Hi everyone, I wanted to bring up a question about Core Audio and its potential for future updates or improvements, specifically regarding latency optimization. As someone who relies on Core Audio for real-time audio processing, any enhancements in this area would be incredibly beneficial for professionals in the industry. Does anyone know if Apple has shared any plans or updates regarding Core Audio’s performance, particularly for low-latency applications? I’d appreciate any insights or advice from the community! Thanks so much! Best, Michael

If I call AudioDeviceStart on an AudioDevice in my application then "Hey Siri!" will not wake Siri up. Our users have complained that Siri does not get activated with my application is running. We found that calling AudioDeviceStart is causing the issue. How should we handle this?

I'm working with modern Core Audio API introduced in macOS Sequoia. I have an AudioHadwareDevice which has several controls of type AudioHardwareControl. I figured out to filter only volume controls I can use classID == kAudioVolumeControlClassID condition. Some devices have volume controls for both input and output. How I can determine the direction of the control? Streams, i.e. AudioHardwareStream object have direction, but I didn't found a way to map controls to streams. There are kAudioObjectPropertyScopeInput and kAudioObjectPropertyScopeOutput property scopes, but no matter what I tried controls always return false to any control.hasProperty(address: whatever). Any other ideas?

I'm experiencing audio issues while developing for visionOS when playing PCM data through AVAudioPlayerNode. Issue Description: Occasionally, the speaker produces loud popping sounds or distorted noise This occurs during PCM audio playback using AVAudioPlayerNode The issue is intermittent and doesn't happen every time Technical Details: Platform: visionOS Device: vision pro / simulator Audio Framework: AVFoundation Audio Node: AVAudioPlayerNode Audio Format: PCM I would appreciate any insights on: Common causes of audio distortion with AVAudioPlayerNode Recommended best practices for handling PCM playback in visionOS Potential configuration issues that might cause this behavior Has anyone encountered similar issues or found solutions? Any guidance would be greatly helpful. Thank you in advance!

I am using an AVAudioPlayer to play a "tick" sound once per second in a SwiftUI app. When running the app on an iPhone 16 (18.2.1) the tick sounds increase in volume after a few seconds. This does not happen in the simulator nor on an iPhone SE 2020 (18.1.1).

I’m currently developing an iOS metronome app using DispatchSourceTimer as the timer. The interval is set very small, around 50 milliseconds, and I’m using CFAbsoluteTimeGetCurrent to calculate the elapsed time to ensure the beat is played within a ±0.003-second margin. The problem is that once the app goes to the background, the timing becomes unstable—it slows down noticeably, then recovers after 1–2 seconds. When coming back to the foreground, it suddenly speeds up, and again, it takes 1–2 seconds to return to normal. It feels like the app is randomly “powering off” and then “overclocking.” It’s super frustrating. I’ve noticed that some metronome apps in the App Store have similar issues, but there’s one called “Professional Metronome” that’s rock solid with no such problems. What kind of magic are they using? Any experts out there who can help? Thanks in advance! P.S. I’ve already enabled background audio permissions. The professional metronome that has no issues: https://link.zhihu.com/?target=https%3A//apps.apple.com/cn/app/pro-metronome-%25E4%25B8%2593%25E4%25B8%259A%25E8%258A%2582%25E6%258B%258D%25E5%2599%25A8/id477960671

Hi, Apple's engineer. Hoping that you can reply to this one. We're developing a Text-to-Speak app. Everything went well until the IOS got upgraded to 18. AVSpeechSynthesisVoice(language: "zh-CN") is running well under IOS 16 AND IOS 17. It speaks Mandarin correctly. In IOS 18, we noticed that Siri's Language setting interrupted the performance of AVSpeechSynthesisVoice. It plays Cantonese instead of Mandarin. Buggy language setting in Siri that affects the AVSpeechSynthesisVoice : Chinese (Cantonese - China mainland) Chinese (Cantonese -Hong Kong)

After investing more than a week into getting a bunch of audio unit projects converted into app + appex + framework, they all are now correctly loaded in-process in the demo host app that is part of Xcode's template. However, Logic Pro adamantly refuses to load them in-process. Does Logic Pro simply not do that ever, or is there some hint or configuration my plugins need to provide to enable that? If it is unsupported, will it be supported in some future version of Logic? The entire point of investing that week was performance, which is moot if it is impossible to test the impact of loading in-process in a real-world usage scenario.

