We have a product where Logic Pro's "process effects only when needed" optimisation blocks the core use case, and we would like to ask for the opt-in that some third-party plug-ins already have. Filed as FB25426476. The plug-in ACENTAUR (Audio Unit v2, type aumf, subtype Acnt, manufacturer EINX; EINAUX, Germany) is an AI music generator that lives in the Audio FX slot of an audio track. It renders its own material from the host's tempo, time signature and transport, so the natural workflow is: empty audio track, insert ACENTAUR, press Play, generate. There is no region and no input signal. The plug-in is the source. What happens On an empty audio track Logic never calls the render callback, so the plug-in never receives the host clock through the HostCallbacks: tempo and transport stay unknown and our UI stays locked. Everything else works: the same build renders in the instrument slot, in other hosts, and on a Logic audio track as soon as a region or live input is present. Inserting Logic's Test Oscillator (bypassed) in the same strip also makes it work, which shows the strip is simply not scheduled. Logic engineering described this optimisation on coreaudio-api in February 2024 (https://www.mail-archive.com/coreaudio-api@lists.apple.com/msg01859.html). What we observed A number of third-party effects (Celemony Melodyne, Antares, Synchro Arts, Waves and others) are processed on an empty track. We verified on Logic Pro 12.4 (6707) / macOS 26.6.2 that this is tied to the plug-in's identity plus a private global property Logic queries when the plug-in is loaded: with a listed manufacturer code and that property answered, our plug-in is rendered immediately on an empty track and the host clock arrives. We are of course not going to ship under another vendor's identity; this was a one-off local test to make sure we understand the mechanism before asking. Log excerpt from that test (plug-in log, out-of-process hosting, empty audio track, 48 kHz): 09:19:38 host asked property 101000 → 0 09:19:38 host asked property 101001 → 1 09:19:38 Initialize → 0 · in 2 ch @ 48000 Hz · out 2 ch 09:19:39 First render after 0s · input callback · tempo 120.00 Same build under our own manufacturer code EINX: "No render after 30s · host clock tempo+transport · flags 0". The request Could ACENTAUR (aumf / Acnt / EINX) be added to the set of plug-ins Logic keeps processing without input? The plug-in already answers the property in question; the only missing piece is on Logic's side. If there is a different or public mechanism you would prefer third parties to adopt (a component tag, an AU property, an AUv3 property), we will implement it right away. Happy to provide a build, a demo project and whatever else helps. Christoph Kahse, EINAUX

Hi, I believe I have found a Core Audio regression in macOS 27. This exact hardware configuration worked correctly on macOS 26, and the issue started immediately after upgrading to macOS 27. Hardware: Mac mini M2 2 × MSI MP243X monitors Monitor 1 connected via HDMI Monitor 2 connected via DisplayPort Both monitors expose a 2-channel audio output to macOS On macOS 26: I used Audio MIDI Setup to create a Multi-Output Device containing both MSI MP243X audio outputs. Audio played simultaneously through both monitors without any issues. On macOS 27: Both audio devices are still detected correctly and both work perfectly when selected individually: HDMI only: WORKS DisplayPort only: WORKS HDMI + DisplayPort simultaneously: FAILS This is reproducible even immediately after a full reboot. When I create a new Multi-Output Device containing both MSI outputs and select it as the system output, audio playback cannot start. For example: afplay /System/Library/Sounds/Glass.aiff returns: Error: AudioQueueStart failed ('stop') I captured Core Audio debug logs while reproducing the problem. Core Audio initially reports that StartIO succeeded, but the physical display audio device then fails to establish a timeline. Relevant log messages include: HALS_IOEngine2::_StartIO succeeded Device 3669B540-0000-0000-2623-0104A5351D78 is not running. could not establish a timeline after waiting 10000000 microseconds stopping with error 1937010544 StartIOThread: the IO thread failed to start, Error: 1937010544 I have already tested the following: Both devices at 44.1 kHz / 24-bit Both devices at 48 kHz / 16-bit Recreating the Multi-Output Device from scratch Using the HDMI device as clock source Using the DisplayPort device as clock source Different drift correction configurations Restarting coreaudiod Full macOS reboot Testing both outputs individually immediately after reboot Alternative multi-device audio routing software The behavior is always reproducible. Each MSI MP243X audio endpoint works correctly by itself. The failure only occurs when both HDMI and DisplayPort audio endpoints are opened simultaneously. system_profiler correctly detects both devices at 48 kHz: MSI MP243X Output Channels: 2 Current Sample Rate: 48000 Transport: HDMI MSI MP243X Output Channels: 2 Current Sample Rate: 48000 Transport: DisplayPort This does not appear to be a problem with either monitor or connection individually, because both outputs continue to work independently. The important difference is the macOS version: macOS 26: HDMI + DisplayPort Multi-Output = WORKING macOS 27: HDMI only = WORKING DisplayPort only = WORKING HDMI + DisplayPort Multi-Output = FAILS with AudioQueueStart 'stop' / Core Audio error 1937010544 No hardware, monitor, cable, or connection changes were made between the working macOS 26 configuration and the macOS 27 configuration. This therefore appears to be a regression in the Core Audio/display-audio path introduced with macOS 27 when two display audio endpoints (HDMI + DisplayPort) are opened simultaneously. Has anyone else been able to reproduce this on macOS 27, particularly on Apple Silicon? I can provide the complete coreaudiod logs and run additional Core Audio diagnostics if needed. Additional isolation tests: Both monitors can remain physically connected to the Mac at the same time. With both HDMI and DisplayPort connected: Selecting the HDMI MSI MP243X as the only output works correctly. Selecting the DisplayPort MSI MP243X as the only output works correctly. Opening both audio endpoints simultaneously causes the failure. Therefore, simply having both displays connected does not trigger the issue. The failure appears specifically when Core Audio attempts to run both display-audio endpoints at the same time. I also tested this using third-party multi-device audio routing implementations instead of relying only on Audio MIDI Setup. The same behavior occurs: either MSI MP243X can be opened and used independently, but attempting to route audio to both devices simultaneously fails. This suggests that the issue is below the Multi-Output Device configuration itself and may be related to starting/synchronizing two display-audio IO engines simultaneously. During the failure, the Core Audio log sequence is particularly interesting: The physical device is detected normally. The audio format is configured successfully. Core Audio reports that StartIO succeeded. The device subsequently reports that it is not running. Core Audio waits 10 seconds for a timeline. Timeline establishment fails. The IO thread terminates with error 1937010544 ('stop'). One captured conversion path was: 2 ch, 48000 Hz, Float32, interleaved -> 2 ch, 48000 Hz, Int16, interleaved so both sides were operating at 48 kHz during this test. Another important observation is that restarting coreaudiod does not resolve the simultaneous-output problem. A complete reboot also does not resolve it: immediately after a fresh boot, before launching any third-party audio-routing software, both physical outputs work individually but a newly created Multi-Output Device still reproduces the failure. This makes the issue highly reproducible on this machine. Minimal reproduction: Boot macOS 27 with both MSI MP243X monitors connected. Open Audio MIDI Setup. Verify both MSI MP243X devices work independently. Set both devices to 48,000 Hz. Create a new Multi-Output Device. Select both MSI MP243X devices. Select the new Multi-Output Device as the system audio output. Run: afplay /System/Library/Sounds/Glass.aiff Expected result: The sound is reproduced simultaneously through both monitors, as it was on macOS 26. Actual result: Error: AudioQueueStart failed ('stop') Switching the system output back to either individual MSI MP243X restores audio playback. The problem can then be reproduced again by selecting the Multi-Output Device.

