RESOLVED MOVED 278507
Animated WEBP plays much slower than in other browsers 
https://bugs.webkit.org/show_bug.cgi?id=278507
Summary Animated WEBP plays much slower than in other browsers
Cat Ball
Reported 2024-08-21 18:55:21 PDT
Created attachment 472260 [details] Tarball containing webpage demo of the above bug. See also the github link in the bug for the same files. Webkit seems to animate WEBP at a much slower framerate than is encoded in the image. This doesn't occur with the same image in Chrome or Firefox. Here is a quick demo of the bug, comparing the same video file encoded as a 24 FPS gif and as a 24 FPS webp: - https://catball.dev/bug_reports/animated_webp_bug/25_seconds.html - https://github.com/catleeball/animated_webp_bug_demo Notably, when 25 seconds on the timer in the gif have elapsed, the webp has only made it to approx 9 seconds. The first few frames appear to be more performant, then the animation slows considerably. Tested on: - MacOS 14.6.1 - Safari 17.6 - Safari Technology Preview 18.0 - iOS 17.6.1 Please let me know if you need any additional details. Thank you! Cat
Attachments
Tarball containing webpage demo of the above bug. See also the github link in the bug for the same files. (14.90 MB, application/octet-stream)
2024-08-21 18:55 PDT, Cat Ball 		no flags
Details
View All Add attachment proposed patch, testcase, etc.
Alexey Proskuryakov
Comment 1 2024-08-22 16:53:03 PDT
Thank you for the report! I can reproduce this on an M3 Mac with macOS 15 beta.
Radar WebKit Bug Importer
Comment 2 2024-08-22 16:53:16 PDT
<rdar://problem/134535157>
Said Abou-Hallawa
Comment 3 2024-08-26 18:17:26 PDT
This is an issue below WebKit, tracked by Apple internally as rdar://134535157.
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