Full screen video tearing in firefox Ubuntu 19.10

While trying to fix a similar problem in 20.04, I've experimented with different options. Switching to Wayland as suggested in https://askubuntu.com/a/1281780/1142212 helps, but has compatibility disadvantages (for instance, Zoom Screen Sharing does not work as smoothely as it does with X11). Trying out the extended about:config parameters from https://askubuntu.com/a/1288650/1142212 did not help me.

What finally helped me was to install the disable unredirect screen gnome shell extension.

https://github.com/kazysmaster/gnome-shell-extension-disable-unredirect

I moved from Mint to Ubuntu 20.10 just couple of days ago. So not exactly the same circumstances but... I also faced annoying tearing when I watched full-screened Youtube videos in Firefox. My desktop's specs are pretty common I'd say - intel core i7 processor with UHD630 gpu. I tried a lot including most common advice that is to set Firefox's config option layers.acceleration.force-enabled to true. Unfortunately, this alone doesn't solve the issue. After quite a research I found bunch of Firefox's config options that finally solved the issue.

1. Open up about:config
2. Set layers.acceleration.force-enabled = true
3. Set layers.force-active = true
4. Add mozilla.widget.use-argb-visuals and set it to false
5. Restart Firefox

Now I can watch videos without an issue.

However, I don't understand why Cannonical doesn't do something with it, because it seems the issue is there for years. I use most generic hw and the issue is there right out of the box.

Hope this helps you as well.

I had the same exact issue on Ubuntu 20.04. Screen tearing on Firefox alone, and only in the upper part of the screen.

Notably, I also observed reduced tearing by enabling layers acceleration.

What I did was simply use wayland instead of X11, and it solved the problem completely:

sudo apt-get install gnome-session-wayland

Then reboot and select a "Ubuntu with Wayland" session before logging in. You should find that by clicking on a little gear somewhere.

---

You can make wayland your default session by editing the file /usr/share/lightdm/lightdm.conf.d/*-ubuntu.conf. You need to change the following line:

user-session=ubuntu

to:

user-session=ubuntu-wayland

Maybe its a codec related issue. Try:

sudo apt-get install ubuntu-restricted-extras

Then restart Firefox.