Title: AUv2: Property Listener Callback Lifetime During AudioComponentInstanceDispose I’m developing a macOS Audio Unit v2 (AUv2) instrument in C++ and investigating the correct lifetime and synchronization requirements for property-listener callbacks. I would appreciate clarification from Apple engineers or developers with direct AUv2 implementation experience. Specifically: Does AudioComponentInstanceDispose guarantee that the Audio Unit’s Close operation has completed before the call returns? Does disposal guarantee that all property-listener callbacks registered through AudioUnitAddPropertyListener have finished executing before the instance and its associated callback data can be destroyed? What are the documented guarantees of AudioUnitRemovePropertyListenerWithUserData regarding callbacks that are currently executing or already queued? Is there a documented synchronization procedure that allows an AUv2 plug-in to safely release listener callback state during instance shutdown? Are there host-ordering requirements or documented assumptions that plug-in developers must follow when registering, removing, and destroying property listeners? My implementation is designed to avoid use-after-free, concurrent access to destroyed objects, and unsafe callback-data reclamation. I want to base the implementation on documented Apple API guarantees rather than assumptions about host behaviour. If relevant, please point me to the authoritative documentation or recommended implementation pattern. Environment: macOS 12 Monterey, Xcode 14.2, AUv2 instrument, C++.

