install H.265 / HEVC codec on Ubuntu Linux

1) Run these commands in your terminal, (To add PPA for libde265 GStreamer integration)

sudo apt-add-repository ppa:strukturag/libde265 
sudo apt-get update

2) Then you can go to software centre and search for x265 and add it using GUI. or you can add it by using the terminal,

sudo apt-get install gstreamer0.10-libde265

Or for GStreamer 1.0 applications:

sudo apt-get install gstreamer1.0-libde265

There is also a VLC plugin available:

sudo apt-get install vlc-plugin-libde265