Hi, I am looking for a good way to play sounds at a high frequency. At the moment I am using the AVAudioEngine, and create a couple AVAudioPlayerNode and for each sound I need to play I create a AVAudioPCMBuffer. When the app needs to play a sound, I get the correct AVAudioPCMBuffer for the sound and use the first available AVAudioPlayerNode and feed it to the buffer. The timing for a metronome app has to be very precise because if it's of by about 16ms the user can hear that it is not playing had the right interval. For low speeds this is working without any problems, but at high speeds it is getting worse. Maybe anyone has an idea on how I can improve my method. Its a Plugin for Flutter. import AVFoundation class FastSoundPlayer { private var audioPlayers: [SoundPlayer?] = [] private var sounds: [String: Sound] = [:] private var engine = AVAudioEngine() let session = AVAudioSession.sharedInstance() init() { do { try session.setCategory(AVAudioSession.Category.playback, mode: AVAudioSession.Mode.default, options: [AVAudioSession.CategoryOptions.mixWithOthers]) try session.setActive(true) createSoundPlayers(count: 20) try engine.start() } catch { print("Error starting audio engine: \(error.localizedDescription)") } } // Selector method to handle applicationDidBecomeActiveNotification func applicationDidBecomeActive() { // Reinitialize AVAudioEngine and reattach all nodes do { engine.reset() objc_sync_enter(audioPlayers) audioPlayers.removeAll() createSoundPlayers(count: 20) objc_sync_exit(audioPlayers) try engine.start() } catch { print("Error starting audio engine: \(error.localizedDescription)") } } func createSoundPlayers(count: Int) { for _ in 0..<count { let player = SoundPlayer() engine.attach(player.player) engine.connect(player.player, to: engine.mainMixerNode, format: nil) audioPlayers.append(player) } } func load(sound: Data, name: String) { let sound = Sound(soundData: sound) sounds[name] = sound } func play(name: String) { if !engine.isRunning { applicationDidBecomeActive() } guard let sound = sounds[name] else { print("Sound not found") return } if let player = getAvailablePlayer() { player.play(sound: sound) } } func getAvailablePlayer() -> SoundPlayer? { for player in audioPlayers { if !player!.isPlaying { return player } } return nil } } class SoundPlayer { let player = AVAudioPlayerNode() var isPlaying = false init() { player.volume = 1.0 } func play(sound: Sound) { player.scheduleBuffer(sound.sound!, at: nil, options: .interrupts, completionCallbackType: .dataPlayedBack) { _ in self.complete() } if (player.engine != nil && player.engine!.isRunning) { player.play() isPlaying = true } } func complete() { isPlaying = false } } class Sound { var sound: AVAudioPCMBuffer? init(soundData: Data) { do { let temporaryURL = FileManager.default.temporaryDirectory.appendingPathComponent("tempSound.wav") try soundData.write(to: temporaryURL) // Create AVAudioFile from the temporary file URL let audioFile = try AVAudioFile(forReading: temporaryURL) // Define the format for the PCM buffer (44100Hz, stereo) let format = AVAudioFormat(commonFormat: .pcmFormatInt16, sampleRate: 44100, channels: 2, interleaved: false) // Create AVAudioPCMBuffer guard let pcmBuffer = AVAudioPCMBuffer(pcmFormat: format!, frameCapacity: AVAudioFrameCount(audioFile.length)) else { // Failed to create PCM buffer self.sound = nil return } // Read audio file into PCM buffer try audioFile.read(into: pcmBuffer) // Assign the created AVAudioPCMBuffer to the sound property self.sound = pcmBuffer } catch { print("Error loading sound file: \(error.localizedDescription)") self.sound = nil } } } Thanks!

Since iOS and tvOS 18, CMCD can now be automatically sent by AVPlayer (https://developer.apple.com/streaming/Whats-new-HLS.pdf). However, after enabling CMCD, our streams occasionally fail with the following error: CoreMediaErrorDomain Error -17383 This issue appears to affect only DRM-protected (FairPlay) streams so far. We activate CMCD via the resource loader of an AVURLAsset, before assigning the item to an AVPlayer. Unfortunately, we haven’t found a reliable way to reproduce the issue, and we’ve been unable to gather any useful diagnostic information. Has anyone else observed this behavior when enabling CMCD on FairPlay streams?

