How to install H.265 / HEVC codec on Ubuntu Linux?

There is also a PPA for libde265 GStreamer integration. With that installed one can playback H.265 with all GStreamer applications (Browsers, Totem, etc.).

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

Now try playing back a .mkv containing HEVC/H.265 content using any GStreamer-aware player (e.g. "totem"). This should detect the missing codec and prompt to install the libde265 GS plugin (make sure to select the 64bit or 32bit version depending on your architecture).

You can also install the corresponding GStreamer plugin directly:

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

Details here: GStreamer plugin for 4K H.265/HEVC video streaming

An alternative to @longsleep's great answer is, if using VLC: as noted here you can upgrade to VLC 2.2.x or higher to get HEVC/H.265 support. If on 14.04, you need to add this repo to get 2.2.x+ versions of VLC:

sudo add-apt-repository ppa:mc3man/trusty-media

sudo apt-get update, and

sudo apt-get dist-upgrade or sudo apt-get install vlc vlc-plugin-libde265

You can also install others if you want: vlc-plugin-*

The repo doesn't have the gstreamer1.0-libde265 package but does have a lot of other "upgraded, advanced or not normally available multimedia packages for Trusty" 14.04 for those who like LTS versions.

Yet another alternative - if you have Google Chrome installed - is to add/install H.265 / HEVC player (in)to your Chrome browser.

After that, you can head straight to "Google Chrome Applications" (at your Ubuntu distro menu) and run the player. Or you can just start Google Chrome, type in the URL chrome://apps and hit Enter. This will cause Google Chrome to show you its installed apps, so you can run H.265 / HEVC player straight from there.

By using this alternative method, there's no need to install any library, codec, player plugin or whatever, because everything you need for H.265/HEVC playback support is already embedded in the H.265 / HEVC player.

I've already used H.265 / HEVC player to watch a couple of two-hour-long H.265/HEVC encoded movies, and I didn't experience any playback issue.