RESOLVED FIXED272095
Seeking troubles on large WebM files in Safari on mac and iOS 
https://bugs.webkit.org/show_bug.cgi?id=272095
Summary Seeking troubles on large WebM files in Safari on mac and iOS
Brooke Vibber
Reported 2024-04-03 09:57:41 PDT
Testing the new native WebM playback in Safari on iOS 17.4.x I found some seeking difficulties with large files from Wikimedia Commons, which I can also reproduce on macOS 14.4.1 with Safari stock and WebKit nightly. Example: https://upload.wikimedia.org/wikipedia/commons/b/bb/House_on_Haunted_Hill_%281959%29_by_William_Castle.webm 2.1 gigabytes, ~75 minutes 1080p WebM VP9/Opus The file loads and plays back, but if you seek to an area beyond what has loaded so far, things go wonky: it'll seek somewhere in the middle and start playing back high-speed video either with no audio or bad synchronization. Sometimes it eventually catches up, other times it freezes after a while. Sometimes when it starts playing there's visible garbage, like it's decoding from in the middle of a GOP without starting at a keyframe. As the download progresses, eventually you can seek around most of the file cleanly -- most of the time; sometimes it still gets stuck in fast-play. It kind of seems like the seeking isn't using the cue data but is approximating a start point based on file size or something, then tries to decode forward -- once things have been buffered the actual timestamps are known and things seem cleaner. Expected results: * seeking anywhere in the stream should work as expected and go directly to that frame, with regular playback, even if it takes a short delay to load the cue data or sync up to the requested frame Actual results: * seeking to later parts of a file that have not yet been downloaded reliably result in unexpected behavior or image corruption visible on screen.
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Radar WebKit Bug Importer
Comment 1 2024-04-03 13:43:15 PDT
<rdar://problem/125867488>
Jean-Yves Avenard [:jya]
Comment 2 2024-10-27 02:26:41 PDT
Pull request: https://github.com/WebKit/WebKit/pull/35771
Jean-Yves Avenard [:jya]
Comment 3 2024-10-27 02:45:56 PDT
Will do the use of cues to seek in https://bugs.webkit.org/show_bug.cgi?id=282151 This PR only fixes that seek could fail and decoding could fail.
Jean-Yves Avenard [:jya]
Comment 4 2024-10-27 22:30:20 PDT
*** Bug 280207 has been marked as a duplicate of this bug. ***
EWS
Comment 5 2024-10-31 16:40:20 PDT
Committed 285986@main (617de4cfcf70): <https://commits.webkit.org/285986@main> Reviewed commits have been landed. Closing PR #35771 and removing active labels.
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