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() } } }

I'm working on an application that uses the iPhone camera for scientific purposes - and, as a result would like to receive video in as unprocessed format as possible. In particular, I'm interested in getting pixel buffers that contain pretty much the bayer data as the sensor sees it - with the minimum processing of color possible. Currently we configure the AVCaptureDevice to fix the focus and exposure, use a low ISO with no gain and set the white balance gains to 1. AVCaptureVideoDataOutput is using 32BGRA. What I'd like to do is remove any additional color and brightness processing such that the data is effectively processed with a linear transfer function (i.e. gamma function is 1). I thought that this might be down to using the AVCaptureDevice activeColorSpace - we currently use P3_D65 for this. But there only seems to be a few choices (e.g. sRGB, HLG_BT2020) all of which I think affect the gamma. So: is it possible to control or specify the gamma / transfer function when using CaptureVideoDelegate? if not, does one of the color space settings have a defined gamma function that I can effectively reverse it from the pixel data without losing too much information? or is there a better way to capture video-ish speed images (15-30fps) from the camera sensor that skips processing like this? Many thanks for any suggestions.

I have DNG files that I want to open and show as EDR content in my app. It seems like the DNG files should have enough per pixel information to show more colors that Display P3 but whenever I load the images using CIRawFilter and then inspect the outputImage color space it is always "DisplayP3", not something like "ITU-R BT.2100 PQ" there doesn't seem to be any way to make it load with a different color space for displaying EDR images. Does this make sense for DNG files, it seems like it should? If I open the same file using CIImage with the expandToHDR option e.g. CIImage(contentsOf: rawURL, options: [.expandToHDR: true]) then it does have the desired EDR color space, but then I don't get any of the properties that are available via the CIRAWFilter class to manipulate the data. Basically I just want to be able to open the DNG file via CIRAWFilter and then display it in my SwiftUI app as an EDR image by adding the allowedDynamicRange(.high) property. Image("my-dng-image").allowedDynamicRange(.high) Or do DNG files (just RAW not ProRAW) not contain enough information to be displayed as EDR images, seems like they should.

FairPlay-Protected HLS Files Not Transferred via Quick Start I have an iOS app that downloads HLS files, which are protected by FairPlay. These files are stored locally, and their locations are managed using Core Data. When playing these tracks, I use AVURLAsset to access the stored file paths. Recently, a client upgraded to a new iPhone and used Quick Start to transfer data from his old device. While all other app data was successfully transferred, including Core Data records and UserDefaults, the actual HLS files were missing. As a result, the app retained metadata about the downloaded content, but the files themselves were gone, causing playback failures. Does Quick Start exclude certain types of locally stored files, especially DRM-protected HLS downloads, or is the issue related to how FairPlay-protected content is handled during the transfer of locally stored files?

I have an iOS app that downloads HLS files, which are protected by FairPlay. These files are stored locally, and their locations are managed using Core Data. When playing these tracks, I use AVURLAsset to access the stored file paths. Recently, a client upgraded to a new iPhone and used Quick Start to transfer data from his old device. While all other app data was successfully transferred, including Core Data records and UserDefaults, the actual HLS files were missing. As a result, the app retained metadata about the downloaded content, but the files themselves were gone, causing playback failures. Does Quick Start exclude certain types of locally stored files, especially DRM-protected HLS downloads, or is the issue related to how FairPlay-protected content is handled during the transfer of locally stored files?

I am trying to stream audio from local filesystem. For that, I am trying to use an AVAssetResourceLoaderDelegate for an AVURLAsset. However, Content-Length is not known at the start. To overcome this, I tried several methods: Set content length as nil, in the AVAssetResourceLoadingContentInformationRequest Set content length to -1, in the ContentInformationRequest Both of these cause the AVPlayerItem to fail with an error. I also tried setting Content-Length as INT_MAX, and setting a renewalDate = Date(timeIntervalSinceNow: 5). However, that seems to be buggy. Even after updating the Content-Length to the correct value (e.g. X bytes) and finishing that loading request, the resource loader keeps getting requests with requestedOffset = X with dataRequest.requestsAllDataToEndOfResource = true. These requests keep coming indefinitely, and as a result it seems that the next item in the queue does not get played. Also, .AVPlayerItemDidPlayToEndTime notification does not get called. I wanted to check if this is an expected behavior or is there a bug in this implementation. Also, what is the recommended way to stream audio of unknown initial length from local file system? Thanks!

