Opus is a very popular audio codec, used for the real-time streaming of audio (such as in VoIP or live-TV applications). Quote from ​Wikipedia:

Opus is a lossy audio compression format developed by the Internet Engineering Task Force (IETF) that is particularly suitable for interactive real-time applications over the Internet.

In order to quickly compile your ​libopus, you can type the following commands in your shell:

$ cd /my/path/where/i/keep/compiled/stuff
$ git clone git://git.opus-codec.org/opus.git
$ cd opus
$ ./autogen.sh
$ ./configure --enable-static --enable-shared
$ make
# make install
# ldconfig