Videos are not playing in qt-multimedia-ffmpeg 6.9.2 4

[herzane52]

When I checked the logs, the videos weren't playing. Also, I was using a video background for KDE on my desktop, and I had the same problem there.

If it helps, here's the error log.

High-DPI autoscaling Enabled
Reading from "/usr/local/share/wayland-sessions/gnome-wayland.desktop"
Reading from "/usr/share/wayland-sessions/gnome-wayland.desktop"
Reading from "/usr/local/share/wayland-sessions/gnome.desktop"
Reading from "/usr/share/wayland-sessions/gnome.desktop"
Reading from "/usr/local/share/wayland-sessions/plasma.desktop"
Reading from "/usr/share/wayland-sessions/plasma.desktop"
Loading theme configuration from "/usr/share/sddm/themes/sddm-astronaut-theme//Themes/cat.conf"
Socket error:  "QLocalSocket::connectToServer: Geçersiz ad"
Loading file:///usr/share/sddm/themes/sddm-astronaut-theme//Main.qml...
No QtMultimedia backends found. Only QMediaDevices, QAudioDevice, QSoundEffect, QAudioSink, and QAudioSource are available.
Failed to initialize QMediaPlayer "Not available"
Failed to create QVideoSink "Not available"
Adding view for "eDP-1" QRect(0,0 1920x1080)
Reading from "/usr/share/wayland-sessions/gnome-wayland.desktop"
QIODevice::write (QLocalSocket): device not open
herzane@archlinux ~> 

I solved the problem by downgrading the version.

[Keyitdev]

You also need to have the correct version of the ffmpeg package. Works for me (up to date packages on arch 14 Oct 2025)

pacman -Qi sddm qt6-multimedia qt6-multimedia-ffmpeg ffmpeg | grep Ver
Version         : 0.21.0-6
Version         : 6.10.0-1
Version         : 6.10.0-1
Version         : 2:8.0-3

Input #0, mov,mp4,m4a,3gp,3g2,mj2, from '/usr/share/sddm/themes/sddm-astronaut-theme/Backgrounds/hyprland_kath.mp4':
  Metadata:
    major_brand     : isom
    minor_version   : 512
    compatible_brands: isomiso2avc1mp41
    encoder         : Lavf58.76.100
  Duration: 00:00:13.67, start: 0.000000, bitrate: 627 kb/s
  Stream #0:0[0x1](und): Video: h264 (High) (avc1 / 0x31637661), yuv420p(progressive), 1920x1080 [SAR 1:1 DAR 16:9], 625 kb/s, 15 fps, 15 tbr, 15360 tbn (default)
    Metadata:
      handler_name    : VideoHandler
      vendor_id       : [0][0][0][0]
qml: Video started.