I need to implement a solution through an API or custom driver to completely block out the built-in speakers and microphone of Mac, because I need other apps to use specified external devices as audio input and output. Is there a way to achieve this requirement? What I mean is that even in system preferences, it should not be possible to choose the built-in microphone and speakers; only my external device can be used.
Audio
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Hi everyone 👋
I’m building an iOS app in Swift where I want to do the following:
Record the user’s voice
Transcribe the spoken sentence (speech-to-text)
Auto-detect the spoken language
Translate it to another language selected by the user (e.g., English → Spanish or Hindi → English)
Speak back (text-to-speech) the translated text on the same device
Is this possible to record via phone mic and play the transcribe voice into headphone's audio?
In my app I use AVAssetReaderTrackOutput to extract PCM audio from a user-provided video or audio file and display it as a waveform.
Recently a user reported that the waveform is not in sync with his video, and after receiving the video I noticed that the waveform is in fact double as long as the video duration, i.e. it shows the audio in slow-motion, so to speak.
Until now I was using
CMFormatDescription.audioStreamBasicDescription.mSampleRate
which for this particular user video returns 22'050. But in this case it seems that this value is wrong... because the audio file has two audio channels with different sample rates, as returned by
CMFormatDescription.audioFormatList.map({ $0.mASBD.mSampleRate })
The first channel has a sample rate of 44'100, the second one 22'050. If I use the first sample rate, the waveform is perfectly in sync with the video.
The problem is given by the fact that the ratio between the audio data length and the sample rate multiplied by the audio duration is 8, double the ratio for the first audio file (4). In the code below this ratio is given by
Double(length) / (sampleRate * asset.duration.seconds)
When commenting out the line with the sampleRate variable definition in the code below and uncommenting the following line, the ratios for both audio files are 4, which is the expected result. I would expect audioStreamBasicDescription to return the correct sample rate, i.e. the one used by AVAssetReaderTrackOutput, which (I think) somehow merges the stereo tracks. The documentation is sparse, and in particular it’s not documented whether the lower or higher sample rate is used; in this case, it seems like the higher one is used, but audioStreamBasicDescription for some reason returns the lower one.
Does anybody know why this is the case or how I should extract the sample rate of the produced PCM audio data? Should I always take the higher one?
I created FB19620455.
let openPanel = NSOpenPanel()
openPanel.allowedContentTypes = [.audiovisualContent]
openPanel.runModal()
let url = openPanel.urls[0]
let asset = AVURLAsset(url: url)
let assetTrack = asset.tracks(withMediaType: .audio)[0]
let assetReader = try! AVAssetReader(asset: asset)
let readerOutput = AVAssetReaderTrackOutput(track: assetTrack, outputSettings: [AVFormatIDKey: Int(kAudioFormatLinearPCM), AVLinearPCMBitDepthKey: 16, AVLinearPCMIsBigEndianKey: false, AVLinearPCMIsFloatKey: false, AVLinearPCMIsNonInterleaved: false])
readerOutput.alwaysCopiesSampleData = false
assetReader.add(readerOutput)
let formatDescriptions = assetTrack.formatDescriptions as! [CMFormatDescription]
let sampleRate = formatDescriptions[0].audioStreamBasicDescription!.mSampleRate
//let sampleRate = formatDescriptions[0].audioFormatList.map({ $0.mASBD.mSampleRate }).max()!
print(formatDescriptions[0].audioStreamBasicDescription!.mSampleRate)
print(formatDescriptions[0].audioFormatList.map({ $0.mASBD.mSampleRate }))
if !assetReader.startReading() {
preconditionFailure()
}
var length = 0
while assetReader.status == .reading {
guard let sampleBuffer = readerOutput.copyNextSampleBuffer(), let blockBuffer = sampleBuffer.dataBuffer else {
break
}
length += blockBuffer.dataLength
}
print(Double(length) / (sampleRate * asset.duration.seconds))
Hi guys,
I am having issue in live-streaming audio from Bluetooth headset and playing it live on the iPhone speaker.
