Songs can be unavailable (greyed out) in Apple Music. How can I check if a song is unavailable via the MusicKit framework? Obviously the playback will fail with MPMusicPlayerControllerErrorDomain Code=6 "Failed to prepare to play" but how can I know that in advance? I need to check the availability of hundreds of albums and therefore initiating a playback for each of them is not an option.
Things I have tried:
Checking if the release date property is set to a future date. This filters out all future releases but doesn't solve the problem for already released songs.
Checking if the duration is 0. This does not work since the duration of unavailable songs does not have to be 0.
Initiating a playback and checking for the "Failed to prepare to play" error. This is not suitable for a huge amount of Albums.
I couldn't find a solution yet but somehow other third-party-apps are able ignore/don't shows these albums. I believe the Apple Music app is only displaying albums where at least one song is available.
I am using this function to fetch all albums of an artist.
private func fetchAlbumsFor(_ artist: Artist) async throws -> [Album] {
let artistWithAlbums = try await artist.with(.albums)
var allAlbums = [Album]()
guard var currentBadge = artistWithAlbums.albums else {
return []
}
allAlbums.append(contentsOf: currentBadge)
while currentBadge.hasNextBatch {
if let nextBatch = try await currentBadge.nextBatch() {
currentBadge = nextBatch
allAlbums.append(contentsOf: nextBatch)
} else {
break
}
}
return allAlbums
}
Here is an example album where I am unable to detect its unavailability (at least in Germany):
https://music.apple.com/de/album/die-haferhorde-immer-den-n%C3%BCstern-nach-h%C3%B6rspiel-zu-band-3/1755774804
Furthermore I was unable to navigate to this album via the Apple Music app directly.
Thanks for any help
Edit: Apparently this album is not included in an apple music subscription but can be bought seperately. The question remains: How can I check that?
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Hello All,
It seems that it's "very easy" (😬) to implement a little Swift code inside the prepared AU using Xcode 16.2 on Sequoia 15.1.1 and a Mac Studio M1 Ultra, but my issue is that I finally don't know... where.
The documentation says that I've to find the AudioUnitViewController.swift file and then modify the render block :
audioUnit.renderBlock = { (numFrames, ioData) in
// Process audio here
}
in the Xcode project automatically generated, but I didn't find such a file...
If somebody can help me in showing where is the file to be modified, I'll be very grateful !
Thank you very much.
J
使用AVSpeechUtterance实现iOS语音播报,选择语言为简体中文“zh-CN”,读取中文“袆”(hui 第一声)错误,读成了“祎”(yi 第一声),希望能优化。
I’ve been researching how to achieve a recording playback effect in iOS similar to the hands-free calling effect in the system’s phone app. How can this be implemented? I tried using the voice chat recording method, but found that the volume of the speaker output is too low. How should this issue be addressed? I couldn’t find a suitable API. Could you provide me with some documentation or sample code? Thank you.
Hello. I am attempting to display the music inside of my app in Now Playing. I've tried a few different methods and keep running into unknown issues. I'm new to Objective-C and Apple development so I'm at a loss of how to continue.
Currently, I have an external call to viewDidLoad upon initialization. Then, when I'm ready to play the music, I call playMusic. I have it hardcoded to play an mp3 called "1". I believe I have all the signing set up as the music plays after I exit the app. However, there is nothing in Now Playing. There are no errors or issues that I can see while the app is running. This is the only file I have in Xcode relating to this feature.
Please let me know where I'm going wrong or if there is another object I need to use!
