Bug 283716 – REGRESSION (iOS 18): Huge audio/video performance degrade

• Status: NEW
• Component: Media

[Avijobo]

Created attachment 473376 [details]
This is a screenshot of how the demo song should play on an iPhone. On iOS 18 not all videos are playing

I am the developer of a website ("puremusicians.com") that allows musicians to record multiple audio and video tracks and play them simultaneously. The multiple audio tracks are mixed to stereo, the video tracks are played next to each other in a video wall or mosaic. Till iOS 17.7 this worked perfectly on an iPhone 12, which is the iPhone I use to test the app on iOS. Since iOS 18 however (I now am on iOS 18.1.1) this has become a disaster... while iOS 17.7 could play more than 10 videos simultaneously without problems, Safari iOS 18 is not able anymore to even play 3 videos simultaneously: the video playback slows down after a while, the audio tracks stop playing and eventually the whole page freezes and becomes unresponsive. I tried everything to fix this (e.g. clearing all Safari website memory, cold reboot iPhone etc...) but nothing worked. I downgraded to iOS 17.7 and all works as expected again. So it seems the Safari audio/video performance since iOS 18 has degraded a lot. I sincerely hope this will be fixed again, otherwise iOS 18 has become unusable for this kind of web applications. Here 's a link to a demo song: "https://puremusicians.com/tryout/page/1%2520-%2520Gun%2520In%2520My%2520Hand" (It may take a while to load). The song contains about 10 video's and 20 audio tracks. All audio and video tracks in this song play perfectly on the iPhone 12 in iOS 17, on IOS 18.x the video and page freezes after a while. FYI: Just tried on an iPhone 15, same results...

[Radar WebKit Bug Importer]

<rdar://problem/140587983>