiguration() currentDevice.activeColorSpace = .sRGB currentDevice.unlockForConfiguration() } } catch { logger.error("Unable to obtain lock on device and can't enable HDR video capture.") } The problem now is toggling HDR on and off no longer works in video mode. If after setting HDR on, you set HDR to off, active format of device does not change (setting sessionPreset has no effect). This does not happen if video data output is not added to session. Is there any workaround available?
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327
Activity
Nov ’25
VideoPlayer crashes on Archive build
I have found that following code runs without issue from Xcode, either in Debug or Release mode, yet crashes when running from the binary produced by archiving - i.e. what will be sent to the app store. import SwiftUI import AVKit @main struct tcApp: App { var body: some Scene { WindowGroup { VideoPlayer(player: nil) } } } This is the most stripped down code that shows the issue. One can try and point the VideoPlayer at a file and the same issue will occur. I've attached the crash log: Crash log Please note that this was seen with Xcode 26.2 and MacOS 26.2.
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Activity
Dec ’25
Are frames returned in presentation or decode order with AVAssetReader
I read somewhere that the frames are returned in decode order instead of presentation order when using AVAssetReader. The documentation seems sparse on the subject. I have so far failed to find a video file where the frames are not returned in presentation order. Can anyone confirm the frames are actually returned in decode order?
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99
Activity
3w
AVAssetDownloadConfiguration: How many video variants are actually downloaded when multiple variants exist in the HLS master playlist?
Hi, I’m trying to better understand how AVAssetDownloadConfiguration selects video variants when downloading HLS content for offline playback. Suppose I have an HLS master playlist (.m3u8) that contains several video variants defined with #EXT-X-STREAM-INF. For example, the master playlist may contain multiple video streams like this: Same resolution, different BANDWIDTH Or different resolutions (for example 720p, 1080p, etc.) My question is: How many video variants are actually downloaded when using AVAssetDownloadConfiguration without specifying any variantQualifiers? In other words: If the master playlist contains multiple video variants, will the download task fetch only one variant, or multiple variants? Does the behavior differ depending on whether the variants differ only by BANDWIDTH or also by RESOLUTION? What I observed in testing In my tests, I always end up with only one video variant downloaded, specifically the one with the highest BANDWIDTH parameter. In the m3u8 files I tested, all video variants had identical parameters (resolution, codec, frame rate, etc.) and differed only by the BANDWIDTH attribute in the master playlist. However, when inspecting the downloaded .movpkg, I noticed something interesting in boot.xml. It lists two video streams: one with complete="true" (the one with highest bandwidth) another with complete="no" (the one with lowest bandwidth) I actually had 3 video streams listed in m3u8, but the one with middle bandwidth wasn't listed in boot.xml file at all. There are also additional streams for audio and subtitles in boot.xml file. This made me wonder whether the system initially attempts to download another video variant (possibly a lower bitrate one), but then switches to the highest-quality variant and only completes that one. Additional question about variantQualifiers If I provide a predicate such as: NSPredicate(format: "peakBitRate > 0") which should theoretically match all variants, will the download task attempt to download all matching video variants, or will it still select only one? Summary So the main questions are: Without variantQualifiers, does AVAssetDownloadConfiguration always download a single video variant, and if so, how is it chosen? Does the behavior differ if variants have different resolutions vs only different bitrates? When a predicate matches multiple variants, can multiple video variants actually be downloaded in a single .movpkg? Why might boot.xml list multiple video streams when only one appears to be fully downloaded? Any clarification on the intended behavior would be greatly appreciated. Thanks!