In the past, when using Lightning, many external devices had to go through MFi certification. However, since the iPhone 15 switched from Lightning to USB-C, is MFi certification still required? Our company has developed several UVC devices, and we have confirmed that iPads can read frames from external cameras through the external device type in AVFoundation. However, this is not supported on iPhones. We are currently exploring feasible ways to enable UVC device support on iPhones. Is MFi certification the only option? If so, is the MFi certification process for USB-C the same as it was for Lightning? Does it still require purchasing an MFi chip and manufacturing specially designed USB-C cables?

I'm trying to write 16-bit interleaved 2-channel data captured from a LiveSwitch audio source to a AVAudioFile. The buffer and file formats match but I get a bad parameter error from the API. Does this API not support the specified format or is there some other issue? Here is the debugger output. (lldb) po audioFile.url ▿ file:///private/var/mobile/Containers/Data/Application/1EB14379-0CF2-41B6-B742-4C9A80728DB3/tmp/Heart%20Sounds%201 - _url : file:///private/var/mobile/Containers/Data/Application/1EB14379-0CF2-41B6-B742-4C9A80728DB3/tmp/Heart%20Sounds%201 - _parseInfo : nil - _baseParseInfo : nil (lldb) po error Error Domain=com.apple.coreaudio.avfaudio Code=-50 "(null)" UserInfo={failed call=ExtAudioFileWrite(_impl->_extAudioFile, buffer.frameLength, buffer.audioBufferList)} (lldb) po buffer.format <AVAudioFormat 0x302a12b20: 2 ch, 44100 Hz, Int16, interleaved> (lldb) po audioFile.fileFormat <AVAudioFormat 0x302a515e0: 2 ch, 44100 Hz, Int16, interleaved> (lldb) po buffer.frameLength 882 (lldb) po buffer.audioBufferList ▿ 0x0000000300941e60 - pointerValue : 12894608992 This code handles the details of converting the Live Switch frame into an AVAudioPCMBuffer. extension FMLiveSwitchAudioFrame { func convertedToPCMBuffer() -> AVAudioPCMBuffer { Self.convertToAVAudioPCMBuffer(from: self)! } static func convertToAVAudioPCMBuffer(from frame: FMLiveSwitchAudioFrame) -> AVAudioPCMBuffer? { // Retrieve the audio buffer and format details from the FMLiveSwitchAudioFrame guard let buffer = frame.buffer(), let format = buffer.format() as? FMLiveSwitchAudioFormat else { return nil } // Extract PCM format details from FMLiveSwitchAudioFormat let sampleRate = Double(format.clockRate()) let channelCount = AVAudioChannelCount(format.channelCount()) // Determine bytes per sample based on bit depth let bitsPerSample = 16 let bytesPerSample = bitsPerSample / 8 let bytesPerFrame = bytesPerSample * Int(channelCount) let frameLength = AVAudioFrameCount(Int(buffer.dataBuffer().length()) / bytesPerFrame) // Create an AVAudioFormat from the FMLiveSwitchAudioFormat guard let avAudioFormat = AVAudioFormat(commonFormat: .pcmFormatInt16, sampleRate: sampleRate, channels: channelCount, interleaved: true) else { return nil } // Create an AudioBufferList to wrap the existing buffer let audioBufferList = UnsafeMutablePointer<AudioBufferList>.allocate(capacity: 1) audioBufferList.pointee.mNumberBuffers = 1 audioBufferList.pointee.mBuffers.mNumberChannels = channelCount audioBufferList.pointee.mBuffers.mDataByteSize = UInt32(buffer.dataBuffer().length()) audioBufferList.pointee.mBuffers.mData = buffer.dataBuffer().data().mutableBytes // Directly use LiveSwitch buffer // Transfer ownership of the buffer to AVAudioPCMBuffer let pcmBuffer = AVAudioPCMBuffer(pcmFormat: avAudioFormat, bufferListNoCopy: audioBufferList) /* { buffer in // Ensure the buffer is freed when AVAudioPCMBuffer is deallocated buffer.deallocate() // Only call this if LiveSwitch allows manual deallocation } */ pcmBuffer?.frameLength = frameLength return pcmBuffer } } This is the handler that is invoked with every frame in order to convert it for use with AVAudioFile and optionally update a scrolling signal display on the screen. private func onRaisedFrame(obj: Any!) -> Void { // Bail out early if no one is interested in the data. guard isMonitoring else { return } // Convert LS frame to AVAudioPCMBuffer (no-copy) let frame = obj as! FMLiveSwitchAudioFrame let buffer = frame.convertedToPCMBuffer() // Hand subscribers a reference to the buffer for rendering to display. bufferPublisher?.send(buffer) // If we have and output file, store the data there, as well. guard let audioFile = self.audioFile else { return } do { try audioFile.write(from: buffer) // FIXME: This call is throwing error -50 } catch { FMLiveSwitchLog.error(withMessage: "Failed to write buffer to audio file at \(audioFile.url): \(error)") self.audioFile = nil } } This is how the audio file is being setup. static var recordingFormat: AVAudioFormat = { AVAudioFormat(commonFormat: .pcmFormatInt16, sampleRate: 44_100, channels: 2, interleaved: true)! }() let audioFile = try AVAudioFile(forWriting: outputURL, settings: Self.recordingFormat.settings)