#import <Foundation/Foundation.h>
#import <UIKit/UIKit.h>
#import <MediaPlayer/MediaPlayer.h>
#import <AVFoundation/AVFoundation.h>
@interface ViewController : UIViewController <AVAudioPlayerDelegate>
@property (nonatomic, strong) AVPlayer *player;
@property (nonatomic, strong) MPRemoteCommandCenter *commandCenter;
@property (nonatomic, strong) MPMusicPlayerController *controller;
@property (nonatomic, strong) MPNowPlayingSession *nowPlayingSession;
@end
@implementation ViewController
- (void)viewDidLoad {
[super viewDidLoad];
NSLog(@"viewDidLoad started.");
[self setupAudioSession];
[self initializePlayer];
[self createNowPlayingSession];
[self configureNowPlayingInfo];
NSLog(@"viewDidLoad completed.");
}
- (void)setupAudioSession {
AVAudioSession *audioSession = [AVAudioSession sharedInstance];
NSError *setCategoryError = nil;
if (![audioSession setCategory:AVAudioSessionCategoryPlayback error:&setCategoryError]) {
NSLog(@"Error setting category: %@", [setCategoryError localizedDescription]);
} else {
NSLog(@"Audio session category set.");
}
NSError *activationError = nil;
if (![audioSession setActive:YES error:&activationError]) {
NSLog(@"Error activating audio session: %@", [activationError localizedDescription]);
} else {
NSLog(@"Audio session activated.");
}
}
- (void)initializePlayer {
NSString *soundFilePath = [NSString stringWithFormat:@"%@/base/game/%@",[[NSBundle mainBundle] resourcePath], @"bgm/1.mp3"];
if (!soundFilePath) {
NSLog(@"Audio file not found.");
return;
}
NSURL *soundFileURL = [NSURL fileURLWithPath:soundFilePath];
self.player = [AVPlayer playerWithURL:soundFileURL];
NSLog(@"Player initialized with URL: %@", soundFileURL);
}
- (void)createNowPlayingSession {
self.nowPlayingSession = [[MPNowPlayingSession alloc] initWithPlayers:@[self.player]];
NSLog(@"Now Playing Session created with players: %@", self.nowPlayingSession.players);
}
- (void)configureNowPlayingInfo {
MPNowPlayingInfoCenter *infoCenter = [MPNowPlayingInfoCenter defaultCenter];
CMTime duration = self.player.currentItem.duration;
Float64 durationSeconds = CMTimeGetSeconds(duration);
CMTime currentTime = self.player.currentTime;
Float64 currentTimeSeconds = CMTimeGetSeconds(currentTime);
NSDictionary *nowPlayingInfo = @{
MPMediaItemPropertyTitle: @"Example Title",
MPMediaItemPropertyArtist: @"Example Artist",
MPMediaItemPropertyPlaybackDuration: @(durationSeconds),
MPNowPlayingInfoPropertyElapsedPlaybackTime: @(currentTimeSeconds),
MPNowPlayingInfoPropertyPlaybackRate: @(self.player.rate)
};
infoCenter.nowPlayingInfo = nowPlayingInfo;
NSLog(@"Now Playing info configured: %@", nowPlayingInfo);
}
- (void)playMusic {
[self.player play];
[self createNowPlayingSession];
[self configureNowPlayingInfo];
}
- (void)pauseMusic {
[self.player pause];
[self configureNowPlayingInfo];
}
@end
I have used AVQueuePlayer in my music app to play sequence of audios from a remote server, this how I have defined things my player in my ViewModel
Variables
private var cancellables = Set()
private let audioSession = AVAudioSession.sharedInstance()
private var avQueuePlayer: AVQueuePlayer?
@Published var playbackSpeed: Float = 1.0
before starting playback, I am making sure that audio session is set properly, the code snippet used for that is
do {
try audioSession.setCategory(.playback, mode: .default, options: [])
try audioSession.setActive(true, options: [])
} catch {
return
}
and this is the function I am using to update playback speed
func updatePlaybackSpeed(_ newSpeed: Float){
if newSpeed > 0.0, newSpeed <= 2.0{
playbackSpeed = newSpeed
avQueuePlayer?.rate = newSpeed
print("requested speed is (newSpeed) and actual speed is (String(describing: avQueuePlayer?.rate))")
}
}
sometimes whatever speed is set, player seems to play at the same speed as it was set,
e.g. Once I got "requested speed is 1.5 and actual speed is 1.5", and player also seemed to play at the speed of 1.5
but another time I got "requested speed is 2.0 and actual speed is 2.0", but player still seemed to play at the speed of 1.0
to observe changes in rate, I used this
**private func observeRateChanges() {
guard let avQueuePlayer = self.avQueuePlayer else { return }
NotificationCenter.default.publisher(for: AVQueuePlayer.rateDidChangeNotification, object: avQueuePlayer)
.compactMap { $0.userInfo?[AVPlayer.rateDidChangeReasonKey] as? AVPlayer.RateDidChangeReason }
.sink { reason in
switch reason {
case .appBackgrounded:
print("The app transitioned to the background.")