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276
Activity
2w
Videos viewed in WKWebView have Spatial Audio issues
I have an app that has a WKWebView for watching YouTube videos. When the videos are windowed the audio seems fine, positionally as well. All perfectly. When I fullscreen the video and it goes into the native visionOS video player the audio messes up. It will suddenly sound like it is in your ears, or maybe even just one ear channel, or the position will be wrong. It might be fine for a moment but the second I touch the controls or move the window the sound jumps across the room, away from the window, or switches to stereo. Sometimes exiting windows entirely you will still hear the videos playing. Even if you open the window back up and go to another screen and open another video, now you hear 2 videos playing at the same time with no way to stop the first one in the background, requiring to force restart the app. It is all sorts of glitchy. I haven't the slightest clue what is happening here. I am strongly feeling this is a visionOS bug. I tried using AVAudioSession to change some of the sound settings, and that makes zero difference in behavior. Multiple testers have also reported this behavior and it has been seen on both visionOS 2.3 and 2.4 betas. Thanks for the help! This is driving me mad! It is extremely consistent behavior!
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184
Activity
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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148
Activity
Mar ’25
Playing m3u8 videos at 3x speed using AVPlayer is not smooth
When I play an m3u8 video using AVPlayer, it can play smoothly at 2x speed. However, when I set it to 3x speed, the playback is not smooth and there is no sound.
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74
Activity
Apr ’25
iOS AVPlayer Subtitles / Captions
As of iOS 18, as far as I can tell, it appears there's still no AVPlayer options that allow users to toggle the caption / subtitle track on and off. Does anyone know of a way to do this with AVPlayer or with SwiftUI's VideoPlayer? The following code reproduces this issue. It can be pasted into an app playground. This is a random video and a random vtt file I found on the internet. import SwiftUI import AVKit import UIKit struct ContentView: View { private let video = URL(string: "https://server15700.contentdm.oclc.org/dmwebservices/index.php?q=dmGetStreamingFile/p15700coll2/15.mp4/byte/json")! private let captions = URL(string: "https://gist.githubusercontent.com/samdutton/ca37f3adaf4e23679957b8083e061177/raw/e19399fbccbc069a2af4266e5120ae6bad62699a/sample.vtt")! @State private var player: AVPlayer? var body: some View { VStack { VideoPlayerView(player: player) .frame(maxWidth: .infinity, maxHeight: 200) } .task { // Captions won't work for some reason player = try? await loadPlayer(video: video, captions: captions) } } } private struct VideoPlayerView: UIViewControllerRepresentable { let player: AVPlayer? func makeUIViewController(context: Context) -> AVPlayerViewController { let controller = AVPlayerViewController() controller.player = player controller.modalPresentationStyle = .overFullScreen return controller } func updateUIViewController(_ uiViewController: AVPlayerViewController, context: Context) { uiViewController.player = player } } private func loadPlayer(video: URL, captions: URL?) async throws -> AVPlayer { let videoAsset = AVURLAsset(url: video) let videoPlusSubtitles = AVMutableComposition() try await videoPlusSubtitles.add(videoAsset, withMediaType: .video) try await videoPlusSubtitles.add(videoAsset, withMediaType: .audio) if let captions { let captionAsset = AVURLAsset(url: captions) // Must add as .text. .closedCaption and .subtitle don't work? try await videoPlusSubtitles.add(captionAsset, withMediaType: .text) } return await AVPlayer(playerItem: AVPlayerItem(asset: videoPlusSubtitles)) } private extension AVMutableComposition { func add(_ asset: AVAsset, withMediaType mediaType: AVMediaType) async throws { let duration = try await asset.load(.duration) try await asset.loadTracks(withMediaType: mediaType).first.map { track in let newTrack = self.addMutableTrack(withMediaType: mediaType, preferredTrackID: kCMPersistentTrackID_Invalid) let range = CMTimeRangeMake(start: .zero, duration: duration) try newTrack?.insertTimeRange(range, of: track, at: .zero) } } }
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116
