Explore the integration of media technologies within your app. Discuss working with audio, video, camera, and other media functionalities.

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TTS Audio Unit Extension: File Write Access in App Group Container Denied Despite Proper Entitlements
I'm developing a TTS Audio Unit Extension that needs to write trace/log files to a shared App Group container. While the main app can successfully create and write files to the container, the extension gets sandbox denied errors despite having proper App Group entitlements configured. Setup: Main App (Flutter) and TTS Audio Unit Extension share the same App Group App Group is properly configured in developer portal and entitlements Main app successfully creates and uses files in the container Container structure shows existing directories (config/, dictionary/) with populated files Both targets have App Group capability enabled and entitlements set Current behavior: Extension can access/read the App Group container Extension can see existing directories and files All write attempts are blocked with "sandbox deny(1) file-write-create" errors Code example: const char* createSharedGroupPathWithComponent(const char* groupId, const char* component) { NSString* groupIdStr = [NSString stringWithUTF8String:groupId]; NSString* componentStr = [NSString stringWithUTF8String:component]; NSURL* url = [[NSFileManager defaultManager] containerURLForSecurityApplicationGroupIdentifier:groupIdStr]; NSURL* fullPath = [url URLByAppendingPathComponent:componentStr]; NSError *error = nil; if (![[NSFileManager defaultManager] createDirectoryAtPath:fullPath.path withIntermediateDirectories:YES attributes:nil error:&error]) { NSLog(@"Unable to create directory %@", error.localizedDescription); } return [[fullPath path] UTF8String]; } Error output: Sandbox: simaromur-extension(996) deny(1) file-write-create /private/var/mobile/Containers/Shared/AppGroup/36CAFE9C-BD82-43DD-A962-2B4424E60043/trace Key questions: Are there additional entitlements required for TTS Audio Unit Extensions to write to App Group containers? Is this a known limitation of TTS Audio Unit Extensions? What is the recommended way to handle logging/tracing in TTS Audio Unit Extensions? If writing to App Group containers is not supported, what alternatives are available? Current entitlements: <dict> <key>com.apple.security.application-groups</key> <array> <string>group.com.<company>.<appname></string> </array> </dict>
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110
Apr ’25
H.265 Decoding with VideoToolBox
I am creating an app that decodes H.265 elementary streams on iOS. I use VideoToolBox to decode from H.265 to NV12. The decoded data is enqueued in the CMSampleBufferDisplayLayer as a CMSampleBuffer. However, nothing is displayed in the VideoPlayerView. It remains black. The decoding in VideoToolBox is successful. I confirmed this by saving the NV12 data in the CMSampleBuffer to a file and displaying it using a tool. Why is nothing displayed in the VideoPlayerView? I can provide other source code as well. // // VideoPlayerView.swift // H265Decoder // // Created by Kohshin Tokunaga on 2025/02/15. // import SwiftUI import AVFoundation struct VideoPlayerView: UIViewRepresentable { // Return an H265Player as the coordinator, and start playback there. func makeCoordinator() -> H265Player { H265Player() } func makeUIView(context: Context) -> UIView { let uiView = UIView(frame: .zero) // Base layer for attaching sublayers uiView.backgroundColor = .black // Screen background color (for iOS) // Create the display layer and add it to uiView.layer let displayLayer = context.coordinator.displayLayer displayLayer.frame = uiView.bounds displayLayer.backgroundColor = UIColor.clear.cgColor uiView.layer.addSublayer(displayLayer) // Start playback context.coordinator.startPlayback() return uiView } func updateUIView(_ uiView: UIView, context: Context) { // Reset the frame of the AVSampleBufferDisplayLayer when the view's size changes. let displayLayer = context.coordinator.displayLayer displayLayer.frame = uiView.layer.bounds // Optionally update the layer's background color, etc. uiView.backgroundColor = .black