Our streaming app uses FairPlay-protected video streams, which previously worked fine when using AVAssetResourceLoaderDelegate to provide CKCs. Recently, we migrated to AVContentKeySession, and while everything works as expected during regular playback, we encountered an issue with AirPlay. Our CKC has a 120-second expiry, so we renew it by calling renewExpiringResponseData.. This trigger the didProvideRenewingContentKeyRequest delegate and we respond with updated CKC. However, when streaming via AirPlay, both video and audio freeze exactly after 120 seconds. To validate the issue, I tested with AVAssetResourceLoaderDelegate and found that I can reproduce the same freeze if I do not renew the key. This suggests that AirPlay is not accepting the renewed CKC when using AVContentKeySession. Additional Details: This issue occurs across different iOS versions and various AirPlay devices. The same content plays without issues when played directly on the device. The renewal process is successful, and segments continue to load, but playback remains frozen. Tried renewing the CKC bit early (100s). I also tried setting player.usesExternalPlaybackWhileExternalScreenIsActive = true, but the issue persists. We don't use persistentKey. Is there anything else that needs to be considered for proper key renewal when AirPlaying? Any help on how to fix this or confirmation if this is a known issue would be greatly appreciated.

Apple provides a function to create TTS voice as a file in TTS. (AVSpeechUtterance/AVSpeechSynthesizer) Or, if the user records the video of TTS playback and uses that video I wonder what the scope of use is if I use this TTS voice to make YouTube, TikTok, or commercial videos. Is it impossible to use it commercially at all? Can I use it commercially with the source indicated? Can I use it commercially without a separate source indication? Is there a difference in commercial use license between Siri voices and regular TTS voices?