case .audioSessionInterrupted:
print("The system interrupts the app’s audio session.")
case .setRateCalled:
print("The app set the player’s rate.")
case .setRateFailed:
print("An attempt to change the player’s rate failed.")
default:
break
}
}
.store(in: &cancellables)
}**
when rate was set properly, I got this "The app set the player’s rate." from the above function, but when it wasn't, I got this "An attempt to change the player’s rate failed.,"
now I am not able to understand why rate is not being set, and if it gave "requested speed is 2.0 and actual speed is 2.0" from updatePlaybackSpeed function, why does the player seems to play with the speed of 1.0?
Topic:
Media Technologies
SubTopic:
Audio
Please Update Andorid MusicKit,the version 1.1.2 will complied fail。the error msg:•SDKUriHandlerActivity>. Apps targeting Android 12 and higher are required to specify an explicit value for android:exported when the corres
Hi!
I get personal recommendations MusicItemCollection using this code:
func getRecommendations() async throws -> MusicItemCollection<MusicPersonalRecommendation> {
let request = MusicPersonalRecommendationsRequest()
let response = try await request.response()
let recommendations = response.recommendations
return recommendations
}
However, all recommendations contain no more than 12 MusicItem's, while the Music.app application provides much more for some recommendations, for example, for the You recently listened recommendation, the Music.app application displays 40 items. Each recommendation has an items property that contains a collection of musical items MusicItemCollection<MusicPersonalRecommendation.Item>, the hasNextBatch property for these collections is always false. I expected that for some collections loading of new items would be available. Please tell me if I'm doing something wrong or is this a MusicKit bug?
Thank you!
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
Hello,
I have a CarPlay Navigation app and utilize the AVSpeechSynthesizer to speak directions to a user. Everything works great on my CarPlay simulator as well as when plugged into my GMC truck. However, I found out yesterday that one of my users with a Ford truck the audio would cut in an out.
After much troubleshooting, I was able to replicate this on my own truck when using Bluetooth to connect to CarPlay. My user was also utilizing Bluetooth. Has anyone else experienced this? Is there a fix to the problem?
import SwiftUI
import AVFoundation
class TextToSpeechService: NSObject, ObservableObject, AVSpeechSynthesizerDelegate {
private var speechSynthesizer = AVSpeechSynthesizer()
static let shared = TextToSpeechService()
override init() {
super.init()
speechSynthesizer.delegate = self
}
func configureAudioSession() {
speechSynthesizer.delegate = self
do {
try AVAudioSession.sharedInstance().setCategory(.playback, mode: .voicePrompt, options: [.mixWithOthers, .allowBluetooth])
} catch {
print("Failed to set audio session category: \(error.localizedDescription)")
}
}
func speak(_ text: String) {
Task(priority: .high) {
let speechUtterance = AVSpeechUtterance(string: text)
speechUtterance.voice = AVSpeechSynthesisVoice(language: AVSpeechSynthesisVoice.currentLanguageCode())
try AVAudioSession.sharedInstance().setActive(true, options: .notifyOthersOnDeactivation)
speechSynthesizer.speak(speechUtterance)
}
}
func speechSynthesizer(_ synthesizer: AVSpeechSynthesizer, didFinish utterance: AVSpeechUtterance) {
Task {
stopSpeech()
try AVAudioSession.sharedInstance().setActive(false)
}
}
func stopSpeech() {
speechSynthesizer.stopSpeaking(at: .immediate)
}
}
Please include the line below in follow-up emails for this request.
Case-ID: 11089799
When using AVSpeechUtterance and setting it to play in Mandarin, if Siri is set to Cantonese on iOS 18, it will be played in Cantonese. There is no such issue on iOS 17 and 16.
1.let utterance = AVSpeechUtterance(string: textView.text)
let voice = AVSpeechSynthesisVoice(language: "zh-CN")
utterance.voice = voice
2.In the phone settings, Siri is set to Cantonese
Hi,
I'm working on an audio mixing app, that comes with bundled audio units that provide some of the app's core functionality.
