AVFoundation

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Work with audiovisual assets, control device cameras, process audio, and configure system audio interactions using AVFoundation.

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AVContentKeySession: Cannot re-fetch content key once obtained — expected behavior?
We are developing a video streaming app that uses AVContentKeySession with FairPlay Streaming. Our implementation supports both online playback (non-persistable keys) and offline playback (persistable keys). We have observed the following behavior: Once a content key has been obtained for a given Content Key ID, AVContentKeySession does not trigger contentKeySession(_:didProvide:) again for that same Key ID We also attempted to explicitly call processContentKeyRequest(withIdentifier:initializationData:options:) on the session to force a new key request for the same identifier, but this did not result in the delegate callback being fired again. The session appears to consider the key already resolved and silently ignores the request. This means that if a user first plays content online (receiving a non-persistable key), and later wants to download the same content for offline use (requiring a persistable key), the delegate callback is not fired again, and we have no opportunity to request a persistable key. Questions Is this the expected behavior? Specifically, is it by design that AVContentKeySession caches the key for a given Key ID and does not re-request it — even when processContentKeyRequest(withIdentifier:) is explicitly called? Should we use distinct Content Key IDs for persistable vs. non-persistable keys? For example, if the same piece of content can be played both online and offline, is the recommended approach to have the server provide different EXT-X-KEY URIs (and thus different key identifiers) for the streaming and download variants? Is there a supported way to force a fresh key request for a Key ID that has already been resolved — for example, to upgrade from a non-persistable to a persistable key? Environment iOS 18+ AVContentKeySession(keySystem: .fairPlayStreaming) Any guidance on the recommended approach for supporting both streaming and offline playback for the same content would be greatly appreciated.
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743
Apr ’26
iPad Pro M4 giving wrong value for layerPointConverted for ultra wide angle
I am using iPad Pro M4 device to apply exposure point to the camera. While converting layerPointConverted from 0 -1 range to device size point it is giving wrong value. But if same code is used for other iPad like Gen2, it gives proper value. In both cases video gravity used is resizeAspectFill. I tried using true depth camera for M4 device but it does not work.
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371
Apr ’26
High bitrate video streaming in avplayer sometimes audio disappears
Hello, I used AVPlayer in my project to play network movie. Most movie could play normally, but I found the sound will disappear sometimes if I play specified 4K video network stream. The video will continue playing but audio stops after video is played for a while. If I pause player and then resume, the sound will be back but disappeared again after several seconds Check AVPlayerItem status: isPlaybackLikelyToKeepUp` == true isPlaybackBufferEmpty` = false player.volume > 0 According the value above, it seems not cause by empty playback buffer or volume issue. I am so confused for this situation. Movie information Video Format : AVC Format/Info : Advanced Video Codec Format profile : High L5.1 Codec ID : avc1 Codec ID/Info : Advanced Video Coding Bit rate mode : Variable Bit rate : 100.0 Mb/s Width : 3 840 pixels Height : 2 160 pixels Display aspect ratio : 16:9 Frame rate mode : Constant Frame rate : 29.970 (30000/1001) FPS Audio Format : AAC LC Format/Info : Advanced Audio Codec Low Complexity Codec ID : mp4a-40-2 Duration : 5 min 19 s Bit rate mode : Constant Bit rate : 192 kb/s Nominal bit rate : 48.0 kb/s Channel(s) : 2 channels Channel layout : L R Sampling rate : 48.0 kHz Frame rate : 46.875 FPS (1024 SPF) Does anyone know if AVPlayer has this limitations when playing high-bitrate movie streams, and are there any solutions?
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Apr ’26
AVCaptureVideoDataOutput stops zooming while AVCaptureVideoPreviewLayer continues — physical wide / ultra-wide / telephoto only
We use a single AVCaptureSession with AVCaptureVideoPreviewLayer and AVCaptureVideoDataOutput (preview-sized buffers, BGRA). When we increase videoZoomFactor, beyond a certain zoom level the image from AVCaptureVideoDataOutput no longer zooms further, while AVCaptureVideoPreviewLayer continues to zoom with the same zoom control. The preview and the video-data output therefore diverge. This behavior appears when the active camera is a physical lens device — wide, ultra-wide, or telephoto (e.g. builtInWideAngleCamera, builtInUltraWideCamera, builtInTelephotoCamera, or similar). It does not appear when the active input is a virtual / multi-camera (e.g. triple camera, dual-wide, or other system multi-camera). Are there known conditions under which this mismatch between preview and video-data output is expected? Thank you.
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398
Apr ’26
AVAudioFile.read extremely slow after seeking in FLAC and MP3 files
I'm developing an audio player app that uses AVAudio​File to read PCM data from various formats. I'm experiencing severe performance issues when seeking in FLAC, while other compressed formats (M4A/AAC) work correctly. I don't intend to use them in my app, but I also tested mp3 files just by curiosity and they also have this issue. Environment: macOS 26 (Tahoe) Xcode 26.3 Apple Silicon (M1) The issue: After setting AVAudio​File​.frame​Position to a position mid-file, the subsequent call to AVAudio​File​.read(into​:frame​Count:) blocks for an unreasonable amount of time for FLAC and MP3 files. The delay scales linearly with the seek target, seeking near the beginning is fast, seeking toward the end is proportionally slower, which suggests the decoder is decoding linearly from the beginning of the file rather than using any seek index. (My app deals with “images” of Audio CDs ripped as a single long audio file.) The issue is particularly severe when reading files from an SMB network share (server on Ethernet, client on Wi-Fi with the access point ~2 meters away in line of sight). Quick Benchmark results: I tested with the same 75-minute audio content (16-bit/44.1 kHz stereo, 200,502,708 frames) encoded in five formats, seeking to the midpoint. Over SMB (Local Network, Server on Ethernet, Client on WiFi): Format | Seek + Read Time ----------|------------------ WAV | 0.007 s AIFF | 0.009 s Apple | 0.015 s Lossless | MP3 | 9.2 s FLAC | 30.2 s Locally (MacBook Air M1 SSD) : Format | Seek + Read Time ----------|------------------ WAV | 0.0005 s AIFF | 0.0004 s Apple | 0.0011 s Lossless | MP3 | 0.1958 s FLAC | 0.7528 s WAV, AIFF, and M4A all seek virtually instantly (< 15 ms). MP3 and FLAC exhibit linear-time behavior, with FLAC being the worst affected. Note that M4A (AAC) is also a compressed format that requires decoding after seeking, yet it completes in 15 ms. This rules out any inherent limitation of compressed formats, the MP4 container's packet index (stts/stco) is clearly being used for fast random access. Both MP3 (Xing/LAME TOC) and FLAC (SEEKTABLE metadata block) have their own seek mechanisms that should provide similar performance. Minimal CLI tool to reproduce: import Foundation guard CommandLine.arguments.count > 1 else { print("Usage: FLACSpeed <audio-file-path>") exit(1) } let path = CommandLine.arguments[1] let fileURL = URL(fileURLWithPath: path) do { let file = try AVAudioFile(forReading: fileURL) let format = file.processingFormat let buffer = AVAudioPCMBuffer(pcmFormat: format, frameCapacity: 8192)! let totalFrames = file.length let seekTarget = totalFrames / 2 print("File: \(fileURL.lastPathComponent)") print("Format: \(format)") print("Total frames: \(totalFrames)") print("Seeking to frame: \(seekTarget)") file.framePosition = seekTarget let start = CFAbsoluteTimeGetCurrent() try file.read(into: buffer, frameCount: 8192) let elapsed = CFAbsoluteTimeGetCurrent() - start print("Read after seek took \(elapsed) seconds") } catch { print("Error: \(error.localizedDescription)") exit(1) } Expected behavior: AVAudio​File​.read(into​:frame​Count:) after setting frame​Position should use the available seek mechanisms in FLAC and MP3 files for fast random access, as it already does for M4A (AAC). Even accounting for the fact that seek tables provide approximate (not sample-precise) positioning, the "jump to nearest index point + decode forward" approach should complete in milliseconds, not seconds. Workaround: For FLAC, I've worked around this by using libFLAC directly, which provides instant seeking via FLAC__stream​_decoder​_seek​_absolute(). libFLAC Performance: For comparison, libFLAC's FLAC__stream​_decoder​_seek​_absolute() performs the same seek + read on the same FLAC file in around 0.015, using the FLAC seek table to jump to the nearest preceding seek point, then decoding forward a small number of frames to the exact target sample.