displayLayer.backgroundColor = UIColor.clear.cgColor // Flush transactions if necessary CATransaction.flush() } } // // H265Player.swift // H265Decoder // // Created by Kohshin Tokunaga on 2025/02/15. // import Foundation import AVFoundation import CoreMedia class H265Player: NSObject, VideoDecoderDelegate { let displayLayer = AVSampleBufferDisplayLayer() private var decoder: H265Decoder? override init() { super.init() // Initial configuration for the display layer displayLayer.videoGravity = .resizeAspect // Initialize the decoder (delegate = self) decoder = H265Decoder(delegate: self) // For simple playback, set isBaseline to true decoder?.isBaseline = true } func startPlayback() { // Load the file "cars_320x240.h265" guard let url = Bundle.main.url(forResource: "temp2", withExtension: "h265") else { print("File not found") return } do { let data = try Data(contentsOf: url) // Set FPS and video size as needed let packet = VideoPacket(data: data, type: .h265, fps: 30, videoSize: CGSize(width: 1080, height: 1920)) // Decode as a single packet decoder?.decodeOnePacket(packet) } catch { print("Failed to load file: \(error)") } } // MARK: - VideoDecoderDelegate func decodeOutput(video: CMSampleBuffer) { // When decoding is complete, send the output to AVSampleBufferDisplayLayer displayLayer.enqueue(video) } func decodeOutput(error: DecodeError) { print("Decoding error: \(error)") } }
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383
Feb ’25
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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171
Mar ’25
AVPlayer error: Too many open files
For some users in production, there's a high probability that after launching the App, using AVPlayer to play any local audio resources results in the following error. Restarting the App doesn't help. issue: [error: Error Domain=AVFoundationErrorDomain Code=-11800 "这项操作无法完成" UserInfo={NSLocalizedFailureReason=发生未知错误(24), NSLocalizedDescription=这项操作无法完成, NSUnderlyingError=0x30311f270 {Error Domain=NSPOSIXErrorDomain Code=24 "Too many open files"}} I've checked the code, and there aren't actually multiple AVPlayers playing simultaneously. What could be causing this?
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434
Feb ’25
MusicKit developer token issue
I'm reaching out regarding a recurring issue I'm experiencing with MusicKit developer tokens. I'm using a valid .p8 private key to sign JWTs for Apple MusicKit integration. Each token I generate includes the appropriate claims (iss, iat, exp) and is signed with the ES256 algorithm, with an expiration date set approximately 6 months ahead. Everything works as expected immediately after generating the token. However, after a few days, the same JWT (still well within its expiration period) suddenly begins returning invalid/unauthorized responses when used in Postman and other API clients. Importantly: I did not delete or revoke the .p8 key during this time. I verified the JWT contains valid claims and a proper structure. The issue consistently resolves only when I create a new .p8 file and regenerate a fresh JWT with it—after which the cycle repeats. This issue occurs even when the environment and app identifiers remain unchanged. I would greatly appreciate it if you could help me understand: Why these tokens become invalid after a few days, despite having a long exp value and an unchanged key. Whether there's any automatic revocation or timeout policy on .p8 keys that could explain this behavior. If there's a better way to maintain long-lived developer tokens without requiring new .p8 key generation every few days. Thank you for your help and clarification on this issue. Best regards, Liad Altif
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147
Jun ’25
Track changes in the browser tab's audibility property.
Hi! I am writing a browser extension that allows you to control the playback of media content on a music service website. Unfortunately Safari does not support tracking changes to the audible property in an event tabs.onUpdated. Is there an alternative to this event? I'm looking for a way to track when the automatic inference engine interrupts playback on a music service website. That you.
