"No video open" when trying to play mp4 or mkv files

[vancha]

software versions:
Pop!_OS: 22.04 LTS
Desktop environmnent: Cosmic
cosmic-player: 0.1.0173678224422.04~7c080fe

Problem:
Trying to play a media file results in cosmic player, either through the terminal or by selecting a file from cosmic-files, does not playing anything. It just opens an empty window and displays the text "No video open".

How to reproduce:
Running cosmic player from the terminal with the path to a video file as an argument, results in the following output:

xkbcommon: ERROR: couldn't find a Compose file for locale "fy_NL.UTF-8" (mapped to "fy_NL.UTF-8")
[2025-01-14T09:20:56Z WARN  cosmic_player] failed to open file:///home/username/Videos/testvideo.mp4: Element failed to change its state
[2025-01-14T09:20:56Z WARN  sctk_adwaita::buttons] Ignoring unknown button type:
[2025-01-14T09:20:56Z WARN  wgpu_hal::gles::adapter] Detected skylake derivative running on mesa i915. Clears to srgb textures will use manual shader clears.

[iamkartiknayak]

Couldn't reproduce the error.

You may not have installed necessary dependencies. I too had problems playing anything at all but then installing these fixed my problem.

sudo apt install -y ubuntu-restricted-extras gstreamer1.0-plugins-bad

https://support.system76.com/articles/codecs/