For the next release of that app, we are planning to make two changes:
make the app sandboxed
package the bundled audio units as .appex bundles instead as .component bundles, so we don't need to take care of the installation at the correct spot in the file system
When trying this new approach, we run into problems where [[AVAudioUnitEffect alloc] initWithAudioComponentDescription:] crashes when trying to load our audio unit with the exception:
AVAEInternal.h:109 [AUInterface.mm:468:AUInterfaceBaseV3: (AudioComponentInstanceNew(comp, &_auv2)): error -10863
Our audio unit has the `sandboxSafe flag enabled, and loads fine when the host app is not sandboxed, so I'm guessing I got the bundle id/code signing requirements for the .appex correct.
It seems, that my .appex isn't even loaded, and the system rejects it because of its metadata. Maybe there something wrong the Info.plist generated by Juice?
"BuildMachineOSBuild" => "23H222"
"CFBundleDisplayName" => "elgato_sample_recorder"
"CFBundleExecutable" => "ElgatoSampleRecorder"
"CFBundleIdentifier" => "com.iwascoding.EffectLoader.samplerecorderAUv3"
"CFBundleName" => "elgato_sample_recorder"
"CFBundlePackageType" => "XPC!"
"CFBundleShortVersionString" => "1.0.0.0"
"CFBundleSignature" => "????"
"CFBundleSupportedPlatforms" => [
0 => "MacOSX"
]
"CFBundleVersion" => "1.0.0.0"
"DTCompiler" => "com.apple.compilers.llvm.clang.1_0"
"DTPlatformBuild" => "24C94"
"DTPlatformName" => "macosx"
"DTPlatformVersion" => "15.2"
"DTSDKBuild" => "24C94"
"DTSDKName" => "macosx15.2"
"DTXcode" => "1620"
"DTXcodeBuild" => "16C5032a"
"LSMinimumSystemVersion" => "10.13"
"NSExtension" => {
"NSExtensionAttributes" => {
"AudioComponents" => [
0 => {
"description" => "Elgato Sample Recorder"
"factoryFunction" => "elgato_sample_recorderAUFactoryAUv3"
"manufacturer" => "Manu"
"name" => "Elgato: Elgato Sample Recorder"
"sandboxSafe" => 1
"subtype" => "Znyk"
"tags" => [
0 => "Effects"
]
"type" => "aufx"
"version" => 65536
}
]
}
"NSExtensionPointIdentifier" => "com.apple.AudioUnit-UI"
"NSExtensionPrincipalClass" => "elgato_sample_recorderAUFactoryAUv3"
}
"NSHighResolutionCapable" => 1
}
Any ideas what I am missing?
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 am developing an iOS app that needs to play spoken audio on demand from a server, while ducking the audio of background music from another app (e.g., SoundtrackYourBrand or Apple Music). This must work even when the app is in the background, and the server dictates when and what audio is played. Ideally, the message should be played within a minute of the server requesting it.
Current Attempt & Observations
I initially tried using Firebase Cloud Messaging (FCM) silent notifications to send a URL to an audio file, which the app would then play using AVPlayer.
This works consistently when the app is active, but in the background, it only works about 60% of the time.
In cases where it fails, iOS ducks the background music (e.g., from SoundtrackYourBrand) but never plays the spoken audio.
Interestingly, when I play the audio without enabling audio ducking, it seems to work 100% of the time from my limited testing, even in the background.
The app has background modes enabled for Audio, Background Fetch, and Remote Notifications.
Best Approach to Achieve This?
I’d like guidance on the best Apple-compliant approach to reliably play audio on command from the server, even when the app is in the background. Some possible paths:
Ensuring the app remains active in the background – Are there recommended ways to prevent the app from getting suspended, such as background tasks, a special background mode, or a persistent connection to the server?
Alternative triggering mechanisms – Would something like VoIP, Push-to-Talk, or another background service be better suited for this use case?
Built-in iOS speech synthesis (AVSpeechSynthesizer) – If playing external audio is unreliable, would generating speech dynamically from text be a more robust approach?
