Hello, I am currently developing a live streaming application using AVPlayer to play LL-HLS (Low-Latency HLS) content. During our testing phase, we consistently encountered the following error in the logs: CoreMediaErrorDomain Code=-15517 The challenge we are facing is that the error description is quite vague. It only provides cryptic messages such as "Key not found" or "No value information," which makes it extremely difficult to identify the root cause or perform a deep-dive analysis. I have searched through the official Apple Developer documentation and technical notes, but I couldn’t find any specific reference to what Code -15517 signifies in the context of LL-HLS or CoreMedia. Regarding this issue, I have the following questions: What is the specific meaning of this error code (-15517)? Does it relate to missing tags in the HLS manifest, or is it an internal state issue within the AVPlayer stack? Specifically, I would like to know if this is a critical error that disrupts playback, or if it is just a warning that can be safely ignored. Is there any additional logging or debugging tool you would recommend to further investigate "Key not found" issues in LL-HLS? Any insights or guidance from the community or Apple engineers would be greatly appreciated. Thank you in advance for your help.

Hi everyone, Our team is encountering a reproducible crash when using VTLowLatencyFrameInterpolation on iOS 26.3 while processing a live LL-HLS input stream. 🤖 Environment Device: iPhone 16 OS: iOS 26.3 Xcode: Xcode 26.3 Framework: VideoToolbox 💥 Crash Details The application crashes with the following fatal error: Fatal error: Swift/ContiguousArrayBuffer.swift:184: Array index out of range The stack trace highlights the following: VTLowLatencyFrameInterpolationImplementation processWithParameters:frameOutputHandler: Called from VTFrameProcessor.process(parameters:) Here is the simplified implementation block where the crash occurs. (Note: PrismSampleBuffer and PrismLLFIError are our internal custom wrapper types). // Create `VTFrameProcessorFrame` for the source (previous) frame. let sourcePTS = sourceSampleBuffer.presentationTimeStamp var sourceFrame: VTFrameProcessorFrame? if let pixelBuffer = sourceSampleBuffer.imageBuffer { sourceFrame = VTFrameProcessorFrame(buffer: pixelBuffer, presentationTimeStamp: sourcePTS) } // Validate the source VTFrameProcessorFrame. guard let sourceFrame else { throw PrismLLFIError.missingImageBuffer } // Create `VTFrameProcessorFrame` for the next frame. let nextPTS = nextSampleBuffer.presentationTimeStamp var nextFrame: VTFrameProcessorFrame? if let pixelBuffer = nextSampleBuffer.imageBuffer { nextFrame = VTFrameProcessorFrame(buffer: pixelBuffer, presentationTimeStamp: nextPTS) } // Validate the next VTFrameProcessorFrame. guard let nextFrame else { throw PrismLLFIError.missingImageBuffer } // Calculate interpolation intervals and allocate destination frame buffers. let intervals = interpolationIntervals() let destinationFrames = try framesBetween(firstPTS: sourcePTS, lastPTS: nextPTS, interpolationIntervals: intervals) let interpolationPhase: [Float] = intervals.map { Float($0) } // Create VTLowLatencyFrameInterpolationParameters. // This sets up the configuration required for temporal frame interpolation between the previous and current source frames. guard let parameters = VTLowLatencyFrameInterpolationParameters( sourceFrame: nextFrame, previousFrame: sourceFrame, interpolationPhase: interpolationPhase, destinationFrames: destinationFrames ) else { throw PrismLLFIError.failedToCreateParameters } try await send(sourceSampleBuffer) // Process the frames. // Using progressive callback here to get the next processed frame as soon as it's ready, // preventing the system from waiting for the entire batch to finish. for try await readOnlyFrame in self.frameProcessor.process(parameters: parameters) { // Create an interpolated sample buffer based on the output frame. let newSampleBuffer: PrismSampleBuffer = try readOnlyFrame.frame.withUnsafeBuffer { pixelBuffer in try PrismLowLatencyFrameInterpolation.createSampleBuffer(from: pixelBuffer, readOnlyFrame.timeStamp) } // Pass the newly generated frame to the output stream. try await send(newSampleBuffer) } 🙋 Questions Are there any known limitations or bugs regarding VTLowLatencyFrameInterpolation when handling live 60fps streams? Are there any undocumented constraints we should be aware of regarding source/previous frame timing, pixel buffer attributes, or how destinationFrames and interpolationPhase arrays must be allocated? Is a "warm-up" sequence recommended after startSession() before making the first process(parameters:) call?

