Video stutter in Firefox, Fedora 42 Kinoite

I installed Fedora 42 Kinoite on my parents’ laptop, then added Firefox from Flatpak.

The problem is that video playback “stutters”, as if images did not arrive in the right sequence.

lspci tells me it is an Intel HD 5300. glxgears works fine. The display is 3200x1800, running at 200%, but using 1600x900 does not solve the issue.

I found many topics with similar problems, but none of them match my problem, I haven’t installed anything from rpmfusion and it is not an nvidia card. Please tell me how I can debug this further.

In a terminal do the following.

sudo flatpak info org.mozilla.firefox

Look for the runtime entry and then install the ffmpeg runtime that matches with…

sudo flatpak install org.freedesktop.Platform.ffmpeg-full

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Sorry, I was mistaken, Firefox came with the install, probably baked in to the image (which firefox tells me it is /usr/bin/firefox).

If you install the Firefox flatpak it will supersede the baked in Firefox. Then you can install the ffmpeg flatpak as outlined above. If you don’t install the flatpak and you end up using the layered Firefox package you will need to install the RPM Fusion repositories and install the associated packages and codecs that way (like a regular version of Fedora).

The runtime of org.mozilla.firefox is org.fedoraproject.Platform/x86_64/f42, but I am not sure which ffmpeg-full matches that. Can I find that out using flatpak list? I tried installing some versions but their runtime field is empty.

(I think I am missing something fundamental here, thanks for your patience. I am coming from Debian and I used very little Flatpak before)

What do you get when you type sudo flatpak info org.mozilla.firefox in a terminal? Post the full output. For example, the below is the output I get.

Firefox - Fast, Private & Safe Web Browser

          ID: org.mozilla.firefox
         Ref: app/org.mozilla.firefox/x86_64/stable
        Arch: x86_64
      Branch: stable
     Version: 140.0.2
     License: MPL-2.0
      Origin: flathub
  Collection: org.flathub.Stable
Installation: system
   Installed: 284.1 MB
     Runtime: org.freedesktop.Platform/x86_64/24.08
         Sdk: org.freedesktop.Sdk/x86_64/24.08

      Commit: 103da1ecd82d8c7cadb721da03cec31fb03c50bd1169cf852ca1493cf66919ed
      Parent: da1a449e6583644aae81b85517c3ca2507c6858ebefcf1f0b82aca82bce164e2
     Subject: Export org.mozilla.firefox
        Date: 2025-06-27 17:00:13 +0000

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$ LANG=en_US sudo flatpak info org.mozilla.firefox

Firefox - Web Browser

          ID: org.mozilla.firefox
         Ref: app/org.mozilla.firefox/x86_64/stable
        Arch: x86_64
      Branch: stable
     Version: 140.0
     License: GPL-3.0+
      Origin: fedora
  Collection: 
Installation: system
   Installed: 286.7�MB
     Runtime: org.fedoraproject.Platform/x86_64/f42
         Sdk: org.fedoraproject.Sdk/x86_64/f42

      Commit: ca5fc1c30e504d6d3b6fdb35332d70cc692b1b7d59b012a13d77625c357078f2
     Subject: Export org.mozilla.firefox
        Date: 2025-06-19 06:39:46 +0000
      Alt-id: 557a18dbb1053fc418f7712a5dd5604ef73d3c2ae0b390d588fbca786d4eb96b

If you don’t want to go with the Flatpak version, and keep Firefox from the base install, you could do the following:

  • Layer/install the RPM-Fusion repos if not already done, see docs
  • Install additional codecs:
rpm-ostree install libavcodec-freeworld

The current installation of Firefox is from Fedora Flatpak repo, which does not support some video format. Instead, you can install Firefox from Flathub using the following command:

flatpak remote-add --if-not-exists flathub https://dl.flathub.org/repo/flathub.flatpakrepo && flatpak install flathub org.mozilla.firefox
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OK. I get the same output for runtime (org.fedoraproject.Platform/x86_64/f42) when I install Firefox from the Fedora repos. I don’t use the Fedora flatpak repositories (or know many who do). The first thing I do on install is…

# DELETE FEDORA FLATPAK REPOSITORIES.
sudo flatpak remote-delete fedora && sudo flatpak remote-delete fedora-testing

# ADD FLATHUB FLATPAK REPOSITORY.
sudo flatpak remote-add --if-not-exists flathub https://dl.flathub.org/repo/flathub.flatpakrepo

The Flathub version will show 24.08 like in my above output. Then when you issue the command to install the ffmpeg package, it will give you a list of packages to choose from. You choose the ffmpeg runtime that matches the firefox runtime.

