Audacious - OLD, PLEASE USE GITHUB DISCUSSIONS/ISSUES

Audacious can play opus files via the FFmpeg plugin if ffmpeg is compiled with opus support ("--enable-libopus").
But with Ubuntu 12.04 this is not the case, so the only way is to recompile ffmpeg and opus manually.

ubuntu 13.10 alpha installed virtual machine to test for the reproduction in Opus audio codec.

installing ubuntu-restricted-extras in ubuntu 13.10 opus codec plays in Totem and Rhythmbox if it works.

installing audacious 3.4 in ubuntu 13.10 and ubuntu-restricted-extras opus codec does not work.

Why?

Then apparently Ubuntu does not compile ffmpeg with Opus support.
You can check if "ffmpeg -version" contains "--enable-libopus".
On Arch Linux this is the case and therefore Audacious can play Opus files.

• THIS PROGRAM IS DEPRECATED ***
  This program is only provided for compatibility and will be removed in a future release. Please use avconv instead.
  ffmpeg 0.8.6-6:0.8.6-1ubuntu2
  libavutil 51. 22. 1 / 51. 22. 1
  libavcodec 53. 35. 0 / 53. 35. 0
  libavformat 53. 21. 1 / 53. 21. 1
  libavdevice 53. 2. 0 / 53. 2. 0
  libavfilter 2. 15. 0 / 2. 15. 0
  libswscale 2. 1. 0 / 2. 1. 0
  libpostproc 52. 0. 0 / 52. 0. 0

• THIS PROGRAM IS DEPRECATED ***
  This program is only provided for compatibility and will be removed in a future release. Please use avconv instead.

Totem and Rhythmbox plays the opus codec for gstreamer, ubuntu version of ffmpeg does not contain the opus codec.

According to http://git.libav.org/?p=libav.git;a=blob;f=Changelog;hb=refs/tags/v9.8#l253
libva (a fork of FFmpeg) supports Opus since version 0.9 but you have 0.8.6 installed.

https://bugs.launchpad.net/ubuntu/+source/libav/+bug/1180288