Gaupol subtitle Editor
Gaupol is a free and open source text based subtitle Editor for Linux and Windows. Using this you can create and translate subtitles. It is simple and easy to use tool. It also comes with build-in video player to load video. You can time the subtitles to match video and more. It also supports launching an external video player.
Install Gaupol on Ubuntu
Gaupol is available as flatpak package. so you need to install flatpak and flathub on your Ubuntu system. If you already have just skip the installation. You can follow below link for the installation steps. After that restart your system.
Open terminal app (ctrl+alt+t) and run below Gaupol flatpak installation command. It will install the latest version Gaupol in your Ubuntu system.
flatpak install flathub io.otsaloma.gaupol
Then run below command to start Gaupol.
flatpak run io.otsaloma.gaupol