Bug 208095

Summary:	Fast <video>.playbackRate incredibly jerky
Product:	WebKit	Reporter:	Jerry Jongerius <jerryj>
Component:	Media	Assignee:	Nobody <webkit-unassigned>
Status:	NEW ---
Severity:	Normal	CC:	webkit-bug-importer
Priority:	P2	Keywords:	InRadar
Version:	Safari 13
Hardware:	iPhone / iPad
OS:	iOS 13

Description Jerry Jongerius 2020-02-22 14:07:26 PST

1. Visit https://www.duckware.com/test/webkit/iosplayvideofails.html
2. Click on 'playbackRate=10' button, and then play video
3. Compare results on iPad vs any Windows computer

On iPad, the result is very 'jerky'.  On Windows, the result is incredibly smooth.  On the iPad, I can obtain very smooth results via other means, which means that setting playbackRate should also be able to.  Why can't it?

Comment 1 Radar WebKit Bug Importer 2020-02-22 14:52:55 PST

<rdar://problem/59701053>

Comment 2 Jerry Jongerius 2020-02-23 13:23:28 PST

A good example: Visit https://www.w3.org/2010/05/video/mediaevents.html, click on "Bunny movie", click on "play()", click on "playbackRate++" six times.

In Chrome/Windows it sure looks like video is being updated at the display 60 fps.  But on iPad, the video looks like it is being updated only a couple of times per second.