Summary On iOS 26, HLS alternate audio track selection behaves inconsistently on both VOD and live streams: the French track falls back to the DEFAULT=YES (English) track after manual selection, and in some cases switching to a non-default track appears to work but it is then impossible to switch back to English. Environment iOS version: 26 Players affected: native Safari on iOS 26 and THEOplayer (issue also reproducible on THEOplayer's own demo page) Stream type: HLS/CMAF with demuxed alternate audio renditions (CMFC container) Affected stream types: both VOD and live streaming Issue NOT present on iOS 17/18 Manifest #EXTM3U #EXT-X-VERSION:4 #EXT-X-INDEPENDENT-SEGMENTS #EXT-X-STREAM-INF:BANDWIDTH=8987973,AVERAGE-BANDWIDTH=8987973,VIDEO-RANGE=SDR,CODECS="avc1.640028",RESOLUTION=1920x1080,FRAME-RATE=29.970,AUDIO="program_audio" video_1080p.m3u8 #EXT-X-MEDIA:TYPE=AUDIO,GROUP-ID="program_audio",LANGUAGE="en",ASSOC-LANGUAGE="en",NAME="English",AUTOSELECT=YES,DEFAULT=YES,CHANNELS="2",URI="audio_ENG.m3u8" #EXT-X-MEDIA:TYPE=AUDIO,GROUP-ID="program_audio",LANGUAGE="de",ASSOC-LANGUAGE="de",NAME="Deutsch",AUTOSELECT=YES,DEFAULT=NO,CHANNELS="2",URI="audio_DEU.m3u8" #EXT-X-MEDIA:TYPE=AUDIO,GROUP-ID="program_audio",LANGUAGE="fr",ASSOC-LANGUAGE="fr",NAME="Francais",AUTOSELECT=YES,DEFAULT=NO,CHANNELS="2",URI="audio_FRA.m3u8" Steps to Reproduce Load the HLS manifest (VOD or live) in Safari on iOS 26, or in any AVFoundation-backed player Start playback — English plays correctly as DEFAULT Manually select "Francais" from the audio track selector Observe that English audio continues playing (French does not play) In a separate scenario: manually select "Deutsch" — German plays correctly Attempt to switch back to English — English does not resume; audio remains on the previously selected track Expected behavior Selecting any track should immediately switch to that language Switching back to English (DEFAULT=YES) should work at any time Behavior should be consistent across VOD and live streams Actual behavior Two distinct anomalies observed, reproducible on both VOD and live streams, in both native Safari and THEOplayer: French-specific fallback: selecting the French track causes playback to fall back to English. This does not happen with German. Cannot return to English: in cases where a non-default track plays correctly, attempting to switch back to the DEFAULT=YES track (English) fails — the previous non-default track continues playing. The fact that the issue reproduces in native Safari confirms this is an AVFoundation/WebKit-level regression, not a third-party player bug. What we have already verified and ruled out LANGUAGE codes are BCP-47 compliant (en, fr, de) ✓ EXT-X-VERSION:4 is present ✓ Audio codec removed from STREAM-INF CODECS (video-only) ✓ ASSOC-LANGUAGE attribute added matching LANGUAGE value ✓ Container metadata verified via ffprobe: mdhd box correctly contains language tags (e.g. "fra") ✓ Audio segment content verified via ffplay: correct audio in each language file ✓ French audio source file contains correct French audio content ✓ Issue reproduces in native Safari on iOS 26, confirming it is not a THEOplayer-specific bug Issue does NOT reproduce on iOS 17/18 with the same manifest and segments Additional notes The VOD stream is packaged with AWS MediaConvert, CMAF output group, SEGMENTED_FILES, AAC-LC codec (mp4a.40.2), 128kbps, 48kHz stereo. English uses AudioTrackType ALTERNATE_AUDIO_AUTO_SELECT_DEFAULT; French and German use ALTERNATE_AUDIO_AUTO_SELECT. The live stream uses AWS MediaPackage with a similar CMAF/HLS output configuration. Please advise whether this is a known regression in AVFoundation on iOS 26 and whether a fix is planned.

