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Alternative for crashing API MPMediaItemArtwork
When setting the now playing info for playing media in MPNowPlayingInfoCenter we can set artwork. But it seems the Apple API for creating the artwork is crashing on iOS 18 (FB15145734). On iOS 17 this gave the warning that the completion handler was not run on the main thread. I've tried to seek help here: https://stackoverflow.com/questions/78989543/swift-data-race-with-appkit-mpmediaitemartwork-function/78990231?noredirect=1#comment139277425_78990231 but it seems that it's not possible to override the completion handler and therefor it's up to Apple to fix this issue. .task { await MainActor.run { let nowPlayingInfoCenter = MPNowPlayingInfoCenter.default() var nowPlayingInfo = [String: Any]() let image = NSImage(named: "image")! // warning: data race detected: @MainActor function at MPMediaItemArtwork/ContentView.swift:22 was not called on the main thread nowPlayingInfo[MPMediaItemPropertyArtwork] = MPMediaItemArtwork(boundsSize: image.size, requestHandler: { _ in // Not on main thread here! return image }) nowPlayingInfoCenter.nowPlayingInfo = nowPlayingInfo } } I'm wondering if there is an alternative method to set the now playing artwork?
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Feb ’25
AVSampleBufferDisplayLayerContentLayer memory leaks.
I noticed that AVSampleBufferDisplayLayerContentLayer is not released when the AVSampleBufferDisplayLayer is removed and released. It is possible to reproduce the issue with the simple code: import AVFoundation import UIKit class ViewController: UIViewController { var displayBufferLayer: AVSampleBufferDisplayLayer? override func viewDidLoad() { super.viewDidLoad() let displayBufferLayer = AVSampleBufferDisplayLayer() displayBufferLayer.videoGravity = .resizeAspectFill displayBufferLayer.frame = view.bounds view.layer.insertSublayer(displayBufferLayer, at: 0) self.displayBufferLayer = displayBufferLayer DispatchQueue.main.asyncAfter(deadline: .now() + 1) { self.displayBufferLayer?.flush() self.displayBufferLayer?.removeFromSuperlayer() self.displayBufferLayer = nil } } } In my real project I have mutliple AVSampleBufferDisplayLayer created and removed in different view controllers, this is problematic because the amount of leaked AVSampleBufferDisplayLayerContentLayer keeps increasing. I wonder that maybe I should use a pool of AVSampleBufferDisplayLayer and reuse them, however I'm slightly afraid that this can also lead to strange bugs. Edit: It doesn't cause leaks on iOS 18 device but leaks on iPad Pro, iOS 17.5.1
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572
Mar ’25
AVContentKeySession key renewal on Airplay
Our streaming app uses FairPlay-protected video streams, which previously worked fine when using AVAssetResourceLoaderDelegate to provide CKCs. Recently, we migrated to AVContentKeySession, and while everything works as expected during regular playback, we encountered an issue with AirPlay. Our CKC has a 120-second expiry, so we renew it by calling renewExpiringResponseData.. This trigger the didProvideRenewingContentKeyRequest delegate and we respond with updated CKC. However, when streaming via AirPlay, both video and audio freeze exactly after 120 seconds. To validate the issue, I tested with AVAssetResourceLoaderDelegate and found that I can reproduce the same freeze if I do not renew the key. This suggests that AirPlay is not accepting the renewed CKC when using AVContentKeySession. Additional Details: This issue occurs across different iOS versions and various AirPlay devices. The same content plays without issues when played directly on the device. The renewal process is successful, and segments continue to load, but playback remains frozen. Tried renewing the CKC bit early (100s). I also tried setting player.usesExternalPlaybackWhileExternalScreenIsActive = true, but the issue persists. We don't use persistentKey. Is there anything else that needs to be considered for proper key renewal when AirPlaying? Any help on how to fix this or confirmation if this is a known issue would be greatly appreciated.
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648
Mar ’25
WideFOV - APMP - Stereo
Does anyone have a template of an Apple Projected Media Profile Format Description or a File of a Stereo wideFOV video? Use case I have 2 compatible cameras that I stereo sync and I want to move the projection information from the compatible video to the Spatial video that combines them. Every version I can come up with crashes the AVP and when viewing as Spatial in Tahoe I just get a black screen.
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210
Jun ’25
After playing an HDR video on iPhone for a while, the HDR effect disappears and the screen brightness decrease
When i use AVPlayer to obtain the video frame CVPixelBufferRef of an HDR video, and use AVSampleBufferDisplayLayer to display it on the screen, after a period of time, the HDR video content and screen gradually darken, losing the HDR effect. Steps to reproduce: Create an AVPlayer to loop an HDR video, specify the video frame format as kCVPixelFormatType_420YpCbCr10BiPlanarVideoRange Create a timer to get the video frame CVPixelBufferRef at 30 frames per second Use AVSampleBufferDisplayLayer to display CVPixelBufferRef on the screen Don't operate the phone, wait for a period of time (such as 40 minutes), the HDR effect disappears and the screen darkens Note: You need to use an iPhone device, iOS 18.5 and below operating system You need to ensure that the HDR video is played in a loop, that is, to ensure that the screen continues to display HDR content, wait for a period of time, depending on different devices, you need to wait for 20-40 minutes. In the iPhone Photos app,the same problem will occur after playing HDR video in a loop for a long time Expected Results: When rendering HDR content for a long time, it is guaranteed that there is always an HDR effect, and the HDR content and screen will not be darkened. Current Results: After about 20-40 minutes, the HDR effect disappears and the screen darkens.
