Environment
Device: iPhone 16e
iOS Version: 18.4.1 - 18.7.1
Framework: AVFoundation (AVAudioEngine)
Problem Summary
On iPhone 16e (iOS 18.4.1-18.7.1), the installTap callback stops being invoked after resuming from a phone call interruption. This issue is specific to phone call interruptions and does not occur on iPhone 14, iPhone SE 3, or earlier devices.
Expected Behavior
After a phone call interruption ends and audioEngine.start() is called, the previously installed tap should continue receiving audio buffers.
Actual Behavior
After resuming from phone call interruption:
Tap callback is no longer invoked
No audio data is captured
No errors are thrown
Engine appears to be running normally
Note: Normal pause/resume (without phone call interruption) works correctly.
Steps to Reproduce
Start audio recording on iPhone 16e
Receive or make a phone call (triggers AVAudioSession interruption)
End the phone call
Resume recording with audioEngine.start()
Result: Tap callback is not invoked
Tested devices:
iPhone 16e (iOS 18.4.1-18.7.1): Issue reproduces ✗
iPhone 14 (iOS 18.x): Works correctly ✓
iPhone SE 3 (iOS 18.x): Works correctly ✓
Code
Initial Setup (Works)
let inputNode = audioEngine.inputNode
inputNode.installTap(onBus: 0, bufferSize: 4096, format: nil) { buffer, time in
self.processAudioBuffer(buffer, at: time)
}
audioEngine.prepare()
try audioEngine.start()
Interruption Handling
NotificationCenter.default.addObserver(
forName: AVAudioSession.interruptionNotification,
object: AVAudioSession.sharedInstance(),
queue: nil
) { notification in
guard let userInfo = notification.userInfo,
let typeValue = userInfo[AVAudioSessionInterruptionTypeKey] as? UInt,
let type = AVAudioSession.InterruptionType(rawValue: typeValue) else {
return
}
if type == .began {
self.audioEngine.pause()
} else if type == .ended {
try? self.audioSession.setActive(true)
try? self.audioEngine.start()
// Tap callback doesn't work after this on iPhone 16e
}
}
Workaround
Full engine restart is required on iPhone 16e:
func resumeAfterInterruption() {
audioEngine.stop()
inputNode.removeTap(onBus: 0)
inputNode.installTap(onBus: 0, bufferSize: 4096, format: nil) { buffer, time in
self.processAudioBuffer(buffer, at: time)
}
audioEngine.prepare()
try audioSession.setActive(true)
try audioEngine.start()
}
This works but adds latency and complexity compared to simple resume.
Questions
Is this expected behavior on iPhone 16e?
What is the recommended way to handle phone call interruptions?
Why does this only affect iPhone 16e and not iPhone 14 or SE 3?
Any guidance would be appreciated!
Audio
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Hi. I work on an audio app for iOS which is successfully using the MPRemoteCommandCenter for commands like next, back, skip forward, skip backward etc.
I am trying to implement playback rate controls in my app (so that users can change the playback speed of audio to 0.5x or 2x for example).
While the above commands work, the changePlaybackRateCommand does not seem to. I have enabled the command, given it a target/handler and set supported rates. With the other commands, this caused the UI to change on lock screen, in command center etc, by adding the control for the command (a next button for the next command for example). However, it does not seem to do anything for the playback rate command.
I can implement my own "rate button" UI and rate change handling, but I'm wondering if this is a known bug within Apple? Looking online, it seems other people face the same issue and haven't been able to get this command to work. Why is this API provided if it doesn't seem to do anything? Is there something I'm missing?
Kind regards.
Topic:
Media Technologies
SubTopic:
Audio
When multiple identical songs are added to a playlist, Playlist.Entry.id uses a suffix-based identifier (e.g. songID_0, songID_1, etc.). Removing one entry causes others to shift, changing their .id values. This leads to diffing errors and collection view crashes in SwiftUI or UIKit when entries are updated.
Steps to Reproduce:
Add the same song to a playlist multiple times.
Observe .id.rawValue of entries (e.g. i.SONGID_0, i.SONGID_1).
Remove one entry.
Fetch playlist again — note the other IDs have shifted.