I am trying to achieve an animated gradient effect that changes values over time based on the current seconds. I am also using AVPlayer and AVMutableVideoComposition along with custom instruction and class to generate the effect. I didn't want to load any video file, but rather generate a custom video with my own set of instructions. I used Metal Compute shaders to generate the effects and make the video to be 20 seconds. However, when I run the code, I get a frozen player with the gradient applied, but when I try to play the video, I get this warning in the console :- Visual isTranslatable: NO; reason: observation failure: noObservations Here is the screenshot :- My entire code :- import AVFoundation import Metal class GradientVideoCompositorTest: NSObject, AVVideoCompositing { var sourcePixelBufferAttributes: [String: Any]? = [ kCVPixelBufferPixelFormatTypeKey as String: kCVPixelFormatType_32BGRA ] var requiredPixelBufferAttributesForRenderContext: [String: Any] = [ kCVPixelBufferPixelFormatTypeKey as String: kCVPixelFormatType_32BGRA ] private var renderContext: AVVideoCompositionRenderContext? private var metalDevice: MTLDevice! private var metalCommandQueue: MTLCommandQueue! private var metalLibrary: MTLLibrary! private var metalPipeline: MTLComputePipelineState! override init() { super.init() setupMetal() } func setupMetal() { guard let device = MTLCreateSystemDefaultDevice(), let queue = device.makeCommandQueue(), let library = try? device.makeDefaultLibrary(), let function = library.makeFunction(name: "gradientShader") else { fatalError("Metal setup failed") } self.metalDevice = device self.metalCommandQueue = queue self.metalLibrary = library self.metalPipeline = try? device.makeComputePipelineState(function: function) } func renderContextChanged(_ newRenderContext: AVVideoCompositionRenderContext) { renderContext = newRenderContext } func startRequest(_ request: AVAsynchronousVideoCompositionRequest) { guard let outputPixelBuffer = renderContext?.newPixelBuffer(), let metalTexture = createMetalTexture(from: outputPixelBuffer) else { request.finish(with: NSError(domain: "com.example.gradient", code: -1, userInfo: nil)) return } var time = Float(request.compositionTime.seconds) renderGradient(to: metalTexture, time: time) request.finish(withComposedVideoFrame: outputPixelBuffer) } private func createMetalTexture(from pixelBuffer: CVPixelBuffer) -> MTLTexture? { var texture: MTLTexture? let width = CVPixelBufferGetWidth(pixelBuffer) let height = CVPixelBufferGetHeight(pixelBuffer) let textureDescriptor = MTLTextureDescriptor.texture2DDescriptor( pixelFormat: .bgra8Unorm, width: width, height: height, mipmapped: false ) textureDescriptor.usage = [.shaderWrite, .shaderRead] CVPixelBufferLockBaseAddress(pixelBuffer, .readOnly) if let textureCache = createTextureCache(), let cvTexture = createCVMetalTexture(from: pixelBuffer, cache: textureCache) { texture = CVMetalTextureGetTexture(cvTexture) } CVPixelBufferUnlockBaseAddress(pixelBuffer, .readOnly) return texture } private func renderGradient(to texture: MTLTexture, time: Float) { guard let commandBuffer = metalCommandQueue.makeCommandBuffer(), let commandEncoder = commandBuffer.makeComputeCommandEncoder() else { return } commandEncoder.setComputePipelineState(metalPipeline) commandEncoder.setTexture(texture, index: 0) var mutableTime = time commandEncoder.setBytes(&mutableTime, length: MemoryLayout<Float>.size, index: 0) let threadsPerGroup = MTLSize(width: 16, height: 16, depth: 1) let threadGroups = MTLSize( width: (texture.width + 15) / 16, height: (texture.height + 15) / 16, depth: 1 ) commandEncoder.dispatchThreadgroups(threadGroups, threadsPerThreadgroup: threadsPerGroup) commandEncoder.endEncoding() commandBuffer.commit() } private func createTextureCache() -> CVMetalTextureCache? { var cache: CVMetalTextureCache? CVMetalTextureCacheCreate(kCFAllocatorDefault, nil, metalDevice, nil, &cache) return cache } private func createCVMetalTexture(from pixelBuffer: CVPixelBuffer, cache: CVMetalTextureCache) -> CVMetalTexture? { var cvTexture: CVMetalTexture? let width = CVPixelBufferGetWidth(pixelBuffer) let height = CVPixelBufferGetHeight(pixelBuffer) CVMetalTextureCacheCreateTextureFromImage( kCFAllocatorDefault, cache, pixelBuffer, nil, .bgra8Unorm, width, height, 0, &cvTexture ) return cvTexture } } class GradientCompositionInstructionTest: NSObject, AVVideoCompositionInstructionProtocol { var timeRange: CMTimeRange var enablePostProcessing: Bool = true var containsTweening: Bool = true var requiredSourceTrackIDs: [NSValue]? = nil var passthroughTrackID: CMPersistentTrackID = kCMPersistentTrackID_Invalid init(timeRange: CMTimeRange) { self.timeRange = timeRange } } func createGradientVideoComposition(duration: CMTime, size: CGSize) -> AVMutableVideoComposition { let composition = AVMutableComposition() let instruction = GradientCompositionInstructionTest(timeRange: CMTimeRange(start: .zero, duration: duration)) let videoComposition = AVMutableVideoComposition() videoComposition.customVideoCompositorClass = GradientVideoCompositorTest.self videoComposition.renderSize = size videoComposition.frameDuration = CMTime(value: 1, timescale: 30) // 30 FPS videoComposition.instructions = [instruction] return videoComposition } #include <metal_stdlib> using namespace metal; kernel void gradientShader(texture2d<float, access::write> output [[texture(0)]], constant float &time [[buffer(0)]], uint2 id [[thread_position_in_grid]]) { float2 uv = float2(id) / float2(output.get_width(), output.get_height()); // Animated colors based on time float3 color1 = float3(sin(time) * 0.8 + 0.1, 0.6, 1.0); float3 color2 = float3(0.12, 0.99, cos(time) * 0.9 + 0.3); // Linear interpolation for gradient float3 gradientColor = mix(color1, color2, uv.y); output.write(float4(gradientColor, 1.0), id); }

