1548376 - Flickering videos when scrolling on Buzzfeed

Status: NEW

(Core :: Graphics, defect, P3)

Description

[Mike Taylor [:miketaylr]]

Note: this reproduces in Fenix, Fennec, and Desktop (when sending the Fenix UA string in RDM) -- maybe this should be moved to a better component.

STR:

1. Navigate to https://www.buzzfeed.com/michellerennex/lets-try?utm_term=.skK75AWqPG#.ysD8gyJlL9
2. Scroll up and down

Actual: The video elements flicker on scroll.
Expected: No flickering, just like in Chrome Mobile.

Originally reported @ https://github.com/webcompat/web-bugs/issues/14575 see comments starteing at https://github.com/webcompat/web-bugs/issues/14575#issuecomment-429973953.

Seems like they re-render (by destroying then creating a new video, maybe?) on scroll and we flicker when Chrome does not.

Comment 1

[Mike Taylor [:miketaylr]]

(I don't really know if this is the right component, or if this is playback or DOM or gfx.)

Comment 2

[Kartikaya Gupta (email:[e-mail])]

I'm not really sure who is the right person to look at this either. I guess somebody needs to instrument the Gecko code and check if the addition and removal of the DOM element is happening within a single vsync tick. If so, then we should be seamlessly doing the swap between two paints and no flickering should be visible to the user. If the swap is happening correctly within a single vsync tick then the layout/graphics side will need more investigation to figure out why the flickering occurs. If the swap is spread across multiple vsync ticks then we will need to move earlier in the flow and look at the JS in more detail to understand if that is intentional, and if they are doing the same thing for Chrome.

Given the amount of effort involved here for what is kind of an edge case (why are they doing this replacement in the first place?) I doubt this bug will get much movement.

Comment 3

[Chris Peterson [:cpeterson]]

Moving to Graphics component.

Twitch bug 1460032 is a similar problem (on Android and desktop in mobile mode) where images turn black during while scrolling the page.