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Jul ’25
"No signal" message when connecting LG tv via HDM
Hi everyone, I am currently on MacOS Tahoe (26.1), and for some weird reason my mac is not connecting via HDMI. To be accurate: it is connecting and the LG TV shows up in the Displays settings, but no image shows up in it, I have no idea why. This used to work as I've tried this cable before with the same exact tv. The cable is a basic Amazon Basics HDMI one. Allow me just to advanced this question a little: usually terminal commands are more advanced recommendations, whereas basic questions like "have you connected it right" are just a waste of time
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703
Oct ’25
CoreMediaErrorDomain -12035 error when playing a Fairplay-protected HLS stream on iOS 18+ through the Apple lightning AV Adapter
Our iOS/AppleTV video content playback app uses AVPlayer to play HLS video streams and supports both custom and system playback UIs. The Fairplay content key is retrieved using AVContentKeySession. AirPlay is supported too. When the iPhone is connected to a TV through the lightning Apple Digital AV Adapter (A1438), the app is mirrored as expected. Problem: when using an iPhone or iPad on iOS 18.1.1, FairPlay-protected HLS streams are not played and a CoreMediaErrorDomain -12035 error is received by the AVPlayerItem. Also, once the issue has occurred, the mirroring freezes (the TV indefinitely displays the app playback screen) although the app works fine on the iOS device. The content key retrieval works as expected (I can see that 2 content key requests are made by the system by the way, probably one for the local playback and one for the adapter, as when AirPlaying) and the error is thrown after providing the AVContentKeyResponse. Unfortunately, and as far as I know, there is not documentation on CoreMediaErrorDomain errors so I don't know what -12035 means. The issue does not occur: on an iPhone on iOS 17.7 (even with FairPlay-protected HLS streams) when playing DRM-free video content (whatever the iOS version) when using the USB-C AV Adapter (whatever the iOS version) Also worth noting: the issue does not occur with other video playback apps such as Apple TV or Netflix although I don't have any details on the kind of streams these apps play and the way the FairPlay content key is retrieved (if any) so I don't know if it is relevant.
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1.5k
Feb ’25
videoCaptureQueue would make the app crashed when I using IOS 18.4.1
Hi All I have some problem when I using the IOS 18.4.1 I have iphone16 pro and ipad Air, both are updated to IOS 18.4.1 I tried to following sample code. However, when I run the app around 30 seconds to 1 minutes, the application would be crashed When I using another Ipad with IOS 17, it would not have the same problem. https://developer.apple.com/documentation/createml/creating-an-action-classifier-model https://developer.apple.com/documentation/createml/detecting_human_actions_in_a_live_video_feed#overview%29,
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181
May ’25
Changing Frame Rate of External Display on iPad
Hello, As far as I know and in all of my testing there is no way for a user or a developer to change the frame rate of the video output on iPadOS. If you connect an iPad via a USB Hub or a USB to HDMI Adaptor and then connect it to an external monitor it will output at 59.94fps. I have a video app where a user monitors live video at 25fps and 30fps, they often output to an external display and there are times when the external display will stutter due to the mismatch in frame rate, ie. using 25fps and outputting at 59.94fps. I thought it was impossible to change the video output frame rate, then in V3.1 of the Blackmagic Camera App I saw an interesting change in their release notes: ‘Support for HDMI Monitoring at Sensor Rate and Resolution’ This means there is some way to modify it, not sure if this is done via a Private API that Apple has allowed Blackmagic to use. If so, how can we access this or is there a way to enable this that is undocumented? Thanks!
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Crash in iOS 18 regarding [AVPlayerController _observeValueForKeyPath:oldValue:newValue:]
There are significant crash reports coming from iOS 18 users regarding AVKit framework that starts from this line [AVPlayerController _observeValueForKeyPath:oldValue:newValue:] which seems to be coming from iOS internal SDK. There are 2 kinds of crash we found: UI modification on background thread From the stack trace it seems like when AVPictureInPictureController is being deallocated and its view is being removed from superview somehow the code is being executed in background thread because there is this line there _AssertAutoLayoutOnAllowedThreadsOnly highlighted before the crash. But I’ve checked our code that plays around AVPictureInPictureController, in the locations where we would deallocate the object it will always be called on main thread which are insideviewDidLoad and deinit inside UIViewController class. From the log, it seems like the crash happened when user try to open another content when PIP player is active resulting in the current PIP instance will be replaced with a new one. My suspect is the observation logic inside AVPlayerController could be the hint to this issue, probably something broken over there since this issue happened across our app versions on iOS 18 users only. Unfortunately, I was unable to reproduce this issue yet but one of my colleagues reproduced it once but haven’t been able to do it again since. The reports keep raising each day up to 1.3k events in the last 30 days now. Over release object This one has lower reports than the first one but I decided to include it since it might have relevant information regarding the first crash since the starting stack trace is similar. The crash timing seems to be similar to the first one, where we deallocate existing AVPictureInPictureController and later replace it with a new one and also found only in iOS 18 users which also refers to [AVPlayerController _observeValueForKeyPath:oldValue:newValue:]. I also was unable to reproduce this issue so far. Oh, and both of the issues happened on both iPhone and iPad. We’d appreciate any advice on what we can do to avoid this in the future and probably any hint on why it could happened. I have reported this issue with bug number: FB15620734 I also attached one sample crash report for each of the crashes here. non ui thread access.crash over release.crash
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2.4k
Jun ’25
Reference White Calculation for HDR Video Rendering in Metal
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
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Feb ’25