I've been generating new Audio Unit Extension apps with Xcode 16 (and newer), and although they generally work initially, it is easy (although I'm not sure how to do it reliably) to cause the app to no longer be able to instantiate the audiounit. Generally the call to AVAudioUnit.findComponent fails and SimplePlayEngine hits the fatalError("Failed to find component with type...") In the most recent project, merely adding files to the extension (without making any use of them) caused it to go off the rails. If I "Archive" the app+plugin, there is no audio unit extension in the bundle. If I switch to the audiounit extension and build it it's fine. If I look at the build folder in Library/Developer/Xcode/project_folder the extension_name.appex is there. Any ideas? If I can coax an unmodified audio unit extension project to exhibit this behavior I'll attach it here. Right now what I have has code I don't want to share.

I have spent a long time refactoring lots of older Swift code to compile without error in Swift 6. The app is a v3 audio unit host and audio unit. Having installed Sonoma and XCode 16 I compile the code using Swift 6 and it compiles and runs without any warnings or errors. My host will load my AU no problem. LOGIC PRO is still the ONLY audio unit host that will load native Mac V3 audio units and so I like to test my code using Logic. In Sonoma with XCode 16... My AU passes the most stringent AUVAL tests both in terminal and Logic pro. If I compile the AU source in Swift 5 Logic will see the AU, load it and run it without problems. But when I compile the AU in Swift 6 Logic sees the AU, will scan it and verify it passes the tests but will not load the AU. In XCode I see a log message that a "helper application failed to run" but the debugger never connects to the AU and I don't think Logic even gets as far as instantiating the AU. So... what is causing this? I'm stumped.. Developing AUv3 is a brain-aching maze of undocumented hurdles and I'm hoping someone might have found a solution for this one. Meanwhile I guess my only option is to continue using the Swift 5 compiler. (appending a little note just to mention that all the DSP code is written in C/C++, Swift is used mainly for the user interface and also does some offline thready work )

I recently got some plugins from Universal Audio, and have licensed them properly through both UA and iLok manager. Whenever I try to load up the plugins (specifically from UA) in GarageBand, it first says that "NSCreateObjectFileImageFromMemory-p47UEwps” because the developper can not be verified. After clicking either 'show in finder' or 'okay', it opens the plugin in a form without its GUI and showing that it is not licensed (even though it is). It also displays error code 100001. I have tried only some basic stuff to troubleshoot like restarting the DAW/my computer and reinstalling/relicensing the softwares. I don't know if the macOS version has anything to do with it but for some reason I just can't get it to work.