Streaming audio instead of sending a URL – Could continuous streaming from the server keep the app active and allow playback at the right moment?
I want to ensure the solution is reliable and works 100% of the time when needed. Any recommendations on the best approach for this would be greatly appreciated.
Thank you for your time and guidance.
I’m working on a macOS app, written in Swift. My goal is to record audio from an external microphone, e.g., one connected via USB.
For this, I’m using an AVCaptureSession and recording its output with an AVAssetWriter. This works perfectly in principle (and reliably with internal microphones, for example).
The problem occurs after my app has successfully completed the first recording and I then want to make additional recordings (which makes me think it might be process-dependent, because it works again after restarting the app).
The problem: Noisy or distorted-sounding audio files. In addition, the following error message appears in the Console from CoreAudio / its AudioConverter:
Input data proc returned inconsistent 512 packets for 2048 bytes; at 3 bytes per packet, that is actually 682 packets
It is easy to reproduce. This problem is reproducible even if I don’t configure the AVAssetWriter manually and instead let it receive its audioSettings using a preset from an AVOutputSettingsAssistant. I’m running on macOS 15.0 (24A335).
I’ve filed a feedback including a demo project → FB15333298 🎟️
I would greatly appreciate any help!
Have a great day,
Martin
In MusicKit Web the playback states are provided as numbers.
For example the playbackStateDidChange event listener will return:
{oldState: 2, state: 3, item:...}
When the state changes from playing (2) to paused (3).
Those are pretty easy to guess, but I'm having a hard time with some of the others: completed,
ended,
loading,
none,
paused,
playing,
seeking,
stalled,
stopped,
waiting.
I cannot find a mapping of states to numbers documented anywhere. I got the above states from an enum in a d.ts file that is often incorrect/incomplete.
Can someone help out pointing to the docs or provide a mapping?
Thanks.
Issue:
Under certain conditions, using CallKit does not automatically enable the microphone.
Steps to Reproduce:
1.Start an outgoing call, then the user manually mutes the audio.
2.Receive a native incoming call, end the current call, then answer the new incoming call.(This order is important.)
3.End the incoming call.
4.Start another outgoing call and observe the microphone; do not manually mute or unmute.
Actual Behavior:
The audio icon indicates that the audio is unmuted, but the microphone remains off, and the small yellow dot in the top status bar (which represents the microphone) does not appear.
Expected Behavior:
The microphone should be on, consistent with the audio icon display, and the small yellow dot should appear in the top status bar.
Device:
iPhone 16 pro & iPhone 15 pro, iOS 18.0+
Can it be reproduced using speakerbox(CallKit Demo)?
YES
I've been trying to use AVMIDIControlChangeEvent with a bankSelect message type to change the instrument the sequencer uses on a AVMusicTrack with no luck.
I started with the Apple AVAEMixerSample, converting the initial setup/loading and portions dealing with the sequencer to Swift. I got that working and playing the "bluesyRiff" and then modified it to play individual notes. So my createAndSetupSequencer looked like
func createAndSetupSequencer() {
sequencer = AVAudioSequencer(audioEngine: engine)
// guard let midiFileURL = Bundle.main.url(forResource: "bluesyRiff", withExtension: "mid") else {
// print (" failed guard trying to get URL for bluesyRiff")
// return
// }
let track = sequencer.createAndAppendTrack()
var currTime = 1.0
for i: UInt32 in 0...8 {
let newNoteEvent = AVMIDINoteEvent(channel: 0, key: 60+i, velocity: 64, duration: 2.0)
track.addEvent(newNoteEvent, at: AVMusicTimeStamp(currTime))
currTime += 2.0
}
The notes played, so then I also replaced the gs_instruments sound bank with GeneralUser GS MuseScore v1.442 first by trying
guard let soundBankURL = Bundle.main.url(forResource: "GeneralUser GS MuseScore v1.442", withExtension: "sf2") else {
return}
do {
try sampler.loadSoundBankInstrument(at: soundBankURL, program: 0x001C, bankMSB: 0x79, bankLSB: 0x08)
} catch{....