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Atomic desktop users should not delete the Fedora repos, that action will prevent apps which come with the installation media to get updated.

I know it does. But in my case, I re-install everything it deletes through Flathub. Flathub has more software, more recently updated software and more “doesn’t have to deal with American litigation worries” software.

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Can you please tell me what the future-proof solution is then? Eg simply install firefox from the Flathub repo? Or something else?

@brianallenby’s solution fixes the issue for me. But this is a machine that my parents use, and I don’t live nearby so I would prefer to keep it working without manual intervention even after (automatic) updates in the future. That’s why I am experimenting with an atomic distribution.

You don’t need to delete the Fedora repo as @tqcharm says. But you have to specify which repo you want to install from if you add the Flathub repository as well. For simplicity sake, it’s also one of the reasons I remove the Fedora flatpak repositories. Everything then just comes from the Flathub repo.

With Firefox and multimedia, installing it from Flathub is probably the easiest method and then adding the corresponding ffmpeg runtime. Otherwise as @tqcharm and I pointed out earlier, you would need to use the RPM Fusion repositories for the layered Firefox package. On Silverblue/Kinoite, I use the Flathub Firefox / ffmpeg method. Otherwise on a regular Fedora install I use the RPM Fusion method.

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It depends on your needs. There have been a couple of discussion threads in the Fedora space already and one is ongoing right now, about which Flatpak remote is better: Fedora or Flathub. The answer is, as usual, it depends:

  • If you want free software which is only built from source, more easily auditable, then you should go with Fedora;
  • If you want best of both worlds: preferably free software, preferably built from source, providing the latest version of apps, and being able to access also packages not built by Fedora, including proprietary packages if needed, then go with Flathub.

If the second alternative suits you more, then you could either go with @brianallenby’s suggestion and replace the Fedora Flatpaks with the Flathub ones, or you keep Fedora as the remote source of those Flatpaks that come with the initial installation, and for the rest generally use Flathub. The software manager will update apps from both sources. Either way, it’s probably best if you replace those Fedora Flatpaks with Flathub ones which handle multimedia content (image, audio, video, browser), in order to benefit the extra codecs provided by the org.freedesktop.Platform.ffmpeg-full runtime.

Also check for resources discussing some of the security concerns around browsers provided as Flatpak.

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I use just this simple and works

After install enable it from Firefox settings plugins and restart all good

Systexts are still considered experimental, with no automatic updates AFAIK. Probably not suitable to be run on the OP’s parents’ laptop.

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So, now that my problem is solved for the moment, I am wondering if Silverblue / atomic is the best choice for a Fedora system that

  1. has a browser, Thunderbird, and Libreoffice,
  2. applies at least security updates on a continuous basis,
  3. while minimizing the chance of breakages that require on-site intervention.

Should I go with plain vanilla Fedora, using dnf for these packages? I am under the impression that at least those remain coherent.

Did I misunderstand the premise of atomic distributions?

I’d say points 1 and 2 apply to both traditional and atomic desktops, whereas point 3 is better handled by atomic desktops. If an update causes issues, in most cases rebooting and selecting a previous deployment keeps the system usable. From there it’s easier to troubleshoot, or just wait for a newer deployment which would fix the issues.

Have a look also to the instructions regarding pinning existing deployments (solved with sudo ostree admin pin <boot-id>, which brings an additional safety net (though usually not necessary, as the system always keeps at least 2 deployments).

The manual for rpm-ostree and ostree should give you additional details.

Overall, for a system less “tweakable”, but also with less chances to break, atomic desktops are a good choice.

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