Java Media Framework
From Sun's JMF site : "The Java Media Framework API (JMF) enables audio, video and other time-based media to be added to applications and applets built on Java technology. This optional package, which can capture, playback, stream, and transcode multiple media formats, extends the Java 2 Platform, Standard Edition (J2SE) for multimedia developers by providing a powerful toolkit to develop scalable, cross-platform technology."
The JMF PKGBUILD can be downloaded from AUR  Run makepkg and install the package
In order to setup JMF for the first time (to recognize audio and capture devices) you'll need to run as root:
Bypassing Java libxcb-xlib Bug
sudo LIBXCB_ALLOW_SLOPPY_LOCK=true jmfinit
You can manually setup JMF running as root:
JMFRegistry User's Guide: 
Adding audio/video codecs support to JMF
Sun MP3 Plugin
Sun MP3 Plugin is included in the JMF package.
In order to add the Mp3Plugin to the JMF Plugin System , you'll have to run as root:
"Jffmpeg is a plugin that allows the playback of a number of common audio and video formats. It is based around a Java port of parts of the FFMPEG project, supporting a number of codecs in pure Java code. Where codecs have not yet been ported, a JNI wrapper allows calls directly into the full FFMPEG code."
The JFFMpeg PKGBUILD can be downloaded form AUR 
Run makepkg and install the package. The install script will register the plugins and associate the mimetypes in the JMF registry
Testing JMF capabilities
A demo player is available to test JMF audio/video playback capabilities.