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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iOS Radio App: Need to extract and stream audio-only from HLS streams with video content
I'm developing an iOS radio app that plays various HLS streams. The challenge is that some stations broadcast HLS streams containing both audio and video (example: https://svs.itworkscdn.net/smcwatarlive/smcwatar/chunks.m3u8), but I want to: Extract and play only the audio track Support AirPlay for audio-only streaming Minimize data usage by not downloading video content Technical Details: iOS 17+ Swift 5.9 Using AVFoundation for playback Current implementation uses AVPlayer with AVPlayerItem Current Code Structure: class StreamPlayer: ObservableObject { @Published var isPlaying = false private var player: AVPlayer? private var playerItem: AVPlayerItem? func playStream(url: URL) { let asset = AVURLAsset(url: url) playerItem = AVPlayerItem(asset: asset) player = AVPlayer(playerItem: playerItem) player?.play() } Stream Analysis: When analyzing the video stream using FFmpeg: CopyInput #0, hls, from 'https://svs.itworkscdn.net/smcwatarlive/smcwatar/chunks.m3u8': Stream #0:0: Video: h264, yuv420p(tv, bt709), 1920x1080 [SAR 1:1 DAR 16:9], 25 fps Stream #0:1: Audio: aac, 44100 Hz, stereo, fltp Attempted Solutions: Using MobileFFmpeg: let command = [ "-i", streamUrl, "-vn", "-acodec", "aac", "-ac", "2", "-ar", "44100", "-b:a", "128k", "-f", "mpegts", "udp://127.0.0.1:12345" ].joined(separator: " ") ffmpegProcess = MobileFFmpeg.execute(command) Issue: While FFmpeg successfully extracts audio, playback through AVPlayer doesn't work reliably. Tried using HLS output: let command = [ "-i", streamUrl, "-vn", "-acodec", "aac", "-ac", "2", "-ar", "44100", "-b:a", "128k", "-f", "hls", "-hls_time", "2", "-hls_list_size", "3", outputUrl.path ] Issue: Creates temporary files but faces synchronization issues with live streams. Requirements: Real-time audio extraction from HLS stream Maintain live streaming capabilities Full AirPlay support Minimal data usage (avoid downloading video content) Handle network interruptions gracefully Questions: What's the most efficient way to extract only audio from an HLS stream in real-time? Is there a way to tell AVPlayer to ignore video tracks completely? Are there better alternatives to FFmpeg for this specific use case? What's the recommended approach for handling AirPlay with modified streams? Any guidance or alternative approaches would be greatly appreciated. Thank you!
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Use AVPlayer for multiple videos
I'm developing a tutorial style tvOS app with multiple videos. The examples I've seen so far deal with only one video. Defining the player and source(url) before body view let avPlayer = AVPlayer(url: URL(string: "https://domain.com/.../.../video.mp4")!)) and then in the body view the video is displayed VideoPlayer(player: avPlayer) This allows options such as stop/start etc. When I try something similar with a video title passed into this view I can't define the player with this title variable. var vTitle: String var avPlayer = AVPlayer(url: URL(string: "https://domain.com/.../.../" + vTitle + ".mp4"")!)) var body: some View { I het an error that vTitle can't be used in the url above the body view. Any thoughts or suggestions? Thanks
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HLS CMAF/fMP4 CENC CBCS pattern encryption
Hello, I'm writing a program to create CMAF compliant HLS files, with encryption. I have a copy of ISO_IEC_23001-7_2023 to attempt to follow the spec. I am following the 1:9 pattern encryption using CBCS, so for every 16 bytes of encrypted NAL unit data (of type 1 and 5), there's 144 bytes of clear data. When testing my output in Safari with 'identity' keys Quickly Diagnosing Content Key and IV Issues, Safari will request the identity key from my test server and first few bytes of the CMAF renditions, but will not play and console gives away no clues to the error. I am setting the subsample bytesofclear/protected data in the senc boxes. What I'm not sure of, is whether HLS/Safari/iOS acknowledges the senc/saiz/saio boxes of the MP4. There are other third party packagers Bento4, who suggest that they do not: those clients ignore the explicit encryption layout metadata found in saio/saiz boxes, and instead rely purely on the video slice header size to determine the portions of the sample that is encrypted So now I'm fairly sure I need to decipher the video slice header size, and apply the protected blocks from that point on. My question is, is that all there is to it? And is there a better way to debug my output? mediastreamvalidator will only work against unencrypted variants (which I'm outputting okay). Thanks in advance!
