How to enable H264 for Firefox?

Question

I noticed that AlmaLinux 8.10 lacks the packages mozilla-openh264 and it's prerequisite openh264, and that both are absent from official repositories too. To my knowledge, I need these both in order to be able to play H264 videos on Firefox, like on https://udemy.com.

I downloaded the packages from these URLs:

1. https://rhel.pkgs.org/8/raven-multimedia-x86_64/openh264-2.4.1-2.el8.x86_64.rpm.html
2. https://rhel.pkgs.org/8/raven-multimedia-x86_64/mozilla-openh264-2.4.1-2.el8.x86_64.rpm.html

Then installed them with:

sudo rpm -i <file name>.rpm

I also activated the H264 plugin on about:addons.

But still, about:support points H264 as not supported.

What am I missing?

Answer 1

The missing program in the ecosystem was ffmpeg. Installing it made the videos play on Firefox.

$ sudo dnf install ffmpeg

Reference: https://unix.stackexchange.com/a/520304/533480