deb-multimedia

wget https://www.deb-multimedia.org/pool/main/d/deb-multimedia-keyring/deb-multimedia-keyring_2016.8.1_all.deb

sudo dpkg -i deb-multimedia-keyring_2016.8.1_all.deb

sudo nano /etc/apt/sources.list.d/multimedia.list.

deb https://www.deb-multimedia.org buster main non-free

sudo apt update

sudo apt upgrade