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513
Apr ’26
AVPictureInPictureController with AVSampleBufferDisplayLayer: Video not scaled in PiP window on macOS
AVPictureInPictureController with AVSampleBufferDisplayLayer: Video not scaled in PiP window on macOS Platform: macOS 26.4 (Tahoe) Framework: AVKit / AVFoundation Xcode: 26.4 Summary When using AVPictureInPictureController with ContentSource(sampleBufferDisplayLayer:playbackDelegate:) on macOS, the video content in the PiP window is not scaled to fit — it renders at 1:1 pixel resolution, showing only the bottom-left portion of the video (zoomed/cropped). The same code works correctly on iOS. Setup let displayLayer = AVSampleBufferDisplayLayer() displayLayer.videoGravity = .resizeAspect // Host displayLayer as a sublayer of an NSView, enqueue CMSampleBuffers let source = AVPictureInPictureController.ContentSource( sampleBufferDisplayLayer: displayLayer, playbackDelegate: self ) let pip = AVPictureInPictureController(contentSource: source) pip.delegate = self The source display layer is 1280×720, matching the video stream resolution. PiP starts successfully — isPictureInPicturePossible is true, the PiP button works, and the PIPPanel window appears. However, the video in the PiP window (~480×270) shows only the bottom-left 480×270 pixels of the 1280×720 content, rather than scaling the full frame to fit. Investigation Inspecting the PiP window hierarchy reveals: PIPPanel (480×270) └─ AVPictureInPictureSampleBufferDisplayLayerView └─ AVPictureInPictureSampleBufferDisplayLayerHostView (layer = CALayerHost) └─ AVPictureInPictureCALayerHostView The CALayerHost mirrors the source AVSampleBufferDisplayLayer at 1:1 pixel resolution. Unlike AVPlayerLayer-based PiP (which works correctly on macOS), the sample buffer display layer path does not apply any scaling transform to the mirrored content. On iOS, PiP with AVSampleBufferDisplayLayer works correctly because the system reparents the layer into the PiP window, so standard layer scaling applies. On macOS, the system uses CALayerHost mirroring instead, and the scaling step is missing. What I tried (none fix the issue) Setting autoresizingMask on all PiP internal subviews — views resize correctly, but CALayerHost content remains at 1:1 pixel scale Applying CATransform3DMakeScale on the CALayerHost layer — creates a black rectangle artifact; the mirrored content does not transform Setting CALayerHost.bounds to the source layer size — no effect on rendering Reparenting the internal AVPictureInPictureCALayerHostView out of the host view — video disappears entirely Hiding the CALayerHost — PiP window goes white (confirming it is the sole video renderer) Resizing the source AVSampleBufferDisplayLayer to match the PiP window size — partially works (1:1 mirror of a smaller source fits), but causes visible lag during resize, affects the main window's "This video is playing in Picture in Picture" placeholder, and didTransitionToRenderSize stops being called after the initial resize Expected behavior The video content should be scaled to fit the PiP window, respecting the display layer's videoGravity setting (.resizeAspect), consistent with: iOS PiP with AVSampleBufferDisplayLayer (works correctly) macOS PiP with AVPlayerLayer (works correctly) Environment macOS 26.4 (Tahoe) Xcode 26.4 Apple Silicon (M-series) Retina display (contentsScale = 2.0) Video: H.264 1280×720, hardware decoded via VTDecompressionSession, enqueued as CMSampleBuffer
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622
Apr ’26
Is 18MP Front Camera Capture Available to Third-Party Apps via AVFoundation?
Hi, I'm investigating whether 18MP photo capture from the front camera on iPhone 17 Pro is available to third-party apps using AVFoundation. I first inspected all available AVCaptureDevice formats, but I could not find any format corresponding to ~18MP resolution (e.g., around 4896×3672). for format in device.formats { let desc = format.formatDescription let dims = CMVideoFormatDescriptionGetDimensions(desc) print("Format: (dims.width) x (dims.height)") } All reported formats appear to be limited to resolutions such as 4032×3024 (12MP) or below. Question: Is 18MP front camera capture actually available to third-party apps via AVFoundation on iPhone 17?
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738
Apr ’26
10-Bit UVC on iPadOS
Hello, I've been very familiar with the UVC Support in iPadOS ever since it launched in iOS 17. There are a number of people that use the software I've developed built around UVC and there are often queries about 8-Bit vs. 10-Bit. My understanding is that the newest UVC Spec is 1.5 which was standardised in 2012 and almost every UVC Capture Card runs at 8-Bit. The only 10-Bit Capture Card that is on my radar is the AJA U-Tap SDI, however it looks like this is 10-Bit up until the UVC Part where the 10-Bit Input is downsampled to 8-Bit. Though I have read in certain places that it works as a 10-Bit Capture Card on macOS but not on iPadOS. I was just wondering if 10-Bit via UVC is even possible on iPadOS? If there was indeed a true 10-Bit Source being passed into an iPad, would iPadOS allow it or would it be downsampled by AVFoundation so it can show up as a valid external video input? All USB Capture Cards that I have encountered use one of the following formats: kCVPixelFormatType_420YpCbCr8BiPlanarVideoRange kCVPixelFormatType_420YpCbCr8BiPlanarFullRange kCVPixelFormatType_32BGRA So if a UVC Device delivered a 10-Bit Format, would that be accessible by iPadOS or would it fallback to these 8-Bit Formats by default? Thanks!
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1.2k
Apr ’26
AXSpeech Thread Crash SEGV_ACCERR
Hi everyone, I've encountered a rare and strange crash in my app that I can't consistently reproduce. The crash seems to occur deep within Apple's internal frameworks, and I can't pinpoint which line of my own code is causing it. Here's the crash stack trace: #44 AXSpeech SIGSEGV SEGV_ACCERR 0 CoreFoundation ___CFCheckCFInfoPACSignature + 4 1 CoreFoundation _CFRunLoopSourceSignal + 28 2 Foundation _performQueueDequeue + 492 3 Foundation ___NSThreadPerformPerform + 88 4 CoreFoundation ___CFRUNLOOP_IS_CALLING_OUT_TO_A_SOURCE0_PERFORM_FUNCTION__ + 28 5 CoreFoundation ___CFRunLoopDoSource0 + 176 6 CoreFoundation ___CFRunLoopDoSources0 + 340 7 CoreFoundation ___CFRunLoopRun + 828 8 CoreFoundation _CFRunLoopRunSpecific + 608 9 Foundation -[NSRunLoop(NSRunLoop) runMode:beforeDate:] + 212 10 TextToSpeech _TTSCFAttributedStringCreateStringByBracketingAttributeWithString + 776 11 Foundation ___NSThread__start__ + 732 12 libsystem_pthread.dylib __pthread_start + 136 Sometimes, instead of line 10 referencing _TTSCFAttributedStringCreateStringByBracketingAttributeWithString, it shows: 10 TextToSpeech LogWarning(char const*, ...) + 7288 Has anyone experienced a similar issue or know what might be triggering this crash? Any guidance on how to investigate or resolve this would be greatly appreciated. Thank you!