Hello Apple engineers and developers, My name is Fumikazu Kondo. I am an independent developer in Japan working on transcription applications, including KF Transcription Mixer. I want to capture two separately connected Bluetooth microphones on a Mac for meeting and conversation transcription. I would appreciate an Apple engineer's response about the supported behavior and a reliable solution. Problem Each microphone works when captured individually. When both are opened, the second input delivers only zeros, even though Core Audio starts successfully and macOS reports two SCO connections. The failure also reproduces with direct native Core Audio capture before any application audio processing. Environment MacBook Pro, Apple M5, model identifier Mac17,2 macOS 27.2; sw_vers reports build 26B123 Xcode 27.1 (27A9275), macOS 27.0 SDK Built-in Bluetooth controller: BCM_4388C2, firmware 24.2.241.1936 Microphones: Beats Pill (firmware 2C336) and SANWA SUPPLY MM-BTCL1 (firmware 1.0.0), both directly connected to the Mac Both input devices expose 16,000 Hz, mono. Bluetooth logs show HFP/mSBC. Microphone Mode: Standard; preferred and active values both read back as 0 Reproduction Connect both microphones to the Mac. Confirm each delivers real audio in a separate, fresh capture process. In Audio MIDI Setup, create an Aggregate Device with the two microphone input devices, one channel each. Use 16 kHz, one clock source, and drift correction for the other device. Start capture of the two channels. Use a controlled speech fixture played through the Mac's built-in speakers so that both microphones receive sound. Observe that one channel has audio and the other is entirely silent. I also reproduced the problem using AudioDeviceCreateIOProcID / AudioDeviceStart directly on the physical input devices, without an aggregate or application processing. Reversing their opening order changed which microphone remained silent: the later-opened device delivered zeros. Measured results Physical Mac XCTest runs on October 30, 2026: MM-BTCL1 alone: 203,520 captured frames; 232 nonzero observation windows; passed. Beats Pill alone: 203,520 captured frames; 233 nonzero observation windows; passed. Two-input aggregate: 202,240 frames; nonzero windows [240, 0]; simultaneous windows 0; application audio error 0. Separate native shared-clock experiment: an aggregate containing both microphone inputs plus the built-in speaker, driven by one full-duplex IOProc. 1,152 input callbacks and 1,152 output buffers; nonzero callback counts [1100, 0]; simultaneous windows 0; invalid samples 0. The last experiment rules out simply lacking a running output clock in the input-only capture path, but it did not fix the issue. Relevant system log messages include: Number of SCO Connections: 2. A2DP Streaming State: 0. Input Decode: Requested 640 bytes, but only read 0 bytes instead. Decoded a total of 0 bytesThe decode message repeats during the silent input. Successful voice-audio connection events appear for both devices. Device identifiers and unrelated logs are omitted here. Already tested Both microphones power-cycled and individually reconnected Mac restarted; issue reproduced afterward Standard microphone mode verified by readback Both microphones individually verified with the same controlled stimulus Reversed native device opening order Persistent and private aggregates; different clock choices and drift correction Direct physical-device IOProc capture Full-duplex shared-clock capture with the built-in speaker Built-in speaker selected as system output, with Bluetooth output streaming stopped during measurement Core Audio and Bluetooth services restarted; issue persisted Software Update reports no new software available I have not established whether the cause is in the OS, driver, controller, or device firmware. I am not claiming a universal Bluetooth specification limitation. Questions for Apple Is simultaneous capture from two directly connected HFP/mSBC microphones supported on this Mac/macOS configuration through Core Audio? If there is a limitation, could you provide the relevant documentation and clarify its scope? If supported, which public API or configuration should be used to keep both input streams delivering audio? Is there a known issue or supported workaround for the all-zero second stream? Which targeted Bluetooth/HCI logs or minimal reproduction details would Apple need to investigate? I can provide a focused reproduction and redacted measurements through an appropriate private channel if needed. This is blocking reliable two-microphone transcription. Please respond with the expected behavior, next diagnostic steps, or the appropriate Apple engineering support route. Thank you for your help. Update: also reproduced with two Beats Pill speakers On October 30, 2026, I replaced the MM-BTCL1 with a second Beats Pill. Both Beats Pill speakers report firmware 2C336 and are independently connected to this Mac. Microphone Mode remains Standard (0). Fresh individual controls after previous SCO connections fully disconnected: both work (235 and 236 nonzero observation windows). Application-created private aggregate, device order A/B: nonzero windows [233, 0]. Reversed participant order: [0, 240]. Direct physical-device IOProc test, opening A before B: callback counts [404, 402], but nonzero callback counts [403, 0]. No simultaneous audio windows. After releasing both and restarting B alone, B delivers audio (381 nonzero callbacks). Opening A while B continues then yields nonzero counts [0, 404]: the later-opened device is again silent. System logs again report two SCO connections and repeated zero-byte input decode messages. Thus the same failure also reproduces with two same-model, same-firmware Apple/Beats devices. Please include this configuration when assessing support status, a possible known issue, and recommended next steps. Additional comparison reported by the user: the MacBook built-in microphone and one Beats Pill can both be heard when used together. This is a user-observed working configuration, separate from the automated tests above. It further narrows the problem to the configuration with two simultaneous Bluetooth microphone inputs.

Hi all, We run Soundmark, a small UK website where people rate and review albums and songs (web only for now, a native app may come later). We'd like to use the Apple Music API in two ways, and want to make sure we stay within the rules before building anything: Show artist images on our artist pages. Let users connect their Apple Music account and import their library, so the albums and songs they already have show up on Soundmark ready to rate. Our setup today: Album and song pages have a small player that plays 30-second previews. On desktop, some pages also show the Spotify embed player. There are no ads on the site. We would show the Apple Music badge and a link to Apple Music alongside any Apple content, following the Apple Music Identity Guidelines. Our questions: Can a website use artist artwork from the Apple Music API if it only plays 30-second previews, or does it need full MusicKit on the web playback (users connecting their Apple Music account)? Can the artist image appear on a page that also shows a Spotify embed player, or does it need to be on pages with Apple Music playback only? Beyond Apple's own terms, do we need separate permission from rights-holders to display artist images, or is the API licence enough when used as described? Can we import catalog data (album and song titles, tracklists, release dates and cover art) from the Apple Music API and store it permanently in our own database, so our album and song pages are built from it? Can those pages be shown to everyone, including visitors without an Apple Music account, and are there limits on caching cover art or on how many albums we import (rate limits)? We also emailed Apple Developer Support on 21st October and chased on the 28th but haven't heard back yet, so any pointers to the relevant terms would be really appreciated. Thanks!

