1479664 - Stuttery scrolling while playing a specific MP4 video in background tab (even if the video is full-buffered)

Status: RESOLVED WORKSFORME

(Core :: Audio/Video: Playback, defect, P3)

Description

[Alice0775 White]

Attachment: about:support

+++ This bug was initially created as a clone of Bug #1477170 +++

Build ID 	20180730221422
User Agent 	Mozilla/5.0 (Windows NT 10.0; Win64; x64; rv:63.0) Gecko/20100101 Firefox/63.0


Steps to reproduce:
1. Go to https://bugs.chromium.org/p/chromium/issues/detail?id=853986
2. Download the MP4 video that is on the #2 comment (filename is: "853986.mp4")
   (Download it beforehand in order to avoid the influence of the network buffering)
3. Open any long page in a new tab and close other tabs
   (e.g. https://developer.mozilla.org/en-US/docs/Mozilla/IME_handling_guide )
4. Open the downloaded mp4 on a new tab and play if not auto started
5. Switch back to tab of step3
6. Start scrolling the page via mouse scrolling or autoscrolling 
   ---- the page scrolling stutterly


Actual results:
The page is scrolling stutterly while playing the MP4 video in background tab.

Expected results:
Page should've scrolled smoothly.


Regression window:
https://hg.mozilla.org/integration/autoland/pushloghtml?fromchange=169fc55f0e8a0af033af153a7df93437f9b66eae&tochange=dbe3662c1799e9887876c4ca735eec1117342617

Comment 1

[Alice0775 White]

It seems to happen only specific video.

Comment 2

[Alice0775 White]

Gecko profiler log: https://perfht.ml/2KbNW9O

Comment 3

[Paul Adenot (:padenot)]

Jean-Yves, you're in the range, is this an expected outcome of your patches?

Comment 4

[Jean-Yves Avenard [:jya]]

Those patches disable HW decoder or fast upload path on machines not supporting it and known to crash. So this would likely increase CPU usage on those as it would now use the software decoder and software rendering.


Could be similar to bug 1461266.

Comment 5

[Liz Henry (:lizzard)]

Too late to fix in 63. We could still take a patch for 65 and potentially for 64.

Comment 6

[Jim Mathies [:jimm]]

Alice, curious are you still seeing this?

Comment 7

[Alice0775 White]

No longer reproduce in Firefox91.0esr and Nightly93.0a1 Windows10.