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2.9k
Mar ’26
HLS VOD Download Resume after Wifi/LTE Change
Hello there, Our application has HLS VOD download option. Users can download VOD which has DRM protection and watch content when device is offline. We use aggregateAssetDownloadTask to download HLS VOD. We want to resume download after Wifi/LTE change but it does not resume. Download is starting from beginning. We use some token algorithms to start download. That's why, our playlist url and chunks urls may change. But playlist and chunk urls' content is unique. If user start to download via Wifi and changed to LTE. Download request responds 403 Forbidden because of some token algorithms after some time func urlSession(_ session: URLSession, task: URLSessionTask, didCompleteWithError error: Error?) AVAssetDownloadDelegate function triggered by system. If we resume it does not resume at this point. It is starting from beginning if we start new download process for same content. Is there any way to resume unfinished HLS Download processes? Thanks
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833
Mar ’26
Strange crash in iOS AudioToolboxCore when using AVSpeechSynthesizer in iOS 16
I'm getting Crashlytics crashes from some my users, deep in the Apple code: Crashed: AXSpeech EXC_BAD_ACCESS KERN_INVALID_ADDRESS 0x00000007ec54b360 0 libobjc.A.dylib 0x3c9c objc_retain_x8 + 16 1 AudioToolboxCore 0x99580 auoop::RenderPipeUser::~RenderPipeUser() + 112 2 AudioToolboxCore 0xe6090 -[AUAudioUnit_XPC internalDeallocateRenderResources] + 92 3 AVFAudio 0x90a0 AUInterfaceBaseV3::Uninitialize() + 60 4 AVFAudio 0x4cbe0 AVAudioEngineGraph::PerformCommand(AUGraphNodeBaseV3&, AVAudioEngineGraph::ENodeCommand, void*, unsigned int) const + 768 5 AVFAudio 0x56b0c AVAudioEngineGraph::_Uninitialize(NSError**) + 132 6 AVFAudio 0x7834 AVAudioEngineImpl::Stop(NSError**) + 388 7 AVFAudio 0x636c -[AVAudioEngine dealloc] + 52 8 TextToSpeech 0x30674 _TTSNameForVoiceInformation + 20864 9 libobjc.A.dylib 0x20a4 object_cxxDestructFromClass(objc_object*, objc_class*) + 116 10 libobjc.A.dylib 0x6e00 objc_destructInstance + 80 11 libobjc.A.dylib 0x104fc _objc_rootDealloc + 80 12 TextToSpeech 0x2d2f4 _TTSNameForVoiceInformation + 7680 13 TextToSpeech 0x496c TTSVocalizerCopyURLForFallbackResource + 8540 14 TextToSpeech 0x26094 TTSSpeechUnitTestingMode + 5548 15 libAXSpeechManager.dylib 0x108b0 -[AXSpeechManager .cxx_destruct] + 192 16 libobjc.A.dylib 0x20a4 object_cxxDestructFromClass(objc_object*, objc_class*) + 116 17 libobjc.A.dylib 0x6e00 objc_destructInstance + 80 18 libobjc.A.dylib 0x104fc _objc_rootDealloc + 80 19 libAXSpeechManager.dylib 0x5298 -[AXSpeechManager dealloc] + 268 20 Foundation 0x3b8a4 __NSThreadPerformPerform + 272 21 CoreFoundation 0xd3208 __CFRUNLOOP_IS_CALLING_OUT_TO_A_SOURCE0_PERFORM_FUNCTION__ + 28 22 CoreFoundation 0xdf864 __CFRunLoopDoSource0 + 176 23 CoreFoundation 0x646c8 __CFRunLoopDoSources0 + 244 24 CoreFoundation 0x7a1c4 __CFRunLoopRun + 828 25 CoreFoundation 0x7f4dc CFRunLoopRunSpecific + 612 26 Foundation 0x420c4 -[NSRunLoop(NSRunLoop) runMode:beforeDate:] + 212 27 libAXSpeechManager.dylib 0x13390 -[AXSpeechThread main] + 552 28 Foundation 0x5b634 __NSThread__start__ + 716 29 libsystem_pthread.dylib 0x16b8 _pthread_start + 148 30 libsystem_pthread.dylib 0xb88 thread_start + 8 It's most likely related to my use of AVSpeechSynthesizer. I do change some of the utterance fields, including the voice that's being used (which is set to a value from speechVoices()). UtilAudioIos_tts = AVSpeechSynthesizer() let utterance = AVSpeechUtterance utterance.voice = AVSpeechSynthesisVoice(identifier: voice.voiceCode) utterance.volume = volume utterance.pitchMultiplier = pitch utterance.rate = rate UtilAudioIos_tts!.speak(utterance) By coincidence or not, the following sometimes appears in the device log: 2023-05-30 20:35:29.948078+0100 <appname>[466:12882] [catalog] Unable to list voice folder and also, sometimes: 2023-05-30 20:37:35.345933+0100 <appname>[466:13298] [catalog] Query for com.apple.MobileAsset.VoiceServices.VoiceResources failed: 2 2023-05-30 20:37:35.360854+0100 rehearserfree[466:13433] [AXTTSCommon] MauiVocalizer: 11006 (Can't compile rule): regularExpression=\Oviedo(?=, (\x1b\\pause=\d+\\)?Florida)\b, message=unrecognized character follows \, characterPosition=1 2023-05-30 20:37:35.363163+0100 <appname>[466:13433] [AXTTSCommon] MauiVocalizer: 16038 (Resource load failed): component=ttt/re, uri=, contentType=application/x-vocalizer-rettt+text, lhError=88602000 2023-05-30 20:37:35.363182+0100 <appname>[466:13433] [AXTTSCommon] Error loading rules: 2147483648 All of these crashes have been on the various versions of iOS 16. Edit: I can't reproduce the crash myself - it's just some (not all) app users. The log entries above appear locally on my device (with no crash) but I can't see the logs of the users who have the crashes. Any idea what this might be caused by, or how to go about tracking the problem down?
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2.8k
Mar ’26
Massive CoreML latency spike on live AVFoundation camera feed vs. offline inference (CPU+ANE)
Hello, I’m experiencing a severe performance degradation when running CoreML models on a live AVFoundation video feed compared to offline or synthetic inference. This happens across multiple models I've converted (including SCI, RTMPose, and RTMW) and affects multiple devices. The Environment OS: macOS 26.3, iOS 26.3, iPadOS 26.3 Hardware: Mac14,6 (M2 Max), iPad Pro 11 M1, iPhone 13 mini Compute Units: cpuAndNeuralEngine The Numbers When testing my SCI_output_image_int8.mlpackage model, the inference timings are drastically different: Synthetic/Offline Inference: ~1.34 ms Live Camera Inference: ~15.96 ms Preprocessing is completely ruled out as the bottleneck. My profiling shows total preprocessing (nearest-neighbor resize + feature provider creation) takes only ~0.4 ms in camera mode. Furthermore, no frames are being dropped. What I've Tried I am building a latency-critical app and have implemented almost every recommended optimization to try and fix this, but the camera-feed penalty remains: Matched the AVFoundation camera output format exactly to the model input (640x480 at 30/60fps). Used IOSurface-backed pixel buffers for everything (camera output, synthetic buffer, and resize buffer). Enabled outputBackings. Loaded the model once and reused it for all predictions. Configured MLModelConfiguration with reshapeFrequency = .frequent and specializationStrategy = .fastPrediction. Wrapped inference in ProcessInfo.processInfo.beginActivity(options: .latencyCritical, reason: "CoreML_Inference"). Set DispatchQueue to qos: .userInteractive. Disabled the idle timer and enabled iOS Game Mode. Exported models using coremltools 9.0 (deployment target iOS 26) with ImageType inputs/outputs and INT8 quantization. Reproduction To completely rule out UI or rendering overhead, I wrote a standalone Swift CLI script that isolates the AVFoundation and CoreML pipeline. The script clearly demonstrates the ~15ms latency on live camera frames versus the ~1ms latency on synthetic buffers. (I have attached camera_coreml_benchmark.swift and coreml model (very light low light enghancement model) to this repo on github https://github.com/pzoltowski/apple-coreml-camera-latency-repro). My Question: Is this massive overhead expected behavior for AVFoundation + Core ML on live feeds, or is this a framework/runtime bug? If expected, what is the Apple-recommended pattern to bypass this camera-only inference slowdown? One think found interesting when running in debug model was faster (not as fast as in performance benchmark but faster than 16ms. Also somehow if I did some dummy calculation on on different DispatchQueue also seems like model got slightly faster. So maybe its related to ANE Power State issues (Jitter/SoC Wake) and going to fast to sleep and taking a long time to wakeup? Doing dummy calculation in background thought is probably not a solution. Thanks in advance for any insights!