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Decode HLS livestream with VideoToolbox
Hi, I'm trying to decode a HLS livestream with VideoToolbox. The CMSampleBuffer is successfully created (OSStatus == noErr). When I enqueue the CMSampleBuffer to a AVSampleBufferDisplayLayer the view isn't displaying anything and the status of the AVSampleBufferDisplayLayer is 1 (rendering). When I use a VTDecompressionSession to convert the CMSampleBuffer to a CVPixelBuffer the VTDecompressionOutputCallback returns a -8969 (bad data error). What do I need to fix in my code? Do I incorrectly parse the data from the segment for the CMSampleBuffer? let segmentData = try await downloadSegment(from: segment.url) let (sps, pps, idr) = try parseH264FromTSSegment(tsData: segmentData) if self.formatDescription == nil { self.formatDescription = try CMFormatDescription(h264ParameterSets: [sps, pps]) } if let sampleBuffer = try createSampleBuffer(from: idr, segment: segment) { try self.decodeSampleBuffer(sampleBuffer) } func parseH264FromTSSegment(tsData: Data) throws -> (sps: Data, pps: Data, idr: Data) { let tsSize = 188 var pesData = Data() for i in stride(from: 0, to: tsData.count, by: tsSize) { let tsPacket = tsData.subdata(in: i..<min(i + tsSize, tsData.count)) guard let payload = extractPayloadFromTSPacket(tsPacket) else { continue } pesData.append(payload) } let nalUnits = parseNalUnits(from: pesData) var sps: Data? var pps: Data? var idr: Data? for nalUnit in nalUnits { guard let firstByte = nalUnit.first else { continue } let nalType = firstByte & 0x1F switch nalType { case 7: // SPS sps = nalUnit case 8: // PPS pps = nalUnit case 5: // IDR idr = nalUnit default: break } if sps != nil, pps != nil, idr != nil { break } } guard let validSPS = sps, let validPPS = pps, let validIDR = idr else { throw NSError() } return (validSPS, validPPS, validIDR) } func extractPayloadFromTSPacket(_ tsPacket: Data) -> Data? { let syncByte: UInt8 = 0x47 guard tsPacket.count == 188, tsPacket[0] == syncByte else { return nil } let payloadStart = (tsPacket[1] & 0x40) != 0 let adaptationFieldControl = (tsPacket[3] & 0x30) >> 4 var payloadOffset = 4 if adaptationFieldControl == 2 || adaptationFieldControl == 3 { let adaptationFieldLength = Int(tsPacket[4]) payloadOffset += 1 + adaptationFieldLength } guard adaptationFieldControl == 1 || adaptationFieldControl == 3 else { return nil } let payload = tsPacket.subdata(in: payloadOffset..<tsPacket.count) return payloadStart ? payload : nil } func parseNalUnits(from h264Data: Data) -> [Data] { let startCode = Data([0x00, 0x00, 0x00, 0x01]) var nalUnits: [Data] = [] var searchRange = h264Data.startIndex..<h264Data.endIndex while let range = h264Data.range(of: startCode, options: [], in: searchRange) { let nextStart = h264Data.range(of: startCode, options: [], in: range.upperBound..<h264Data.endIndex)?.lowerBound ?? h264Data.endIndex let nalUnit = h264Data.subdata(in: range.upperBound..<nextStart) nalUnits.append(nalUnit) searchRange = nextStart..<h264Data.endIndex } return nalUnits } private func createSampleBuffer(from data: Data, segment: HLSSegment) throws -> CMSampleBuffer? { var blockBuffer: CMBlockBuffer? let alignedData = UnsafeMutableRawPointer.allocate(byteCount: data.count, alignment: MemoryLayout<UInt8>.alignment) data.copyBytes(to: alignedData.assumingMemoryBound(to: UInt8.self), count: data.count) let blockStatus = CMBlockBufferCreateWithMemoryBlock( allocator: kCFAllocatorDefault, memoryBlock: alignedData, blockLength: data.count, blockAllocator: nil, customBlockSource: nil, offsetToData: 0, dataLength: data.count, flags: 0, blockBufferOut: &blockBuffer ) guard blockStatus == kCMBlockBufferNoErr, let validBlockBuffer = blockBuffer else { alignedData.deallocate() throw NSError() } var sampleBuffer: CMSampleBuffer? var timing = [calculateTiming(for: segment)] var sampleSizes = [data.count] let sampleStatus = CMSampleBufferCreate( allocator: kCFAllocatorDefault, dataBuffer: validBlockBuffer, dataReady: true, makeDataReadyCallback: nil, refcon: nil, formatDescription: formatDescription, sampleCount: 1, sampleTimingEntryCount: 1, sampleTimingArray: &timing, sampleSizeEntryCount: sampleSizes.count, sampleSizeArray: &sampleSizes, sampleBufferOut: &sampleBuffer ) guard sampleStatus == noErr else { alignedData.deallocate() throw NSError() } return sampleBuffer } private func decodeSampleBuffer(_ sampleBuffer: CMSampleBuffer) throws { guard let formatDescription = CMSampleBufferGetFormatDescription(sampleBuffer) else { throw NSError() } if decompressionSession == nil { try setupDecompressionSession(formatDescription: formatDescription) } guard let session = decompressionSession else { throw NSError() } let flags: VTDecodeFrameFlags = [._EnableAsynchronousDecompression, ._EnableTemporalProcessing] var flagOut = VTDecodeInfoFlags() let status = VTDecompressionSessionDecodeFrame( session, sampleBuffer: sampleBuffer, flags: flags, frameRefcon: nil, infoFlagsOut: nil) if status != noErr { throw NSError() } } private func setupDecompressionSession(formatDescription: CMFormatDescription) throws { self.formatDescription = formatDescription if let session = decompressionSession { VTDecompressionSessionInvalidate(session) self.decompressionSession = nil } var decompressionSession: VTDecompressionSession? var callback = VTDecompressionOutputCallbackRecord( decompressionOutputCallback: decompressionOutputCallback, decompressionOutputRefCon: Unmanaged.passUnretained(self).toOpaque()) let status = VTDecompressionSessionCreate( allocator: kCFAllocatorDefault, formatDescription: formatDescription, decoderSpecification: nil, imageBufferAttributes: nil, outputCallback: &callback, decompressionSessionOut: &decompressionSession ) if status != noErr { throw NSError() } self.decompressionSession = decompressionSession } let decompressionOutputCallback: VTDecompressionOutputCallback = { ( decompressionOutputRefCon, sourceFrameRefCon, status, infoFlags, imageBuffer, presentationTimeStamp, presentationDuration ) in guard status == noErr else { print("Callback: \(status)") return } if let imageBuffer = imageBuffer { } }
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Fairplay error on MacOS catalyst
Hi, I have a IOS app and we are using fairplay DRM to play videos. In IOS app we are allowing offline download of the videos and hence we are getting a persistent fairplay license. In IOS app everything is working fine. Now we have used the same app and built for MacOS catalyst. In MAC OS catalyst app we are not able to play the video and getting error code -42650 We are able to get the persistent license from server, but when we play the video with the license we are getting the error. Below are the logs: 2024-12-06 22:05:48.911266+0530 0x4dffe2 Default 0x0 85505 0 teachonline: (MediaToolbox) [com.apple.coremedia:] &lt;&lt;&lt;&lt; FigPKDKeyManager &gt;&gt;&gt;&gt; keyManager_processOfflineKeyInternal: 0x600000322000 160D4519-C60B-4FD0-B69A-20B2A4597017 created decrypt context:0x0 with offline key; updated offline key:0x0 err:-42650 2024-12-06 22:05:48.911369+0530 0x4dffe2 Default 0x0 85505 0 teachonline: (MediaToolbox) [com.apple.coremedia:player] &lt;&lt;&lt;&lt; FigStreamPlayer &gt;&gt;&gt;&gt; fpfs_ensureDecryptorHasStarted: [0x7fc44e4dc520|P/NW] &lt;0x7fc44fa44000|I/SRA.01&gt;: track 1 latching decryptorFailure -42650 85505 0 teachonline: (MediaToolbox) [com.apple.coremedia:player] &lt;&lt;&lt;&lt; FigStreamPlayer &gt;&gt;&gt;&gt; fpfs_StopPlayingItem: [0x7fc44e4dc520|P/NW] &lt;0x7fc44fa44000|I/SRA.01&gt;: Pausing, err=Error Domain=CoreMediaErrorDomain Code=-42650 "(null)" I have copied only the lines which has errors. You can download the full logs from https://drive.google.com/file/d/1feb9pKZERUr--PMt6m-6IrO_mDvoFbjO/view?usp=sharing Can you please help me to fix the issue.