I am able to redirect audio back to the headset but this is not what I want.
The issue happens when I am trying to override output - the iPhone switches to speaker but also switches a microphone.
This is example of the code:
import AVFoundation
class AudioRecorder {
let player: AVAudioPlayerNode
let engine:AVAudioEngine
let audioSession:AVAudioSession
let audioSessionOutput:AVAudioSession
init() {
self.player = AVAudioPlayerNode()
self.engine = AVAudioEngine()
self.audioSession = AVAudioSession.sharedInstance()
self.audioSessionOutput = AVAudioSession()
do {
try self.audioSession.setCategory(AVAudioSession.Category.playAndRecord, options: [.defaultToSpeaker])
try self.audioSessionOutput.setCategory(AVAudioSession.Category.playAndRecord, options: [.allowBluetooth]) // enables Bluetooth HFP profile
try self.audioSession.setMode(AVAudioSession.Mode.default)
try self.audioSession.setActive(true)
// try self.audioSession.overrideOutputAudioPort(.speaker) // doens't work
} catch {
print(error)
}
let input = self.engine.inputNode
self.engine.attach(self.player)
let bus = 0
let inputFormat = input.inputFormat(forBus: bus)
self.engine.connect(self.player, to: engine.mainMixerNode, format: inputFormat)
input.installTap(onBus: bus, bufferSize: 512, format: inputFormat) { (buffer, time) -> Void in
self.player.scheduleBuffer(buffer)
print(buffer)
}
}
public func start() {
try! self.engine.start()
self.player.play()
}
public func stop() {
self.player.stop()
self.engine.stop()
}
}
I am not sure if this is a bug or not.
Can somebody point me into the right direction?
I there a way to design a custom audio routing?
I would also appreciate some good documentation besides AVFoundation docs.
Hi,
I've had a new deck installed in my car for about 1.5 weeks.
I'm having compatibility issues with my 15PM.
It happens both wired and wirelessly, I get the error "Accessory not supported by this device". It used to happen all the time, now it's 50/50. Sometimes it works.
I've removed and added Bluetooth multiple times on phone and deck, I bought a belkin usb-c to usb-a cable today and it seems to fix it but the problem comes back.
I've changed the setting "FaceID and passcode-allow access when locked-accessories."
The car stereo guy reckons it's definitely an issue with the phone not the deck, I'm inclined to believe him since the error states "by this device".
Any advice appreciated.
Topic:
Media Technologies
SubTopic:
Audio
My audio app shows a control bar at the bottom of the window. The controls show nicely, but there is a black "slab" appearing behind the inline controls, the same size as the playerView. Setting the player view background color does nothing:
playerView.wantsLayer = true playerView.layer?.backgroundColor = NSColor.clear.cgColor
How can I clear the background?
If I use .floating controlsStyle, I don't get the background "slab".
Topic:
Media Technologies
SubTopic:
Audio
Hi,
Not sure if this is the right forum to ask this question in, but could you please advise if I can use Apple Digital Masters logo (badge) in my iOS app that is playing music from Apple Music service?
Topic:
Media Technologies
SubTopic:
Audio
Hello everyone,
I am working on an app that allows you to review your own music using Apple Music. Currently I am running into an issue with the skipping forwards and backwards outside of the app.
How it should work: When skipping forward or backwards on the lock or home screen of an iPhone, the next or previous song on an album should play and the information should change to reflect that in the app.
If you play a song in Apple Music, you can see a Now Playing view in the lock screen.
When you skip forward or backwards, it will do either action and it would reflect that when you see a little frequency icon on artwork image of a song.
What it's doing: When skipping forward or backwards on the lock or home screen of an iPhone, the next or previous song is reflected outside of the app, but not in the app.
When skipping a song outside of the app, it works correctly to head to the next song.