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1.4k
Mar ’26
Video Audio + Speech To Text
Hello, I am wondering if it is possible to have audio from my AirPods be sent to my speech to text service and at the same time have the built in mic audio input be sent to recording a video? I ask because I want my users to be able to say "CAPTURE" and I start recording a video (with audio from the built in mic) and then when the user says "STOP" I stop the recording.
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1.8k
Mar ’26
Random EXC_BAD_ACCESS using AVFoundation
My app uses the AVFoundation to pronounce some words. Running the app from Xcode, either to a simulator or device, I frequently get this crash at start-up: AXSpeech (13): EXC_BAD_ACCESS (code=EXC_I386_GPFLT). It seems to occur randomly, maybe 20%-30% of the time I launch the app. When it does not crash, using audio works as expected. When launched from the device, it never crashes (so far, at least). Here's the code that outputs speech: Declared at the top level of the View struct: @State var synth = AVSpeechSynthesizer() In the View, as part of a Button's action closure: let utterance = AVSpeechUtterance(string: answer) utterance.voice = AVSpeechSynthesisVoice(language: "en_US") synth.speak(utterance) Any idea on how to stop this? It's annoying having to launch the app multiple times to test on a simulator or device.
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639
Mar ’26
Recurring FigXPCUtilities / FigCaptureSourceRemote err=-17281 logs when using AVCaptureVideoDataOutput on iOS 26.x
Hi everyone, I’m seeing recurring internal AVFoundation camera logs on iOS 26.2 and I’m trying to understand whether this is expected behavior or a regression in the capture pipeline. These logs appear shortly after starting an AVCaptureSession, while video frames are being delivered, and also when the camera is stopped or the capture session is torn down. <<<< FigXPCUtilities >>>> signalled err=-17281 at <>:302 <<<< FigCaptureSourceRemote >>>> Fig assert: "err == 0 " at bail (FigCaptureSourceRemote.m:569) - (err=-17281) Even in this clean, minimal setup, the same logs appear on iOS 26.2 The exact same logic did not produce these logs on iOS 18.x. To rule out issues caused by my own code, GPT created a minimal SwiftUI example from scratch. My primary interest is to perform real-time processing on the video frames delivered by the camera (via AVCaptureVideoDataOutput), for tasks such as analysis, computer vision, or custom frame handling, while simultaneously displaying the live preview. Thanks in advance for any insight. Example Code
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1.2k
Mar ’26
AVAudioSession.outputVolume does not reflect system volume changes made while app is in background
I have a question regarding the behavior of AVAudioSession.sharedInstance().outputVolume. Observed behavior: When the app is in the foreground, I read audioSession.outputVolume (for example, 0.1). The app is then moved to the background. While the app is in the background, the user changes the system volume using the hardware buttons (for example, to 0.5). When the app returns to the foreground, audioSession.outputVolume still reports the previous value (0.1). From my testing, outputVolume only seems to update when the system volume is changed while the app is in the foreground. Volume changes made while the app is in the background are not reflected when the app returns to the foreground. Questions: According to Apple’s documentation for AVAudioSession.outputVolume: “The systemwide output volume set by the user.” https://developer.apple.com/documentation/avfaudio/avaudiosession/outputvolume However, based on our testing on iOS 18.6.2 and iOS 18.1, the observed behavior seems to differ from this description. Questions: The documentation states that outputVolume represents the system-wide volume set by the user. In our testing, the value does not reflect volume changes made while the app is in the background and only updates when the app is in the foreground.Is this the expected behavior of AVAudioSession.outputVolume? Is there any other recommended way in Swift to retrieve the current system volume that reflects user changes made both while the app is in the foreground and while it is in the background? Any clarification on the intended behavior or recommended handling would be greatly appreciated.
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422
Mar ’26
How should playback readiness be determined with AVSampleBufferAudioRenderer when using AirPlay?
I’m implementing a custom playback pipeline using AVSampleBufferAudioRenderer together with AVSampleBufferRenderSynchronizer. hasSufficientMediaDataForReliablePlaybackStart appears to be the intended signal for determining when enough media has been queued to start playback. For local playback, this works well in practice — the property becomes true after a reasonable amount of media is enqueued. However, when the output route is AirPlay, using this property becomes difficult: AirPlay requires significantly more buffered media before the renderer reports sufficient data. The required preroll amount is much larger than for local playback. For short assets, it is possible to enqueue the entire audio track and still never observe hasSufficientMediaDataForReliablePlaybackStart == true. In that situation there is no more media data to enqueue, but the renderer still reports that playback is not ready. Given this behavior, what is the recommended way to determine playback readiness when using AVSampleBufferAudioRenderer with AirPlay?
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456
Mar ’26
Lock Screen shows skip buttons instead of next/previous when using MPRemoteCommandCenter with AVPlayer playlist
Hello, I’m building an iOS video player using AVPlayer and a custom playback queue. I implemented remote controls using MPRemoteCommandCenter and enabled: nextTrackCommand previousTrackCommand playCommand pauseCommand I disabled: skipForwardCommand skipBackwardCommand seekForwardCommand seekBackwardCommand I also set queue metadata in MPNowPlayingInfoCenter: MPNowPlayingInfoPropertyPlaybackQueueIndex MPNowPlayingInfoPropertyPlaybackQueueCount Even with these commands enabled and the queue count greater than 1, the iOS lock screen continues to display the 10-second skip buttons instead of the previous/next track buttons. The commands themselves work correctly when triggered externally (Control Center, headphones, etc.), but the UI still shows the skip controls. Is there a way to force the lock screen UI to display previous / next track buttons for a video playlist? Or is this behavior expected when using AVPlayer with video content? Thanks.
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181
Mar ’26
UVC over MFi – Is there official support? Implementation guidance?
Hello everyone, I’m looking for more detailed information regarding UVC (USB Video Class) over MFi within the Apple ecosystem and would appreciate some clarification. I’m interested in developing (or interfacing with) an accessory that transmits video over USB using the UVC standard, and I’d like to better understand how this works within the MFi (Made for iPhone) program. Here are my main questions: 1. Do iOS devices provide native support for UVC over USB-C or Lightning within the MFi framework? 2. Are there any specific firmware or authentication requirements when the accessory is MFi-certified? 3. Does UVC support depend solely on the hardware interface (USB-C vs Lightning), or are there additional software-level requirements? 4. Is there any official documentation outlining the recommended flow for implementing UVC-based video capture accessories on iOS? From what I understand, USB-C iPads appear to offer more direct support for standard UVC devices, but it’s not entirely clear how this integrates with the MFi ecosystem with iOS, especially for commercial product development. If anyone has gone through this process or can point me to relevant technical documentation, I would greatly appreciate the guidance. Thank you!
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1k
Mar ’26
AVContentKeySession: Cannot re-fetch content key once obtained — expected behavior?