I'm trying to implement Ambisonic B-Format audio playback on Vision Pro with head tracking. So far audio plays, head tracking works, and the sound appears to be stereo. The problem is that it is not a proper binaural playback when compared to playing back the audiofile with a DAW. Has anyone successfully implemented B-Format playback on Vision Pro? Any suggestions on my current implementation: func playAmbiAudioForum() async { do { try AVAudioSession.sharedInstance().setCategory(.playback) try AVAudioSession.sharedInstance().setActive(true) // AudioFile laoding/preperation guard let testFileURL = Bundle.main.url(forResource: "audiofile", withExtension: "wav") else { print("Test file not found") return } let audioFile = try AVAudioFile(forReading: testFileURL) let audioFileFormat = audioFile.fileFormat // create AVAudioFormat with Ambisonics B Format guard let layout = AVAudioChannelLayout(layoutTag: kAudioChannelLayoutTag_Ambisonic_B_Format) else { print("layout failed") return } let format = AVAudioFormat( commonFormat: audioFile.processingFormat.commonFormat, sampleRate: audioFile.fileFormat.sampleRate, interleaved: false, channelLayout: layout ) // write audiofile to buffer guard let buffer = AVAudioPCMBuffer(pcmFormat: format, frameCapacity: UInt32(audioFile.length)) else { print("buffer failed") return } try audioFile.read(into: buffer) playerNode.renderingAlgorithm = .HRTF // connecting nodes audioEngine.attach(playerNode) audioEngine.connect(playerNode, to: audioEngine.outputNode, format: format) audioEngine.prepare() playerNode.scheduleBuffer(buffer, at: nil) { print("File finished playing") } try audioEngine.start() playerNode.play() } catch { print("Setup error:", error) } }

i have a CarPlay implementation eand I want to show previous/next track button on player UI MPRemoteCommandCenter.shared().seekForwardCommand.isEnabled = false MPRemoteCommandCenter.shared().seekBackwardCommand.isEnabled = false MPRemoteCommandCenter.shared().previousTrackCommand.isEnabled = true MPRemoteCommandCenter.shared().nextTrackCommand.isEnabled = true It works correctly on CarPlay simulator , but on some car only SEEK button are shown . I have to suppose that it is that a problem on the car side , but I would ask about your opinion , maybe there is some pieces I'm missing

iPadOS 18.3 beta 3 (22D5055b) fixed the issue for me and my 7th generation iPad.

I tried adding watermarks to the recorded video. Appending sample buffers using AVAssetWriterInput's append method fails and when I inspect the AVAssetWriter's error property, I get the following: Error Domain=AVFoundation Error Domain Code=-11800 "This operation cannot be completed" UserInfo={NSLocalizedFailureReason=An unknown error occurred (-12780), NSLocalizedDDescription=This operation cannot be completed, NSUnderlyingError=0x302399a70 {Error Domain=NSOSStatusErrorDomain Code=-12780 "(null)"}} As far as I can tell -11800 indicates an AVErrorUknown, however I have not been able to find information about the -12780 error code, which as far as I can tell is undocumented. Thanks! Here is the code

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.

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.

Hi. I am working on an audio app for iOS. I have implemented UI and handling which allows the user to change playback rate of audio. When the user selects a different rate, I update the rate property on my AVQueuePlayer. This is working well on device. When I use Airplay, it works for some devices and not for others. Some devices won't change playback rate and will always play at 1x speed. Is this possibly a limitation of those 3rd-party devices? Or is there something I'm missing/should check? Would love to get playback rate changes working across all Airplay devices with our app. Kind regards.

HI Guys, I'm using Shazamkit in my IOS app and successfully capturing the currently playing track details, when using the devices (iPhone) built-in mic. When I test with AirPods though, my app cannot both send the output to through the AirPods and capture that same output with the AirPods mic, for Shazamkit recognition. I believe this must be possible, because the Shazamkit widget on IOS can do this. Is it restricted in some way for third party apps? If not, I'd appreciate some guidance on how to achieve this in Swift code. Thanks in advance.

Hi all! I have been experiencing some issues when using the AVAudioEngine to play audio and record input while doing a voice chat (through the PTT Interface). I noticed if I connect any players to the AudioGraph OR call start that the audio session becomes active (this is on iOS). I don't see anything in the docs or the header files in the AVFoundation, but is it possible that calling the stop method on an engine deactivates the audio session too? In a normal app this behavior seems logical, but when using PTT all activation and deactivation of the audio session must go through the framework and its delegate methods. The issue I am debugging is that when the engine with the input node tapped gets stopped, and there is a gap between the input and when the server replies with inbound audio to be played and something seems to be getting the hardware/audio session into a jammed state. Thanks for any feedback and/or confirmation on this behavior!