We're experiencing significant issues with AVPlayer when attempting to play partially downloaded HLS content in offline mode. Our app downloads HLS video content for offline viewing, but users encounter the following problems: Excessive Loading Delay: When offline, AVPlayer attempts to load resources for up to 60 seconds before playing the locally available segments Asset Loss: Sometimes AVPlayer completely loses the asset reference and fails to play the video on subsequent attempts Inconsistent Behavior: The same partially downloaded asset might play immediately in one session but take 30+ seconds in another Network Activity Despite Offline Settings: Despite configuring options to prevent network usage, AVPlayer still appears to be attempting network connections These issues severely impact our offline user experience, especially for users with intermittent connectivity. Technical Details Implementation Context Our app downloads HLS videos for offline viewing using AVAssetDownloadTask. We store the downloaded content locally and maintain a dictionary mapping of file identifiers to local paths. When attempting to play these videos offline, we experience the described issues. Current Implementation Here's our current implementation for playing the videos: - (void)presentNativeAvplayerForVideo:(Video *)video navContext:(NavContext *)context { NSString *localPath = video.localHlsPath; if (localPath) { NSURL *videoURL = [NSURL URLWithString:localPath]; NSDictionary *options = @{ AVURLAssetPreferPreciseDurationAndTimingKey: @YES, AVURLAssetAllowsCellularAccessKey: @NO, AVURLAssetAllowsExpensiveNetworkAccessKey: @NO, AVURLAssetAllowsConstrainedNetworkAccessKey: @NO }; AVURLAsset *asset = [[AVURLAsset alloc] initWithURL:videoURL options:options]; AVPlayerViewController *playerViewController = [[AVPlayerViewController alloc] init]; NSArray *keys = @[@"duration", @"tracks"]; [asset loadValuesAsynchronouslyForKeys:keys completionHandler:^{ dispatch_async(dispatch_get_main_queue(), ^{ AVPlayerItem *playerItem = [AVPlayerItem playerItemWithAsset:asset]; AVPlayer *player = [AVPlayer playerWithPlayerItem:playerItem]; playerViewController.player = player; [player play]; }); }]; playerViewController.modalPresentationStyle = UIModalPresentationFullScreen; [context presentViewController:playerViewController animated:YES completion:nil]; } } Attempted Solutions We've tried several approaches to mitigate these issues: Modified Asset Options: NSDictionary *options = @{ AVURLAssetPreferPreciseDurationAndTimingKey: @NO, // Changed to NO AVURLAssetAllowsCellularAccessKey: @NO, AVURLAssetAllowsExpensiveNetworkAccessKey: @NO, AVURLAssetAllowsConstrainedNetworkAccessKey: @NO, AVAssetReferenceRestrictionsKey: @(AVAssetReferenceRestrictionForbidRemoteReferenceToLocal) }; Skipped Asynchronous Key Loading: AVPlayerItem *playerItem = [AVPlayerItem playerItemWithAsset:asset automaticallyLoadedAssetKeys:nil]; Modified Player Settings: player.automaticallyWaitsToMinimizeStalling = NO; [playerItem setPreferredForwardBufferDuration:2.0]; Added Network Resource Restrictions: playerItem.canUseNetworkResourcesForLiveStreamingWhilePaused = NO; Used File URLs Instead of HTTP URLs where possible Despite these attempts, the issues persist. Expected vs. Actual Behavior Expected Behavior: AVPlayer should immediately begin playback of locally available HLS segments When offline, it should not attempt to load from network for more than a few seconds Once an asset is successfully played, it should be reliably available for future playback Actual Behavior: AVPlayer waits 10-60 seconds before playing locally available segments Network activity is observed despite all network-restricting options Sometimes the player fails completely to play a previously available asset Behavior is inconsistent between playback attempts with the same asset Questions: What is the recommended approach for playing partially downloaded HLS content offline with minimal delay? Is there a way to force AVPlayer to immediately use available local segments without attempting to load from the network? Are there any known issues with AVPlayer losing references to locally stored HLS assets? What diagnostic steps would you recommend to track down the specific cause of these delays? Does AVFoundation have specific timeouts for offline HLS playback that could be configured? Any guidance would be greatly appreciated as this issue is significantly impacting our user experience. Device Information iOS Versions Tested: 14.5 - 18.1 Device Models: iPhone 12, iPhone 13, iPhone 14, iPhone 15 Xcode Version: 15.3-16.2.1