We are developing a video streaming app that uses AVContentKeySession with FairPlay Streaming. Our implementation supports both online playback (non-persistable keys) and offline playback (persistable keys). We have observed the following behavior: Once a content key has been obtained for a given Content Key ID, AVContentKeySession does not trigger contentKeySession(_:didProvide:) again for that same Key ID We also attempted to explicitly call processContentKeyRequest(withIdentifier:initializationData:options:) on the session to force a new key request for the same identifier, but this did not result in the delegate callback being fired again. The session appears to consider the key already resolved and silently ignores the request. This means that if a user first plays content online (receiving a non-persistable key), and later wants to download the same content for offline use (requiring a persistable key), the delegate callback is not fired again, and we have no opportunity to request a persistable key. Questions Is this the expected behavior? Specifically, is it by design that AVContentKeySession caches the key for a given Key ID and does not re-request it — even when processContentKeyRequest(withIdentifier:) is explicitly called? Should we use distinct Content Key IDs for persistable vs. non-persistable keys? For example, if the same piece of content can be played both online and offline, is the recommended approach to have the server provide different EXT-X-KEY URIs (and thus different key identifiers) for the streaming and download variants? Is there a supported way to force a fresh key request for a Key ID that has already been resolved — for example, to upgrade from a non-persistable to a persistable key? Environment iOS 18+ AVContentKeySession(keySystem: .fairPlayStreaming) Any guidance on the recommended approach for supporting both streaming and offline playback for the same content would be greatly appreciated.
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743
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Apr ’26
iPad Pro M4 giving wrong value for layerPointConverted for ultra wide angle
I am using iPad Pro M4 device to apply exposure point to the camera. While converting layerPointConverted from 0 -1 range to device size point it is giving wrong value. But if same code is used for other iPad like Gen2, it gives proper value. In both cases video gravity used is resizeAspectFill. I tried using true depth camera for M4 device but it does not work.
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371
Activity
Apr ’26
High bitrate video streaming in avplayer sometimes audio disappears
Hello, I used AVPlayer in my project to play network movie. Most movie could play normally, but I found the sound will disappear sometimes if I play specified 4K video network stream. The video will continue playing but audio stops after video is played for a while. If I pause player and then resume, the sound will be back but disappeared again after several seconds Check AVPlayerItem status: isPlaybackLikelyToKeepUp` == true isPlaybackBufferEmpty` = false player.volume > 0 According the value above, it seems not cause by empty playback buffer or volume issue. I am so confused for this situation. Movie information Video Format : AVC Format/Info : Advanced Video Codec Format profile : High L5.1 Codec ID : avc1 Codec ID/Info : Advanced Video Coding Bit rate mode : Variable Bit rate : 100.0 Mb/s Width : 3 840 pixels Height : 2 160 pixels Display aspect ratio : 16:9 Frame rate mode : Constant Frame rate : 29.970 (30000/1001) FPS Audio Format : AAC LC Format/Info : Advanced Audio Codec Low Complexity Codec ID : mp4a-40-2 Duration : 5 min 19 s Bit rate mode : Constant Bit rate : 192 kb/s Nominal bit rate : 48.0 kb/s Channel(s) : 2 channels Channel layout : L R Sampling rate : 48.0 kHz Frame rate : 46.875 FPS (1024 SPF) Does anyone know if AVPlayer has this limitations when playing high-bitrate movie streams, and are there any solutions?
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984
Activity
Apr ’26
AVCaptureVideoDataOutput stops zooming while AVCaptureVideoPreviewLayer continues — physical wide / ultra-wide / telephoto only
We use a single AVCaptureSession with AVCaptureVideoPreviewLayer and AVCaptureVideoDataOutput (preview-sized buffers, BGRA). When we increase videoZoomFactor, beyond a certain zoom level the image from AVCaptureVideoDataOutput no longer zooms further, while AVCaptureVideoPreviewLayer continues to zoom with the same zoom control. The preview and the video-data output therefore diverge. This behavior appears when the active camera is a physical lens device — wide, ultra-wide, or telephoto (e.g. builtInWideAngleCamera, builtInUltraWideCamera, builtInTelephotoCamera, or similar). It does not appear when the active input is a virtual / multi-camera (e.g. triple camera, dual-wide, or other system multi-camera). Are there known conditions under which this mismatch between preview and video-data output is expected? Thank you.
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398
Activity
Apr ’26
AVAudioFile.read extremely slow after seeking in FLAC and MP3 files
I'm developing an audio player app that uses AVAudio​File to read PCM data from various formats. I'm experiencing severe performance issues when seeking in FLAC, while other compressed formats (M4A/AAC) work correctly. I don't intend to use them in my app, but I also tested mp3 files just by curiosity and they also have this issue. Environment: macOS 26 (Tahoe) Xcode 26.3 Apple Silicon (M1) The issue: After setting AVAudio​File​.frame​Position to a position mid-file, the subsequent call to AVAudio​File​.read(into​:frame​Count:) blocks for an unreasonable amount of time for FLAC and MP3 files. The delay scales linearly with the seek target, seeking near the beginning is fast, seeking toward the end is proportionally slower, which suggests the decoder is decoding linearly from the beginning of the file rather than using any seek index. (My app deals with “images” of Audio CDs ripped as a single long audio file.) The issue is particularly severe when reading files from an SMB network share (server on Ethernet, client on Wi-Fi with the access point ~2 meters away in line of sight). Quick Benchmark results: I tested with the same 75-minute audio content (16-bit/44.1 kHz stereo, 200,502,708 frames) encoded in five formats, seeking to the midpoint. Over SMB (Local Network, Server on Ethernet, Client on WiFi): Format | Seek + Read Time ----------|------------------ WAV | 0.007 s AIFF | 0.009 s Apple | 0.015 s Lossless | MP3 | 9.2 s FLAC | 30.2 s Locally (MacBook Air M1 SSD) : Format | Seek + Read Time ----------|------------------ WAV | 0.0005 s AIFF | 0.0004 s Apple | 0.0011 s Lossless | MP3 | 0.1958 s FLAC | 0.7528 s WAV, AIFF, and M4A all seek virtually instantly (< 15 ms). MP3 and FLAC exhibit linear-time behavior, with FLAC being the worst affected. Note that M4A (AAC) is also a compressed format that requires decoding after seeking, yet it completes in 15 ms. This rules out any inherent limitation of compressed formats, the MP4 container's packet index (stts/stco) is clearly being used for fast random access. Both MP3 (Xing/LAME TOC) and FLAC (SEEKTABLE metadata block) have their own seek mechanisms that should provide similar performance. Minimal CLI tool to reproduce: import Foundation guard CommandLine.arguments.count > 1 else { print("Usage: FLACSpeed <audio-file-path>") exit(1) } let path = CommandLine.arguments[1] let fileURL = URL(fileURLWithPath: path) do { let file = try AVAudioFile(forReading: fileURL) let format = file.processingFormat let buffer = AVAudioPCMBuffer(pcmFormat: format, frameCapacity: 8192)! let totalFrames = file.length let seekTarget = totalFrames / 2 print("File: \(fileURL.lastPathComponent)") print("Format: \(format)") print("Total frames: \(totalFrames)") print("Seeking to frame: \(seekTarget)") file.framePosition = seekTarget let start = CFAbsoluteTimeGetCurrent() try file.read(into: buffer, frameCount: 8192) let elapsed = CFAbsoluteTimeGetCurrent() - start print("Read after seek took \(elapsed) seconds") } catch { print("Error: \(error.localizedDescription)") exit(1) } Expected behavior: AVAudio​File​.read(into​:frame​Count:) after setting frame​Position should use the available seek mechanisms in FLAC and MP3 files for fast random access, as it already does for M4A (AAC). Even accounting for the fact that seek tables provide approximate (not sample-precise) positioning, the "jump to nearest index point + decode forward" approach should complete in milliseconds, not seconds. Workaround: For FLAC, I've worked around this by using libFLAC directly, which provides instant seeking via FLAC__stream​_decoder​_seek​_absolute(). libFLAC Performance: For comparison, libFLAC's FLAC__stream​_decoder​_seek​_absolute() performs the same seek + read on the same FLAC file in around 0.015, using the FLAC seek table to jump to the nearest preceding seek point, then decoding forward a small number of frames to the exact target sample.
