Aegisub is an open-source, cross-platform, highly customizable subtitle editor that features a lot of convenient tools to help you with timing, typesetting, editing and translating subtitles, as well as a powerful scripting environment called Automation (originally mostly intended for creating karaoke effects, Automation can now be used much else, including creating macros and various other convenient tools).

Although Ubuntu 18.04 dropped the Aegisub binary package from its universe repository, it’s still easy to install Aegisub via one of the developer’s PPA.

1. Open terminal either via Ctrl+Alt+T shortcut key, or by searching for ‘terminal’ from software launcher. When it opens, run command to add the PPA:

sudo add-apt-repository ppa:alex-p/aegisub

Type your password (no asterisks feedback) when it prompts and hit Enter to continue.

2. Then run command to install the subtitle eidtor:

sudo apt-get install aegisub

Uninstall:

To remove the PPA, either open Software & Updater and navigate to Other Software tab, or run command:

sudo add-apt-repository --remove ppa:alex-p/aegisub

To remove Aegisub subtitle editor, run command:

sudo apt-get remove --autoremove aegisub