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.

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)

I'm using an iPhone 15 Pro, which has switched from Lightning to USB Type-C. My iOS version is 18.3. According to Apple's documentation, AVCaptureDevice.DeviceType should support external device types. 🔗 Apple's Official Documentation: https://developer.apple.com/documentation/avfoundation/avcapturedevice/devicetype-swift.struct/external The documentation clearly states that iPadOS 17.0+ and iOS 17.0+ support external devices. However, in my actual tests: On iPhone, discoverySession does not detect any external devices. On iPad, discoverySession can detect external devices without any issues. My Question: Does iPhone USB-C actually support external devices (e.g., UVC cameras)? If not, why does Apple's documentation claim that iOS 17 supports external devices instead of specifying iPadOS 17 only?

I have been using SDAVAssetExportSession to compress videos in an app I am building, everything goes very smoothly until I have my new Iphone16, on the device, the spatial audio in camera setting is turned on by default, then the SDAVAssetExportSession starts to fail. I know it has something to do with audioSetting. the current setting is something like this: exportSession.audioSettings = [ AVFormatIDKey: kAudioFormatMPEG4AAC, AVNumberOfChannelsKey: 2, AVSampleRateKey: 44100, AVEncoderBitRateKey: 128000 ] And also, this is passed to the underlying object AVAssetReader or AVAssetWriter. I am not experienced in this area, and I really had a hard time trying to figure out. Does anyone know how to set up AVAssetReader or AVAssetWriter to process video with spatial audio tracks ? thanks in advance.

When we use AVPlayer to play DRM encrypted streams, it will not play normally under iOS 17.6.1 system version, and there is a high probability of system restart. This is the relevant core error log: error 14:47:53.323369+0800 audiomxd [AirPlayError] carManager_copyProperty_block_invoke:499: got error -12784/0xFFFFCE10 kCMBaseObjectError_PropertyNotFound error 14:47:53.323414+0800 audiomxd [SPEndpointManagerFactory] SidePlay Endpoint Manager creation failed with -72390/0xFFFEE53A error 14:47:53.364949+0800 audiomxd [APBrowserCarSessionHelper] [0xF6AA] [Bonjour/WiFi] Unrecognized ConnectivityHelper event 101 error 14:47:53.375313+0800 audiomxd AddInstanceForFactory: No factory registered for id <CFUUID 0xa5c5118c0> F8BB1C28-BAE8-11D6-9C31-00039315CD46

If you have two video segments, one HDR and one SDR, next to one another in a composition, the SDR one appears dark, since its max luminance will be lower than the max luminance of the HDR clip. iMovie handles this well by (reverse) tone mapping the SDR content to make it look HDR in an HDR composition. This is what I want to achieve. I've looked into algorithms to do this, and the best that I can find is the conversion from RGB to YCbCr described in Table 4 of BT.2020, followed by conversion method A (Section 4.2, table 4) of BT.2446-1. I have these implemented in a Core Image kernel, available at this repo. The issue that I'm seeing is that the colors are still much too hot, and while there are frames that appear close to properly tone mapped, it doesn't come close to the accuracy of iMovie's approach. If someone is an expert in colorimetry, etc., I'd really appreciate a breakdown of what I'm doing wrong here. To be specific: Assuming non-constant luminance for the YCbCr conversion Using a Metal Core Image kernel for the actual tone mapping The video composition uses Core Image filters directly The video composition is using BT.2020 colorimetry and the PQ transfer function. Below is a comparison of two screenshots, one using an unaltered HDR asset, and the other using the same asset transcoded to SDR with QuickTime, and reverse tone mapped to HDR for playback. Is there something I'm missing?