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Custom FairPlay DRM error handling mechanics
Hi, I have a usecase where I'd like to handle and prevent automatic retries whenever certain errors occur during FairPlay content key requests. Here's the current flow: FairPlay certificate is requested and obtained from my server makeStreamingContentKeyRequestData is called on the keyRequest The license server will return a 403 along with a body response containing a json with the detailed code and message The error is caught and handled properly by calling AVContentKeyRequest.processContentKeyResponseError The AVContentKeySession automatically retries up to 8 times by providing a new key request through public func contentKeySession(_ session: AVContentKeySession, didProvide keyRequest: AVContentKeyRequest) My license server gets hit with 8 requests that will always result in a 403, these retries are useless My custom error is succesfully caught later down the line through AVPlayerItem.observe(\.status), this is great Thing is.. I'd like to catch the 403 error and prevent any retry from being made at step 5, ideally through public func contentKeySession(_ session: AVContentKeySession, contentKeyRequest keyRequest: AVContentKeyRequest, didFailWithError err: Error) I've looked for quite a while and just can't seem to find any way of achieving this. Is this not supported at all?
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Fairplay 4k streams decode errors - no video, audio only
HLS live streaming 4k is not displaying any video, but is streaming audio. Getting the following errors in the console where it shows that it is failing to decode every frame. Can I get some help as to what these error codes refer to and why it would fail to decode? 08:30:42.675879-0800 videocodecd AppleAVD: AppleAVDDecodeFrameInternal(): avdDec - Frame# 3588, DecodeFrame failed with error: 0x196 08:30:42.675908-0800 videocodecd AppleAVD: AppleAVDDisplayCallback(): Asking fig to drop frame # 3588 with err -12909 - internalStatus: 315 08:30:42.697412-0800 videocodecd AppleAVD: AppleAVDDecodeFrameResponse(): Frame# 3589 DecodeFrame failed with error 0x00000196 08:30:42.697876-0800 videocodecd AppleAVD: AppleAVDDecodeFrameInternal(): failed - error: 406
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2w
High bitrate video streaming in avplayer sometimes audio disappears
Hello, I used AVPlayer in my project to play network movie. Most movie could play normally, but I found the sound will disappear sometimes if I play specified 4K video network stream. The video will continue playing but audio stops after video is played for a while. If I pause player and then resume, the sound will be back but disappeared again after several seconds Check AVPlayerItem status: isPlaybackLikelyToKeepUp` == true isPlaybackBufferEmpty` = false player.volume > 0 According the value above, it seems not cause by empty playback buffer or volume issue. I am so confused for this situation. Movie information Video Format : AVC Format/Info : Advanced Video Codec Format profile : High L5.1 Codec ID : avc1 Codec ID/Info : Advanced Video Coding Bit rate mode : Variable Bit rate : 100.0 Mb/s Width : 3 840 pixels Height : 2 160 pixels Display aspect ratio : 16:9 Frame rate mode : Constant Frame rate : 29.970 (30000/1001) FPS Audio Format : AAC LC Format/Info : Advanced Audio Codec Low Complexity Codec ID : mp4a-40-2 Duration : 5 min 19 s Bit rate mode : Constant Bit rate : 192 kb/s Nominal bit rate : 48.0 kb/s Channel(s) : 2 channels Channel layout : L R Sampling rate : 48.0 kHz Frame rate : 46.875 FPS (1024 SPF) Does anyone know if AVPlayer has this limitations when playing high-bitrate movie streams, and are there any solutions?
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228
Nov ’24
CallKit breaks web based MediaStreams
We're integrating a web based group calling application within a native iOS application and finding that every time a CallKit session gets fully established the web based media streams break, rendering as gray with no audio. Up to iOS 18 we worked around it by not fulfilling the call start action but that's no longer an option as the audio stopped getting automatically redirected to the speakers. We would now need the CXProvider's didActivateAudioSession callback but that would break the video. The sample project loads up a simple webpage in a WKWebView which contains a video tag streaming the media from the device's camera. At the same time it sets up a new CallKit session by requesting and fulfilling a CXStartCallAction transaction. You will notice that the media doesn't render and, if you are to follow the warnings we left, you will find that not fulfilling the CXStartCallAction fixes it. Unfortunately that's not a workaround we can use as we need the CXProvider delegate to inform us about audio session changes so we can redirect the audio to the speaker (so the proximity sensor doesn't activate and locking the screen doesn't end the call) Any insights or workarounds would be greatly appreciated.
