As you may know, Curlew is an open-source multimedia converter written in python and GTK, using ffmpeg, avconv and mencoder in the background. Among others, it has support for more than 100 formats, enabling the users to convert only portions of files, combine subtitles with video files, remove file during convertion process and preview files before conversion.
The latest version available is Curlew 2.1, which has been recently released.
In order to install Curlew on Ubuntu, you have to add the PPA to your system, update the local repository index and install the curlew package:
$ sudo add-apt-repository ppa:noobslab/apps
$ sudo apt-get update
$ sudo apt-get install curlew
Optional, to remove curlew, do:
$ sudo apt-get remove curlew
The installation instructions should work on Ubuntu 16.04 Xenial Xerus and Ubuntu 15.10 Wily Werewolf.