Bug 240601

Summary: AX: Captions not displayed in Safari video player when MacOS setting is checked
Product: WebKit Reporter: Shawn Butler <shawnpaul_butler>
Component: AccessibilityAssignee: Nobody <webkit-unassigned>
Status: RESOLVED INVALID    
Severity: Major CC: andresg_22, bfulgham, webkit-bug-importer
Priority: P2 Keywords: InRadar
Version: Safari 15   
Hardware: All   
OS: All   

Description Shawn Butler 2022-05-18 14:38:00 PDT 
In the past the native video player in Safari in MacOS and iOS would automatically display captions when this setting was checked: "System Preferences > Accessibility > Prefer closed captions and SDH". Unfortunately this is no longer working.

This issue is impacting video accessibility across Apple.com (including Support and OnlineStore)

Here are a few example HLS video examples:
 - https://www.apple.com/105/media/us/iphone-13-pro/2021/404b23a8-f9c5-466c-b0e6-3d36705b959d/films/product/iphone-13-pro-product-tpl-us-2021_16x9.m3u8
 - https://www.apple.com/105/media/us/mac-studio/2022/eb784018-d0ea-4669-b844-fed626ab0367/films/product/mac-studio-product-tpl-us-2022_16x9.m3u8
 - https://www.apple.com/105/media/us/ipad-air/2022/5abf2ff6-ee5b-4a99-849c-a127722124cc/films/product/ipad-air-product-tpl-us-2022_16x9.m3u8

Steps to recreate:
 - Create a new Mac User (System Pref > User and Groups > +)
 - Log in as new user, when asked turn on Accessibility > Hearing > Captions
 - Open Safari browser
 - Open a video in the Safari browser
 - click play
 - see captions are available, but not enabled
 - In the video player select (>> Subtitles > Auto)
 - Reload the video and play
 - see captions are available, but still not enabled

I have been able to reproduce this on 
 - MacOS 12.4 with Safari 15.5
 - MacOS 12.3 with Safari 15.5
 - MacOS 11.7 with Safari 15.3
 - MacOS 11.5 with Safari
 - iOS 15.4.1

Please let me know if you have any questions or need more details. Thanks!!!
Comment 1 Radar WebKit Bug Importer 2022-05-18 14:38:07 PDT 
<rdar://problem/93527686>
Comment 2 Shawn Butler 2022-05-19 08:48:54 PDT 
iOS 15.5 also reported to have the same issue
Comment 3 Brent Fulgham 2022-06-24 14:03:15 PDT 
Unfortunately, this behavior is correct because AVFoundation and WebKit are doing what the manifest says they should do.

The author of these m3u8 files have not set any caption files to the auto-select target (AUTOSELECT=YES can be applied to a caption file link). Since none are specified, none are displayed unless the user chooses to activate them.

This would need to be fixed in the media being served.