We develop SpinCut DJ, a free-to-download proprietary DJ application by LALAMO CORPORATION for iPhone, iPad and Mac Catalyst. We want to add Apple Music subscription playback for users with an active subscription, similar to the integrations featured in DJ with Apple Music. This question is about the officially supported integration path, not extracting or bypassing protected audio. Our existing engine uses app-owned PCM for two independently controlled decks, scratch/reverse playback, tempo changes, hot cues, loops, beat synchronization and independent master/headphone outputs. We have reviewed MusicAuthorization, MusicSubscription, catalog/library requests, ApplicationMusicPlayer and SystemMusicPlayer. We understand that ordinary catalog access and protected queue playback do not establish a documented route to feed subscription audio into our custom engine, or permission to modify or synchronize MusicKit content. We have not enabled subscription-catalog DJ playback. Apple Developer Support advised us to ask the Developer Forums about the required technical integration. Could an Apple representative clarify: Is there a documented public API for two independent, simultaneous Apple Music DJ decks with scratch/reverse/tempo control? If a separate Apple Music DJ integration, agreement, SDK or capability is required, what is the current official application or referral process for a Japan-based developer? Are iOS, iPadOS and Mac Catalyst supported through the same integration, and what technical material is required for evaluation? What approved interfaces govern waveform/beat analysis, seeking and separate master/headphone routing? We are not requesting recording/export, stem separation, offline file extraction or rebroadcast permission through ordinary MusicKit. Those features would remain unavailable for subscription content unless separately and expressly supported. We can provide a product demonstration and integration brief through an appropriate private channel. Product: https://spincutdj.com/ App Store: https://apps.apple.com/app/id6804328893 Please point us to the supported technical and onboarding path rather than an undocumented entitlement or workaround.

TTS Stuttering & Noise When using Apple’s native TTS API on an iPhone or iPad—specifically while connected to Bluetooth earphones or headsets—users are experiencing audio noise or intermittent gaps in speech, causing parts of sentences to drop out during playback. There were no reports or inquiries regarding such issues up through iOS/iPadOS 26. Since the release of iOS/iPadOS 27, however, there has been a significant increase in reports and inquiries about this problem. If you happen to know the cause of this issue or have any suggestions for a fix, please leave a reply. The issue persists even after removing the AirPods or headset from the device and reconnecting them. The issue persists even after rebooting the device. The issue occurs even on the latest versions, from iOS/iPadOS 27 through 27.2.

Hello Apple engineers and fellow developers, I am developing CloudMusic Bridge, a Windows desktop music application integrating the official MusicKit Web v3 SDK. MusicKit initialization succeeds, but authorize() consistently rejects with AUTHORIZATION_ERROR after the user clicks Allow in Apple's official authorization window. Environment Windows, Google Chrome and Microsoft Edge MusicKit Web v3 from Apple's official CDN Local HTTPS origin: https://localhost:4318 Valid ES256 developer token with a matching origin claim MusicKit-enabled Media ID and associated Media Services key Active Apple Music subscription, with full-song playback working on music.apple.com Catalog API requests succeed (HTTP 200) Actual MusicKit SDK build: UNKNOWN Reproduction I created a standalone minimal reproduction that loads MusicKit, initializes it, obtains the instance and invokes instance.authorize() directly from a user click. The user signs in and clicks Allow, but the authorization Promise rejects. I also tested a separate page that explicitly allows https://play.itunes.apple.com in both CSP connect-src policies. This eliminated the previously observed document CSP violations during the comparison, but authorization still failed with AUTHORIZATION_ERROR after approximately 46.6 seconds. The application did not reach its 120-second timeout. Questions for Apple DTS How can I verify that my browser is loading the current supported stable MusicKit Web v3 build? Is there any additional developer configuration required for web authorization? How can I safely identify the underlying authorization exchange failure? Since this reproduces on Windows, what diagnostics should I provide instead of macOS sysdiagnose? Could an Apple engineer help investigate my existing report, FB25267497? I have already contacted Apple Developer Support and was directed to the Developer Forums for SDK-related technical assistance. I can provide a sanitized minimal reproduction and diagnostic timeline. Thank you for your help.

Hello, I develop an audio processing demo app that has been working fine on iOS/iPad and on Mac ("developed for iPad") until I upgraded to MacOS27. The app is demonstrating low latency / high temporal resolution audio spectral analysis. I am using AVAudioSession, I request the audio IO buffer to be 32 samples. This still works fine on iOS/iPadOS, but it seems that when running on MacOS27 the buffer size always defaults to 512 samples no matter what I request (smaller or larger). This applies to the "Designed for iPad" version running on MacOS and any version running in the iPhone and iPad simulators on MacOS. The app seems to be working as intended on physical iPhones and iPads. I made a catalyst version and used AudioObjectSetPropertyData to force the IO bugger sizes to 32 samples on the system's active hardware device. This seems to succeed but still results in incorrect behaviour in my app; I am still diagnosing but I believe it's because this leaves AVAudioSession with incorrect data, and I am using AudioKit which relies on AVAudioSession (not confirmed). Regardless, is this change in behaviour intentional in MacOS27? Is there a way around it? The whole point of my app is to demonstrate efficient audio processing with very low latency - I need small input buffer size for that. Thank you for any help with this

I’m building a personal iPhone app that organizes my music library. When I tap an album in my app, I want Apple’s Music app to open directly to that album’s page in Library, showing the tracks synced from my computer. My app can already read the albums and their tracks using MusicKit. I’ve tried normal Apple Music sharing links, but those open the catalog version of the album. I need the page I see when I find the album through Library in the Music app. Starting or changing playback is fine, but the album page must appear. Only starting the music or opening Now Playing would not be enough. Is there a supported API or link format that can do this? A documentation link or a small code example would be helpful.