FB18879062
Hi. I am working on an audio app for iOS. I have added the CPNowPlayingPlaybackRateButton to my CPNowPlayingTemplate.
When the button is clicked, my handler changes the rate in the AVPlayer and updates the MPNowPlayingInfoCenter to the new rate, for example, 2.0.
Throughout, the Carplay button always displays "0x". I am wondering how to get this UI to accurately reflect the playback rate the user has selected, as always displaying 0x is a poor user experience.
You may suggest MPChangePlaybackRateCommand is relevant here, but I have not been able to get that to work either, and judging by posts online, not many other people have either. I have made a post about that here: https://developer.apple.com/forums/thread/773099
Is this a known Apple bug? Is there a way to get the UI to accurately reflect the playback rate of my audio?
Kind regards.
Topic:
Media Technologies
SubTopic:
Audio
Hi,
when a CoreMIDI driver controls physical HW it is probably quite commune to have to control the amount of MIDI data received from the system.
What comes to mind is to just delay returning control of the MIDIDriverInterface::Send() callback to the calling process. While the application trying to send MIDI really stalls until the callback returns it seems only to be a side effect of a generally stalled CoreMIDI server. Between the callbacks the application can send as much MIDI data as it wants to CoreMIDI, it's buffering seems to be endless... However the HW might not be able to play out all the data.
It seems there is no way to indicate an overflow/full buffer situation back the application/CoreMIDI. How is this supposed to work?
Thanks, any hints or pointers are highly appreciated!
Hagen.
Recently, after the update of 26.3 Mac OS (Tahoe), the ordering of my music app has been horrible at best - music disappearing, tracks not aligning with albums (even if the albums are different years).
It's created quite a problem, because the disappearing tracks issue seems to be replicating to iOS devices as well (although track numbering and album association seem to be stable). Has anyone else heard of this issue?
Topic:
Media Technologies
SubTopic:
Audio
I'm using the new SpeechAnalyzer framework to detect certain commands and want to improve accuracy by giving context. Seems like AnalysisContext is the solution for this, but couldn't find any usage example. So I want to make sure that I'm doing it right or not.
let context = AnalysisContext()
context.contextualStrings = [
AnalysisContext.ContextualStringsTag("commands"): [
"set speed level",
"set jump level",
"increase speed",
"decrease speed",
...
],
AnalysisContext.ContextualStringsTag("vocabulary"): [
"speed", "jump", ...
]
]
try await analyzer.setContext(context)
With this implementation, it still gives outputs like "Set some speed level", "It's speed level", etc.
Also, is it possible to make it expect number after those commands, in order to eliminate results like "set some speed level to" (instead of two).
Environment
Windows 11 [edition/build]: [e.g., 23H2, 22631.x]
Apple Music for Windows version: [e.g., 1.x.x from Microsoft Store]
Library folder: C:\Users<user>\Music\Apple Music\Apple Music Library.musiclibrary
Summary
I need a supported way to programmatically enumerate the local Apple Music library on Windows (track file paths, playlists, etc.) for reconciliation with the on-disk Media folder. On macOS this used to be straightforward via scripting/export; on Windows I can’t find an equivalent.
What I’m seeing in the library bundle
Library.musicdb → not SQLite. First 4 bytes: 68 66 6D 61 ("hfma").
Library Preferences.musicdb → also starts with "hfma".
artwork.sqlite → SQLite but appears to be artwork cache only (no track file paths).
Extras.itdb → has SQLite format 3 header but (from a quick scan) not seeing track locations.
Genius.itdb → not a SQLite database on this machine.
What I’ve tried
Attempted to open Library.musicdb with SQLite providers → error: “file is not a database.”
Binary/string scans (ASCII, UTF-16LE/BE, null-stripped) of Library.musicdb → did not reveal file paths or obvious plist/XML/JSON blobs.
The Windows Apple Music UI doesn’t appear to expose “Export Library / Export Playlist” like legacy iTunes did, and I can’t find a public API for local library enumeration on Windows.
What I’m trying to accomplish
Read local track entries (absolute or relative paths), detect broken links, and reconcile against the Media folder. A read-only solution is fine; I do not need to modify the library.
Questions for Apple
Is the Library.musicdb file format documented anywhere, or is there a supported SDK/API to enumerate the local library on Windows?