Hello,We have been working on FPS for a while and managed to play an encrypted asset with it, using version 2 of FairPlay Streaming Server SDK 2.03.Now we are working on "Download and Play Offline" functionality. For this I have downloaded the FairPlay Streaming Server SDK 3.0 and in SDK Folder there is "OfflineHLSGuide_withFPS.pdf" document beside "FairPlayStreaming_PG.pdf" where they tell about how it works and what need to be done.In that document ("OfflineHLSGuide_withFPS.pdf") there is new version of Content Key Duration TLLV which is slightly different than the structure shown in "FairPlayStreaming_PG.pdf"For Content Key Duration TLLV (0x47acf6a418cd091a) in "FairPlayStreaming_PG" there is "Lease Duration" between bytes 16-19.But in the document about OfflineHLSGuide, it says "Reserved" for bytes between 16-19.Where has LeaseDuration gone for offline? ORShould I use one ContentKeyDuration TLLV for non-persist and other version of ContentKeyDuration TLLV for (persist)offline?Thanks

The same H265 encrypted Fairplay content can be played in all Apple devices except A1625. The clear H265 content is played in A1625. The question is: will this model (A1625) support H265 Fairplay encrypted content? A ticket was created here: https://discussions.apple.com/thread/255658006?sortBy=best

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?

The app registers a periodic time observer to the AVPlayer when the playback starts and it works fine. When switching to AirPlay during playback, the periodic time observation continues working as expected. However, when switching back to local playback, the periodic time observer does not fire anymore until a seek is performed. The app removes the periodic time observer only when the playback stops. I can see that when switching back to local playback, the timeControlStatus successively changes to .waitingToPlayAtSpecifiedRate (reason: .evaluatingBufferingRate) then to .waitingToPlayAtSpecifiedRate (reason: .toMinimizeStalls) and finally to .playing But the time observation does not work anymore. Also, the issue is systematic with Live and VOD streams providing a program date (with HLS property #EXT-X-PROGRAM-DATE-TIME), with or without any DRM, and is never reproduced with other VOD streams.

Hi everyone! I’ve been working with AVFoundation and trying to use the AVMetricEventStreamPublisher to discover media performance metrics, as described in the Apple documentation. https://developer.apple.com/cn/videos/play/wwdc2024/10113/?time=508 However, when following the example code, I’m not getting the expected results. The performance metrics for both audio and video don’t seem to be captured properly. Has anyone successfully used this example code? If so, could you share your experience or any solutions you’ve found? Any tips or insights would be greatly appreciated. Thanks in advance! Ps. the example code: AVPlayerItem *item = ... AVMetricEventStream *eventStream = [AVMetricEventStream eventStream]; id subscriber = [[MyMetricSubscriber alloc] init]; [eventStream setSubscriber:subscriber queue:mySerialQueue] [eventStream subscribeToMetricEvent:[AVMetricPlayerItemLikelyToKeepUpEvent class]]; [eventStream subscribeToMetricEvent:[AVMetricPlayerItemPlaybackSummaryEvent class]]; [eventStream addPublisher:item];

the problem is when using HLS live stream with AVPlayer on iOS/ tvOS the player chooses first highest bandwidth then slowly steps down to lowest (within 1-3min) and eventually steps up again then repeats to step down. the AVPlayer error log sends events: errorStatusCode: -12888, errorDomain: Optional("CoreMediaErrorDomain"), errorComment: Optional("The operation couldn't be completed. (CoreMediaErrorDomain error -12888 - Playlist File unchanged for longer than 1.5 * target duration we use standard segments in CMAF format, 2sec duration #EXTM3U #EXT-X-VERSION:6 #EXT-X-TARGETDURATION:2 #EXT-X-MEDIA-SEQUENCE:147065903 #EXT-X-MAP:URI="video_1_4660000_init.mp4?device_profile=cmaf_cbcs_verimatrix_cei%26seg_size=2%26cmaf=2" #EXT-X-PROGRAM-DATE-TIME:2025-04-30T12:51:07 #EXTINF:2.000, video_1_4660000_t17460174670001555.mp4?device_profile=cmaf_cbcs_verimatrix_cei%26seg_size=2%26cmaf=2 #EXTINF:2.000, video_1_4660000_t17460174690001555.mp4?device_profile=cmaf_cbcs_verimatrix_cei%26seg_size=2%26cmaf=2 #EXTINF:2.000, video_1_4660000_t17460174710001555.mp4?device_profile=cmaf_cbcs_verimatrix_cei%26seg_size=2%26cmaf=2 when using 6sec segments the player stays stable at highest bandwidth. is there a way to avoid this error? in AVPlayer or HLS configuration?