When wrapping CABTMIDICentralViewController in a UIViewControllerRepresentable and presenting modally, I experience layout crashes since iOS 27. Does anyone have a workaround? import SwiftUI import CoreAudioKit struct BluetoothButton: View { @State var showsBluetooth = false let title = "Check for Bluetooth MIDI Devices" var body: some View { #if os(macOS) Button { let wc = CABTLEMIDIWindowController() wc.showWindow(nil) } label: { label } #else Button { showsBluetooth = true } label: { label } .sheet(isPresented: $showsBluetooth) { BluetoothCentralView() } #endif } var label: some View { Text(title) } } #if os(iOS) struct BluetoothCentralView: UIViewControllerRepresentable { func makeUIViewController(context: Context) -> CABTMIDICentralViewController { return CABTMIDICentralViewController() } func updateUIViewController(_ uiViewController: CABTMIDICentralViewController, context: Context) { } } #endif

Hi everyone, I’m developing a native Apple TV application using MusicKit for Swift. The app provides a custom interface for browsing and playing the user’s personal Apple Music library. The application was working correctly for several months, but recently certain songs from the user’s personal library have stopped playing. I’ve been investigating this issue extensively and have reproduced it in a completely separate, minimal tvOS test application. The issue I retrieve songs using MusicLibraryRequest() and play them using ApplicationMusicPlayer. Some songs play successfully, while others consistently fail during playback preparation with: `MPMusicPlayerControllerErrorDomain Code=6 "Prepare to play failed"` The underlying errors include : NSCocoaErrorDomain Code=4099 Example of a failing song Michael Jackson — Bad (2012 Remaster) Library song ID: i.ldDOAp0UrAa62J Successfully retrieved using MusicLibraryRequest() Fails when queued with ApplicationMusicPlayer Also fails with SystemMusicPlayer Example of a working song Harry Nilsson — Everybody’s Talkin’ (1971 Mix) Library song ID: i.WmYQp9PcdZ4Y0E Retrieved using the exact same MusicLibraryRequest() Successfully plays using ApplicationMusicPlayer Both songs have library identifiers beginning with i.. What I’ve tested ApplicationMusicPlayer with prepareToPlay() followed by play(). SystemMusicPlayer with the same library song. Direct play() without explicitly calling prepareToPlay(). Retrieving songs directly using MusicLibraryRequest(), rather than accessing them through albums. A completely separate minimal tvOS application. An older version of my application’s code, recompiled using the current Xcode version. The issue persists across these tests. Interestingly, the corresponding Apple Music catalog song plays successfully when retrieved through MusicCatalogSearchRequest. However, replacing library songs with catalog equivalents is not an acceptable solution because the application needs to support users’ actual personal libraries, including imported music. Important observation The exact same failing song plays correctly on the same Apple TV and Apple Music account in: The official Apple Music application. Sleeve, another third-party Apple TV music player. This suggests that the song itself is playable and that another third-party application can successfully initiate playback. Environment Platform: tvOS Device: Physical Apple TV Framework: MusicKit for Swift Apple Music authorization: Granted MusicKit App Service: Enabled Signing: Automatic, using a paid Apple Developer account Question Is there a known issue with resolving or playing certain personal library songs through MusicKit on tvOS? Are there additional playback parameters, library synchronization requirements, or recommended queue configurations that could explain why some MusicLibraryRequest() items fail while others work? Has anyone encountered a similar issue or found a workaround that preserves playback of the user’s actual library items? Any guidance would be greatly appreciated. Thank you!

While an AVAudioPlayer/AudioUnit is rendering to AirPods over A2DP with system Spatial Audio + Head Tracking enabled, switching the shared AVAudioSession to playAndRecord + voiceChat (A2DP → HFP) blocks the main thread for tens of seconds on synchronous AVAudioSession APIs (setCategory / setMode / channel getters / setPreferred*). iOS hang detection reports a Severe Hang of 41.02 s. Stopping playback and deactivating the session before the identical switch completes in ~87 ms. Feedback: FB25324099 Environment iPhone 15 Pro (iPhone16,1), iOS 27.0.1 (24A446) AirPods worn; Spatial Audio + Head Tracking on AVFoundation-only repro (no third-party SDK): https://github.com/shinobuwz/ios27-spatial-audio-stall-repro Info.plist: LSApplicationCategoryType = public.app-category.games, LSSupportsGameMode = YES; does NOT set AVGameBypassSystemSpatialAudio (those two keys are required for system Spatial Audio on this path) Steps Wear AirPods with Spatial Audio + Head Tracking enabled Launch the repro app; allow mic (or use auto-repro) Play 440 Hz (BluetoothA2DP, spatial=1) After ~2 s, run Repro: keep playing and switch to PlayAndRecord + VoiceChat Compare with Control: stop playback + setActive:NO, then the same switch Expected: each call returns in ms; whole reconfiguration ≪ 50 ms Actual (cold launches): configuration total 20.8–28.9 s (options=13); with options=237 ≈ 36.2 s; first input buffer ~40–58 s from switch start. Control ≈ 87 ms. Evidence in the repo: docs/MEASUREMENTS-2026-10-26.md, evidence/*.log, hangs.xml, main-thread stacks in avas::client::SessionCore (sync XPC to the audio daemon). Even inputNumberOfChannels / outputNumberOfChannels getters stall for seconds. Question: Is this a known regression on iOS 27? Any workaround besides stopping all rendering AudioUnits before the HFP switch? Happy to attach sysdiagnose / Instruments / screen recording if useful.

I’m developing Segue, an iPhone and Apple Watch app for discovering concerts and keeping personal concert memories. Apple Music artist pages display upcoming concerts, including dates, venues, lineups, and ticket links. I would like users to search for an artist and view those concerts directly within Segue. Is there a supported public API or Apple framework for accessing these concert listings? I reviewed MusicKit and Apple Music API documentation but couldn’t find concert-related endpoints. Example Apple Music concert: https://music.apple.com/us/concerts/ce.91c8bd7d-0669-4c33-8c2a-6809b9f65129 If this requires separate partner access or approval, could you direct me to the appropriate team?