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Nov ’24
Playback problem on AVPlayer with MPEGTS streams
We are experiencing an issue with our HLS MPEG-TS streams on Apple devices, where the AVPlayer in our iOS app and Safari jumps back to the start when the player automatically changes quality. This occurs despite the stream still indicating that it is live and there is no change in the seekbar. After testing our streams with the Apple HLS Validator, the only problem that occured was an "Measured peak bitrate compared to multivariant playlist declared value exceeds error tolerance"-Error. On Chrome and on our Android-App this playback bug does not happen. Has someone else experienced similar issues with the AVPlayer?
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Nov ’24
AVPlayer HLS Restirect Stream Resulotion
Hello, we have HLS stream app and we use AVPlayer for HLS stream. We want to implement dynamic resulotion feature as user's selection. For example, if user want to watch only 1080p user has to watch only 1080p but we have tried to implement "preferredMaximumResolution" and "preferredPeakBitRate" parameters and but AVPlayer does not force it which means that setting preferredMaximumResolution= CGSize(width: 1920, height: 1080) player does not only force to play 1080p profile, player drops resulotion to 720p but we do not want 720p stream if user selected 1080p resulotion. Is there any method to force it even if stream stalls? Thank you in advance
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221
Oct ’24
Airplay and Screen Mirroring
I cannot mirror or extend my screen from mac mini m2 to iPad 10 gen. Whenever I click on "mirror or extend screen" my external display for mac refreshes after showing "no signal" and comes back on meanwhile my iPad locks out and screen mirror or extending is unsuccessful. But I can mirror my iPad screen to mac mini m2. Earlier everything was working, suddenly it is not working
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Oct ’24
Receiving eventMetadata from AVPlayerItemMetadataOutput stops responding on iOS18 only
Case-ID: 9391388 Our application uses timed Metadata as part of a rating control system. We noticed a problem in production and diagnosis shows that we stop receiving timed Metadata on iOS18 only Our live streams are primed with metadata at least once per second but we are seeing extended gaps in receiving this content, in excess of 10 minutes. We have also observed that this happens more as the player climbs the bitrate ladder, and doesn't happen if we cap to a low resolution i.e. a preferredMaximumResolution of 768x432. Furthermore, if we throttle network conditions after we stop receiving metadata the we start receiving them again. Following is a simple example that demonstrates the above behaviour, unfortunately I cannot share the live stream endpoint which is primed with metadata publicly, but can provide privately to Apple to reproduce the problem. import UIKit import AVKit class ViewController: UIViewController, AVPlayerItemMetadataOutputPushDelegate { var player: AVPlayer? var itemMetadataOutput: AVPlayerItemMetadataOutput? override func viewDidAppear(_ animated: Bool) { guard let url = URL(string: "endpoint redacted") else { return } let player = AVPlayer(url: url) let controller = AVPlayerViewController() controller.player = player self.player = player present(controller, animated: true) { player.play() let currentItem = player.currentItem let itemMetadataOutput = AVPlayerItemMetadataOutput(identifiers: nil) self.itemMetadataOutput = itemMetadataOutput self.itemMetadataOutput?.setDelegate(self, queue: .main) currentItem?.add(itemMetadataOutput) } } public func metadataOutput(_ output: AVPlayerItemMetadataOutput, didOutputTimedMetadataGroups groups: [AVTimedMetadataGroup], from track: AVPlayerItemTrack?) { print("received metadata \(Date())") } }
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569
Oct ’24
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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353
Sep ’24
iOS 18: ApplicationMusicPlayer.Queue breaks if one more songs in Library
Hi there, After upgrading to iOS 18, I noticed that ApplicationMusicPlayer.Queue behavior has broken if at least one song that is added to the queue is also in to the Apple Music Library on the device. The resulting behavior is that the queue does not accept all the items, and only items that are in the Library are playable in the queue. The expected behavior and the previous behavior on iOS 17 was that all the items would be added to the queue successfully. I confirmed this behavior on a separate test device running iOS 17.7. The items added are all being fetched via MusicCatalogResourceRequest<Song> so I would expect that a requested song being present in the library would have no effect.
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549
Sep ’24