}
This appears to work, the instrument (8 which is "Funk Guitar") plays. If I change to bankLSB: 0x00 I get the "Palm Muted guitar". So I know that the soundfont has these instruments
Stuff goes off the rails when I try to change the instruments in createAndSetupSequencer. Putting
let programChange = AVMIDIProgramChangeEvent(channel: 0, programNumber: 0x001C)
let bankChange = AVMIDIControlChangeEvent(channel: 0, messageType: AVMIDIControlChangeEvent.MessageType.bankSelect, value: 0x00)
track.addEvent(programChange, at: AVMusicTimeStamp(1.0))
track.addEvent(bankChange, at: AVMusicTimeStamp(1.0))
just before my add note loop doesn't produce any change. Loading bankLSB 8 (Funk) in sampler.loadSoundBankInstrument and trying to change with bankSelect 0 (Palm muted) in createAndSetupSequencer results in instrument 8 (Funk) playing not Palm Muted.
Loading bankLSB 0 (Palm muted) and trying to change with bankSelect 8 (Funk) doesn't work, 0 (Palm muted) plays
I also tried sampler.loadInstrument(at: soundBankURL) and then I always get the first instrument in the sound font file (piano)no matter what values I put in my programChange/bankChange
I've also changed the time in the track.addEvent to be 0, 1.0, 3.0 etc to no success
The sampler.loadSoundBankInstrument specifies two UInt8 parameters, bankMSB and BankLSB while the AVMIDIControlChangeEvent bankSelect value is UInt32 suggesting it might be some combination of bankMSB and BankLSB. But the documentation makes no mention of what this should look like. I tried various combinations of 0x7908, 0X0879 etc to no avail
I will also point out that I am able to successfully execute other control change events
For example adding
if i == 1 {
let portamentoOnEvent = AVMIDIControlChangeEvent(channel: 0, messageType: AVMIDIControlChangeEvent.MessageType.portamento, value: 0xFF)
track.addEvent(portamentoOnEvent, at: AVMusicTimeStamp(currTime))
let portamentoRateEvent = AVMIDIControlChangeEvent(channel: 0, messageType: AVMIDIControlChangeEvent.MessageType.portamentoTime, value: 64)
track.addEvent(portamentoRateEvent, at: AVMusicTimeStamp(currTime))
}
does produce a change in the sound. (As an aside, a definition of what portamento time is, other than "the rate of portamento" would be welcome. is it notes/seconds? freq/minute? beats/hour?)
I was able to get the instrument to change in a different program using MusicPlayer and a series of MusicTrackNewMIDIChannelEvent on a track but these operate on a MusicTrack not the AVMusicTrack which the sequencer uses.
Has anyone been successful in switching instruments through an AVMIDIControlChangeEvent or have any feedback on how to do this?
Is it possible to play WebM audio on iOS? Either with AVPlayer, AVAudioEngine, or some other API?
Safari has supported this for a few releases now, and I'm wondering if I missed something about how to do this. By default these APIs don't seem to work (nor does ExtAudioFileOpen).
Our usecase is making it possible for iOS users to play back audio recorded in our webapp (desktop versions of Chrome & Firefox only support webm as a destination format for MediaRecorder)
Bug Report: ScreenCaptureKit System Audio Capture Crashes with EXC_BAD_ACCESS
Summary
When using ScreenCaptureKit to capture system audio for extended periods, the application crashes with EXC_BAD_ACCESS in Swift's error handling runtime. The crash occurs in swift_getErrorValue when trying to process an error from the SCStream delegate method didStopWithError. This appears to be a framework-level issue in ScreenCaptureKit or its underlying ReplayKit implementation.
Environment
macOS Sonoma 14.6.1
Swift 5.8
ScreenCaptureKit framework
Detailed Description
Our application captures system audio using ScreenCaptureKit's audio capture capabilities. After successfully capturing for several minutes (typically after 3-4 segments of 60-second recordings), the application crashes with an EXC_BAD_ACCESS error. The crash happens when the Swift runtime attempts to process an error in the SCStreamDelegate.stream(_:didStopWithError:) method.
The crash consistently occurs in swift_getErrorValue when attempting to access the class of what appears to be a null object. This suggests that the error being passed from the system framework to our delegate method is malformed or contains invalid memory.