I am testing SFSpeechRecognizer using the en_US locale. When the iPhone Simulator’s system language is set to Japanese, SFSpeechRecognizer.isAvailable returns false for en_US, so speech recognition is unavailable. As far as I have tested, this issue does not occur on iOS Simulator 26.2 or earlier. Is this a Simulator-specific issue, or is it a behavior change that could also occur on physical devices? Has any additional setup become necessary to use speech recognition in Simulator? I then changed the iPhone Simulator’s system language to English. After doing so, SFSpeechRecognizer.isAvailable returned true for en_US. However, starting a recognition task still failed immediately with kLSRErrorDomain Code=300, “Failed to initialize recognizer.” The following error was returned: Error Domain=kLSRErrorDomain Code=300 "Failed to initialize recognizer" UserInfo={ NSLocalizedDescription=Failed to initialize recognizer, NSUnderlyingError={ Error Domain=kLSRErrorDomain Code=300 "Failed to create recognizer from=/Users/<USERNAME>/Library/Developer/CoreSimulator/Devices/<DEVICE-UUID>/data/private/var/MobileAsset/AssetsV2/com_apple_MobileAsset_UAF_Siri_Understanding/purpose_auto/ c079bfa6b8856202dc8cb2135fef3b06229ced6e.asset/AssetData/mini.json" UserInfo={ NSLocalizedDescription=Failed to create recognizer from=/Users/<USERNAME>/Library/Developer/CoreSimulator/Devices/<DEVICE-UUID>/data/private/var/MobileAsset/AssetsV2/com_apple_MobileAsset_UAF_Siri_Understanding/purpose_auto/ c079bfa6b8856202dc8cb2135fef3b06229ced6e.asset/AssetData/mini.json } } } I have not observed either of these issues on iOS Simulator 26.2 or earlier: With the Simulator language set to Japanese, the en_US recognizer does not become unavailable. When SFSpeechRecognizer.isAvailable is true, recognition does not fail with kLSRErrorDomain Code=300. Environment Xcode: 26.6 (17F113) iOS Simulator 26.5 (23F77), iPhone 17 (A3258J/A) iOS Simulator 26.4 (23E244), iPhone 17 (A3258J/A)

I’m migrating to the new notifications described in Handling audio interruptions. On an iPhone 14 running iOS 27.0.1 (24A446), I call pause() when the system deactivates the session. On .shouldResume, I await successful session.activate() and call record() on the same recorder. It returns true, but the saved file contains only the audio recorded after Siri. To reproduce: record for five seconds, invoke and dismiss Siri, record for another five seconds, then stop and play. The earlier five seconds are missing. A legacy-notification control preserved both portions on the same phone. Is another step required to preserve the recording with the new notifications, or is this a known issue? I found this similar report, although it uses the legacy API. Minimal reproduction Built with Xcode 27.1. Create a SwiftUI iOS app targeting iOS 27, replace its generated App.swift with the code below, and add these Info.plist entries: NSMicrophoneUsageDescription: Test audio recording UIBackgroundModes: an array containing audio import SwiftUI import AVFoundation @main struct RecorderReproApp: App { var body: some Scene { WindowGroup { RecorderReproView() } } } @MainActor struct RecorderReproView: View { private let session = AVAudioSession.sharedInstance() private let file = URL.documentsDirectory.appendingPathComponent("recording.m4a") @State private var recorder: AVAudioRecorder? @State private var player: AVAudioPlayer? @State private var running = false @State private var interrupted = false @State private var status = "Ready" var body: some View { VStack(spacing: 24) { Button("Start") { Task { await start() } }.disabled(running) Button("Stop") { running = false interrupted = false recorder?.stop() status = file.path }.disabled(!running) Button("Play") { do { player = try AVAudioPlayer(contentsOf: file) status = "Saved duration: \(player!.duration) seconds" player?.play() } catch { status = error.localizedDescription } }.disabled(running) Text(status) } .padding() .task { for await notification in NotificationCenter.default.notifications( named: AVAudioSession.didBecomeInactiveNotification, object: session ) { guard running, let context = notification.userInfo?[AVAudioSession.deactivationContextKey] as? AVAudioSession.DeactivationContext, context.source == .system else { continue } recorder?.pause() interrupted = true status = "Interrupted" } } .task { for await notification in NotificationCenter.default.notifications( named: AVAudioSession.resumptionRecommendationNotification, object: session ) { guard running, interrupted, let context = notification.userInfo?[AVAudioSession.resumptionContextKey] as? AVAudioSession.ResumptionContext else { continue } guard context.recommendation == .shouldResume else { interrupted = false continue } do { guard try await session.activate(), running, interrupted else { continue } status = "Resumed: \(recorder!.record())" interrupted = false } catch { status = error.localizedDescription } } } } private func start() async { guard await AVAudioApplication.requestRecordPermission() else { return } do { try session.setCategory(.playAndRecord) guard try await session.activate() else { return } recorder = try AVAudioRecorder(url: file, settings: [ AVFormatIDKey: kAudioFormatMPEG4AAC_HE, AVSampleRateKey: 44_100, AVEncoderBitRateKey: 32_000, AVNumberOfChannelsKey: 2 ]) running = recorder!.record() status = "Recording: \(running)" } catch { status = error.localizedDescription } } }

I have not seen any issues with didActivateAudioSession not getting called by iOS in many many years with many thousands of devices. However with iOS27 beta code I have seen a few times that when making an outgoing call it never gets called. All subsequent outgoing calls fail until I dismiss and relaunch the App.