Is there a supported export mechanism (CLI, UI, or API) on Windows Apple Music to dump the local library and/or playlists (XML/CSV/JSON)?
Is there a Windows-specific equivalent to the old iTunes COM automation or any MusicKit surface that can return local library items (not streaming catalog) and their file locations?
If none of the above exist today, is there a recommended workaround from Apple for library reconciliation on Windows (e.g., documented support for importing M3U/M3U8 to rebuild the local library from disk)?
Are there any plans/timeline for adding Windows feature parity with iTunes/Music on macOS for exporting or scripting the local library?
Why this matters
For large personal libraries, users occasionally end up with orphaned files on disk or broken links in the app. Without an export or API, it’s difficult to audit and fix at scale on Windows.
Reference details (in case it helps triage)
Library.musicdb header bytes: 68-66-6D-61-A0-00-00-00-10-26-34-00-15-00-01-00 (ASCII shows hfma…).
artwork.sqlite is readable but doesn’t contain track file paths (appears limited to artwork).
I can supply a minimal repro tool and logs if that’s helpful.
Feature request (if no current API)
Add an official Export Library/Playlists action on Windows Apple Music, or
Provide a read-only Windows API (or schema doc) that surfaces track file locations and playlist membership from the local library.
Thanks in advance for any guidance or pointers to docs I might have missed.
Hi, In my project I am using AVFoundation for recording the audio. We are using AVAudioMixerNode class below method to record the audio packet.
**func installTap(
onBus bus: AVAudioNodeBus,
bufferSize: AVAudioFrameCount,
format: AVAudioFormat?,
block tapBlock: @escaping AVAudioNodeTapBlock
)
**
It works perfectly fine.
But in production env some small percentage of the user we are facing issue like after recording few packets it stops automatically without stopping the audio engine. Can anyone help here that why this happens? I have also observed for mediaServicesWereResetNotification and added log on receiving this notification but when this issue happens I don't see any occurence of this log. Also is there any callback when the engine stops?
Everytime I put my AirPods in and connect them to my phone or my Mac or my iPad since the iOS 18.3 update on my devices they’ve been disconnecting without reason, pausing songs I’m in the middle of playing, and only partially reconnecting in one pod and it’s getting really frustrating
Topic:
Media Technologies
SubTopic:
Audio
I ran 5.1 audio tests in both YouTube and Apple Music, and I noticed that when sound is supposed to play from the rear or front surround speakers, it’s also duplicated in the front left and right channels. I’m absolutely sure the issue is with the Apple TV, because I played the same video directly through my TV’s native system, and the channel separation was correct.
Everything used to work perfectly before, so this must be a software issue. I’m currently on tvOS 26 Developer Beta 5, but I’m certain the problem also existed on the stable tvOS 18.5.
I’ve already reset and updated my Apple TV, and I also tried switching the audio format to forced Dolby Atmos 5.1. On the forums, I mostly see complaints about Dolby Atmos not working at all — in my case, everything technically works, but not the way it’s supposed to.
Topic:
Media Technologies
SubTopic:
Audio
Hi everyone,
I’m working on an iOS MusicKit app that overlays a metronome on top of Apple Music playback, using ApplicationMusicPlayer. To line the clicks up perfectly I’d like access to low-level audio analysis data—ideally a waveform / spectrogram or beat grid—while the track is playing.
I’ve noticed that several approved DJ apps (e.g. djay, Serato, rekordbox) can already:
• Display detailed scrolling waveforms of Apple Music songs
• Scratch, loop or time-stretch those tracks in real time
That implies they receive decoded PCM frames or at least high-resolution analysis data from Apple Music under a special entitlement.
My questions:
Does MusicKit (or any public framework) expose real-time audio buffers, FFT bins, or beat markers for streaming Apple Music content?
If not, is there an Apple program or entitlement that developers can apply for—similar to the “DJ with Apple Music” initiative—to gain that deeper access?
Where can I find official documentation or a point of contact for this kind of request?
I’ve searched the docs and forums but only see standard MusicKit playback APIs, which don’t appear to expose raw audio for DRM-protected songs. Any guidance, links or insider tips on the proper application process would be hugely appreciated!
Thanks in advance.
It's only occurs on iOS 18+. Backtrace attached below.