TL;DR How to solve possible racing issue of EXT-X-SESSION-KEY request and encrypted media segment request? I'm having trouble using custom AVAssetResourceLoaderDelegate with video manifest containing VideoProtectionKey(VPK). My master manifest contains rendition manifest url and VPK url. When not using custom resource delegate, everything works fine. My custom resource delegate is implemented in way where it first append prefix to scheme of the master manifest url before creating the asset. And during handling master manifest, it puts back original scheme, make the request, modify the scheme for rendition manifest url in the response content by appending the same prefix again, so that rendition manifest request also goes into custom resource loader delegate. Same goes for VPK request. The AES-128 key is stored in memory within custom resource loader delegate object. So far so good. The VPK is requested before segment request. But the problem comes where the media segment requests happen. The media segment request url from rendition manifest goes into custom resource loader as well and those are encrypted. I can see segment request finish first then the related VPK requests kick in after a few seconds. The previous VPK value is cached in memory so it is not network causing the delay but some mechanism that I'm not aware of causing this. So could anyone tell me what would be the proper way of handling this situation? The native library is handling it well so I just want to know how. Thanks in advance!

Hi everyone, We’re currently developing a music-based app using MusicKit, and we recently noticed that iOS 26 beta introduces a new “Automix” feature in the Apple Music app. This enables seamless DJ-style transitions between songs—beyond the standard crossfade functionality. We’re trying to understand: Will this Automix feature be accessible to third-party apps that use MusicKit? If not available in the initial iOS 26 release, is there a plan to expose it through public APIs in a future update? Is there any technical documentation, WWDC session, or roadmap info regarding Automix support via MusicKit? This functionality would be a significant enhancement for our app, especially for intelligent audio transitions and curated playlists. Thanks.

The documentation for the Apple Music API indicates that the genreNames field for a given artist (see https://developer.apple.com/documentation/applemusicapi/artists/attributes-data.dictionary) is an array of strings. However, it only appears as though you return ONE SINGLE GENRE per Artist, regardless of how many genres might be attached to that artist's albums. Am I missing something? Is there an artist where multiple genres may be returned, or is this a bug in the documentation?

Hi everyone, I noticed that Apple recently added a few new beta sample codes related to video encoding: Encoding video for low-latency conferencing Encoding video for live streaming While experimenting with H.264 encoding, I came across some questions regarding certain configurations: When I enable kVTVideoEncoderSpecification_EnableLowLatencyRateControl, is it still possible to use kVTCompressionPropertyKey_VariableBitRate? In my tests, I get an error. It also seems that kVTVideoEncoderSpecification_EnableLowLatencyRateControl cannot be used together with kVTCompressionPropertyKey_ConstantBitRate when encoding H264. Is that expected? When using kVTCompressionPropertyKey_ConstantBitRate with kVTCompressionPropertyKey_MaxKeyFrameInterval set to 2, the encoder outputs only keyframes, and the frame size keeps increasing, which doesn’t seem like the intended behavior. Regarding the following code from the sample: let byteLimit = (Double(bitrate) / 8) * 1.5 as CFNumber let secLimit = Double(1.0) as CFNumber let limitsArray = [ byteLimit, secLimit ] as CFArray // Each 1 second limit byte as bitrate err = VTSessionSetProperty(session, key: kVTCompressionPropertyKey_DataRateLimits, value: limitsArray) This DataRateLimits setting doesn’t seem to have any effect in my tests. Whether I set it or not, the values remain unchanged. Since the documentation on developer.apple.com/documentation doesn’t clearly explain these cases, I’d like to ask if anyone has insights or recommendations about the proper usage of these settings. Thanks in advance!

Hi there, We're working on offline playback of DRM tracks. The persistent keys (also known as track licenses) for offline playback are stored locally on the device and are served from cache when a user initiates playback of a downloaded track. Our persistent keys have a limited validity time and need to be refreshed when they expire. To prevent a situation where a persistent key expires while the user is offline, we've decided to eagerly refresh these keys one week before their expiration date. To make that happen we need to be able to obtain the expiration date of the given track license. We've been attempting to use the makeSecureTokenForExpirationDateOfPersistableContentKey API to facilitate this process. The documentation states that this API returns a secret token representing the persistent key, which we can then exchange with our license server for the expiration date: https://developer.apple.com/documentation/avfoundation/avcontentkeysession/makesecuretokenforexpirationdate(ofpersistablecontentkey:completionhandler:)?language=objc However, every time we call makeSecureTokenForExpirationDateOfPersistableContentKey, we receive an error with code -46250. We haven't been able to find any public references or documentation for this specific error code, which is preventing us from troubleshooting the issue. We are conducting our tests on a physical device, as the simulator does not support FairPlay playback. We don't use dual expiry approach. Is our understanding of how to obtain the expiration timestamp correct? Are we using the makeSecureTokenForExpirationDateOfPersistableContentKey API as it was intended? What does the -46250 error code mean, and what steps should we take to fix our FairPlay implementation to make this work? Thanks in advance for your assistance.