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513
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Apr ’26
AVPictureInPictureController with AVSampleBufferDisplayLayer: Video not scaled in PiP window on macOS
AVPictureInPictureController with AVSampleBufferDisplayLayer: Video not scaled in PiP window on macOS Platform: macOS 26.4 (Tahoe) Framework: AVKit / AVFoundation Xcode: 26.4 Summary When using AVPictureInPictureController with ContentSource(sampleBufferDisplayLayer:playbackDelegate:) on macOS, the video content in the PiP window is not scaled to fit — it renders at 1:1 pixel resolution, showing only the bottom-left portion of the video (zoomed/cropped). The same code works correctly on iOS. Setup let displayLayer = AVSampleBufferDisplayLayer() displayLayer.videoGravity = .resizeAspect // Host displayLayer as a sublayer of an NSView, enqueue CMSampleBuffers let source = AVPictureInPictureController.ContentSource( sampleBufferDisplayLayer: displayLayer, playbackDelegate: self ) let pip = AVPictureInPictureController(contentSource: source) pip.delegate = self The source display layer is 1280×720, matching the video stream resolution. PiP starts successfully — isPictureInPicturePossible is true, the PiP button works, and the PIPPanel window appears. However, the video in the PiP window (~480×270) shows only the bottom-left 480×270 pixels of the 1280×720 content, rather than scaling the full frame to fit. Investigation Inspecting the PiP window hierarchy reveals: PIPPanel (480×270) └─ AVPictureInPictureSampleBufferDisplayLayerView └─ AVPictureInPictureSampleBufferDisplayLayerHostView (layer = CALayerHost) └─ AVPictureInPictureCALayerHostView The CALayerHost mirrors the source AVSampleBufferDisplayLayer at 1:1 pixel resolution. Unlike AVPlayerLayer-based PiP (which works correctly on macOS), the sample buffer display layer path does not apply any scaling transform to the mirrored content. On iOS, PiP with AVSampleBufferDisplayLayer works correctly because the system reparents the layer into the PiP window, so standard layer scaling applies. On macOS, the system uses CALayerHost mirroring instead, and the scaling step is missing. What I tried (none fix the issue) Setting autoresizingMask on all PiP internal subviews — views resize correctly, but CALayerHost content remains at 1:1 pixel scale Applying CATransform3DMakeScale on the CALayerHost layer — creates a black rectangle artifact; the mirrored content does not transform Setting CALayerHost.bounds to the source layer size — no effect on rendering Reparenting the internal AVPictureInPictureCALayerHostView out of the host view — video disappears entirely Hiding the CALayerHost — PiP window goes white (confirming it is the sole video renderer) Resizing the source AVSampleBufferDisplayLayer to match the PiP window size — partially works (1:1 mirror of a smaller source fits), but causes visible lag during resize, affects the main window's "This video is playing in Picture in Picture" placeholder, and didTransitionToRenderSize stops being called after the initial resize Expected behavior The video content should be scaled to fit the PiP window, respecting the display layer's videoGravity setting (.resizeAspect), consistent with: iOS PiP with AVSampleBufferDisplayLayer (works correctly) macOS PiP with AVPlayerLayer (works correctly) Environment macOS 26.4 (Tahoe) Xcode 26.4 Apple Silicon (M-series) Retina display (contentsScale = 2.0) Video: H.264 1280×720, hardware decoded via VTDecompressionSession, enqueued as CMSampleBuffer
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Apr ’26
Is 18MP Front Camera Capture Available to Third-Party Apps via AVFoundation?
Hi, I'm investigating whether 18MP photo capture from the front camera on iPhone 17 Pro is available to third-party apps using AVFoundation. I first inspected all available AVCaptureDevice formats, but I could not find any format corresponding to ~18MP resolution (e.g., around 4896×3672). for format in device.formats { let desc = format.formatDescription let dims = CMVideoFormatDescriptionGetDimensions(desc) print("Format: (dims.width) x (dims.height)") } All reported formats appear to be limited to resolutions such as 4032×3024 (12MP) or below. Question: Is 18MP front camera capture actually available to third-party apps via AVFoundation on iPhone 17?
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Apr ’26
10-Bit UVC on iPadOS
Hello, I've been very familiar with the UVC Support in iPadOS ever since it launched in iOS 17. There are a number of people that use the software I've developed built around UVC and there are often queries about 8-Bit vs. 10-Bit. My understanding is that the newest UVC Spec is 1.5 which was standardised in 2012 and almost every UVC Capture Card runs at 8-Bit. The only 10-Bit Capture Card that is on my radar is the AJA U-Tap SDI, however it looks like this is 10-Bit up until the UVC Part where the 10-Bit Input is downsampled to 8-Bit. Though I have read in certain places that it works as a 10-Bit Capture Card on macOS but not on iPadOS. I was just wondering if 10-Bit via UVC is even possible on iPadOS? If there was indeed a true 10-Bit Source being passed into an iPad, would iPadOS allow it or would it be downsampled by AVFoundation so it can show up as a valid external video input? All USB Capture Cards that I have encountered use one of the following formats: kCVPixelFormatType_420YpCbCr8BiPlanarVideoRange kCVPixelFormatType_420YpCbCr8BiPlanarFullRange kCVPixelFormatType_32BGRA So if a UVC Device delivered a 10-Bit Format, would that be accessible by iPadOS or would it fallback to these 8-Bit Formats by default? Thanks!
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Apr ’26
AXSpeech Thread Crash SEGV_ACCERR
Hi everyone, I've encountered a rare and strange crash in my app that I can't consistently reproduce. The crash seems to occur deep within Apple's internal frameworks, and I can't pinpoint which line of my own code is causing it. Here's the crash stack trace: #44 AXSpeech SIGSEGV SEGV_ACCERR 0 CoreFoundation ___CFCheckCFInfoPACSignature + 4 1 CoreFoundation _CFRunLoopSourceSignal + 28 2 Foundation _performQueueDequeue + 492 3 Foundation ___NSThreadPerformPerform + 88 4 CoreFoundation ___CFRUNLOOP_IS_CALLING_OUT_TO_A_SOURCE0_PERFORM_FUNCTION__ + 28 5 CoreFoundation ___CFRunLoopDoSource0 + 176 6 CoreFoundation ___CFRunLoopDoSources0 + 340 7 CoreFoundation ___CFRunLoopRun + 828 8 CoreFoundation _CFRunLoopRunSpecific + 608 9 Foundation -[NSRunLoop(NSRunLoop) runMode:beforeDate:] + 212 10 TextToSpeech _TTSCFAttributedStringCreateStringByBracketingAttributeWithString + 776 11 Foundation ___NSThread__start__ + 732 12 libsystem_pthread.dylib __pthread_start + 136 Sometimes, instead of line 10 referencing _TTSCFAttributedStringCreateStringByBracketingAttributeWithString, it shows: 10 TextToSpeech LogWarning(char const*, ...) + 7288 Has anyone experienced a similar issue or know what might be triggering this crash? Any guidance on how to investigate or resolve this would be greatly appreciated. Thank you!
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Activity
Mar ’26
How to hide route button `showsRouteButton = false` in `MPVolumeView` without deprecation warning?
MPVolumeView's showsRouteButton was deprecated (https://developer.apple.com/documentation/mediaplayer/mpvolumeview/showsroutebutton?language=objc). It's not clear how can we now hide this button without deprecation warning. The documentation is lacking. Please advise. Thank you!