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82
Apr ’25
WWDC25 Camera & Photos group lab summary (Part 3 of 3)
(Note: this is part 3 of a 3 part posting. See Part 1 or Part 2) At WWDC25 we launched a new type of Lab event for the developer community - Group Labs. A Group Lab is a panel Q&A designed for a large audience of developers. Group Labs are a unique opportunity for the community to submit questions directly to a panel of Apple engineers and designers. Here are the highlights from the WWDC25 Group Lab for Camera & Photos. WWDC25 Camera & Photos group lab ran for one hour at 6 PM PST on Tuesday June 10th, 2025 Question 24 What’s the best approach for optimizing barcode scanning using AVFoundation or Vision in low-light or angled scenarios Turn on flash in low-light scenarios Lower framerate to improve exposure and reduce noise Wait until the capture is in focus/notify your user that they need to get closer Question 25 Recent iPhone models introduced macro mode which automatically switch between lenses to take into account of the focal distance difference. Is there official API to implement this, or should I implement them myself using LiDAR values. Using builtInTripleCamera and builtInDualWideCamera will automatically switch to macro when available Question 26 Is there a way to quickly create a thumbnail after the user selects an image with PhotosPicker? File provider API Additional questions from the WWDC25 in-person labs that occurred later in the WWDC week Question 1 When should I build my custom photo picker instead of using the system one? Always start with the system picker -> try embeddable customization APIs -> fallback to custom picker for very special needs Question 2 I'm building a new camera app for pros and I want to give my users the most un-processed image possible, and the most control over the capture as possible. How can I do that with AVCapture? If stills, Brief Bayer RAW capture overview, or Pro RAW if you want Apple's processing and dynamic range If video, talk about prores LOG. Custom exposure settings are available throguh the apis maybe global/local tonemapping discussion?
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300
Jul ’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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152
May ’25
Wi-Fi Access Point Not Reconnecting While AVAudioSession Is Active
We’ve encountered a reproducible issue where the iPhone fails to reconnect to a Wi-Fi access point under the following conditions: The device is connected to a 2.4GHz Wi-Fi network. A Bluetooth audio accessory is connected (e.g. headset). AVAudioSession is active (such as during a voice call or when using the Voice Memos app). The user moves away from the access point, causing a disconnect. Upon returning within range, the access point is no longer recognized or reconnected while AVAudioSession remains active. However, if the Bluetooth device is disconnected or the AVAudioSession is deactivated, the Wi-Fi access point is immediately recognized again. We confirmed this behavior not only in my app but also using Apple's built-in Voice Memos app, suggesting this is not specific to our implementation. It appears that the Wi-Fi system deprioritizes reconnection while AVAudioSession is engaged. Could this be by design? Or is this a known issue or limitation with Wi-Fi and AVAudioSession interaction? Test Environment: Device: iPhone 13 mini iOS: 17.5.1 Wi-Fi: 2.4GHz band Accessories: Bluetooth headset We’d appreciate clarification on whether this is expected behavior or a bug. Thank you!
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160
Jun ’25
How to write RGB & Depth Frames Without Losing Synchronization
I’m currently working on a project where I capture both depth frames and RGB frames using AVCaptureDataOutputSynchronizer. Depth frames are stored as raw binary data and RGB frames are saved with AVAssetWriter. The issue I’m facing is that AVAssetWriter enforces a fixed framerate, meaning it adds or discards frames to maintain that rate (as I understand it). This causes a desynchronization between the depth and RGB frames, which is a problem because I need each depth frame to be exactly matched with the corresponding RGB frame as they were captured. How can I ensure that the RGB frames are saved without AVAssetWriter modifying the frame count?
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388
Feb ’25
RealityKit/ARKit Memory Not Fully Released After AR Session Cleanup
Hi, I'm developing a SwiftUI app using RealityKit and ARKit for an AR measuring feature. I’ve noticed that after navigating away from my AR view and performing extensive cleanup (including removing all anchors/entities, pausing the ARSession, and nil-ing out all references), memory usage remains elevated and sometimes grows with repeated AR sessions. Each time I enter and exit the AR view, memory increases The memory does not return to the baseline after cleanup, even though all custom objects are deallocated. Are there best practices beyond what I’ve described to ensure all ARKit/RealityKit resources are released after an AR session?
