299164 2025-09-19 02:18:58 -0700 REGRESSION (iOS 26): MediaRecorder produces corrupted video/audio files, resulting in some loss of content 2025-11-18 09:46:54 -0800 1 1 1 Unclassified WebKit Media Safari 26 iPhone / iPad iOS 26 RESOLVED FIXED InRadar P2 Normal --- 1 liuyun jean-yves.avenard ap axel.ballarin jer.noble webkit-bug-importer oldest_to_newest 2144296 0 liuyun 2025-09-19 02:18:58 -0700 Hello WebKit Team, We are writing to report a critical regression in the MediaRecorder API behavior observed in the iOS 26 beta. This issue is causing critical failures in our application, as well as in several other third-party libraries we have tested. After recording audio or video, the playback duration is significantly shorter than expected. For instance, a one-minute recording might only have 20 seconds captured correctly, with the remaining 40 seconds of content being lost. We are unsure how to resolve this problem and would appreciate your confirmation and guidance. Thank you. 2144584 1 ap 2025-09-19 19:08:06 -0700 Thank you for the report! Could you please provide more information to make it actionable? E.g. - whether this reproduces with iOS 26 release; - a URL and steps for us to reproduce this; - which hardware models you have seen this with. 2144585 2 webkit-bug-importer 2025-09-19 19:08:12 -0700 <rdar://problem/160982017> 2144757 3 liuyun 2025-09-21 19:57:07 -0700 Thank you for your reply. -Yes, this issue occurs in iOS 26 release. -I've provided a URL that demonstrates the problem： <https://addpipe.com/media-recorder-api-demo-audio> when you click on the video at this URL, the resulting MP4 file, which should be one minute long, only has 29 seconds of footage. -I encountered this issue on my iPhone 13 Pro. I haven't observed this problem on Android devices or another versions of iOS (18). Thank you. 2145999 4 jer.noble 2025-09-25 15:45:13 -0700 Is this unique to MP4 or does it happen when recording in WebM as well? 2146030 5 liuyun 2025-09-25 18:13:35 -0700 Thanks for your reply. -Yes, I've only found issues with MP4. I've tested WebM and found no issues. It's recording in WebM fine. Thank you! 2146204 6 jer.noble 2025-09-26 09:51:48 -0700 It looks like this is not unique to iOS; I can reproduce the same problem on macOS Safari 26, and only when the output file is .mp4. 2146205 7 jer.noble 2025-09-26 09:52:25 -0700 It also looks like it's the _end_ of the recording that's missing. A 30 second recording where I'm just listing numbers from 1-30 will cut off at around 15. 2147306 8 jean-yves.avenard 2025-09-30 15:08:27 -0700 Pull request: https://github.com/WebKit/WebKit/pull/51596 2147503 9 ews-feeder 2025-10-01 05:52:55 -0700 Committed 300824@main (812a4cd88295): <https://commits.webkit.org/300824@main> Reviewed commits have been landed. Closing PR #51596 and removing active labels. 2151908 10 liuyun 2025-10-16 19:15:05 -0700 Hello WebKit Team, Thank you for your prompt reply. It seems the issues mentioned above have been fixed, is that correct? I haven't seen an iOS version update yet. May I ask when this fix is approximately scheduled for release? Thank you. 2159544 11 axel.ballarin 2025-11-18 02:05:52 -0800 Hello WebKit Team We are still encountering this issue on iOS 26.1: when using the MediaRecorder API, only the first 20–30 seconds of the recording are present in the final file. The behavior matches the original report for this bug. I have not seen any reference to the associated fix in the release notes for iOS 26.1 or for the iOS 26.2 Beta 3 builds. Could you provide any information on whether the fix has been included in the 26.x branch, or when it is expected to ship? Thanks for looking into this 2159623 12 ap 2025-11-18 09:46:54 -0800 Thank you for the follow up, this should be fixed in 26.2 beta 3 (probably earlier betas too).