Steps to Reproduce
Create an SCStream with audio capture enabled
Add audio output to the stream
Start capture and write audio data to disk
Allow the capture to run for several minutes (3-5 minutes typically triggers the issue)
The app will crash with EXC_BAD_ACCESS in swift_getErrorValue
Code Sample
func stream(_ stream: SCStream, didStopWithError error: Error) {
print("Stream stopped with error: \(error)") // Crash occurs before this line executes
}
func stream(_ stream: SCStream, didOutputSampleBuffer sampleBuffer: CMSampleBuffer, of type: SCStreamOutputType) {
guard type == .audio, sampleBuffer.isValid else { return }
// Process audio data...
}
Expected Behavior
The error should be properly propagated to the delegate method, allowing for graceful error handling and recovery.
Actual Behavior
The application crashes with EXC_BAD_ACCESS when the Swift runtime attempts to process the error in swift_getErrorValue.
Crash Log Details
Thread #35, queue = 'com.apple.NSXPCConnection.m-user.com.apple.replayd', stop reason = EXC_BAD_ACCESS (code=1, address=0x0)
frame #0: 0x0000000194c3088c libswiftCore.dylib`swift::_swift_getClass(void const*) + 8
frame #1: 0x0000000194c30104 libswiftCore.dylib`swift_getErrorValue + 40
frame #2: 0x00000001057fba30 shadow`NewScreenCaptureService.stream(stream=0x0000600002de6700, error=Swift.Error @ 0x000000016b7b5e30) at NEW+ScreenCaptureService.swift:365:15
frame #3: 0x00000001057fc050 shadow`@objc NewScreenCaptureService.stream(_:didStopWithError:) at <compiler-generated>:0
frame #4: 0x0000000219ec5ca0 ScreenCaptureKit`-[SCStreamManager stream:didStopWithError:] + 456
frame #5: 0x00000001ca68a5cc ReplayKit`-[RPScreenRecorder stream:didStopWithError:] + 84
frame #6: 0x00000001ca696ff8 ReplayKit`-[RPDaemonProxy stream:didStopWithError:] + 224
Printing description of stream._streamQueue:
error: ObjectiveC.id:4294967281:18: note: 'id' has been explicitly marked unavailable here
public typealias id = AnyObject
^
error: /var/folders/v4/3xg1hmp93gjd8_xlzmryf_wm0000gn/T/expr23-dfa421..cpp:1:65: 'id' is unavailable in Swift: 'id' is not available in Swift; use 'Any'
Swift._DebuggerSupport.stringForPrintObject(Swift.UnsafePointer<id>(bitPattern: 0x104ae08c0)!.pointee)
^~
ObjectiveC.id:2:18: note: 'id' has been explicitly marked unavailable here
public typealias id = AnyObject
^
warning: /var/folders/v4/3xg1hmp93gjd8_xlzmryf_wm0000gn/T/expr23-dfa421..cpp:5:7: initialization of variable '$__lldb_error_result' was never used; consider replacing with assignment to '_' or removing it
var $__lldb_error_result = __lldb_tmp_error
~~~~^~~~~~~~~~~~~~~~~~~~
_
Before the crash, we observed this error message in the console:
[ERROR] *****SCStream*****RemoteAudioQueueOperationHandlerWithError:1015 Error received from the remote queue -16665
Additional Context
The issue occurs consistently after approximately 3-4 successful audio segment recordings of 60 seconds each
Commenting out custom segment rotation logic does not prevent the crash
The crash involves XPC communication with Apple's ReplayKit daemon
The error appears to be corrupted or malformed when crossing the XPC boundary
Workarounds Attempted
Added proper thread safety for all published properties using DispatchQueue.main.async
Implemented more robust error handling in the delegate methods
None of these approaches prevented the crash since it occurs at the Swift runtime level before our code executes.
Impact
This issue prevents reliable long-duration audio capture using ScreenCaptureKit.
This bug significantly limits the usefulness of ScreenCaptureKit for any application requiring continuous system audio capture for more than a few minutes.
Perhaps this issue might be related to a macOS bug where the system dialog indicates that the screen is being shared, even though nothing is actually being shared. Moreover, when attempting to stop sharing, nothing happens.