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104
Jun ’25
issue in recording using AVAudio
Hi, In my project I am using AVFoundation for recording the audio. We are using AVAudioMixerNode class below method to record the audio packet. **func installTap( onBus bus: AVAudioNodeBus, bufferSize: AVAudioFrameCount, format: AVAudioFormat?, block tapBlock: @escaping AVAudioNodeTapBlock ) ** It works perfectly fine. But in production env some small percentage of the user we are facing issue like after recording few packets it stops automatically without stopping the audio engine. Can anyone help here that why this happens? I have also observed for mediaServicesWereResetNotification and added log on receiving this notification but when this issue happens I don't see any occurence of this log. Also is there any callback when the engine stops?
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122
Apr ’25
CMFormatDescription.audioStreamBasicDescription has wrong or unexpected sample rate for audio channels with different sample rates
In my app I use AVAssetReaderTrackOutput to extract PCM audio from a user-provided video or audio file and display it as a waveform. Recently a user reported that the waveform is not in sync with his video, and after receiving the video I noticed that the waveform is in fact double as long as the video duration, i.e. it shows the audio in slow-motion, so to speak. Until now I was using CMFormatDescription.audioStreamBasicDescription.mSampleRate which for this particular user video returns 22'050. But in this case it seems that this value is wrong... because the audio file has two audio channels with different sample rates, as returned by CMFormatDescription.audioFormatList.map({ $0.mASBD.mSampleRate }) The first channel has a sample rate of 44'100, the second one 22'050. If I use the first sample rate, the waveform is perfectly in sync with the video. The problem is given by the fact that the ratio between the audio data length and the sample rate multiplied by the audio duration is 8, double the ratio for the first audio file (4). In the code below this ratio is given by Double(length) / (sampleRate * asset.duration.seconds) When commenting out the line with the sampleRate variable definition in the code below and uncommenting the following line, the ratios for both audio files are 4, which is the expected result. I would expect audioStreamBasicDescription to return the correct sample rate, i.e. the one used by AVAssetReaderTrackOutput, which (I think) somehow merges the stereo tracks. The documentation is sparse, and in particular it’s not documented whether the lower or higher sample rate is used; in this case, it seems like the higher one is used, but audioStreamBasicDescription for some reason returns the lower one. Does anybody know why this is the case or how I should extract the sample rate of the produced PCM audio data? Should I always take the higher one? I created FB19620455. let openPanel = NSOpenPanel() openPanel.allowedContentTypes = [.audiovisualContent] openPanel.runModal() let url = openPanel.urls[0] let asset = AVURLAsset(url: url) let assetTrack = asset.tracks(withMediaType: .audio)[0] let assetReader = try! AVAssetReader(asset: asset) let readerOutput = AVAssetReaderTrackOutput(track: assetTrack, outputSettings: [AVFormatIDKey: Int(kAudioFormatLinearPCM), AVLinearPCMBitDepthKey: 16, AVLinearPCMIsBigEndianKey: false, AVLinearPCMIsFloatKey: false, AVLinearPCMIsNonInterleaved: false]) readerOutput.alwaysCopiesSampleData = false assetReader.add(readerOutput) let formatDescriptions = assetTrack.formatDescriptions as! [CMFormatDescription] let sampleRate = formatDescriptions[0].audioStreamBasicDescription!.mSampleRate //let sampleRate = formatDescriptions[0].audioFormatList.map({ $0.mASBD.mSampleRate }).max()! print(formatDescriptions[0].audioStreamBasicDescription!.mSampleRate) print(formatDescriptions[0].audioFormatList.map({ $0.mASBD.mSampleRate })) if !assetReader.startReading() { preconditionFailure() } var length = 0 while assetReader.status == .reading { guard let sampleBuffer = readerOutput.copyNextSampleBuffer(), let blockBuffer = sampleBuffer.dataBuffer else { break } length += blockBuffer.dataLength } print(Double(length) / (sampleRate * asset.duration.seconds))
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125
Aug ’25
AVPlayerItem. externalMetadata not available