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489
Activity
Mar ’26
HLS VOD Download Resume after Wifi/LTE Change
Hello there, Our application has HLS VOD download option. Users can download VOD which has DRM protection and watch content when device is offline. We use aggregateAssetDownloadTask to download HLS VOD. We want to resume download after Wifi/LTE change but it does not resume. Download is starting from beginning. We use some token algorithms to start download. That's why, our playlist url and chunks urls may change. But playlist and chunk urls' content is unique. If user start to download via Wifi and changed to LTE. Download request responds 403 Forbidden because of some token algorithms after some time func urlSession(_ session: URLSession, task: URLSessionTask, didCompleteWithError error: Error?) AVAssetDownloadDelegate function triggered by system. If we resume it does not resume at this point. It is starting from beginning if we start new download process for same content. Is there any way to resume unfinished HLS Download processes? Thanks
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833
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Mar ’26
Strange crash in iOS AudioToolboxCore when using AVSpeechSynthesizer in iOS 16
I'm getting Crashlytics crashes from some my users, deep in the Apple code: Crashed: AXSpeech EXC_BAD_ACCESS KERN_INVALID_ADDRESS 0x00000007ec54b360 0 libobjc.A.dylib 0x3c9c objc_retain_x8 + 16 1 AudioToolboxCore 0x99580 auoop::RenderPipeUser::~RenderPipeUser() + 112 2 AudioToolboxCore 0xe6090 -[AUAudioUnit_XPC internalDeallocateRenderResources] + 92 3 AVFAudio 0x90a0 AUInterfaceBaseV3::Uninitialize() + 60 4 AVFAudio 0x4cbe0 AVAudioEngineGraph::PerformCommand(AUGraphNodeBaseV3&, AVAudioEngineGraph::ENodeCommand, void*, unsigned int) const + 768 5 AVFAudio 0x56b0c AVAudioEngineGraph::_Uninitialize(NSError**) + 132 6 AVFAudio 0x7834 AVAudioEngineImpl::Stop(NSError**) + 388 7 AVFAudio 0x636c -[AVAudioEngine dealloc] + 52 8 TextToSpeech 0x30674 _TTSNameForVoiceInformation + 20864 9 libobjc.A.dylib 0x20a4 object_cxxDestructFromClass(objc_object*, objc_class*) + 116 10 libobjc.A.dylib 0x6e00 objc_destructInstance + 80 11 libobjc.A.dylib 0x104fc _objc_rootDealloc + 80 12 TextToSpeech 0x2d2f4 _TTSNameForVoiceInformation + 7680 13 TextToSpeech 0x496c TTSVocalizerCopyURLForFallbackResource + 8540 14 TextToSpeech 0x26094 TTSSpeechUnitTestingMode + 5548 15 libAXSpeechManager.dylib 0x108b0 -[AXSpeechManager .cxx_destruct] + 192 16 libobjc.A.dylib 0x20a4 object_cxxDestructFromClass(objc_object*, objc_class*) + 116 17 libobjc.A.dylib 0x6e00 objc_destructInstance + 80 18 libobjc.A.dylib 0x104fc _objc_rootDealloc + 80 19 libAXSpeechManager.dylib 0x5298 -[AXSpeechManager dealloc] + 268 20 Foundation 0x3b8a4 __NSThreadPerformPerform + 272 21 CoreFoundation 0xd3208 __CFRUNLOOP_IS_CALLING_OUT_TO_A_SOURCE0_PERFORM_FUNCTION__ + 28 22 CoreFoundation 0xdf864 __CFRunLoopDoSource0 + 176 23 CoreFoundation 0x646c8 __CFRunLoopDoSources0 + 244 24 CoreFoundation 0x7a1c4 __CFRunLoopRun + 828 25 CoreFoundation 0x7f4dc CFRunLoopRunSpecific + 612 26 Foundation 0x420c4 -[NSRunLoop(NSRunLoop) runMode:beforeDate:] + 212 27 libAXSpeechManager.dylib 0x13390 -[AXSpeechThread main] + 552 28 Foundation 0x5b634 __NSThread__start__ + 716 29 libsystem_pthread.dylib 0x16b8 _pthread_start + 148 30 libsystem_pthread.dylib 0xb88 thread_start + 8 It's most likely related to my use of AVSpeechSynthesizer. I do change some of the utterance fields, including the voice that's being used (which is set to a value from speechVoices()). UtilAudioIos_tts = AVSpeechSynthesizer() let utterance = AVSpeechUtterance utterance.voice = AVSpeechSynthesisVoice(identifier: voice.voiceCode) utterance.volume = volume utterance.pitchMultiplier = pitch utterance.rate = rate UtilAudioIos_tts!.speak(utterance) By coincidence or not, the following sometimes appears in the device log: 2023-05-30 20:35:29.948078+0100 <appname>[466:12882] [catalog] Unable to list voice folder and also, sometimes: 2023-05-30 20:37:35.345933+0100 <appname>[466:13298] [catalog] Query for com.apple.MobileAsset.VoiceServices.VoiceResources failed: 2 2023-05-30 20:37:35.360854+0100 rehearserfree[466:13433] [AXTTSCommon] MauiVocalizer: 11006 (Can't compile rule): regularExpression=\Oviedo(?=, (\x1b\\pause=\d+\\)?Florida)\b, message=unrecognized character follows \, characterPosition=1 2023-05-30 20:37:35.363163+0100 <appname>[466:13433] [AXTTSCommon] MauiVocalizer: 16038 (Resource load failed): component=ttt/re, uri=, contentType=application/x-vocalizer-rettt+text, lhError=88602000 2023-05-30 20:37:35.363182+0100 <appname>[466:13433] [AXTTSCommon] Error loading rules: 2147483648 All of these crashes have been on the various versions of iOS 16. Edit: I can't reproduce the crash myself - it's just some (not all) app users. The log entries above appear locally on my device (with no crash) but I can't see the logs of the users who have the crashes. Any idea what this might be caused by, or how to go about tracking the problem down?
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Mar ’26
Massive CoreML latency spike on live AVFoundation camera feed vs. offline inference (CPU+ANE)
Hello, I’m experiencing a severe performance degradation when running CoreML models on a live AVFoundation video feed compared to offline or synthetic inference. This happens across multiple models I've converted (including SCI, RTMPose, and RTMW) and affects multiple devices. The Environment OS: macOS 26.3, iOS 26.3, iPadOS 26.3 Hardware: Mac14,6 (M2 Max), iPad Pro 11 M1, iPhone 13 mini Compute Units: cpuAndNeuralEngine The Numbers When testing my SCI_output_image_int8.mlpackage model, the inference timings are drastically different: Synthetic/Offline Inference: ~1.34 ms Live Camera Inference: ~15.96 ms Preprocessing is completely ruled out as the bottleneck. My profiling shows total preprocessing (nearest-neighbor resize + feature provider creation) takes only ~0.4 ms in camera mode. Furthermore, no frames are being dropped. What I've Tried I am building a latency-critical app and have implemented almost every recommended optimization to try and fix this, but the camera-feed penalty remains: Matched the AVFoundation camera output format exactly to the model input (640x480 at 30/60fps). Used IOSurface-backed pixel buffers for everything (camera output, synthetic buffer, and resize buffer). Enabled outputBackings. Loaded the model once and reused it for all predictions. Configured MLModelConfiguration with reshapeFrequency = .frequent and specializationStrategy = .fastPrediction. Wrapped inference in ProcessInfo.processInfo.beginActivity(options: .latencyCritical, reason: "CoreML_Inference"). Set DispatchQueue to qos: .userInteractive. Disabled the idle timer and enabled iOS Game Mode. Exported models using coremltools 9.0 (deployment target iOS 26) with ImageType inputs/outputs and INT8 quantization. Reproduction To completely rule out UI or rendering overhead, I wrote a standalone Swift CLI script that isolates the AVFoundation and CoreML pipeline. The script clearly demonstrates the ~15ms latency on live camera frames versus the ~1ms latency on synthetic buffers. (I have attached camera_coreml_benchmark.swift and coreml model (very light low light enghancement model) to this repo on github https://github.com/pzoltowski/apple-coreml-camera-latency-repro). My Question: Is this massive overhead expected behavior for AVFoundation + Core ML on live feeds, or is this a framework/runtime bug? If expected, what is the Apple-recommended pattern to bypass this camera-only inference slowdown? One think found interesting when running in debug model was faster (not as fast as in performance benchmark but faster than 16ms. Also somehow if I did some dummy calculation on on different DispatchQueue also seems like model got slightly faster. So maybe its related to ANE Power State issues (Jitter/SoC Wake) and going to fast to sleep and taking a long time to wakeup? Doing dummy calculation in background thought is probably not a solution. Thanks in advance for any insights!