But when I return to the app, it is not reflected
NOTE: I am not using MusicKit variables such as Track, Album to display the songs. Since I want to grab the songs and review them I need a rating so I created my own that grabs the MusicItemID, name, artist(s), etc.
NOTE: I am using ApplicationMusicPlayer.shared
Is there a way to get the song to reflect in my app?
(If its easier, a simple example of it would be nice. No need to create an entire xprod file)
ApplicationMusicPlayer is not available on watchOS but all other platforms. Is there a technical reason for that like battery life? Same goes for SystemMusicPlayer and MPMusicPlayerController. I already filed feedbacks for that.
Hello,
I'm observing an intermittent memory leak being reported in the iOS Simulator when initializing and starting an AVAudioEngine. Even with minimal setup—just attaching a single AVAudioPlayerNode and connecting it to the mainMixerNode—Xcode's memory diagnostics and Instruments sometimes flag a leak.
Here is a simplified version of the code I'm using:
// This function is called when the user taps a button in the view controller:
#import "ViewController.h"
@interface ViewController ()
@end
@implementation ViewController
- (void)viewDidLoad {
[super viewDidLoad];
}
- (IBAction)myButtonAction:(id)sender {
NSLog(@"Test");
soundCreate();
}
@end
// media.m
static AVAudioEngine *audioEngine = nil;
void soundCreate(void)
{
if (audioEngine != nil)
return;
[[AVAudioSession sharedInstance] setCategory:AVAudioSessionCategoryAmbient error:nil];
[[AVAudioSession sharedInstance] setActive:YES error:nil];
audioEngine = [[AVAudioEngine alloc] init];
AVAudioPlayerNode* playerNode = [[AVAudioPlayerNode alloc] init];
[audioEngine attachNode:playerNode];
[audioEngine connect:playerNode to:(AVAudioNode *)[audioEngine mainMixerNode] format:nil];
[audioEngine startAndReturnError:nil];
}
In the memory leak report, the following call stack is repeated, seemingly in a loop:
ListenerMap::InsertEvent(XAudioUnitEvent const&, ListenerBinding*) AudioToolboxCore
ListenerMap::AddParameter(AUListener*, void*, XAudioUnitEvent const&) AudioToolboxCore
AUListenerAddParameter AudioToolboxCore
addOrRemoveParameterListeners(OpaqueAudioComponentInstance*, AUListenerBase*, AUParameterTree*, bool) AudioToolboxCore
0x180178ddf
Let's consider the following code.
I've created an actor that loads a list of .mp3 files from a Bundle and then makes it available for audio reproduction.
Unfortunately, I'm experiencing a memory leak.
At the play method.
player.play()
From Instruments I get
_malloc_type_malloc_outlined libsystem_malloc.dylib
start_wqthread libsystem_pthread.dylib
private actor AudioActor {
enum Failure: Error {
case soundsNotLoaded([AudioPlayerClient.Sound: Error])
}
enum Player {
case music(AVAudioPlayer)
}
var players: [Sound: Player] = [:]
let bundles: [Bundle]
init(bundles: UncheckedSendable<[Bundle]>) {
self.bundles = bundles.wrappedValue
}
func load(sounds: [Sound]) throws {
try AVAudioSession.sharedInstance().setActive(true, options: [])
var errors: [Sound: Error] = [:]
for sound in sounds {
guard let url = bundle.url(forResource: sound.name, withExtension: "mp3")
else { continue }
do {
self.players[sound] = try .music(AVAudioPlayer(contentsOf: url))
} catch {
errors[sound] = error
}
}
guard errors.isEmpty
else { throw Failure.soundsNotLoaded(errors) }
}
func play(sound: Sound, loops: Int?) throws {
guard let player = self.players[sound]
else { return }
switch player {
case let .music(player):
player.numberOfLoops = loops ?? -1
player.play()
}
}
func stop(sound: Sound) throws {
guard let player = self.players[sound]
else { throw Failure.soundsNotLoaded([:]) }
switch player {
case let .music(player):
player.stop()
}
}
}
When using the Apple Devices to sync Apple Music to iPhone where is the Apple Devices backup being written to?
