Bug 105125 – Safari / HTML5 video no longer perfectly Frame Accurate

• Status: RESOLVED
• Resolution: CONFIGURATION CHANGED
• Component: Media

[Rob Coenen]

I just updated my HTML5 / frame accuracy test ( http://www.rob-coenen.nl/lab/html5/frame_accuracy/ ).

-The H.264 video has been re-encoded using a baseline profile. This was done as Jae Park (cc:) pointed out that MS IE10 only supports proper frame accurateness with the baseline profile (higher profiles shift the SMPTE offset upon initialization to 00:00:00:01 or even 00:00:00:02)

However, this also causes Safari to mis-behave; as show in the screen capture video below

http://www.youtube.com/watch?v=rsTkYvaqPY8

Note how the calculated timecodes are off by 1 frame after I clicked the Jump to 00:00:12:21 button.

Please note that the Javascript that calculates the SMPTE codes have not been changed.

Tested with: 
Safari / Mac / Version 6.0.2 (8536.26.17)
Mac Software  OS X 10.8.2 (12C60)

Same problem with
WebKit Nightly WebKit-SVN-r137808

[Ahmad Saleem]

By opening website via Wayback Machine, it seems that the error was resolved in Safari 6:

https://web.archive.org/web/20120901025117/http://www.rob-coenen.nl/lab/html5/frame_accuracy/

Mentions - "known problem with WebKit: start at 00:00:00:00 and step +1 13 times. You will get frame 00:00:00:12 twice rather than 00:00:00:13 fixed! Get Safari 6!"

I am unable to find working test case or any WPT test, which can try to replicate this bug. I think this can be considered as "RESOLVED WONTFIX" or "RESOLVED CONFIGURATION CHANGED"? Thanks!

[Eric Carlson]

Thanks for checking this Ahmad!