According to the documentation (https://developer.apple.com/documentation/avfoundation/avplayeritem/externalmetadata), AVPlayerItem should have an externalMetadata property. However it does not appear to be visible to my app. When I try, I get: Value of type 'AVPlayerItem' has no member 'externalMetadata' Documentation states iOS 12.2+; I am building with a minimum deployment target of iOS 18. Code snippet: import Foundation import AVFoundation /// ... in function ... // create metadata as described in https://developer.apple.com/videos/play/wwdc2022/110338 var title = AVMutableMetadataItem() title.identifier = .commonIdentifierAlbumName title.value = "My Title" as NSString? title.extendedLanguageTag = "und" var playerItem = await AVPlayerItem(asset: composition) playerItem.externalMetadata = [ title ]
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85
Apr ’25
AVURLAsset with AVURLAssetHTTPCookiesKey - Cookies not persisting on retry requests
I'm experiencing an unexpected behavior with AVURLAsset and cookies. When setting cookies through AVURLAssetHTTPCookiesKey option, they seem to be sent only on the initial request but not on retry attempts. Here's my current implementation: let cookieProperties: [HTTPCookiePropertyKey: Any] = [ .name: "sessionCookie", .value: "testValue", .domain: url.host ?? "", .path: "/", .secure: true ] if let cookie = HTTPCookie(properties: cookieProperties) { let asset = AVURLAsset(url: url, options: [ AVURLAssetHTTPCookiesKey: [cookie], ]) } According to the documentation, AVURLAssetHTTPCookiesKey should apply the cookies to all requests made by this asset. However, when the initial request fails and AVPlayer retries, the cookies are not included in subsequent requests. Only when I store the cookie with HTTPCookieStorage.shared.setCookie, then it persists. Questions: Is this the expected behavior? If not, what could be causing the cookies to not persist for retry attempts? Is using HTTPCookieStorage.shared the recommended approach instead? Environment: iOS 16+ Using AVPlayer with AVURLAsset Streaming HLS content Any insights would be greatly appreciated.
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367
Feb ’25
Issue with Audio Sample Rate Conversion in Video Calls
Hey everyone, I'm encountering an issue with audio sample rate conversion that I'm hoping someone can help with. Here's the breakdown: Issue Description: I've installed a tap on an input device to convert audio to an optimal sample rate. There's a converter node added on top of this setup. The problem arises when joining Zoom or FaceTime calls—the converter gets deallocated from memory, causing the program to crash. Symptoms: The converter node is being deallocated during video calls. The program crashes entirely when this happens. Traditional methods of monitoring sample rate changes (tracking nominal or actual sample rates) aren't working as expected. The Big Challenge: I can't figure out how to properly monitor sample rate changes. Listeners set up to track these changes don't trigger when the device joins a Zoom or FaceTime call. Please, if anyone has experience with this or knows a solution, I'd really appreciate your help. Thanks in advance! ⁠
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84
Apr ’25
Making DataScannerViewController work in the Simulator
Before you post —Camera doesn't work on the Simulator— that's no longer true. I've made a solution that makes the Simulator believe there's an actual hardware device connected, allowing users to stream the macOS camera to the iOS Simulator (see for more info RocketSim's documentation: https://docs.rocketsim.app/features/hzQMSrSga7BGWvxdNVdwYs/simulator-camera-support/58tQ5jvevLNSnyUEA7VgAv) Now, it works for VNDocumentCameraViewController, but when I try opening DataScannerViewController, I directly run into: Failed to start scanning: The operation couldn’t be completed. (VisionKit.DataScannerViewController.ScanningUnavailable error 0.) My question: How does this view controller determine whether scanning is available? Is there a certain capability the available AVCaptureDevice's need to support maybe? Any direction would be helpful for me to make this work for developers, making them build apps faster!
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338
Jul ’25
AVAudioMixerNode outputVolume range?
According to the header file the outputVolume properties supported range is 0.0-1.0: /*! @property outputVolume @abstract The mixer's output volume. @discussion This accesses the mixer's output volume (0.0-1.0, inclusive). @property (nonatomic) float outputVolume; However when setting the volume to 2.0 the audio does indeed play louder. Is the header file out of date and if so, what is the supported range for outputVolume? Thanks
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109
Apr ’25