Exception Codes: 0x0000000000000000, 0x0000000000000000
Termination Reason: SIGNAL 6 Abort trap: 6
Terminating Process: NoteKeys [24384]
Triggered by Thread: 0
Last Exception Backtrace:
0 CoreFoundation 0x1a2d4c7cc __exceptionPreprocess + 164 (NSException.m:249)
1 libobjc.A.dylib 0x1a001f2e4 objc_exception_throw + 88 (objc-exception.mm:356)
2 CoreFoundation 0x1a2e47748 +[NSException raise:format:] + 128 (NSException.m:0)
3 AVFAudio 0x1bd41f4c8 -[AVMIDIPlayer play:] + 300 (AVMIDIPlayer.mm:145)
4 NoteKeys 0x1023c0670 SoundGenerator.playData() + 20 (SoundGenerator.swift:170)
5 NoteKeys 0x1023c0670 EditViewController.playBtnTapped(startIndex:) + 940 (EditViewController.swift:2034)
6 NoteKeys 0x1024497fc specialized Keyboard.playBtnTapped(sender:) + 1904 (Keyboard.swift:1249)
7 NoteKeys 0x10244631c Keyboard.playBtnTapped(sender:) + 4 (<compiler-generated>:0)
8 NoteKeys 0x10244631c @objc Keyboard.playBtnTapped(sender:) + 48
9 UIKitCore 0x1a58739cc -[UIApplication sendAction:to:from:forEvent:] + 100 (UIApplication.m:5816)
10 UIKitCore 0x1a58738a4 -[UIControl sendAction:to:forEvent:] + 112 (UIControl.m:942)
11 UIKitCore 0x1a58736f4 -[UIControl _sendActionsForEvents:withEvent:] + 324 (UIControl.m:1013)
12 UIKitCore 0x1a5fe8d8c -[UIButton _sendActionsForEvents:withEvent:] + 124 (UIButton.m:4198)
13 UIKitCore 0x1a5fea5a0 -[UIControl touchesEnded:withEvent:] + 400 (UIControl.m:692)
14 UIKitCore 0x1a57bb9ac -[UIWindow _sendTouchesForEvent:] + 852 (UIWindow.m:3318)
15 UIKitCore 0x1a57bb3d8 -[UIWindow sendEvent:] + 2964 (UIWindow.m:3641)
16 UIKitCore 0x1a564fb70 -[UIApplication sendEvent:] + 376 (UIApplication.m:12972)
17 UIKitCore 0x1a565009c __dispatchPreprocessedEventFromEventQueue + 1048 (UIEventDispatcher.m:2686)
18 UIKitCore 0x1a5659f3c __processEventQueue + 5696 (UIEventDispatcher.m:3044)
19 UIKitCore 0x1a5552c60 updateCycleEntry + 160 (UIEventDispatcher.m:133)
20 UIKitCore 0x1a55509d8 _UIUpdateSequenceRun + 84 (_UIUpdateSequence.mm:136)
21 UIKitCore 0x1a5550628 schedulerStepScheduledMainSection + 172 (_UIUpdateScheduler.m:1171)
22 UIKitCore 0x1a555159c runloopSourceCallback + 92 (_UIUpdateScheduler.m:1334)
23 CoreFoundation 0x1a2d20328 __CFRUNLOOP_IS_CALLING_OUT_TO_A_SOURCE0_PERFORM_FUNCTION__ + 28 (CFRunLoop.c:1970)
24 CoreFoundation 0x1a2d202bc __CFRunLoopDoSource0 + 176 (CFRunLoop.c:2014)
25 CoreFoundation 0x1a2d1ddc0 __CFRunLoopDoSources0 + 244 (CFRunLoop.c:2051)
26 CoreFoundation 0x1a2d1cfbc __CFRunLoopRun + 840 (CFRunLoop.c:2969)
27 CoreFoundation 0x1a2d1c830 CFRunLoopRunSpecific + 588 (CFRunLoop.c:3434)
28 GraphicsServices 0x1eecfc1c4 GSEventRunModal + 164 (GSEvent.c:2196)
29 UIKitCore 0x1a5882eb0 -[UIApplication _run] + 816 (UIApplication.m:3844)
30 UIKitCore 0x1a59315b4 UIApplicationMain + 340 (UIApplication.m:5496)
31 NoteKeys 0x10254bc10 main + 68 (AppDelegate.swift:15)
32 dyld 0x1c870aec8 start + 2724 (dyldMain.cpp:1334)
Thanks very much for any help: )
Topic:
Media Technologies
SubTopic:
Audio
I was testing audio playback from YouTube in Safari, and the sound was clipping heavily. At first, I thought it might be due to the poor quality of my small sound system. However, when I took a screenshot and the screenshot sound effect itself produced a loud clipping noise, it became clear that this is not a mechanical problem with my speakers, nor an issue specific to YouTube or Safari. This appears to be a system-wide audio issue in macOS Tahoe 26 - Beta 5.