Activity
Apr ’25
How correctly setup AVSampleBufferDisplayLayer
How can I setup correctly AVSampleBufferDisplayLayer for video display when I have input picture format kCVPixelFormatType_32BGRA? Currently video i visible in simulator, but not iPhone, miss I something? Render code: var pixelBuffer: CVPixelBuffer? let attrs: [String: Any] = [ kCVPixelBufferPixelFormatTypeKey as String: kCVPixelFormatType_32BGRA, kCVPixelBufferWidthKey as String: width, kCVPixelBufferHeightKey as String: height, kCVPixelBufferBytesPerRowAlignmentKey as String: width * 4, kCVPixelBufferIOSurfacePropertiesKey as String: [:] ] let status = CVPixelBufferCreateWithBytes( nil, width, height, kCVPixelFormatType_32BGRA, img, width * 4, nil, nil, attrs as CFDictionary, &pixelBuffer ) guard status == kCVReturnSuccess, let pb = pixelBuffer else { return } var formatDesc: CMVideoFormatDescription? CMVideoFormatDescriptionCreateForImageBuffer( allocator: nil, imageBuffer: pb, formatDescriptionOut: &formatDesc ) guard let format = formatDesc else { return } var timingInfo = CMSampleTimingInfo( duration: .invalid, presentationTimeStamp: currentTime, decodeTimeStamp: .invalid ) var sampleBuffer: CMSampleBuffer? CMSampleBufferCreateForImageBuffer( allocator: kCFAllocatorDefault, imageBuffer: pb, dataReady: true, makeDataReadyCallback: nil, refcon: nil, formatDescription: format, sampleTiming: &timingInfo, sampleBufferOut: &sampleBuffer ) if let sb = sampleBuffer { if CMSampleBufferGetPresentationTimeStamp(sb) == .invalid { print("Invalid video timestamp") } if (displayLayer.status == .failed) { displayLayer.flush() } DispatchQueue.main.async { [weak self] in guard let self = self else { print("Lost reference to self drawing") return } displayLayer.enqueue(sb) } frameIndex += 1 }
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Activity
Apr ’25
Pip custom view in Xcode16, iOS18, does not display when the camera is turned on
I have added some custom views on my pip. These controls disappeared after opening the camera in the Xcode16 environment and iOS 18 system, and it was found that these custom views were not removed and seemed to be obscured. They were displayed normally in the Xcode15.4 environment. I would like to ask how to make my custom views display normally
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Activity
Apr ’25
AirDropped Videos from Photos Save to Files Instead of Photos on Receiving Device
My app allows users to capture and save videos to the Photos app using the following Swift code: PHPhotoLibrary.shared().performChanges { PHAssetChangeRequest.creationRequestForAssetFromVideo(atFileURL: fileURL) } completionHandler: { success, error in Videos are successfully saved to Photos and play correctly. However, users report that when they AirDrop these videos from the Photos app to another device (e.g., iPad to iPhone), the videos are saved in the Files app on the receiving device instead of the Photos app. This issue is more common with higher-resolution videos, such as 2K, recorded in HEVC format at 30 fps. I wasn't able to reproduce the issue locally. I've found a thread in public apple forum: https://discussions.apple.com/thread/255276865?sortBy=rank but I wonder maybe there are some special flags that I should clear or add to my videos (e.g. PHAssetChangeRequest)? Thank you!
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153
Activity
May ’25
​​Can VideoToolbox properly decode HEVC bitstreams when a single frame is split into multiple slice NALUs?​
I am currently developing an HEVC player using VideoToolbox on an iOS device. I have successfully created an HEVC decoder that receives HEVC streams from our custom image capture and encoding device, and it can decode and display images properly. However, when my image capture and encoding device configures the encoder to output HEVC streams with ​​fragmented NALUs​​ (i.e., an I-frame or P-frame is split and stored across multiple slice NALUs), the iOS decoder can be initialized successfully but fails to decode and output images. ​​Can VideoToolbox properly decode HEVC bitstreams when a single frame is split into multiple slice NALUs?​​ Key Observations: ​​1. Single-NALU frames​​ work fine. ​​2. Multi-NALU frames​​ (sliced I/P-frames) cause decoding failure. 3. The decoder session is created successfully (VTDecompressionSessionCreate returns no error).
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194
Activity
May ’25