As you may know, Selene Media Encoder is a video converting tool, with support for the most popular video and audio formats: OGG, OGV, MKV, MP4, WEBM, OPUS, AAC, FLAC, MP3 and WAV.
The latest version available is Selene Media Encoder 17.7 which has been recently released, coming with changes.
The latest version of the software is available via some third party PPA, so installing the software on Ubuntu systems is easy.
All you need to do is add the PPA to your system, update the local repository index and install the selene package:
$ sudo apt-add-repository ppa:teejee2008/ppa
$ sudo apt-get update
$ sudo apt-get install selene
Optional, to remove selene, do:
$ sudo apt-get remove selene
The installation instructions should work on Ubuntu 18.10 Cosmic Cuttlefish, Ubuntu 18.04 Bionic Beaver, Linux Mint, Elementary OS and other Ubuntu derivative systems.