MythTV is a Free Open Source software digital video recorder (DVR) project distributed under the terms of the GNU GPL. It has been under heavy development since 2002, and now contains most features one would expect from a good DVR (and many new ones that you soon won’t be able to live without).
If you are interested in learning more about MythTV (or just want to check out some screenshots), please take a look at MythTV In Detail.
You can install MythTV on Ubuntu by either clicking this link or by typing the following in your terminal.
sudo apt-get install mythtv