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Mar ’26
Video Audio + Speech To Text
Hello, I am wondering if it is possible to have audio from my AirPods be sent to my speech to text service and at the same time have the built in mic audio input be sent to recording a video? I ask because I want my users to be able to say "CAPTURE" and I start recording a video (with audio from the built in mic) and then when the user says "STOP" I stop the recording.
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Mar ’26
Random EXC_BAD_ACCESS using AVFoundation
My app uses the AVFoundation to pronounce some words. Running the app from Xcode, either to a simulator or device, I frequently get this crash at start-up: AXSpeech (13): EXC_BAD_ACCESS (code=EXC_I386_GPFLT). It seems to occur randomly, maybe 20%-30% of the time I launch the app. When it does not crash, using audio works as expected. When launched from the device, it never crashes (so far, at least). Here's the code that outputs speech: Declared at the top level of the View struct: @State var synth = AVSpeechSynthesizer() In the View, as part of a Button's action closure: let utterance = AVSpeechUtterance(string: answer) utterance.voice = AVSpeechSynthesisVoice(language: "en_US") synth.speak(utterance) Any idea on how to stop this? It's annoying having to launch the app multiple times to test on a simulator or device.
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639
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Mar ’26
Recurring FigXPCUtilities / FigCaptureSourceRemote err=-17281 logs when using AVCaptureVideoDataOutput on iOS 26.x
Hi everyone, I’m seeing recurring internal AVFoundation camera logs on iOS 26.2 and I’m trying to understand whether this is expected behavior or a regression in the capture pipeline. These logs appear shortly after starting an AVCaptureSession, while video frames are being delivered, and also when the camera is stopped or the capture session is torn down. <<<< FigXPCUtilities >>>> signalled err=-17281 at <>:302 <<<< FigCaptureSourceRemote >>>> Fig assert: "err == 0 " at bail (FigCaptureSourceRemote.m:569) - (err=-17281) Even in this clean, minimal setup, the same logs appear on iOS 26.2 The exact same logic did not produce these logs on iOS 18.x. To rule out issues caused by my own code, GPT created a minimal SwiftUI example from scratch. My primary interest is to perform real-time processing on the video frames delivered by the camera (via AVCaptureVideoDataOutput), for tasks such as analysis, computer vision, or custom frame handling, while simultaneously displaying the live preview. Thanks in advance for any insight. Example Code
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Mar ’26
AVAudioSession.outputVolume does not reflect system volume changes made while app is in background
I have a question regarding the behavior of AVAudioSession.sharedInstance().outputVolume. Observed behavior: When the app is in the foreground, I read audioSession.outputVolume (for example, 0.1). The app is then moved to the background. While the app is in the background, the user changes the system volume using the hardware buttons (for example, to 0.5). When the app returns to the foreground, audioSession.outputVolume still reports the previous value (0.1). From my testing, outputVolume only seems to update when the system volume is changed while the app is in the foreground. Volume changes made while the app is in the background are not reflected when the app returns to the foreground. Questions: According to Apple’s documentation for AVAudioSession.outputVolume: “The systemwide output volume set by the user.” https://developer.apple.com/documentation/avfaudio/avaudiosession/outputvolume However, based on our testing on iOS 18.6.2 and iOS 18.1, the observed behavior seems to differ from this description. Questions: The documentation states that outputVolume represents the system-wide volume set by the user. In our testing, the value does not reflect volume changes made while the app is in the background and only updates when the app is in the foreground.Is this the expected behavior of AVAudioSession.outputVolume? Is there any other recommended way in Swift to retrieve the current system volume that reflects user changes made both while the app is in the foreground and while it is in the background? Any clarification on the intended behavior or recommended handling would be greatly appreciated.
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422
Activity
Mar ’26
How should playback readiness be determined with AVSampleBufferAudioRenderer when using AirPlay?
I’m implementing a custom playback pipeline using AVSampleBufferAudioRenderer together with AVSampleBufferRenderSynchronizer. hasSufficientMediaDataForReliablePlaybackStart appears to be the intended signal for determining when enough media has been queued to start playback. For local playback, this works well in practice — the property becomes true after a reasonable amount of media is enqueued. However, when the output route is AirPlay, using this property becomes difficult: AirPlay requires significantly more buffered media before the renderer reports sufficient data. The required preroll amount is much larger than for local playback. For short assets, it is possible to enqueue the entire audio track and still never observe hasSufficientMediaDataForReliablePlaybackStart == true. In that situation there is no more media data to enqueue, but the renderer still reports that playback is not ready. Given this behavior, what is the recommended way to determine playback readiness when using AVSampleBufferAudioRenderer with AirPlay?
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456
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Mar ’26
Lock Screen shows skip buttons instead of next/previous when using MPRemoteCommandCenter with AVPlayer playlist
Hello, I’m building an iOS video player using AVPlayer and a custom playback queue. I implemented remote controls using MPRemoteCommandCenter and enabled: nextTrackCommand previousTrackCommand playCommand pauseCommand I disabled: skipForwardCommand skipBackwardCommand seekForwardCommand seekBackwardCommand I also set queue metadata in MPNowPlayingInfoCenter: MPNowPlayingInfoPropertyPlaybackQueueIndex MPNowPlayingInfoPropertyPlaybackQueueCount Even with these commands enabled and the queue count greater than 1, the iOS lock screen continues to display the 10-second skip buttons instead of the previous/next track buttons. The commands themselves work correctly when triggered externally (Control Center, headphones, etc.), but the UI still shows the skip controls. Is there a way to force the lock screen UI to display previous / next track buttons for a video playlist? Or is this behavior expected when using AVPlayer with video content? Thanks.
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181
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Mar ’26
UVC over MFi – Is there official support? Implementation guidance?
Hello everyone, I’m looking for more detailed information regarding UVC (USB Video Class) over MFi within the Apple ecosystem and would appreciate some clarification. I’m interested in developing (or interfacing with) an accessory that transmits video over USB using the UVC standard, and I’d like to better understand how this works within the MFi (Made for iPhone) program. Here are my main questions: 1. Do iOS devices provide native support for UVC over USB-C or Lightning within the MFi framework? 2. Are there any specific firmware or authentication requirements when the accessory is MFi-certified? 3. Does UVC support depend solely on the hardware interface (USB-C vs Lightning), or are there additional software-level requirements? 4. Is there any official documentation outlining the recommended flow for implementing UVC-based video capture accessories on iOS? From what I understand, USB-C iPads appear to offer more direct support for standard UVC devices, but it’s not entirely clear how this integrates with the MFi ecosystem with iOS, especially for commercial product development. If anyone has gone through this process or can point me to relevant technical documentation, I would greatly appreciate the guidance. Thank you!
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Mar ’26