Summary On iOS build 24A446, an incoming CallKit VoIP call is reported and answered, but the system never creates or activates the CallKit audio session, so CXProviderDelegate provider:didActivateAudioSession: is never called. Both directions of call audio stay silent. The failure is inside callservicesd / audiomxd, before the app starts its audio unit. Once it starts, later calls from the same processes keep failing until the app process is killed. App and device Bundle ID: us.zoom.videomeetings OS build: 24A446 (iPhone) Log: sysdiagnose_2026.10.16_11-15-45-0700_iPhone-OS_iPhone_24A446 Sample call: 2026-10-15 13:29:06–13:29:22 PDT Processes in that window: Zoom PID 816, callservicesd PID 2474, audiomxd PID 115 How the user hits it The app is not in the foreground. A VoIP push wakes it and we call reportNewIncomingCallWithUUID:update:completion:. The user answers from the system incoming-call UI (phone locked or unlocked). The ringtone plays. After answer there is no call audio. The same failure then happens on later calls, including a call started from inside the app, until the Zoom process is killed. Signing out or rebooting only clears it temporarily. We cannot reproduce it in our lab. It became much more frequent after devices moved to this OS. What the app does We configure one CXProvider (PlayAndRecord is applied when the system activates the session). We fulfill CXAnswerCallAction when the user answers. We start the voice audio unit only from provider:didActivateAudioSession:. We do not call AVAudioSession setActive: during this answered call. Our log line "ZMCallKitManager::didActivateAudioSession" is not present for this call. System log for the sample call 13:29:06 — incoming call reported Zoom log: Provider was asked to report a new incoming call At that moment Zoom's existing primary session is sid:0x7304f, Zoom(816), 'prim', and the app is BackgroundRunning. callservicesd then fails while creating the CallKit session: audiomxd AVAudioSessionXPCServer.mm:231 -[AVAudioSessionRemoteXPCClient createProxySession:reply:] failed due to session lookup failure for SessionID 0x0 callservicesd AVAudioSession_iOS.mm:643 Creating proxy session failed, session ID = 0x0, NSOSStatusErrorDomain -50, "Session lookup failed" audiomxd ServerSessionManager.mm:192 Sibling session creation failed. Source sessionID: 0x0. SessionID is not valid. Source PID: 2474 audiomxd AVAudioSessionXPCServer.mm:1287 Session creation failed callservicesd SessionCore_Create.mm:92 AudioSession creation failed, NSOSStatusErrorDomain 2003329396, "Session creation failed in server" callservicesd Audio session not found for call. Returning nil The ringtone still plays. That audio is callservicesd's own session sid:0x732fa, category Ringtone/Default, which activates at 13:29:06.650. It is not the call session. 13:29:15 — user answers callservicesd: Performing answer request / Perform answer call callservicesd: No provider returned for descriptor callservicesd: Audio session not found for call. Returning nil callservicesd: Answer call action fulfilled callservicesd: Error retrieving AVAudioSession provider with ID 0 Sibling session creation fails again with Source sessionID 0x0, Source PID 2474. The ringtone session is stopped. From 13:29:15 to 13:29:22 there is no "action":"activate" for a CallKit call audio session, and no provider:didActivateAudioSession: notification to Zoom. Zoom's primary session 0x7304f is still inactive. Its category is updated to PlayAndRecord / VoiceChat, but it is not activated while this call is up. 13:29:22 — call ends Provider was asked to report that call ended with reason 2 callservicesd: Setting disconnected reason to remote hangup because ended reason is 2 sid:0x732fa callservicesd going inactive The call lasted about 7 seconds with no call audio session ever created. 13:29:33 — following call, same stuck state About 11 seconds later a CXStartCallAction is fulfilled. Zoom's own session then activates: sid:0x7304f, Zoom(816), 'prim' PlayAndRecord_WithBluetooth / VoiceChat, NonMixable, going active callservicesd still cannot build its session: "No existing proxy AVAudioSession interruption provider for ID 0, creating a new one" Session creation failed in server Error retrieving AVAudioSession provider with ID 0 Audio session not found for call So an app-side setActive: after the failed call does not repair the CallKit provider. The system session id remains 0x0. How often it happens in this sysdiagnose Filtering the archive for the hard failure (not the generic "Audio session not found" line, which also appears on earlier days): "Sibling session creation failed. Source sessionID: 0x0": 93 hits, grouped into 57 bursts First burst: 2026-10-15 09:52:11 PDT Last burst: 2026-10-16 11:14:30 PDT (about a minute before this sysdiagnose was taken) "Error retrieving AVAudioSession provider with ID 0": 34 hits "Session creation failed in server": 93 hits Every one of these sibling-session failures is Source PID 2474. callservicesd stays PID 2474 and audiomxd stays PID 115 across the whole window, including overnight. The bad session id is stuck in those daemons, not in one Zoom call object. There is no log line in this archive showing callservicesd successfully activating a provider audio session for these calls. Request Please confirm this is the known CallKit failure where didActivateAudioSession is not delivered because callservicesd cannot create the audio session (Session lookup failed / Session creation failed in server, session ID 0x0). Related public reports: Feedback FB19429215, "CallKit does not activate audio session after iOS 18.4.1", and the iOS 27 thread "iOS 27 CallKit didActivateAudioSession". DTS previously advised apps not to call setActive: themselves, because the CallKit session has higher priority and an app activation can fail or disturb system state. This log matches that: the session is never created, so there is nothing for the system to activate. Please also advise which of these is safe on 24A446 when provider:didActivateAudioSession: does not arrive: Call CXProvider setConfiguration: again (same configuration) before every reportNewIncomingCallWithUUID:update:completion:. On a timeout, fail the unanswered CXAnswerCallAction so the CallKit state machine resets, without invalidating or recreating the CXProvider. Anything else that clears the stuck session ID 0x0 inside callservicesd without a device reboot. I can provide another sysdiagnose if you need a logging profile installed before the next reproduction.

