Streaming

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Deep dive into the technical specifications that influence seamless playback for streaming services, including bitrates, codecs, and caching mechanisms.

Streaming Documentation

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HLS CMAF playlist with multiple DRM changes
Hi Is it possible to have a playlist where I have a indication of a stream in clear, but then, someone started a DRM encrypted period and then someone turns it off. Can I just do the following (I've removed the video segments part, I'm just interested in the parts where I want notify the new drm region )? #EXT-X-MAP:URI="video_2_10000000_t17586401730000000_init.mp4" #EXT-X-KEY:METHOD=NONE ... #EXT-X-MAP:URI="video_2_10000000_t17587374640000000_init.mp4" #EXT-X-KEY:METHOD=SAMPLE-AES,URI="skd://5df0b36ac4bb4d0ff954a73b502ac332",KEYFORMAT="com.apple.streamingkeydelivery",KEYFORMATVERSIONS="1" ... #EXT-X-MAP:URI="video_2_10000000_t17587376740000000_init.mp4?" #EXT-X-KEY:METHOD=NONE Should I insert discontinuity tags or something else? Right now what I can observe is that I got some audio drops when I try to do this.
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359
Dec ’25
Query regarding migrating from Fairplay Streaming SDK version 4.5.4 to version 26
Our license service is based on version 4.5.4 and we make use of sample .c/.h files for building license service. We are told that version 4.5.4 is going to be deprecated in 2026 and we should migrate to latest SDK version 26. When explored the SDK, we noticed that only python and Swift based SDk is provided. Does Apple also provide C/C++ based SDK as it is going to easier for us to integrate. If yes, please share the SDK package and sample license service solution.
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171
Dec ’25
Why doesn’t AVPlayer / AVFoundation support MPEG-DASH (MPD)? Any public rationale?
Hi, I understand that AVPlayer/AVFoundation doesn’t natively play MPEG-DASH manifests (.mpd) today, while HLS is supported and widely documented by Apple. I’m not asking for roadmap commitments, but I’d like to understand whether there is any publicly documented rationale for not supporting DASH/MPD in AVFoundation (e.g., technical constraints, platform integration, DRM ecosystem, power/performance considerations, etc.). Questions: Is there any Apple statement / documentation explaining why DASH (MPD) isn’t supported in AVFoundation? Is Apple’s recommended approach still “provide HLS for Apple clients” (potentially sharing CMAF segments and generating separate manifests)? If there’s no public rationale, is filing Feedback Assistant the best channel for requesting MPD playback support? Thanks!
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3w
FairPlay Client Question
The ASk is used by the KSM to derive the dASk, which is then used to decrypt the SK...R1. If the only thing we give the client is the certificate, how does it encrypt the SK...R1 so the server is able to process it. Would be nice to know it it works generally, because I've been getting questions about it and can't provide a helpful answer. Thanks in advance.
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99
1w
What does CoreMediaErrorDomain code -15418 indicate during LL-HLS live playback?
Hello, I am currently developing a video player using Custom AVPlayer SDK and testing LL-HLS live streaming. I encountered a specific error, CoreMediaErrorDomain -15418, during playback. I have searched through the official documentation and the forums, but I could not find any information regarding this error code. I would like to inquire about the following: Description & Cause: What does the error code -15418 specifically represent in the context of CoreMedia and LL-HLS? Severity: Is this a critical error that halts playback, or is it merely a warning? Environment Details: iOS Version: iOS 26.2 Device: iPhone 15 Pro Max Stream Type: LL-HLS (Low-Latency HLS) Impact: Quality drops Any insights or references to documentation would be greatly appreciated. Thank you.
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1w
macOS Sonoma 'Cannot Decode' HLS Video
I use AVPlayer to play HLS video successfully on macOS Sonoma, but I encountered this error on macOS Sequoia. Please help me: Error Domain=AVFoundationErrorDomain Code=-11833 ‘Cannot Decode’ UserInfo={NSUnderlyingError=0x600001e57330 {Error Domain=CoreMediaErrorDomain Code=-12906 ‘(null)’}, NSLocalizedFailureReason=The decoder required for this media cannot be found., AVErrorMediaTypeKey=vide, NSLocalizedDescription=Cannot Decode} Thanks!
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658
Mar ’25
Problem with UVC Device Access on visionOS
No external cameras show up in the app on visionOS. We use this sample code as a basis for our tests: https://developer.apple.com/documentation/visionos/displaying-video-from-connected-devices We also received the needed entitlement from Apple, but every camera we tried so far does not show up on visionOS. We tried the following devices and hubs: Insta360 X4 Somikon Endoscope Camera: USB HD Endoscope Camera EMEET Full HD Webcam - C960 BENFEI Video/Audio Capture Card, 4K HDMI auf USB C/A Logitech C920 HD PRO Webcam, Anker PowerConf C200 Insta360 GO 3S Anker 341 USB-C Hub UGREEN Revodok Pro 10Gbps USB-C Hub All Vision Pro devices we tried run with visionOS 2.3. When trying the same code on iPad we can actually use external cameras. Steps to reproduce: Start the app on a Vision Pro device and connect an external camera. The connected camera does not show up in the dropdown. Development environment: Xcode 16.2, macOS 15.3 Run-time configuration: iOS 18.3, visionOS 2.3
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640
Feb ’25
How to receive AVMetricEvent performance data?
I am would like to look at AVMetricEvent data during video playback, so I have added this code to a test video player app: let playerItem: AVPlayerItem = ... let allMetrics = playerItem.allMetrics() Task.init { print("metrics task started") do { for try await metricEvent in allMetrics { print("metric event: \(metricEvent.description)") } } catch { print("unexpected metric iterator error \(error)") } } Running this in Simulator on iPhone 16 Pro (18.0) does not result in any "metric event" diagnostic messages being printed when the video associated with this AVPlayerItem is playing. Only the "metric task started" diagnostic message is seen. What am I doing wrong that prevents metric data being received?
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404
Feb ’25
FairPlay-Protected HLS Files Not Transferred via Quick Start
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?
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203
Mar ’25
AVPlayer periodic time observer stops notifying when switching back from AirPlay to local playback
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.
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131
Apr ’25
Issues with "AVMetricEventStreamPublisher Discover Media Performance Metrics in AVFoundation" Example Code
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];
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Nov ’25
CoreMediaErrorDomain -12888: Bandwidth down-stepping when using 2sec segment duration
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?
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May ’25
Race issue - Custom AVAssetResourceLoaderDelegate cannot work with EXT-X-SESSION-KEY
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!
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130
Jun ’25
Will the new Automix feature in iOS 26 be available for third-party apps using MusicKit?
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.
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770
Nov ’25
Apple Music Artist - genres
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?
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538
Jul ’25
Questions about H.264 encoding settings with low-latency rate control
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!
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Sep ’25
-46250 error when calling `makeSecureTokenForExpirationDateOfPersistableContentKey`
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.
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1w
AVPlayer HLS High Bitrate Problem on Apple TV HD (A1625) tvOS 26
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
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499
Oct ’25