[Webkit-unassigned] [Bug 174768] New: [GTK] Possible Twitter MP4 Video-Tag Glitch

[bugzilla-daemon at webkit.org]

https://bugs.webkit.org/show_bug.cgi?id=174768

            Bug ID: 174768
           Summary: [GTK] Possible Twitter MP4 Video-Tag Glitch
           Product: WebKit
           Version: WebKit Local Build
          Hardware: PC
                OS: Linux
            Status: NEW
          Severity: Normal
          Priority: P2
         Component: WebKit Gtk
          Assignee: webkit-unassigned at lists.webkit.org
          Reporter: contact at ibiscybernetics.com
                CC: bugs-noreply at webkitgtk.org

This was originally on the mailing list, and the source can be found here:

https://lists.webkit.org/pipermail/webkit-gtk/2017-July/003114.html

---

Currently I develop a browser using the WebKit2 engine, called sighte,
which you can find here:

https://gitlab.com/ibiscybernetics/sighte

Whenever I view Twitter using my browser, I notice a sort of odd glitching
behaviour that seems to involve the height of the contents of a <video>
being reduced to about half of it's intended height. Though, this seems to
occur only in the first / last second of video playback; the remainder of
the playback is fine.

Playing around with the WebKit2 source, I was able to adjust the CSS values
in the following file to make it work properly:

https://trac.webkit.org/browser/webkit/trunk/Source/WebCore/css/html.css

At lines:

---

106  video {
107      object-fit: contain;
108  #if defined(WTF_PLATFORM_IOS) && WTF_PLATFORM_IOS
109      -webkit-tap-highlight-color: transparent;
110  #endif
111  }

---

I altered those lines to the following:

---

106  video {
107  #if defined(WTF_PLATFORM_IOS) && WTF_PLATFORM_IOS
108      -webkit-tap-highlight-color: transparent;
109  #endif
110  }

---

Specifically, I deleted line 107... "object-fit: contain;" and the problem
appears to be solved.

I trac'd that line down to the following changeset:

https://trac.webkit.org/browser/webkit/trunk/Source/WebCore/css/html.css?rev=154858

The changelog in that revision mentions the following:

---

css/html.css: (video): Set object-fit to 'contain'. This is how VIDEO
elements work, apparently.

---

Mostly I'm curious if that line is still necessary. Perhaps it was
originally added for adherence to the HTML5 standard, but the latest
internal C/C++ logic has since made it redundant? Or maybe some mobile
phone requires it? Not sure, as I am not well-versed in the history of
your code base. 

A sample affected twitter/mp4-video can be seen here:

https://twitter.com/ibiscybernetics/status/871961194931900416

---

The platform I develop for is Linux x86-64, and it seems to occur in
at least the following distros with browsers using the WebKit2 engine via
standard packages:

* arch
* debian
* ubuntu

(Firefox and Chrome appear to work fine, so I figure this isn't a
GStreamer / video codec bug)

I've noticed the problem mentioned in this email for at least a year now,
but did not think to email as I assumed I had some suboptimal configuration
present. However, at this point, I would like your thoughts on this odd
video tag w/ Twitter glitch. If that line is still needed, then I would ask
whether a work-around exists to improve Twitter usability.

If you like you can do a test of my browser by obtained the latest version
from the below git repo and run 'make' at the command line:

https://gitlab.com/ibiscybernetics/sighte

Alternatively, there exists another Linux browser which suffers from the
same problem; the suckless.org 'surf' browser. That one has packages in
the most popular Linux distros. You can use that one to test as well.

-- 
You are receiving this mail because:
You are the assignee for the bug.
-------------- next part --------------
An HTML attachment was scrubbed...
URL: <http://lists.webkit.org/pipermail/webkit-unassigned/attachments/20170724/31a5f5ef/attachment.html>