I'm investigating an intermittent crash in an iOS audio app when launching it through an Inter-App Audio (IAA) host Audiobus and AUM. The crash occurs during the host connection/startup process. The app begins initializing its audio engine, successfully creates and registers an ABAudioSenderPort, starts its output audio unit, and then crashes. Crash details Crash Report Exception: EXC_BAD_ACCESS KERN_INVALID_ADDRESS at 0x50 Backtrace: #0 _dispatch_sync_f #1 caulk::concurrent::details::dispatch_receiver::~dispatch_receiver #2 std::__1::__shared_weak_count::__release_shared #3 caulk::concurrent::messenger::~messenger #4 CADeprecated::CAAutoDelete<caulk::concurrent::messenger>::set #5 AURemoteIO::IPC_Uninitialize #6 AURemoteIO::IPC_Uninitialize #7 AUWrappedOutputUnit::AUUninitialize #8 _XUninitialize #9 IPCAudioUnit_server #10 dispatch_mig_server #11 _dispatch_client_callout #12 _dispatch_continuation_pop #13 _dispatch_source_latch_and_call #14 _dispatch_source_invoke #15 _dispatch_lane_serial_drain #16 _dispatch_lane_invoke #17 _dispatch_root_queue_drain_deferred_wlh #18 _dispatch_workloop_worker_thread #19 _pthread_wqthread Repro: Quit Audiobus completely. Relaunch Audiobus. Launch the app from Audiobus. The app begins initialization, but crashes during or shortly after the initial host connection. Interestingly, if Audiobus remains open and I attempt to launch the app again, the crash doesn't appear to occur. Reloading the app via AUM is also reproducing the crash. A number of other apps are able to launch via Audiobus, so I think it must be how we are initialising our engine, but I haven't been able to find where we are going wrong. The app configures its audio session as follows: Category: AVAudioSessionCategoryPlayback Mode: AVAudioSessionModeDefault Preferred sample rate: 48000 Hz Preferred I/O buffer duration: approximately 5.3 ms Reported buffer size: 256 frames Input channels: 0 Output channels: 2 Audio-unit initialization The engine creates and initializes its audio unit successfully: AudioComponentInstanceNew: status = 0 AudioUnitInitialize: status = 0 AudioOutputUnitStart: status = 0 The app then creates an ABAudioSenderPort, configures its client format, and registers it with ABAudiobusController. These operations also complete successfully. The engine's RemoteIO audio unit and the sender port's audio unit are separate instances. I haven't yet worked out which instance is being uninitialized when the crash occurs. This seems to be happening across multiple iPhone and iPad models, back to at least iOS 17, and my test environment, Xcode 26.6 and iPadOS 26.5.2. Questions Has anyone encountered this caulk::concurrent::messenger::~messenger / AURemoteIO::IPC_Uninitialize crash when using IAA, Audiobus, AUM? Could this indicate a race or invalid lifecycle transition in Apple's RemoteIO/IAA IPC implementation? Are there known requirements concerning the order of audio-unit initialization, sender-port registration, host connection, and uninitialization that could explain this behavior? What additional diagnostics would help determine which audio-unit instance is being uninitialized and what triggers the failure? Any suggestions or reports of similar behavior would be greatly appreciated.

Hi everyone, I'm building a tvOS app that shows analog VU meters for the music playing, in the style of vintage hi-fi amplifiers and tape decks. It works well with local and network files played through AVAudioEngine, where I can tap the signal and measure real levels. With Apple Music, though, there's no way to get even basic level information. The content is DRM-protected, SystemMusicPlayer and ApplicationMusicPlayer render audio outside the app's audio graph, and MusicKit has no metering API. My current workaround is to analyze the song's 30-second preview and replay its level envelope in a loop. It looks plausible, but it isn't in sync with the actual music. I filed FB25234486 asking for a read-only metering API on MusicPlayer, similar to what AVAudioPlayer already offers: let rms = musicPlayer.averagePower(forChannel: 0) // dBFS let peak = musicPlayer.peakPower(forChannel: 0) // dBFS This wouldn't expose any audio samples: just one RMS and one peak value per channel, at a low, capped rate (around 30 Hz). Those numbers can't be turned back into audio, so content protection wouldn't be weakened, and the values could be computed inside the system's playback process. It would make a number of use cases possible: VU and peak meters, audio-reactive visualizers, ambient lighting synced to the music (HomeKit, smart lights), loudness displays, and accessibility features such as visual feedback of the music for hard-of-hearing users. If you need this too, please file your own feedback and mention FB25234486. Duplicate reports help Apple gauge demand. And if anyone has found a supported way to get playback levels from MusicKit today, I'd love to hear about it. Thanks!