The operation couldn’t be completed. (CoreMediaErrorDomain error -19156 - The operation couldn’t be completed. (CoreMediaErrorDomain error -19156.

Hello, We have Video Stream app. It has HLS VOD Content. We supply 1080p, 4K Contents to users. Users were watching 1080p content before tvOS 26. Users can not watch 1080p content anymore when they update to tvOS 26. We have not changed anything at HLS playlist side and application version. This problem only occurs on Apple TV 4th Gen (A1625) tvOS 26 version. There is no problem with newer Apple TV devices. Would you help to resolve problem? Thanks in advance

quotes are displayed incorrectly in subtitles of AVPlayerViewController when streaming VOD content using HLS. single quote ' (escaped ') is displayed as apos; double quotes " (escaped ") is displayed as quot; following the vtt specification. The same stream works fine in VLC player, showing quotes correctly in subtitles. subtitle vtt files use Content-Type: text/vtt WEBVTT X-TIMESTAMP-MAP=LOCAL:490014:06:04.000,MPEGTS:158764568760056 example line: 490014:05:46.000 --> 490014:05:50.440 align:start line:83% position:14% and the playlist has: #EXT-X-MEDIA:TYPE=SUBTITLES,GROUP-ID="subs",LANGUAGE="da",NAME="Dansk",AUTOSELECT=YES,CHARACTERISTICS="public.accessibility.transcribes-spoken-dialog,public.accessibility.describes-music-and-sound",URI="subs/dan_5/playlist.m3u8 #EXT-X-STREAM-INF:BANDWIDTH=780000,CODECS="mp4a.40.5,avc1.42c01e",RESOLUTION=256x144,AUDIO="audio-aac",SUBTITLES="subs" lære dig endnu bedre at kende." adding 'wvtt' to CODECS list in playlist does not make a difference. Is this a known bug? Is there a workaround? I guess the AVResourceLoaderDelegate can be used to intercept and parse the subtitle files, but it seems like quite a hack and not really intended to be used for this.

Hello there, I'm trying to implement feature which uses AirPlay with Apple TV. I want to disconnect from the device programmatically when something happens. Under something I mean a situation when a user wants to stop broadcasting (for example close the PiP window on his phone). I use this snippet: try audioSession.setCategory(.playAndRecord, options: .defaultToSpeaker) try audioSession.setActive(true, options: .notifyOthersOnDeactivation) It works fine sometimes but not always (it works on iOS 18 but it doesn't on iOS 17 or ). So I thought it's a bug and create a ticker to feedback assistant (FB21220013). The support told me write a post on the forum.

Hello, I am developing a custom player SDK using AVPlayer to support HLS and LL-HLS live streaming. I have some questions about the internal logic of AVPlayer regarding ABR, as this information is not explicitly covered in the documentation. ABR Switching Logic: Does AVPlayer trigger bitrate switching primarily based on stall occurrences (buffer starvation)? I am curious if the switching logic is reactive to stalls or if it proactively switches to prevent them based on throughput estimation. Developer Controls for ABR: To influence or control the ABR selection, are preferredPeakBitRate and preferredForwardBufferDuration the only properties available to developers? Are there any other recommended APIs to assist with ABR decisions? Thank you for your help.

Hi We’re updating our KSM to support SPC v2/v3 and currently operate with both legacy SDK4 credentials (ASK + 1024 cert) and SDK26 credentials (certificate bundle + provisioning data + 1024/2048 keys). Our client apps run across a wide range of iOS/tvOS versions, so we want to follow Apple’s recommended client strategy for certificate selection. The docs describe SHA‑1 vs SHA‑256 in the SPC header, but do not specify which OS versions should use SDK4 vs SDK26 credentials. Could you clarify: Is there an official minimum iOS/tvOS version where you recommend SDK26 credentials for client apps? For older OS versions (e.g. iOS 15), is SDK4 still the recommended choice for client apps? Are there any official migration guidelines for client apps moving from SDK4 to SDK26 credentials? Thanks in advance.