I have tried everything. The songs load unto the playlists and on searches, but when prompted to play, they just won't play.
I have a wrapper since my main player (which carries the buttons for play/rewind/forward/etc.), is in Objc.
//
// ApplePlayerWrapper.swift
// UniversallyMac
//
// Created by Dorian Mattar on 11/10/24.
//
import Foundation
import MusicKit
import MediaPlayer
@objc public class MusicKitWrapper: NSObject {
@objc public static let shared = MusicKitWrapper()
private let player = ApplicationMusicPlayer.shared
// Play the current track
@objc public func play() {
guard !player.queue.entries.isEmpty else {
print("Queue is empty. Cannot start playback.")
return
}
logPlayerState(message: "Before play")
Task {
do {
try await player.prepareToPlay()
try await player.play()
print("Playback started successfully.")
} catch {
if let nsError = error as NSError? {
print("NSError Code: \(nsError.code), Domain: \(nsError.domain)")
}
}
logPlayerState(message: "After play")
}
}
// Log the current player state
@objc public func logPlayerState(message: String = "") {
print("Player State - \(message):")
print("Playback Status: \(player.state.playbackStatus)")
print("Queue Count: \(player.queue.entries.count)")
// Only log current track details if the player is playing
if player.state.playbackStatus == .playing {
if let currentEntry = player.queue.currentEntry {
print("Current Track: \(currentEntry.title)")
print("Current Position: \(player.playbackTime) seconds")
print("Track Length: \(currentEntry.endTime ?? 0.0) seconds")
} else {
print("No current track.")
}
} else {
print("No track is playing.")
}
print("----------")
}
// Debug the queue
@objc public func debugQueue() {
print("Debugging Queue:")
for (index, entry) in player.queue.entries.enumerated() {
print("\(index): \(entry.title)")
}
}
// Ensure track availability in the queue
public func queueTracks(_ tracks: [Track]) {
Task {
do {
for track in tracks {
// Validate Play Parameters
guard let playParameters = track.playParameters else {
print("Track \(track.title) has no Play Parameters.")
continue
}
// Log the Play Parameters
print("Track Title: \(track.title)")
print("Play Parameters: \(playParameters)")
print("Raw Values: \(track.id.rawValue)")
// Ensure the ID is valid
if track.id.rawValue.isEmpty {
print("Track \(track.title) has an invalid or empty ID in Play Parameters.")
continue
}
// Queue the track
try await player.queue.insert(track, position: .afterCurrentEntry)
print("Queued track: \(track.title)")
}
print("Tracks successfully added to the queue.")
} catch {
print("Error queuing tracks: \(error)")
}
debugQueue()
}
}
// Clear the current queue
@objc public func resetMusicPlayer() {
Task {
player.stop()
player.queue.entries.removeAll()
print("Queue cleared.")
print("Apple Music player reset successfully.")
}
}
}
I opened an Apple Dev. ticket, but I'm trying here as well. Thanks!
I recently installed a rear-view camera in my car, and ever since, I've been experiencing a frustrating issue with my CarPlay. After about 15 seconds of playing audio via Bluetooth, the sound stops coming out of the speakers, even though the song continues to run in the background.
For context, my stereo system is an aftermarket unit that I installed to enable CarPlay functionality. Everything worked perfectly before adding the rear-view camera. Unfortunately, my unit does not have a port for a wired connection, so I can't test the audio using a cable.
Has anyone experienced a similar issue? Could the camera installation be interfering with the Bluetooth or audio system somehow? Any advice or troubleshooting tips would be greatly appreciated!