Apple Devices->music->sync.
Not trying to backup the iPhone via Apple Devices app.
Hi all,
i can successfully match music using shazamkit on Apple using SwiftUI, a simple app that let user to load an audio file and exctracts the relative match, while i am unable to match music using shamzamkit on Android. I am trying to make the same simple app but i cannot match music as i get MATCH_ATTEMPT_FAILED every time i try to. I don't know what i am doing wrong but the shazam part in the kotlin Android code is in this method :
suspend fun processAudioFileInBackground(
filePath: String,
developerTokenProvider: DeveloperTokenProvider
) = withContext(Dispatchers.IO) {
val bufferSize = 1024 * 1024
val audioFile = FileInputStream(filePath)
val byteBuffer = ByteBuffer.allocate(bufferSize)
byteBuffer.order(ByteOrder.LITTLE_ENDIAN)
var bytesRead: Int
while (audioFile.read(byteBuffer.array()).also { bytesRead = it } != -1) {
val signatureGenerator = (ShazamKit.createSignatureGenerator(AudioSampleRateInHz.SAMPLE_RATE_44100) as ShazamKitResult.Success).data
signatureGenerator.append(byteBuffer.array(), bytesRead, System.currentTimeMillis())
val signature = signatureGenerator.generateSignature()
println("Signature: ${signature.durationInMs}")
val catalog = ShazamKit.createShazamCatalog(developerTokenProvider, Locale.ENGLISH)
val session = (ShazamKit.createSession(catalog) as ShazamKitResult.Success).data
val matchResult = session.match(signature)
println("MatchResult : $matchResult")
setMatchResult(matchResult)
byteBuffer.clear()
}
audioFile.close()
}
I noticed that changing Locale in catalog creation results in different result as i get NoMatch without exception. Can you please help me with this?
Topic:
Media Technologies
SubTopic:
Audio
hi all,
as soon an audio is played in a whatever app, coreaudiod inserts a sleep prevent assertion for both, the system AND the display.
can i somehow stop the insertion of the display sleep assertion?
pid 223(coreaudiod): [0x00004e9e00058dc2] 00:03:18 PreventUserIdleDisplaySleep named: "com.apple.audio.AppleGFXHDAEngineOutputDP:10001:0:{B31A-08C6-00000000}.context.preventuseridledisplaysleep"
Created for PID: 4145.
where PID 4145 is spotify.
but it doesn't matter which app is playing the audio.
any help would be appreciated
thanks
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
I’m an amateur developer working on a free utility for composers/producers, for which the macOS release needs to create and name RTP-MIDI sessions in Audio MIDI Setup from the command line (so I can ship a small C helper instead of telling users to click through the UI). Here’s what I’ve tried so far, without luck:
• Plist hacks: Injecting entries into ~/Library/Audio/MIDI Configurations/*.mcfg works when AMS is closed, but AMS immediately locks and reverts my changes when it’s open.
• CoreMIDI C API: I can create virtual ports with MIDISourceCreate, but attempting MIDIObjectGetDataProperty on the apple.midirtp.session plugin always returns err –10836.
• Obj-C & Swift: Loading MIDINetworkSession and calling defaultSession, init, setNetworkName: and setting enabled = YES doesn’t produce a new session object in the Network panel.
• dlopen/dlsym: I extracted the real CoreMIDI binary out of the dyld shared cache and tried binding _MIDINetworkSessionCreate, _SetName, _SetEnabled, etc., but all the symbols come back null or my tool segfaults.
• Plugin registration: I’ve pulled the factory UUID (70C9C5EA-7C65-11D8-B317-000393A34B5A) from /System/Library/Extensions/AppleMIDIRTPDriver.plugin/Contents/Info.plist and called CFPlugInRegisterFactories, but it still never exposes the session-creation calls.
At this point I’m convinced I’m either loading the wrong binary or missing one critical step in registering the RTP-MIDI plugin’s private API. Can anyone point me to:
The exact path of the dylib or bundle that actually exports the MIDINetworkSessionCreate/MIDINetworkSessionSetName/MIDINetworkSessionSetEnabled symbols?
A minimal working snippet (C or Obj-C) that reliably creates and names a Network-MIDI session?
Any pointers, sample code, or even ideas about where Apple hides this functionality on macOS 15 would be hugely appreciated. Thanks!
I'm working on adding CarPlay support to an audio app and am running into an issue. Occasionally, when a user opens the app from CarPlay while the main app scene is either not connected or is currently in the background, I will receive an error when attempting to activate the audio session. The code below mimics my setup:
do {
try AVAudioSession.sharedInstance().setCategory(.playback, mode: .spokenAudio)
try AVAudioSession.sharedInstance().setActive(true)
} catch {
print(error) // NSOSStatusErrorDomain - 560557684: Session activation failed
}
That error code maps to AVAudioSession.ErrorCode.cannotInterruptOthers.
Once in this state, all subsequent attempts to play different pieces of content will fail. However, things will start working normally if the user opens the app on their phone and tries again from CarPlay (while the app is in the foreground on their phone).
I'm not sure why it would behave this way and want to note that I do have the audio background mode capability enabled.
Has anyone else encountered this? Are there any workarounds or changes I could make to prevent this from happening?
Does an artist similarity station broaden selection variety compared to a song similarity station?
You don't have to answer if it is against nondisclosure terms.
Hello everyone,
I’m new to Swift development and have been working on an audio module that plays a specific sound at regular intervals - similar to a workout timer that signals switching exercises every few minutes.
Following AVFoundation documentation, I’m configuring my audio session like this:
let session = AVAudioSession.sharedInstance()
try session.setCategory(
.playback,
mode: .default,
options: [.interruptSpokenAudioAndMixWithOthers, .duckOthers]
)
self.engine.attach(self.player)
self.engine.connect(self.player, to: self.engine.outputNode, format: self.audioFormat)
try? session.setActive(true)
When it’s time to play cues, I schedule playback on a DispatchQueue:
// scheduleAudio uses DispatchQueue
self.scheduleAudio(at: interval.start) {
do {
try audio.engine.start()
audio.node.play()
for sample in interval.samples {
audio.node.scheduleBuffer(sample.buffer, at: AVAudioTime(hostTime: sample.hostTime))
}
} catch {
print("Audio activation failed: \(error)")
}
}
This works perfectly in the foreground. But once the app goes into the background, the scheduled callback runs, yet the audio engine fails to start, resulting in an error with code 561015905.
Interestingly, if the app is already playing audio before going to the background, the scheduled sounds continue to play as expected.
I have added the required background audio mode to my Info plist file by including the key UIBackgroundModes with the value audio.
Is there anything else I should configure? What is the best practice to play periodic audio when the app runs in the background? How do apps like turn-by-turn navigation handle continuous audio playback in the background?
Any advice or pointers would be greatly appreciated!
According to the documentation (https://developer.apple.com/documentation/avfoundation/avplayeritem/externalmetadata), AVPlayerItem should have an externalMetadata property. However it does not appear to be visible to my app. When I try, I get:
Value of type 'AVPlayerItem' has no member 'externalMetadata'
Documentation states iOS 12.2+; I am building with a minimum deployment target of iOS 18.
Code snippet:
import Foundation
import AVFoundation
/// ... in function ...
// create metadata as described in https://developer.apple.com/videos/play/wwdc2022/110338
var title = AVMutableMetadataItem()
title.identifier = .commonIdentifierAlbumName
title.value = "My Title" as NSString?
title.extendedLanguageTag = "und"
var playerItem = await AVPlayerItem(asset: composition)
playerItem.externalMetadata = [ title ]