Hello,
Has anyone else experienced variations in the accuracy of the playbackTime value? After a few seconds of playback, the reported time adjusts by a fraction of a second, making it difficult to calculate the actual playbackTime of the audio.
This can be recreated by playing a song in MusicKit, recording the start time of the audio, playing for at least 10-20 seconds, and then comparing the playbackTime value to one calculated using the start time of the audio. In my experience this jump occurs after about 10 seconds of playback.
Any help would be appreciated.
Thanks!
I have an app that records a health provider’s conversation with a patient. I am using Audio Queue Services for this. If a phone call comes in while recording, the doctor wants to be able to ignore the call and continue the conversation without touching the phone. If the doctor answers the call, that’s fine – I will stop the recording. I can detect when the call comes in and ends using CXCallObserver and AVAudioSession.interruptionNotification. Unfortunately, when a call comes in and before it is answered or dismissed, the audio is suppressed. After the call is dismissed, the audio continues to be suppressed. How can I continue to get audio from the mic as long as the user does not answer the phone call?
Topic:
Media Technologies
SubTopic:
Audio
I'm working in Swift/SwiftUI, running XCode 16.3 on macOS 15.4 and I've seen this when running in the iOS simulator and in a macOS app run from XCode. I've also seen this behaviour with 3 different audio files.
Nothing in the documentation says that the speechRecognitionMetadata property on an SFSpeechRecognitionResult will be nil until isFinal, but that's the behaviour I'm seeing.
I've stripped my class down to the following:
private var isAuthed = false
// I call this in a .task {} in my SwiftUI View
public func requestSpeechRecognizerPermission() {
SFSpeechRecognizer.requestAuthorization { authStatus in
Task {
self.isAuthed = authStatus == .authorized
}
}
}
public func transcribe(from url: URL) {
guard isAuthed else { return }
let locale = Locale(identifier: "en-US")
let recognizer = SFSpeechRecognizer(locale: locale)
let recognitionRequest = SFSpeechURLRecognitionRequest(url: url)
// the behaviour occurs whether I set this to true or not, I recently set
// it to true to see if it made a difference
recognizer?.supportsOnDeviceRecognition = true
recognitionRequest.shouldReportPartialResults = true
recognitionRequest.addsPunctuation = true
recognizer?.recognitionTask(with: recognitionRequest) { (result, error) in
guard result != nil else { return }
if result!.isFinal {
//speechRecognitionMetadata is not nil
} else {
//speechRecognitionMetadata is nil
}
}
}
}
Further, and this isn't documented either, the SFTranscriptionSegment values don't have correct timestamp and duration values until isFinal. The values aren't all zero, but they don't align with the timing in the audio and they change to accurate values when isFinal is true.
The transcription otherwise "works", in that I get transcription text before isFinal and if I wait for isFinal the segments are correct and speechRecognitionMetadata is filled with values.
The context here is I'm trying to generate a transcription that I can then highlight the spoken sections of as audio plays and I'm thinking I must be just trying to use the Speech framework in a way it does not work. I got my concept working if I pre-process the audio (i.e. run it through until isFinal and save the results I need to json), but being able to do even a rougher version of it 'on the fly' - which requires segments to have the right timestamp/duration before isFinal - is perhaps impossible?
3
I am working on an application to get when input audio device is being used. Basically I want to know the application using the microphone (built-in or external)
This app runs on macOS. For Mac versions starting from Sonoma I can use this code:
int getAudioProcessPID(AudioObjectID process)
{
pid_t pid;
if (@available(macOS 14.0, *)) {
constexpr AudioObjectPropertyAddress prop {
kAudioProcessPropertyPID,
kAudioObjectPropertyScopeGlobal,
kAudioObjectPropertyElementMain
};
UInt32 dataSize = sizeof(pid);
OSStatus error = AudioObjectGetPropertyData(process, &prop, 0, nullptr, &dataSize, &pid);
if (error != noErr) {
return -1;
}
} else {
// Pre sonoma code goes here
}
return pid;
}
which works.
However, kAudioProcessPropertyPID was added in macOS SDK 14.0.
Does anyone know how to achieve the same functionality on previous versions?